Seized 175 HP 1995 Power Head, I'm taking it apart but would like to know my options

[Fishinmymission]

Hello All,

So I've had this boat and motor for about 5 years now. Last year I took off the whole motor, chainsawed out 18" of rotten transom, treated the remainder with some penetrating epoxy and hammered in my coosa transom sandwich surrounded with epoxy. One trick was to use steel straps around my composite sandwich hammer it in, then hydraulically jack it out sand off the high point till i could hammer it in all the way without using too much force. Lots of hiccups of course and it took me a few months but I added a custom aluminum cap and the boat served me well for the past two years. This spring I pulled the Oil injection components switched to mixed gas and noticed some metal in the crankcase. I got a 5 more months out of it till it seized on the water.

Earlier this year I redid the timing and was scared to further advance because I didn't have someone with my to check while going full speed. I did everything myself then took it out and heard detonation for like 2 seconds and the boat could not get past the mid range. So I moved the set screw retarded from its previous contact marks off the pad inboard to the wall of powerhead. So I'm 95% sure that I was retarded ending up with a 4950 WOT RPM.

Now all this year I kept hearing a misfire (maybe every 20 seconds at first if at all)at wot and I would see the rpms flutter every time I heard it. Back a little off throttle and it would disappear. 2 hours before engine seizure the misfire became very frequent and I lost about 200 RPM from WOT so now at 4800. When I pulled the heads I saw crud on the plug of the number 4 cylinder which always had marginally lower compression and salt build up on the piston head, and rust on the sleeve only one week after it was run. Below are the compression numbers from this spring.
115 cylinder1
110
115
108
113
111 cylinder 6
I'm almost certain this cylinder was actually misfiring due to a gasket leak or crack which always cause low compression. I'm a Failure Analyst (degree in Materials Engineering) for a helicopter company and spend lots of time looking for evidence with microscopes and can't say for certain the gasket leaked. Possibly at lower RPM less water pressure did not really cause misfires but this is still a mystery. Any ways i don't think it was detonating and it actually was misfires due to water intrusion.

So the moment it seized i was going maybe 2000 rpm and it shuts off. Starter wont turn it props spins freely in neutral, I immediately pull the cowling and no cylinders were hotter than another (temp gun and by feel).

I pulled the heads and I see evidence of water intrusion in number 4 cylinder and small debris damage between the number 2 piston and the head, likely secondary damage to whatever bearing bit the dust.

Yesterday I removed the ten bolts etc that connect the powerhead and I'm waiting for the marina to have a lift operator lift it from my boat to my truck (maybe tomorrow or wed).

So Ill upload more pics as I get them as this will be an interesting project. I'm just thinking forward an looking at parts for a full rebuild, vs buying a used engine, vs used powerhead, vs re-manufactured powerhead.
What powerheads are a bolt on replacement? years models etc.
I would not mind an increase in efficiency but I pulled the whole motor off once and would like to only pull and replace a power head. Are there any more efficient powerheads that are dependable motors?
I also might do a rebuild depending on if the crankshaft and housing are damaged and was wondering what I could do to get a few more HP.
https://lh3.googleusercontent.com/-qSDxwJB0x0iHESLdJHtPH-YueNVRJ9ZptRUDVFmjueDGtE1W43RA80zsDXFFqIsRISnrPvRTv7IusENSWEqDcG-8DmN6MDMFWTPt5aosaapxTwRt_dvSkUrjvk831as96LMwq3tM_V9iXX4S66ARxzaZfnJMlh-E5Lw3NkdMJEVJq_9FIhp9UH00QetZmiGp5vg2DUazc4w4hrlWxHpRaloDWfny4qOGJ88RxUJKeINzumfAAx-sCwf3DZo2dNy6DEicP8wiNZkV6EKTvAd-JMaJvlaXKSIi8nsoNkeNiAhx5I9VttyObaMpc68rvETqP6-04wCQBSZllWNS3Jn5rJEE3QLnSw09_6hyJAPZHtkBb7Z1WOuq8t_YA2BAUjk5ZDsA9x2W4RhpxX-p39_r-trr15v4s_Kw6_u7sxX59HRhpxREfn7_niYdVxpvmPbM4oLZ3QNSgZlKgiQkPF8jrwMcswucRdxKuVNi12WSxuLOCqlS59e9R-xVJ_RIkiOkLOHPKV3HAqLTg0ZYvmEzBaWpHYbIGxLPQ4WVlacjxUnXLqVgeAHuyzPV0nSyuLd2HDE4mN7rQG_9NfaF4PTkSspJOx ZixsQTv7omthL-g=w696-h930-nohttps://lh3.googleusercontent.com/BQV-EZvTHykoWmj72IMHogDgcjbm__QqLfJLN1KiemKpbMjK7X0Hwq8TzTwGR60BroKegRQ8mzeWusHZ--zc0y5kxbTrQ8frKqtcsu9DLRfxizbsa5nnS_7HHCUEGt4o-mskcwlUiPyJfD6GAAJnpSSBI1uoHnLKxggha0WzlbxMmB6QwRx8WF8EhgVEameioEWWPbzSyUy7wHruqNIjAiDaAO71nOxZfmIE1 FxiTRWEyHoVxVJl1oL_JSjF65AM4_aYD23_qFt6qPpwC0TXdjpXgiajefXi8BC-vvh2FDA7zdNUCE_NXG4cBsvDuWpuZXXnqQ8Fuba_TQa1jdtOimG9bALpNqYJuk41zDFYzRp22SZ9hoX942SgLxmpCZonFC_O2K8y bU9h_7e9EhCCSjm-5YcLrF70ATzrGUYy3YLFL9XCFJ7I677Vif2uboxEOXGK5WVaGWAFsJ3SodXchHpq92jTnkI_Qn4DRgVICt7OzneJdoS8VkGCQByD e0ldrEgp2Ndlm2hzVUv1AXFy9RCRDsFAhbJn8qq9W2GgEv6LGTyA-cCUwZ4gsJZ_edNpss41X33MrlX-Si6UoedJwZUCn2YudmC0By-2b6_WTg=w958-h717-nohttps://lh3.googleusercontent.com/aN_l35o0QxIqa72sVPwKZnCzQOMDg6rFesNwcp5SmnCL73S5Zwnf6HyihvQXmWMAFJh-armu87Aa0YJhuGpFNsC2AqBj1RNR3n1r2aV6rPuo7DtHiL4K_fr2PzIg5i3lpBihGuWz4d_ZirecXYAtj4T-h049ryT-eWX3REBsjx0NvXa3oFY6CaJancIZ08piTE8ntnKMeIt0WnkFTXKRYsEa40iUCOnWCRXt9xsaQNQXWhu3_icE0_DddonWPVhHZi9s VzqNu1P8oNItMHS63ft44X2t8ZWkrvDs8SaOrF5L8VUfed2z203c0JJcxu7txnwJEXv-1F147tgxMPBv_07juTeLOJCLujg-2Deu2SNe0MF_M2xOhxY_CcXzBssxoqsH0frxoZwflaI9th5AQlIJn-FFXPJsnhS7aRSbAUU4Y4lcB9vmNbtxF59LhyNOYAlcahun4TnXNH0wS8PCfxzNZfvP5EVdqnTiWvP440rfluCPArxjKPonTzlden a10ChjapLeHpsfTVxhcMCUu1_Yg5vw0fOkGMsbHmL1EteAJ5yoOHgve6U9_EdFy_leDXm7JDOZ79RgKCnnL2QWAceoUOS_Qm2jgx tmpaRk2w=w958-h717-no



(https://photos.google.com/photo/AF1QipMsqrwCiQxYi55BWD1PiX_snSSqI3gGCVjfEoDj)


(https://photos.google.com/photo/AF1QipMsqrwCiQxYi55BWD1PiX_snSSqI3gGCVjfEoDj)

[Fishinmymission]

(https://photos.google.com/photo/AF1QipMsqrwCiQxYi55BWD1PiX_snSSqI3gGCVjfEoDj)


(https://photos.google.com/photo/AF1QipMsqrwCiQxYi55BWD1PiX_snSSqI3gGCVjfEoDj)Here I have shown the two heads. The close up of the debris damaged second cylinder, and fouled fourth cylinder with rusting and salt deposits after running only 1 week earlier. I believe that prooves water intrusion but may not have been the source of the seizure. More to come as I get the powerhead apart.
387550387551387552387553387554
My model number is 0G258680 (1995 2 stroke carbureted 175 hp). Are there any more efficient quality powerheads that will bolt onto my setup? Which heads are compatible?

[roadkill636]

How do you see metal in the crankcase? Do you KNOW what your timming was set at or just screwing it in and out?
Looks like the head gasket was not sealing the cylinder well at all with all the rust and corossion on the sleaves

[Fishinmymission]

I set it up the timing this spring with spark plugs removed per the manual and I tried to advance a degree past what the manual said to see if I could get anymore top speed and higher rpms. When I took it out on the water that extra degree, the added back pressure of water on the exhaust and drag on the prop let me know that setting was not going to work. I heard the gurgling of detonation for maybe 2 seconds and the engine could not accelerate through the mid range. So I put the set screw back to where the motor was previously running for five years (could see the corrosion stains on the screw and fretting on the crank case paint) maybe one turn retarded from its previous contact just in case i was one turn off with setting the trigger arm nut. I got 4 months out of it running pretty good. I had to raise the idle the last week before failure(probably to overcome drag from a failing bearing or weaing piston ring) I took this picture after it seized where my set screw is basically off the pad when pushing throttle to WOT. So I'm 95% sure I was retarded and it wasn't detonation. Piston damage may provide further proof? but I'm not a piston engine expert. I don't know for sure cause I never hit it with a light while moving but hopefully this knowledgeable forum will either help me rebuild or replace my powerhead while identifying the cause for the failure so it doesn't happen again on my rebuild.
https://lh3.googleusercontent.com/J10ta5M2CQRRbVozVk5mkiaAJ9PcGD6U0IOUwENQ5a9XtqtEmHdB0sre2VO6CfxRuRCHUYQgLuOKtghuSlev_CMZNvDqA3oa4hjC YyWziEZx_Yx43dO8PBQrRMrTaNqB09FYrhEpBn1Y8jirxEbifWuKvTMW0mDjF7ZQF2yZqP1gBThglfUyUxZFoiWs6u-OaozYK6GyShkKiWfxkS2x4hqga4QmMLVK29m_gY4e3hpt635ZcJ-0JRCVVzq0KSBU5LQAyx5b48Q3ZEiPNGwyO8d51-g09BONjWOYHajufxDkpPKS64W-z-kOTnlw8dpS2IO5YFcZ1kn7JEFSi1Nh9eVM_IPCJefSXk6IzOpkYcS4ojKxv5zZ3Jl67Core6Jk_mKf5ieIf1jgwY15QFHBn5HcT2 7__PZC9aDeBeGEDuWADqFMWmqtgwc6ic0auZ5h_HSJZ_HWxPUtvPlU5c0lcf47yoBfu9wOv7F_vYQCGIDVe2nAW1WgTtRHNoW4-yoe_GwH6JEgqwgpPP0d18Pi1i6v3R-gwL24ppX0aTMmhRI9gMNyKZTCoNTB31L4UbdS6Y-LArJynwTIrZeIIfE9fe0aPxdLBLXQyNiYPX2Ovw=w698-h930-no
Five possible scenarios I can think of listed from most likely to least IMO. I write alot of reports on bearing and transmission failures for helicopters and do alot of metallurgy etc so this will be up my ally. I can't wait to get the power head apart.

1. I used an impact wrench 3 years ago to tighten the flywheel nut. (when i removed it this spring it was tight, and i properly torqued it back this spring) I may have damaged the lower crank bearing which spalled and eventually seized.
2. Head gasket leak or housing crack allowed water intrusion into the number 4 cylinder, corrosion over time affected some bearing causing it to eventually create interference and seize.
3. Head gasket leak or housing crack allowed water intrusion, Water volume increased and got so severe it hydrolocked and bent the rod or destroyed some corresponding bearing.
4. I had a slightly worn plastic oiling worm gear for 4 years and it sometimes skipped a few teeth at idle giving a slightly lower oil mixture below 1500 rpms. The engine was heavy hours and maybe just old but possibly less lube may have accelerated wear and caused a bearing failure.
5. I ****ed up the timing and had detonation (maybe this forum could help me confirm what damage to look for but viewing from the heads removed its not matching pictures of detonation damage i see on internet pistons)

[roadkill636]

What was your timming set at?
Do you still have the timming advance module or spark advance box?

Are these pics how long are these pics taken after the heads were taken off?

[Fishinmymission]

My memory is fuzzy from the spring when I made the timing changes. I accounted for the shift advance module but i remember on purpose advancing a little extra just to see. I never ran it like this for more than 2 seconds because it was way overadvanced and made horrible noise and could not get past the midrange in those 2 seconds. I set it way back to where it was previously(based on contact marks from the screw) and even slightly more retarded ( I think) because I did not have a person with me to drive the boat and view with a light running. I remember wanting to do this to ensure that my advance module was actually working but never got around to it.

Pictures were taken immediatly after I removed the heads. I removed the heads one week after it seized. Here is the starboard bank which looked pretty good for reference. Head gasket still attached here.https://lh3.googleusercontent.com/s4p9VHiGThC4zA928gazYnzUNF0kXnK3BhskB6A-S_GDy8BVQtL44z71FjJ-Mi_chnnW_tmCBbRuxdt12ws26RT3MyQgOs88x2M06u961bAOguwgH_2uL2agv6awPuTeocdazOMlPLxRtHJ-_8fOFthDF9rjoRWFj-EgtwnCgij6wHk4YyDoVT-aCrILTRHFm2GLjb_OiwBJs6frLOFzSADXd22ARewFMAbgdrhIKa9NZAK2t0hiU0ThdZ5lSkAox6qMFrT5k0UVzLLqa3zl2kukA1m 4Ysh8IPH1sZkQXyUicG_io2GVqEVVvQ2ZXnC_Pdnye9UZOhDtMW_FuDq2XS_20-d8Yh5LGu05QYK7TZ_FebyrELX346kKWnBtdATcc-rewQT0Slg_6GgMyqakBfWCgQLydDWf1oZcC-tSLQ6p_Qb6H6w1YeY50ZimvBiS-pttXKxn3gbaINHHkZFwuozJ2tBIismXgt0DgLI1UIWd-rZmRoF9ARG0F-duUf00R9YfXiKG4M9mMQngwHQp8xW-_QrXcl-UnfpvBqlZLocZTL9TSaTJd3cvXAIlGME0LIcvRXsb2_wbRaPVEULYUEENnUdpYVjFxAKgNvqPvg=w661-h881-no

[eli]

you dont drive the boat while someone timing the motor yikes if you do please youtube it ,as roadkill said you need to know where timing is at not just move things around and run

[Fishinmymission]

There is a chance I messed something up. This was my first time messing around with ignition timing. I have the manual and the internet but by no means did I have any prior experience doing this. I followed the manual exactly with the spark plug boots grounded to the engine and cranking. Then i ran the engine in garbage can briefly and it seemed fine, I also may have added this extra degree here to experiment around and see what would happen, all seemed fine with breif revving. When I put the boat in the water and in gear the engine bogged in the mid range and would not accelerate through it. I attributed the "bogging" to the fly wheel not being able to spin fast enough while the timing was rapidly advancing through the throttle lever mid range, and the timing was falling into the detonation zone? I let this happen once or twice for a second each time before putting the set screw back. I simply returned the set screw back to its original position that it had run at for the last 5 years and the engine ran great again. I have no idea if my thinking is correct though. There is also always a chance that I misread some number from the manual to and i cannot remember what number i was shooting with the timing light in the early spring.

I would think that checking the timming while running (on a flat day) might show me that my advance module was working, and that some faulty electronics weren't causing misfires. I probably should have just not added that extra degree and it might have been optimal but I was too scared and did not want to damage something. Anyways my flywheel is keyed and TDC was exactly where the arrow pointer was previously set when i checked so by returning to the exact set screw position and slightly retarded I don't think i was over advanced. And correct me if in wrong but if I'm slightly under advanced don't I simply just lose RPM and power?

[roadkill636]

The timming is extreamly critical to the mota being able to rev up and spin at its wot range. You need to know exactly what the timming degree is to set it and where the throttle cam and butterflies are set at during all of this "link and synk" process.
My guess is that the timming was way off and the head gaskets were not sealing the cylinder and with water getting in the cylinder and messed up timming is what caused failure. Were you able to find where the metel came from that you saw in the crankcase?
Also what exact motor is this? Merc didnt have a flywheel key. Its splined

What carburetors are on it?
Poat a couple of pictures of the powerhead.

On a Merc a 1/2 turn of the timming screw mite be 8*-10* of timming

[Fishinmymission]

One of the splines on my flywheel is extra thick it only goes on one way onto the crankshaft. I'm waiting for the marina to have someone available to use the over water crane to lift it from my boat to my truck so i can split and find what made it seize and any other damage. My trailer is far away and I might as well use the boat with the trolling motor for the rest of the year. I did the lync and sync basically not changing much of anything from how it was set. When i went through the manual i held calipers to the trigger arm and felt like it was one turn off from manual values(cant remember which way and its also hard to measure with no flats) so I adjusted that one turn. It's upsetting to hear I may have ruined something with the timing and I actually thought and feared this till i rechecked the position of the set screw(seeing that i had returned it all the way back this spring after the first time giving throttle) and removed the heads not finding significant piston damage. Also I ran all year like this and either was having an intermittent misfire or knock, but I think it was a misfire.
Looks like I dont have a photo of the carbs but I'll get one tomorrow or Wednesday. Thanks for the guidance.
So for my job I get to investigate and do analysis on helicopter parts from tests and from the field. This commonly includes transmission parts (every bearing and gear set configuration imaginable) that are tested in no oil conditions, with defects, with debris, with induced damage(test), or non induced damage (from the field), exposed to corrosion etc. When i pulled the oil shaft this spring before I touched the timing i was alarmed by the amount of metal chips I saw in the crankcase but I wasn't going to split it apart till it died or maybe this winter. I just didn't quite make it to the winter. I have zero experience working on piston's from an internal combustion engine though and this will be my first time examining those but I can do a good job looking at all the bearing surfaces in the crankcase to see if any root cause can be deduced.
https://lh3.googleusercontent.com/MhV4Xbi87SltizWbSn0r_7c8ka1DhsgZBQw69vqzU7nQMm7veNvwKOt5jLWqLD0laEsCA6xNaUPXe6zqtNUw9OIx-KqmVJONEdLbJgTxb3EaQ58WbZMtKAUklQqEWf6PdHfNOiElhrB_WQwqZosXlTndJelBudveaIkc3I5m7Q1xXAQP4H07uml3HQWGl gSMYzNNq4GnjkEk5wT_dO05KP9r2eahWX379W85AgT_nFHX45wnjYtVGY157GAtCJtrup7cYW6RARhSKM9phGuVxdwqXb84IInw2 szmT_6bVdVnSDkrIi3-VnSlywT1TIc7UbGRNsSsOP0ipbs2Me0spHd4k1BWxyUGFmM2eisNBLvSdP_0ejsDDUcxadUvod_GRl36Ngv_R3mVgJG3OiJ2xS1K aG1GBbmpUsBYVb5obAXO0tbWqSxdSyNAjx_J7T-0S-Q4gXQBGsDm20dC0HMGMahl21ok030dTjBpqLXYRrurqNsyoy5g1CqPmaJ1RtaWn_1GjmrYSSEZ36s1OsP7YztckdR8u02-u7QUSQZBTfxmejiG6EJUJF-oEWUwN4ARt2_0xT2N9K0OtlKOTMMT0kM9YamJVMB3WI5xPXex4g=w698-h930-no

[rock]

By the looks of the rust my guess is you are going to need a new crankshaft maybe a rod or two and bearings. I have seen several motors in the past few years that could have been saved had they not sat with water in them which is almost always due to head gasket failure. Your original question about more efficient motors fitting your mid the answer is yes. The Optimax motor will give you about 4 times the fuel mileage and only requires a different cowl and an adapter change or modification. Good luck.Rock

[Fishinmymission]

Thanks I'm expecting to see a damaged or pitted crank which is possibly going to push me towards a remanufactured or used powerhead. If I get an optimax I'll need a used head though because I won't have any of the electronics or ignition components. Will any year optimax or pro xs fit my mid with a proper adapter plate or is there a certain newer year that they changed the bolt pattern? Which ones are the 2.5l and which are the 3.0. Also any years to steer clear of? I had a friend with an earlier optimax and something was always breaking on it. I'm looking for a 175 or 200 to replace my 175 hp. Looks like 40% to 100% increase or I would have bought an opti long ago if it was 4x.

[rock]

I have ran my 2.5 200xs for the past 6 years or so and never had a bit of trouble. I went from about 2 mpg to nearly 8 mpg. A 3.0 opti will NOT mount on your mid and you will need a complete 2.5 drop on, not just a rotating assembly. I have heard many horror stories about the Optimax but have had nothing but great performance and trouble free operation with mine. Good gas, good oil, and regular maintenance goes a long way.

Rock

[Fishinmymission]

Looks like as of today only the Pro-XS 175 is the last 2.5L made by merc. Optimax is all 3.0L. Does anyone know the last year optimax came as a 2.5L?

[Fishinmymission]

http://www.ebay.com/itm/TWO-MERCURY-Optimax-Outboard-Engines-200XL-AND-200CXL-/253129166604?epid=2114000467&hash=item3aefac8f0c:g:S3oAAOSw-89ZPXIR&vxp=mtr

So this is actually driving distance to pick up for me and I have a pickup truck. I should probably contact the seller to get the year and confirm its a 2.5 or can somone tell from the pictures.
So does the counter rotating engine just have a different lower unit and everything else is the same? So i could drop the opti head from the counter rotating outboard and the adapter plate onto my mid and I'm done? And i'll have a second engine for parts!
Can I bring a battery and check compression or are the plugs not readily accessible on optimax? anything else I need to look for or should I set up some kind of return deal if this turns to be a nightmare and the engines are toast or to expensive to fix?
After removing the ten bolts from my power head I might consider putting them back and just swapping the engines. Tough decisions.

[Fishinmymission]

Those motors sold already.
Anyways I pulled my head today. Saw a piece of impeller pump that I knew was missing in the exhaust plate that would randomly move and give me an overheat maybe once out of every 30 times after I would get up on plane.
I tried to quickly loosen the fly wheel nut before removing it but of course it wasnt seized hard enough to free the nut without more tools to hold the flywheel. It feels like ****ty ****ty bearing. Ill split it this weekend to find the culprit.
So I'm getting quotes for a new Pro XS but i think its way out of my price range to have a marina install a new engine (I'm only 28).
I'm going to keep my eyes peeled for a used 175 opti head or proxs because i really don't want any extra weight of a larger engine.
There are plenty of used 850814T4 exhaust plates that look to be an almost exact match so Ill get one.

Lastly it was mentioned the opti head would not fit in my blackmax 175 cowl? Anyone have a sure way to get a cowl (whether just upper or upper and Lower) to fit onto parts of 1995 lower and mid. Maybe I should start a new thread for this?

[rkmirage]

I have a complete cowl from a 150 opti I'll sell you.

[Fishinmymission]

I would certainly be interested once I find out what's needed, and I purchase a powerhead with all the guts. I'm not sure at this point if i need the complete cowl or if the opti lower cowl mates with the seal on my engine. Rock might know it looks like he mentioned doing the conversion in another thread.

Also Rock mentions an Opti tuner in that thread ... I have no clue what that is if someone wanted to elaborate.

[rkmirage]

The opti tuner is long and narrow

[Fishinmymission]

Thanks I was having a brain fart and couldnt figure out it was an exhaust tuner that was being talked about (i was thinking electronics). Saw from the parts list mine is much shorter.
Anyone know what it means when mercury adds like A2 to the end of the part#. I found a cracked worn exact part number 812834A2, and good looking exhaust tuner but its missing the A2.

http://www.ebay.com/itm/812834A2-EXHAUST-EXTENSION-ASSEMBLY-110-200HP-2000-06-10-MERCURY-MARINER-282-/112573979522?epid=1334578348&hash=item1a35ee9b82:g:vpcAAMXQBNlRippk&vxp=mtr

http://www.ebay.com/itm/AA1A6325-Mercury-150-HP-OG724613-Exhaust-Extension-PN-812834-Fits-1992-2010-/122684722974?hash=item1c90944f1e:g:foUAAOSw0bJZrELr&vxp=mtr&autorefresh=true

[rock]

Issue is not the tuner but the adapter plate the tuner bolts to. Optis need a water supply for the compressor.

Rock

[Fishinmymission]

Rock,
So I think I have the exhaust plate covered. I see how the opti exhaust plate needs the coolant fitting and then drain to exhaust for the compressor. But you mentioned you need a tuner and that you used a 260 tuner. It appears that the tuner mounts to a second exhaust plate. I can't tell the difference between the opti part# 18233A20 and mine 18233A3 which makes me think I can use my plate with the longer Opti tuner. Please correct me if I'm wrong. It also looks like these two exhaust plates hold the seal for the lower cowl and since they look the same I'm guessing a complete Opti cowl will bolt right up? The rubber seals between the exhaust plates and lower cowl is the same part number so I'm betting the opti cowl will bolt up.

[Fishinmymission]

I confirmed with Mercury 812834 was the original tuner so it should work. Bought it so lets see it it bolts to my lower exhaust plate but I think it will. I also bought the upper exhaust plate. I'm fairly certain my lower exhaust plate is fine and will match the upper and bolt to the tuner.
Leaves me to find a cowl and purchase the power head im eyeing plus gaskets and studs.
Anyone know if the shift shaft easily connects?

[Fishinmymission]

https://lh3.googleusercontent.com/F3mdoXWaJQolV6rJ2Ij6iLrWek-yYoHdqmOHsUgq-mg5V-d9E8_IsP-3AMDbYlVDAaTm8q7m5A2hArg6iwXHc7wJFsp7tSJlq8-HGagp19BgmMJZzqpskOJXl1Tn2lu_HN-BoocnvX0rjStLT3LMZEl61zou5lvd2Q3TDazIggYe2yFTZcihoHGfRsxrC9fr31mdu9gMPpfluK8JW2zdkWRTOvjWoZOK3UuKmXR whFZskOFesCxhgFAWhIDZ9vW1GcCTLpcLXSkBLKltr2sQYAi8jOmQJQHuzYIdZzZEmCN2DRWMArCiMmGkOCK6HZKnaD8EQZy9rax 3E-8lqXECPr7fVdb7Q7dqWtBXvt0mPDttZtgwR0YCijQPPGwXaHUS2j5LuzOzVNUvqC8hrPUEWHMw8J5dyzUdC3tLoeIeWVPPrSJ7BY 3m1Wf1yMTnTZQ0HCOpxQvCHB_eZW0A-ttiIaTqlbRxJ1a7AuGKKy0PSXip8Z5gXOt052h3evAbpXuNj2S273YXnEPp9EUTvjwoZbbRGzWFsgYR8OAsjOyDXXgM6rsbWa5wS gwYOjdQ4xBt993sKoZ_QeE-XcqRJSDOdjYRC96AKcqv65Oi6xVxKw=w712-h949-nohttps://lh3.googleusercontent.com/xlRQc2w93BbcQEbTSobkvv8TtH31ysIiquJ3RubQmlaMpwwjy_rw06F9Q2M2bYnVGza-dtfrXCWkkHdUVyCgDDSi7HHpYFhPg2Uq-sEdp8nlYq6Kbp6GruZV9cHZNd33WmleiGLRnoIn_unzUfL7IurY0CQgFQjRGK0gPwEzZG_HK4r_ZnU6ejmjVWGrI3dhTFP7wpc7a v79XIMfbgfH-sTusit75c5Cw6rMZAOxadb9VGs5AVwUCuE0Plbf0XDYL1zhORtrTLCfuzSkEEiob9tPGXxFf-I92bPFH471GZfHHtNPf2pExdE4c3rK2DqFOMRPD8MeUxqIlq1ZZ-l_Bm7d3CcnA6vNYbZKwIC4N_Lqt8fpvm-Q2vf-oEJjC1-DGYnIdoV6QRhhXzj39gNQpgoJBbksNBb5OGEt_tGYqutIKuO4h4pPk2e1Ycbe4YmlbcF806yNy3k5efAIia56cyebcy6XOl9_vTt Nn8-Tw4Td9GSGSLhb9-Dka-v-F8IdpJiaW-vTwm61JCreiQy0iX5yR7x3vsK_XRJLE2iVtyYzVQI8JPuIS6oDMbS66jsrCUWouCvzGnKQ5b4sEpA5mkph00d58bw9fkO2sqwC4Q =w712-h949-nohttps://lh3.googleusercontent.com/IK9gntmiTBTyKwAlbzOoMjzc-akt01WBtTqMB-EEMP8XE8seoXP4wqmi_3LaQf5amNgI-Gn3hoXY9uFR7j-a7Fu0mJ3XI7KoCsgI0gG5cFghGii7PkAEeRz85vx4L7Erw36Vog4uagG5Pn0dXQAeZyg8Md2ffUPoR1twKO4wmUOx7Ef-i5LD-pzSKTsqKQ6NKFCvNafajIriKOliqrcHGwGn5RhmaHP4jEn9p6vClAdEBT_8o5dIJp731KU5MGbLlMcOi27M_kRFkBpuOUD3Z2-WViD1FbNGRJqVu1z2S1CkZfwm7hZmLu45o0CnfMSmv3TZBv1SgFip2JvF9izYvS96ZNDX7LMTmmrSvlfFRbR6w-WzNkW9fDLMnBNDcYcdMJp2QcS6mmNdm9TyDRZLFYaegHcmwzE5r5s8xlA_NoLdkJSn66MLqphtPLz8g8IYWFWlPBEQwySJ8kFURr m0P2-q4V77Av2aL6iVe0wJcsrPYLWrpGSvuBs2TPTLgl4o81Vq4WbTIZkZ_2s12Fr48Z7tKLE260kW-yHpQj6VDDbKLIhy9PQ70HF8iGXy-FogOaNTG5AOg2AGc11ns271OGOzP_PXhd1C_LsWynm3LQ=w1266-h949-nohttps://lh3.googleusercontent.com/A8-CW28Ij8EUoBZxmUDWxEgzd1Tz1gHv2H9zYAhsIe2QJzra9Pdv7rR--cdjYSyGEGd9Cfxm9el_Gel06yhdFTT4S3wOep3i3agesNJC49-5y-I5ka0dwc8eaeziLA0i_a5sObgU5weJSrIfOK55Yr9KOEQHTzY5h_lH-sCz_2JfcVQS17flYBpfiM-fysbs6p_uTU6Ox5dErmyo9Fjvh3y-n0dMmLLFk-iHQIwhRMSbLLgf_NghY2kViir9TaIBFula7UelAum8Lt8U-VJGdTKtXZChUmpneKbVFasG8hQDKIU5O_nxxRvxwEnNYl8zojwTnb3aBIivFqoaWhKgAWR2jOEj_Gi3bPJ-n8dKNqmAb8vAJ7j__f1sYTkU3329-0DCWhPuj2dUsVQcNufXfoI7t6QJLwJb2ptEnNKUaGaoFqteadiTHykIPanKdm625ZyIE5hn1-i39RI5x5htKrZ5UNfIq3KA5hiA0e4rL4f7-fFhudGCB_ghdXlDtP-6ZXeg2_YZlEEaxtjZPEG50o6c-u-DQOw-94Ei8in8NBM3K1KJYe0U5pQTNzUfJG3KYGmA03cbyxUS26vbnBsmvRp9FKHvcMrjRzUa_k0Trg=w1266-h949-nohttps://lh3.googleusercontent.com/FywuTtIkLPXIPkMm5O7617nq9GgEd2MupMrEtIjkRJIyf_cw22vRA4DF41RTgXpylcITqgQl52EN0jpS_k5ElGClf1X_KvcWGq8-mx2iQ-N1K0JQVdLpJ4A2xehdO5x36TPAxKYbYm3SL7JC7AagZuyDyCyvxeIp2eCjBDJH73W1m-4jUZ5mlYAb5NBTPRaGFk_nqJxGDeHtS-7bMATzMi9rSj-IqlDC7clRfkkMBgyA5jMAvPpFlPoKfTdU75xvdQdwoHovPj9-uxgxfcesCc2GxF2LhfR8MI86KhVsCo89uuoykRlRM20s-vK9Z4bXKdxkNpizbmrwSUyqFi1KGLDKFDs7xnVL9wAAoAySodtd4w-MlxJBqIGHE_ZccXJU37fDL-yQ-li5D4qlspoMUe6F70OPZG_o3mD-3Ou3oVU-9In2cehyytQQA5WzsbnAWjsE3GzovhvGLYtj1SHJdpK4NP0MQDqh5EFXNRa8km-hPkHlDt4qvFxS_44DNusf-OoXTacPF8dB7-AwXHXKah9YMeGOpN45X90FvJYc-tDVi_XHBZr9Y-CTVy7PDBiAv6qAUpQ_apeXbD_3SD-_35E5ISOAhq4u9tsWZSzrtg=w712-h949-nohttps://lh3.googleusercontent.com/iR9NNwHqi0-4xxL6BjOzK7Wjw1bT8PcV3JqdNDlRrnj6gT7XRXl0Irzk1to7rChhhqv3QH-2GfhQdY1nzgzw3QBEFCdWQ2azPdvnUoXEf4hb0U3jvYW7p1EHbQRwhrKzOjQA8UGrVw6NwGv2nUNuuTRLtTbXp2BjaEyIuN0Apc1 NbxiY5VSCJN0rZ4MCWd-cpe3IroAq7x8DTY6FuJLN1qkvv3oLcm5pdtWchx7wTgP2TdT552mvKZokuiandN-3fmAdBmmWO3cTMcipWCGsN2LlQZSFHLen6Mv1P0HHTpSeB4717VnO_EsUzyArDLPdtpduzm-tPU8_U7CrptOCTm2LnT-3K24bdu9bQSPqPf42caBb0ZTbcr8jJZM5zWpadmm81eAOa3Fo9SQYYm5e9QF_1cYdizYj2lrweBhxbZ6Q09x0MrGV4bOOfZLXcKG TucpqDlQrQQnIL1MGXtgppH0F9Lh1YoPB0mTGbYVUSgC6KLdb59K7y-m4-ILBLbKTrmTKf-OdYrtVGt7qF5O7n4il1I7TqpHrkoVfRmuLzJmY-NpUsvCLpQrz8pBbHirMmkdUaPS_Igx3Ltp14Jq-UOUFsHTdoQn7YgcCqYvB2A=w1266-h949-nohttps://lh3.googleusercontent.com/9wLPu7EKvISoVZxR_hFPaUCqaurOz30EwEqN1Tc7EsjHXmCQc-1t_do83l1yB54M91_67Hc483BJyx7AfUxrJL9oaTXPTcpfNI0iy1BlJVsngMTnp02V-HxV2ABF0BzYwQ3jJim5ciHDXYDYnzPNMlO12fXR1G6XfqSERKaiZiOG67ILsAWLUV2tGsxyyINA0mzgfw8JAaN60aws3RCEYUOqd uOwwubZCZLvbi5OF0Jma78EC19EuYNGvzEKdEo_z_81weh5SFMoNTHS4WP4Yx5A9tfNbglhh_pOSgtBja-xCASIx_1TkVJm6EUKwpzsRIkGZSrPhljzdTRBoMgF98loTaLGpM7cH1ceh907FXZkDqKYouCalcS35aHNng-vpYvLnXsjLthfLxOn4kA0SYmVoI-IZYp4Ebe1n1RcGhASoDRkzzrarWoAW33wTLlIU6fJEEHHKeby9RBnTQeqBrAG1grfFp48_oomr-lF1TtfJaW1rsjOvIMmO8WfhEyQjczaQjplOpwLd8gk0U-WRgSXU6erilrNkgBTqkdvSD72MxCREI2yd5wSBXVENGW-0yMeQ8K3J6yoZ5q_uQMlKsxeMBhis2IXY_1RftEV_g=w1266-h949-noSo engine seizure was due cracking of the outer raceways, which then jammed into the block housing, of the two split crank shaft bearings on the middle of the crank shaft. The rollers of these two bearings exhibit significant spalling which would have came prior to outer race cracking. Likely what I thought was misfires was actually momentary light seizing of a roller or particle in these badly spalled bearings. The journals of the crank shaft that act as the inner raceways also exhibit spalling. So the crank shaft is toast since it would create chips if used again. Top and bottom crank shaft bearings were prestine, rolling smoothly with no play or damage. All the wrist pin and connecting rod bearings was also flawless on all pistons. Not even debris impacting damage was present on the other bearing surfaces. 99% of the outer raceway chunks were actually contained and only fell apart as I touched them after splitting the block. Only a few small chunks appeared to separate and make it to the fourth cylinder causing that minor debris damage between the piston and head. No evidence of corrosion or saltwater intrusion into the crankcase. So if any water leaked into that fourth cylinder it must have exited through the exhaust passages. So now I have little experience when it comes to internal combustion engine failure analysis but looking at pictures online of pistons and detonation damage I do not believe I had detonation damage. My pistons rings and bores all appear to be in great condition for the age. As to what caused the spalling of the cam shaft journals and rollers may not ever be discovered. Possibly some foreign debris impact damage, or a detonation stresses from the past may have started some sub surface cracks which just got worse over time. I remember I blew a switch box once three years ago and ran back in for 30 minutes on three cylinders once I wonder if that could have put a funky high stress on the bearings. After 23 years that just might be the expected life of the bearings as this engine has never been rebuilt. The block looks like it could be fixed with some JB weld or have a liner installed so that it has the correct clamp up to hold those crank shaft bearings where it got damaged.

[Fishinmymission]

So I should have my 2006 optimax head coming next week which I will be installing. Anyone have any idea where to get a crankshaft and how to repair the block area for the bearing that got gouged? It might be so difficult to install a liner or repair with jb weld that its not worth saving the block. It might be a cool project to rebuild this or I could sell off the parts if anyone is interested. Parts have been coated with fogging oil as needed to preserve.
https://lh3.googleusercontent.com/vJnw7eIJMEKQjkflVJHXLEgUcFhy7OGB4Y-Nd4dWZ2Lnxr7VsEnKHSCAs2FV45GDHYzDiH-33MxG5R7t2yWjLTRqRvfqzMSUY65ymgUstzLp9B1Tv-yTIrDEtyNNi9tRWXpRi3lhFUvASJAncoY5lBvlYzPfJxMSsqyH26KWSJWk1MtBJK6sfWpLXhvsETfT_mET7S7Zhwtl_T-0M_byf5tFKdBXFXqTtHPX4ruot0qcj9FO7BYn77Rsfw6q1pl5JhdL7nWt9DK3-L0SIQMtuJ-4RT87JjHlkl38-h4yrYH0TKBOhQVVpxAZUWC9sCriGLasBbMmpcW0Ij1waMf_SF5sP-n-7B3061-3SEgxlwoqNLRfq2zLjATSK_HDoFVtzTg48osoeYPcfTIS8o8hPaYY-lBdCum1CRCauniALkmQ6dN8AF3Iw3UpE0ftnk9OOKC89j3P20DVcvMNgpsdGBMmzY3v27WN3N4WijdYO45-f0j_D10Jde4SNawcFhkanXaM7W13vOa3U-rfMPJZktTRuiIxfd841FbsdgcH2Te4cJgUOldcZKir2frIzmdGEumwgrv5sziuWsj3D617wx4F9DY9oNPxGyrBzTt3Yg=w1266-h949-no

[Dave S]

Spalling.... good to see someone know what that is. Could be caused by over pitching motor. Could be caused by someone rebuilding motor and too much goop on mateing of haves of block.

[Fishinmymission]

Hey Dave, I researched yesterday and found many suggestions that over pitching could be the source of extra stress and is commonly associated with main bearing crank failures. I ran the prop calculators which say I should have a 16 pitch but I've been running a 14.5 dia by 19 pitch that the previous owner had on for the last five years. Sounds like this is what did it. I have a spare 17 pitch prop that will be going on before the Optimax head arrives this week. If the engine got that many years being three degrees over I'm betting one degree will not be that bad. If I'm not happy with my rpm range maybe I'll make a purchase for a 16 pitch prop

I'm a failure analyst for helicopters and a metallurgist so I spend all day writing reports about heat treatments and transmission component failures, I just never have internal combustion engines in my line of work. I work on spalled bearings or journals at least once a week. If you cant see it originating from any sort of corrosion pitting its usually originates from damage or a high stress. Having two bearings/journals fail is another indication of a high stess in that area and If I match up the spalling origins on the two crank shaft journals I bet I will see some sort of correspondence to the stroke from surrounding pistons. Its unlikely that one bearing got damaged threw chips into the other bearing but that's also a possibility.

[Dave S]

HeeHee....Failure analyst .... optiblow should keep ya busy for the rest of your boating time. I like carb rich and snotty..... keeps pistons happy....

[Fishinmymission]

Yea I wanted the fuel efficiency and range extension of DFI but almost didn't get it because I finally felt like I learned everything about my carbed motor. I also had a friend with an early 2000s 200 opti that spent $10,000+ on his mechanic and it failed on the water the only two times I went out. But i researched the motor and years and feel like 2006 was a very good year. Plus the engine has 800 hours and the black painted compressor which apparently was updated after 2010 and is much more robust.

[Fishinmymission]

So I finished dropping the 2006 175 HP optimax head onto my boat. I took it for a spin with the old slightly banged up aluminum 14.5X19" Vortex propeller part# 992004 That has been on the boat for the last 5 years since I owned it. Similar performance to my old Motor top speed around 33 mph top speed on a rough day, could only hit 5070 rpm max but much better hole shot. Now if the last motor failed from being over propped I don't want to run that high of a pitch again right?

I used the mercury prop calculator which for a 3250 lb hull plus 800 lbs of gear and people (average) and 120 gallons of fuel. its recommending a max pitch of a 15X17" black max prop.
I had a spare 14.5x17" michigan wheel aluminum prop lieing around and installed it today but at maybe a little past 3/4 throttle it would isntantly race to redline about 6000 rpm and the boat would lose thrust at that moment. I could not get on plane with this prop. I'm guessing this is cavitation?

Any suggestions on which propeller to use? I'm thinking either enertia eco 16x17 but I here its the same as 19 pitch, or a black max 15x17, or mirage plus 15.5x17.

[rock]

It could be cavitation but I would have that prop checked for a spun hub.

Rock

[Fishinmymission]

Thanks Rock I did not even consider that. I'll check for that. I think that ended up being it.

[Fishinmymission]

I'm amazed with my new mercury blackmax 15x17" prop. The other 17" pitch prop was indeed spun I tossed it as its an aluminum prop with a rubber hub and figured its worthless for its price to press in a new hub. I gained about 350 RPM so I'm now at 5400 WOT and amazingly I picked up 6 MPH (39mph) by going down 2 inches pitch to the 17" pitch prop.

All this probably just further confirms that the engine was severly over propped, lugging, and outside of its powerband from running on the 19" pitch prop. Very likely that this caused the bearing and crank failures and possible even the gearcase that I blew 4 year prior.

The boat has been taken out for the year and I should be ready for some fishing come spring!

[rock]

I love a happy ending.

Rock