225 Promax connecting rod cap n bolt

[redstv169]

I was changing injectors today and checking reeds for 1st time and found this rod cap not mated perfectly. I've probably only put 50 hrs or so on it in the 5yrs I have owned it. I bought it not knowing any verified history. It has standard bore pistons and was super clean so for price I thought I got fair deal and had something to work with for many years. It runs great, I have a extra set injectors so plan was swap out and put back together. I did say runs great but sneezes a good bit at idle. I found bottom reeds with 2 bad corners on both sides at one end, chipped looking. Couple others reeds weren't sealing good on other blocks, so there is my idle issues. Reeds are fiber 2 stage type. So questions are do I need to immediately quit running and tear down based on this rod cap? It feels tight like the rest, just worries me with it not lined up like it should. Are these rod bolts merc factory? Were 2stage fiber reeds stock? I want to rebuild it and get rid of the plastic cages which I do see on this rod better than the others and do a couple of minor things but last couple years of low oil prices cost me in wages so freely spending on this motor is tight now. I can make myself stay out of the max rpm, but am I pushing my luck. I'm really curious if this is factory or was it re-ringed on the std bore pistons and the rebuilder did this? I'm sitting about 6-7% avg on leakdown so I was hoping I could get another season which for me would be 10-12hrs run time. I was gonna post cylinder picks and get your thoughts on if re-ring looked possible without boring but will do it in another since this got long. Thanks for suggestions and comments on this. I've heard of this happening but hoped to never see it in a engine of mine.

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[flabum1017]

That don't look good, I would tear it down, replace that rod and bearings, get a close look at the crank shaft and check the rest of the rods and re- torque everything.

[patchesII]

^^^^^^^What he said. That rod is junk now, bearings are no good. Hopefully it didn't hurt the crank. If the crank isn't hurt you can pull that piston and rod with the motor on the boat. Just have to be careful to get the caps lined up before torquing. I use a dental pick and flashlight

[Capt.Insane-o]

There is no way it would have run 50 hrs if it is mismatched that bad. You can pull off the cap and look without tearing the motor all the way down just be sure to clean out all the old loctite crumbs.

[rock]

At least pull the cap and look but as all above posts have already stated don't run it like that. Can't believe it held together.

Rock

[redstv169]

I knew the answer, but just really didn't want to face it I guess. Scares me someone had to of rebuilt it right before my purchase to have this cap like this. I'm guessing the hours on high side I put on it but not many, I'm gone 2-3 weeks a month to work and that doesn't leave a lot of boating hrs after I get other stuff done. Good thing I just got a couple big items done on house for wife. Stock bores for sure and I believe stock pistons, have to look closer. Got a lot of projects and I thought I was about done with this one getting my Allison together. Well ****, leakdown and cylinder walls tell me it is close enough I just need to do it all. Let me know what you think of these pics please. Following/ reading threads over the years I respect and thank each of your opinions.
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[WillySteve]

Wonder which rod has the cap that's pose to be on that rod or is it turned backwards?? Someone without any common sense put that thing together.....at least the bearing face ID of the rod must be fairly close or it would have exploded by now!!!!

[Capt.Insane-o]

Looks like it was taken apart and put back together dirty. Clean a piston top off and of course were all curious whats under that rod cap. :)

[W2F a V-King]

There is no way it would have run 50 hrs if it is mismatched that bad. You can pull off the cap and look without tearing the motor all the way down just be sure to clean out all the old loctite crumbs.

:iagree: YUP.. ^^^^ would be a miracle if the crank is OK. Wonder if because it's a top guided motor is the reason it's still alive....

[patchesII]

Wonder which rod has the cap that's pose to be on that rod or is it turned backwards?? Someone without any common sense put that thing together.....at least the bearing face ID of the rod must be fairly close or it would have exploded by now!!!!

Its on right, just zero effort to get it lined up before torquing

[redstv169]

Well this brings everything into question on the build quality by whoever did this, what else is wrong that I can't see? I can see it still has the plastic cages and If I don't have it all rebuilt I'll always be wondering. I've got to leave Monday, so when I get back from work in a couple weeks I'm pulling PH and getting it rebuilt. I always had a few ounces heavy on oil mix and when I did turn it up it wasn't for long so maybe I will get lucky and the rod is all that is bad. Sure appreciate you guys and this site for being able to get input from knowledgeable guys that are willing to help. I didn't have proper socket to remove the cap so probably be a month before I know extent of the damage if any. Thanks again all!

[Capt.Insane-o]

Ya know I'm looking at this...the pic is a bit potato but the parting line looks to be where the copper ends. Even purposely trying not to line it up the bearing itself will pull the cap together way closer than that appears. Ive seen motors that had caps mixed up what appears that far off and they don't make it 5 minutes let alone 50 hrs. Guess we'll find out later.

[90 5.0]

Well this brings everything into question on the build quality by whoever did this, what else is wrong that I can't see? I can see it still has the plastic cages and If I don't have it all rebuilt I'll always be wondering. I've got to leave Monday, so when I get back from work in a couple weeks I'm pulling PH and getting it rebuilt. I always had a few ounces heavy on oil mix and when I did turn it up it wasn't for long so maybe I will get lucky and the rod is all that is bad. Sure appreciate you guys and this site for being able to get input from knowledgeable guys that are willing to help. I didn't have proper socket to remove the cap so probably be a month before I know extent of the damage if any. Thanks again all!


Plastic cage bearings in a 225 promax????

[JCSmile]

Didn't the promax come with SPS rodbolts or no?

[flabum1017]

Ya know I'm looking at this...the pic is a bit potato but the parting line looks to be where the copper ends. Even purposely trying not to line it up the bearing itself will pull the cap together way closer than that appears. Ive seen motors that had caps mixed up what appears that far off and they don't make it 5 minutes let alone 50 hrs. Guess we'll find out later.


This is why I suggested looking at the rest of the caps, it's possible someone mixed up the rods and caps. Could also be a different powerhead etc.....There is always the slight chance that mixed up caps can match close enough not to blow up, maybe you got lucky...........better make sure the pistons are in correctly too.

[redstv169]

All the rest of caps look good, the top surface of rod and cap joining are definitely not even for sure and why I can see more of the plastic cage than on the others. My thoughts are with the 2 not lined up properly there may be a very few thousandths of a lip on each side at break that would prevent a needle from rolling over/past the break. So that being my possible theory I would think maybe needles not rolling as they should and could be worn flat? I'm just theorizing, you all have a lot more exp than me with motor builds / and running harder motors. I have built car motors, OMC V-4 & V-6, several VW's for offroad but last time was 20+ yrs ago. Perf Mercs I had were built by someone else in TX and never had to go in them. No offense to any of you that are builders but I'm just going to send to Jay and let him do his thing. I knew when I bought it that is what I would do and not knowing any history it could be sooner than later. So it's here now. Watching Comp and Leakdown each year I thought it was changing too quick in my opinion for the same amount of run time and looking at the walls the hone job certainly isn't the best pattern I've seen. Think I did better years ago on engines I did. Not trying to get every last bit of performance I always ran extra oil and with only getting to lake 3 maybe 4 times a year my guess at hrs is just that. Block Serial # is a '98 225 Promax sitting on a '96 mid with same vintage electrics, etc. Again I knew all this so, when you take that buy on something pieced together and don't know the seller or builder there you go. You all have been great and appreciate telling me what I needed to hear-Don't run it. So glad I decided to change the injectors and look at reeds. Other wise I could have been crying thru a window later.

[H2OPERF]

:iagree: YUP.. ^^^^ would be a miracle if the crank is OK. Wonder if because it's a top guided motor is the reason it's still alive....

I was thinking the same thing...Top guided may be the only reason its in one piece ,the sharp edge would have cut a groove in the crank like a lathe. Must have gotten lucky with near zero lateral mismatch even though it has the big vertical miss match or it would have windowed the block within minutes not hours. Dave

[flabum1017]

Good choice to send to Jay, he will get it done right.....

[W2F a V-King]

I don't believe the rollers were sliding. To much friction...with the load they carry, they "have" to roll. A sliding roller would begin a really ugly overheat/welding situation.

Very curious to hear or better yet see some pictures of what is found. Really sorry to see you having this issue, but Very Happy you aren't looking at a windowed block.

Maybe those plastic caged brgs and being top guide helped to save your block. Hope your luck holds out for the crank as well!!

[Capt.Insane-o]

The end of the rod would be black or every color of the rainbow if something bad was going on.

[redstv169]

Yep Capt, didn't think about that, rod itself looked normal color. Hoping too that I got lucky on crank. If so it's all good as I wanted Jay to rebuild it anyway and I was keeping eye on leakdown and all to catch when that said it was time. I was hoping to get another season but again, its all good if it ends up all he has to do is his normal tweaks and go 0.015 over with no crank replacement.

[90 5.0]

No one else sees a problem with the plastic cage bearings in a 225 promax?? That's not what came in them!!!!!!

[Capt.Insane-o]

They came with plastic caged bearings.

[redstv169]

I was always told they came with plastic cages and reason besides pistons why you didn't want to turn higher RPM's 7000+ sustained.

[90 5.0]

None of mine I have ever torn down did and I owned a new one from factory also
look up the part number I the merc part search it's a metal cage bearing

[tlwjkw]

why ya'll gettin' so excited 'bout whats "probably tore up"?.. hell, its run for 50+ hours and hasn't exploded!...
jus take it apart NOW jus to be sure....... jmo

[Go Time]

The factory promaxes I've disassembled had plastic caged rod bearings....all of them.

[Capt.Insane-o]

None of mine I have ever torn down did and I owned a new one from factory also
look up the part number I the merc part search it's a metal cage bearing

All of them (many) I've worked on or owned have plastic cages.

[myron]

I have owned 5 of them from new, never had one come with metal cage bearings

[90 5.0]

Weird, when I look up the bearing by serial number of motor it shows metal cage I'm 99% sure last time I looked

maybe it's a year thing or because mine were SS motors??

[Steve Pope]

The metal caged bearings supperseded the plastic ones on pro max.

[redstv169]

Well I got lucky, no damage to crank or other wise but that bearing didn't have long left. Nothing else found terribly alarming but it was time for a rebuild even without this issue, rings and cylinder wear and it still had plastic cages. The reeds, injectors, bearings and locator pins all worried me not knowing anything of the motor build or usage. So I'm happy, Jay will get me fixed up with one of his great builds and I'll have peace of mind knowing what I have and that it was done right. Sure appreciate all of the input.

[W2F a V-King]

That's really great!! Very Glad all went well. :cheers:

I know the woes of buying a used motor with the "unknown" possibilities.:o

My PM 225 had an issue I didn't find until I took it apart. I went for a ride with the man before I bought it, ran good, sounded sweet and pulled hard.

Compression all good. Didn't get to do a leak down ( no electricity at his storage place ).

Bought it, and brought it home.............Pulled the heads because I was curious and found #6 had a sleeve for a 150 or 175 with exhaust a relief slot. The man had run it for 3 years on his bass boat with no issues, never knew it was down on power. He had bought it from a man in NC that told him he had "freshened up" the motor...:rolleyes: .

I did call to ask him about my findings, and he was shocked...said he had never had any issue what so ever with the motor. He up graded to a new 300 Yamaha, which made sense to me. He really needed the grunt of the bigger cubed Yamaha for his 21 ft. Bass boat...

So it's getting a rebuild....flywheel nut to the prop nut. :thumbsup:

[CircleHook]

Gents- to my simple eyes the cylinder walls look pretty badly scared- did I not see that correctly? How could that have single digit leak down numbers?

[redstv169]

A lot didn't seem to add up and it ran great minus the whiz sneeze idling sometimes. Some of the walls were like scratched randomly to me, like sand paper looking scratches but none of the dark wear streaks could be really felt easily. Looks worse than it felt, at least to me. But what little I know is dangerous and why I referred to you all for input. Jay did say one was getting out round some but all good for .015 over and new pistons etc. It was time for rebuild and glad it was caught before it got really expensive. I knew there was a few different years of parts on it -vst etc but Jay told me more mismatched/ going years back than I knew. It was all good for use, just showed it was a compilation of several vintages. He'll get me fixed up and be set for years no more than I get out.

[wrechin2]

No one else sees a problem with the plastic cage bearings in a 225 promax?? That's not what came in them!!!!!!
I have rebuilt several and they all had plastic. Answer me this....what are the center mains and upper bearing cages made of??:eek::eek::D:D:D

[tux974]

I have rebuilt several and they all had plastic. Answer me this....what are the center mains and upper bearing cages made of??:eek::eek::D:D:D

James, I'm with you rod bearings from Mercury came plastic and on center and upper buddy! I just think the saving grace to the main and upper is the size....Would never dispute your knowledge and experience though...;):D

[wrechin2]

James, I'm with you rod bearings from Mercury came plastic and on center and upper buddy! I just think the saving grace to the main and upper is the size....Would never dispute your knowledge and experience though...;):D

No dispute.:D:D The center are larger bearings yes but so is the journal that they ride on. If you take the diameter of the journal and the diameter of the bearing and figure out a ratio of how many times the bearing spins 1 complete round on the journal and do the same for the rod you would probably find they are probably close, just from the naked eye:thumbsup:. I have had metal and plastic cages fail. If a rod bearing is going to fail it will take out what ever cage is around it. Just my thoughts.

[WillySteve]

Well I can say this, you are correct on a failed bearing taking out whatever the cage is made of from a failure but IMO there's no way plastic will outlive steel and if a cage fails, a bearing fails!
I just don't trust plastic and will never buy a bearing with a plastic cage!

[powerabout]

there is quite a bit of centrifugal force on a rod bearing roller jamming it into the cage that is way less on a centremain
looks like merc worked that out hence the SS of the part.
How long to cages last on F1 engines...

[wrechin2]

I am not talking about a 10k engine. This thread was about a promax. How many promaxes are running around turning 7k with no failures from the cages being plastic? This conversation is like that all promax engines fail due to a locator pin coming out. Not saying they don't, but i could fill a dump truck with the pistons that I have taken out of 2.5's I have built and locator pin failure would be about 1%. Most would be detonation and half the piston melted away and then the pin came out and was not what actually failed but people see the pin is out and of course that is what blew the engine. These are my experiences and I actually reuse the plasic cages as I can buy a dealer pack of loose rod bearing and replace only the bearing and have done so for many years without any issues and many are turning near 7k. Just my experiences.:thumbsup::thumbsup::D

[powerabout]

I am not talking about a 10k engine. This thread was about a promax. How many promaxes are running around turning 7k with no failures from the cages being plastic? This conversation is like that all promax engines fail due to a locator pin coming out. Not saying they don't, but i could fill a dump truck with the pistons that I have taken out of 2.5's I have built and locator pin failure would be about 1%. Most would be detonation and half the piston melted away and then the pin came out and was not what actually failed but people see the pin is out and of course that is what blew the engine. These are my experiences and I actually reuse the plasic cages as I can buy a dealer pack of loose rod bearing and replace only the bearing and have done so for many years without any issues and many are turning near 7k. Just my experiences.:thumbsup::thumbsup::D


sure I was just pointing out that a cage on a rod does more work than a main on any engine.

[redstv169]

Well been while on this since I posted but finally a couple hours and registration stickers away from being on the water. I sent the PH down to Jay in Tx for the rebuild, nothing against any of you but I knew years back when I lived down there an met him at a race then a couple years ago spent a afternoon at the old shop with him that I wanted him to build me a motor. It was good thing I found this issue, there was more mismatched parts; 3- 2.4 teardrop reed cages and 3 PM cages. The rod was just starting to get bad but crank was fine. Couple other minor things but Jay was great and sent me pics and video regular of it all while I was dealing with my Dad n open heart surgery that 20 days later he lost battle and passed. Jay had some minor delays on my end thru it but sent prayers regular and was there patiently for me waiting till I could get back to him and then coming down to pick it up in person. So I pretty much got the full meal deal for a Jay Smith PM rebuild-top pinned , Hi-PO bearing, cut front n back breathing treatment, cut heads, a little red paint to set it off and great service from a awesome guy. I got it fired a few days ago before having to head back to work, but she sounds great. Next trip home slap stickers on and go to lake to start break in cycle. Dang pic from I-phone. Was going to post some more but until I get used to and figure out how when they do this I will spare you all the tilt.

[W2F a V-King]

Very sorry to hear of the passing of your father. Words can hardly help lighten the pain, but do let you know others sympathize with you.

Glad you got your motor all straightened out and ready for good times!

[redstv169]

Thanks W2F. Appreciate them words. Yep ready to get the motor broke in and learn the new setup and all.