Re: Please Help revisited

[gaineso]

To refresh memories: (Originally posted April 1, Not an April Fool)

Please HHEELLPP (Oh S**t)
1986 Mariner Inline 6 115.

Runnin' over near Palatka today. Cruisin' along nicely at about 5200K and 50MPH and saw a place I wanted to stop and fish. Backed down and as I gave it a little gas to get past the following wave, it sounded like it had a bad miss. Didn't think too much, 'cause I figured it would clear when I took off again.

It didn't. Missing on takeoff, but seemed to run okay once on plane. Idled smoothly and started easily. Had to run back to the ramp, because I was about 10 miles away.

Loaded up with no problems and brought it home. Pulled the plugs. Number 4 is fouled, looks like aluminum. Shined a flashlight in the hole and it looks like there is a clean spot right on the top of the ridge on the piston. Also a couple of very smal silver spots on other parts of the piston.

Couldn't get a picture inside the cylinder, and no head to pull off on an I-6. Broke out Balzy's Leakdown tester and it was less than 3%. Checked the other 5 and they were the same. Compression test showed 132 to 135 on all 6. Stuck an old plug in and fired on hose. Seemed to run good.

Plan to fill tank with 93 Premium and 40+:1 oil in the morning and try again. I think I have about a half tank of 6 week old gas with Quicksilver stabilizer in it. 89 mid-grade.

Questions:
Is it possible for 1 cylinder to somehow advance timing to the point of detonation???

Is it possible or probable for one cylinder, of the 2 fed by the center carb to lean out to this point?

Is my plan to add 93 gas and run it tomorrow dumb until I know more of what happened???

Please HELP

[gaineso]

Pulled the plugs today and indexed #4. Well, best I could using a digital caliper.

Hooked up homemade spark checker and checked timing at cranking speed with the plugs out and a very hot battery. Tach showing about 700.

#1 showed about 6* advance with new Craftsman timing light. #4 showed about 14 or 15* at the same cranking speed.

Ordered a TDC indicator from JSRE, overnight. As soon as it arrives, I will index the top 5, and try to get #6 as close as I can. That bottom cowl is in the way.

Sebastian Harbor Marine replaced the stator, trigger and both switch boxes late last summer. Switch boxes are aftermarket, not Merc.

Am I really going to be lucky and just have to replace a switch box or something? Not tear it down??? Opinions please. This motor has always been propped to run right at 6K and run 40:1 Quicksilver oil.

[sosmerc]

That engine may also be equipped with an idle stabilizer box...it's mounted on the plate in front of the carbs...has 3 wires coming out, red with white tracer, black, and white with black tracer. Disconnect all three wires and recheck your timing. By all means index the flywheel for all cylinders and check to see that timing is the same on all cylinders. Ditch the idle stabilizer...you don't need it. You very likely lost some aluminum off the top of that piston.
Make darn sure your max spark advance while running at wide open is no more than 18 degrees....run premium with a good quality oil at 40:1 and you may live a little longer. If your timing is still off with that idle box disconnected, you may have a bias voltage problem between the two switchboxes. There's a white wire with black tracer that connects the two boxes together. Negative voltage is applied to that circuit to keep the timing stable between the two boxes. This negative voltage should increase smoothly as you bring up the rpm's. This check should be made with an analog meter, not a digital peak reading voltmeter that is required for all other voltage output tests. Any sudden swings in the meter would indicate a bad bias circuit....replace BOTH switchboxes if this happens. I recommend CDI boxes...2 year warranty and double grounded. 114-7778 is the CDI part number.
Hope this helps.
sosmerc

[gaineso]

Thanks sosmerc. That's exactly the kind of info I need now. Waiting on a manual from Rickracer and indicator from JSRE. Then I can really do some more checks.

[gaineso]

Skip

Somehow, it's showing in e-mail notification that you posted a reply. However, it's not showing on the thread. What' happening?

[gaineso]

Continuing saga:

Got my dial indicator from JSRE today, Nice piece and works great. Indexed top 5 and measured carefully between 1 and 3 to find the tdc for #6.

Plugs out and using homemade spark checker to ground ignition, #1 showed 21* BTC and #4 showed 28* at cranking speed of about 750 RPM.

Disconnected idle stabilizer and #1 was -5 and # 4 was 0.

Put the plugs back in, hooked everything back up, pulled it outside and hooked up the hose. Hard to start and 1, 3 & 5 were the only cyls firing. those are the ones on the top switch box. The idle stabilizer was connected to the bottom switch box. Disconected it and all six ran great.

Checked the timing:

1200 RPM idle 2500 RPM
1 -3* 10*
2 +0 * 17*
3 -1* 12*
4 -2* 12*
5 0 to -4* 15*
6 +4* 18*

Evidently blew the idle satibiler, 'cause everytime I hooked it back up, 2, 4 and 6 died.

Tried a short burst to 3200, I was on the hose ,and got 15* on #1 and 18* on #4. Didn't want to run it much at that RPM on the hose.

Have not had time yet to pull the plugs again and try to see what the timing is set at WOT. That's tomorrow morning.

The Stator, trigger and both switch boxes were replaced last summer by Sebastan Harbor Marine, here in St' Augustine. I know the switch boxes were after market and the cheapest they could get. They don't use real Merc parts if something cheaper is available. They are also the only dealer here that will work on a motor more than 10 years old.

I have definitely decided that I will do my own from now on. Anyway, It seems to me like I need 2 switch boxes and probably a trigger. Then run it on 93 gas and 32:1 Quicksilver oil.

Comments please.

[QUICKSILVER]

Are you going to replace the #4 piston? I can get you the piston and CDI boxes. My cost plus shipping.

[sosmerc]

Best to check your max spark advance running at WOT. You can do this on the trailer, backed down the boatramp. Just make sure boat is secure on the trailer. This is like pushing a brick wall, so your engine probably won't get much above 4000 rpm, but it should give you a pretty good idea where your timing is.
Timing while running will be slightly reduced as opposed to timing while "cranking"....it just happens to be the nature of this particular ADI ignition. Like I said earlier, max advance at WOT should not be above 18 degrees BTDC...and all cylinders should be very close.
I like to run .076 main jets in late model 115 inlines....this is probably .002-.004 larger than you currently are running. I also like to remove the backdraft jets (or bowl vent jets as some folks call them)...they lean out the fuel mixture at midrange for improved fuel economy.....but it's false economy if it causes the engine to run too lean and fries a piston. The extra fuel helps to cool the pistons...and I doubt you will really notice any performance drop.
I'd also recommend checking the negative bias voltage while running to make sure it is within spec and stable....using an analog meter....put the red lead to ground and the black lead on the either of the switchbox terminals that has the white wire with black tracer. Be sure the bias wire connects to both boxes...do not disconnect anything. I have seen a number of inline-6 engines live for a few more seasons after encountering a near-death experience (the blob of aluminum on spark plug syndrome).....maybe you'll get lucky too!!

[gaineso]

sosmerc

Thanks for the tips. Went to the ICW and backed it in. Made sure all the tie downs were tight.

Cranked right up. Timing at idle, about 750 RPM in gear in the water was -3* on all 6.

Reved it up to 2000 RPM in gear, boat shaking a little and had 35* on all 6.

Went WFO and only checked 1 and 4 cause it was making me nervous and there were a couple of boats coming in to the ramp. 35*.

Bias voltage at idle was 4.5 to 5.0 varying and at 2500 on the hose was varying from 8.0 to 9.0.

I know that timing number is seriously bad. What next?

[sosmerc]

Did you try adjusting the max advance timing stop in to bring the timing back down to 18?
Do you have the correct factory manual for your engine?

[gaineso]

I've got a manual ordered from Rickracer, but I don't think it's the Merc book. Not going to try anything else until I get a book.

Want to be sure what I'm adjusting.

[sosmerc]

That's very smart on your part. I can't believe the number of folks that try to work on their stuff without proper tools or manual.
Heck, I've been in the business for over 25 years and I still feel comfortable only when I know I have the correct information at my disposal. My brain is a very small hard-drive...and I'll take all the help I can find!!

[gaineso]

Thanks for the confirmation. Gonna call BTB tomorrow to check on delivery.

[sho305]

My '73 inline is set to 23 on the starter w/ plugs out, but my lake is short too. I have to find a dial indicator to set it and check it in the water like that. Did you sport a cool rooster? Would have been worth it to me:cool:

I think my thnderbolt distributor ignition is different than yours. I only use premo gas, and it says 23 on the motor but the manuals all say 21. Gave more grunt out of the hole that way.

[gaineso]

Gonna try it today with the plugs out spinning the engine on the starter at WOT. Just for a comparo.

Yeah, it was throwing some water. I actually tried to keep the roost down some 'cause I wanted to be sure the water pickups stayed buried and I didn't want to back in any further than absolutely necessary. Salt water and I didn't want to splash it all over the motor with the cowl off.

[sho305]

I forgot, I turned the timing up higher than 23. It had more power that way, but I still get my last mph top speed at the far end of the lake:) It has the belt driven distributor on it, and I am going to set it before I run it again to be safe. I think it retards from idle setting too, but I want to know for sure. Mostly only helped on the holeshot anyway. Mine has the high dome pistons too, so I should not be doing that even with the 94 octane.

35 sounds way out of line though. Has to be something wrong there. Mine just has a stop on the distributor for rotation. My Clymer goes to '89, and says 20 on starter and 18 running for 90-140 inline distributor-less I6. Looks like there is two screws together and the right one is the max advance. Also says these figures are to be set with the idle stabilizer disconnected.

[gaineso]

Thanks sho305. I know the 35* is way out of line. I think the idiots at Sebastian Harbor didn't know a lot more about it than I do.

I've got a book ordered from Rickracer and I'm not gonna go any further until I have the book in front of me. I want to be sure what I'm doing, unlike the people at some dealers.

[sho305]

I can send you a copy of my clymers pages...so long as you return it when your done to be legal:D and I will not look at it while you do:eek: ;) Maybe I can scan it to a jpg and email ya. Only 2 pages for yours I think?

[gaineso]

sho305, that would be very helpful, Barbara said that mine should be there and then here sometime the middle of next week. I am trying to do whatever I do correctly and don't want to rush through this, but it is hard to be patient.

At this point I'm not sure if I'm gonna tear it completely down, but whatever I do, I want to be very sure what happened BEFORE I tear it apart or decide to run it. I don't want the same thing to happen again, ever.

Still think I need to put a V-6 on it, but maybe next year.

[sho305]

Check your mail:cool: let me know.

[gaineso]

Latest:

I figured out I screwed up when I checked the timing at the ramp. It was actually 17* not 35*. Sears Advance Timing Light reads double on this engine.

Checked advance with plugs out in the garage and all 6 at WOT are within about 3* and all close to 18*.

Did compression, cold WOT, and got 132 to 136 on all 6. Leakdown, using Balzy's tester, was 96 to 97 on all 6. On easing down from Top Center, just before exhaust ports, there was a small area where it would drop to about 70% and then back to 95% and then exhaust. This was on all six at the same place. No way to check it coming up from intake. It was all I could do to hold it going down. No way to pull aginst it coming up.

Going to go back to ramp and try full compression test again, but can't do it until Monday or Tuesday. For one thing, you can't get close to ramps on the weekend.

sho305, I accidently deleted your e-mail just as I realized it was from you not spam. Please forgive a too fast spam finger and resend.

Thanks all

[sho305]

Just sent it, hope not too big:)

Mine only gets 120-122psi, but on an old tester. Nice tool but maybe I should test the psi it reads. Or it is that low.

[gaineso]

I got the pages. About 8 minutes download. Found one problem. Maybe. The way it describes the idle stabilizer hookup is different than the way it was on my motor and it really would not surprise me if it had been hooked up wrong and ran anyway, just not right in mid-range. I know that the guy that worked on it has been known to (very frequently) have a little too much to drink.

I just didn't think I was ready to dig into this thing. Of course, I wasn't and S&Fer then. Guess I was lucky it ran as long as it did. I'll definitely do it myself from now on.

I think 120# is probably pretty good from everything I've read here. Especially if they are all uniform. For some reason, my motor is just very tight. I used 2 different compression testers, a new Actron from Advance Auto Parts and an old Mac Tools. They both read together as close as I could read the dials.

Gotta read those pages again to be sure I do it right. Went ahead and put in the new water pump impeller I got from Rickracer. By the book, I had sufficient water pressure anyway, but I just wanted to be sure.

Thanks a bunch for the help.

[sho305]

Think I have the wiring diagram too, hold on....:)

[gaineso]

Don't know how different the wiring is for a V-6 as opposed to my I-6, but that is NOT the way my idle stabilizer was connected.

Everything I've seen on this site says to lose the d**ned thing anyway.

Thanks again sho305

[sho305]

After I put the 20p Laser on mine, I had to run the idle about 900-1000 in neutral or it dies when I shift forward. Sometimes I still have to gas it as soon as it gets in gear to keep it running; like when cold. I'll get that safety switch out of there before I run it anymore. Maybe a hotfoot too:) Not a problem with the aluminum prop. It will run pretty slow in gear, just the shift is too much with that heavy cupped prop. It seems like it would idle better if the carbs shut off more so I could run more timing, but maybe not. They have big air flow for the idle passages, the boat is trolling pretty fast before the carbs move.

Have to take this manual with a grain of salt, I seen other screwups in there. Could be they just couldn't follow all the changes from Merc. It does say V6 for it, just thought maybe it was the same. Nothing found there for the I6 stablizer.

[gaineso]

The test page say V-6 but the diagrams say 90, 115 and 140 and I know they never built 90 or 115 V-6s. I'm gonna assume that's right, but the stabilizer is in a box on the shelf anyway.