Spark issuse solved, now low compression in one cylinder

[petryshyn]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

is this a crack in the head gasket? or are my eyes failing me..... if so you have found the cause....

While in there, change out the deflector hoses.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

is this a crack in the head gasket? or are my eyes failing me..... if so you have found the cause....

While in there, change out the deflector hoses.

I didn't notice any cracks but could be. If it were the cause, injecting oil in the cylinder should not have increased the compression if it were a bad gasket. Thats only for rings right?

I have new gaskets coming in from my iboats order tomorrow. I hope to get the new gaskets on eventually. Too many things going on. I'll post up the results if I get any improvement on compression. As of now, I expect the same numbers since the cylinder wall is scorched a bit.

Considering the age, what are the chances the factory sealed heads have never been pulled in 31yrs till now! Paint was not cracked between the bolts and cover and no tool markings. That's a tough little motor!

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Not at 100%? That makes sense but the marginal difference must be very little or small enough I don't notice. If the spark issue had not have happened, I would have never checked the compression. The boat is running as strong as it ever has since I got it and last summer, it had 120-125psi in all 4 cylinders. I've only averaged 38-39mph and now I'm getting 39-40mph. Odd huh! I will definately keep an eye on that cylinder. If replacing the gasket increases pressure, all the better.


So how involved is that? Pulling flywheel makes me more nervous than pulling heads. Pulling the heads was so easy, I was lucky. All the bolts turned pretty easy with no tapping invovled. I think this is the first time they've been pulled because there were no tool marks at all. Original factory paint still on the bolt heads and the paint was not cracked between the bolts and the head cover. Amazing!


So if it's safe to run with only 3 strong cylinders and one weaker one, I'll run it a bit longer, keep an eye on it and possibly re-ring that cylinder this winter. Maybe then I'll track down that leak while I'm at it.

Again, thanks for all of your help. I very much appreciate it!



Anyone else want to offer advise based on my photos?

Compression will improve most noticeably in the leaking cylinder(s?), compressed charge will not escape, water will not enter, allowing proper ring lubrication. The oil in the fuel will do it's job and the ring seal will improve now that oil isn't being washed off. The excessive wear on the bad cylinder will show as the pressure difference on comp test post repair, not 100%.

Do your best to clean mating surfaces. Do not wire wheel or gouge them, hand clean with solvent, rag and a dull putty knife if you need it. Fine/medium scotch-bright pad is OK to use by hand, no power tools on aluminum.

Pulling flywheel is not very involved. It sits on the end of crankshaft in a tapered seat with a keyway that keeps it in a fixed position. Remove flywheel nut and spray blaster down in taper. Attach a harmonic balancer puller to flywheel using the threaded bolt holes, tighten down on puller and give center pushing bolt a hammer rap. If it doesn't pop off, let soak overnight, repeat. Repeat again if not successful, real stuck ones can take a few nights.

Safe to run with a low cylinder? Yes.
Do routine visual spark plug and comp tests to monitor.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I'll use a little engine cleaner to clean off the fuel/oil mix and run the motor (after replacing gaskets) to see if I can trace the leak. Depends on where the leak is as to when I'll replace the gasket.

Thanks for the help! I'm feeling much better now.

 

[Cap'n Chaos]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Isn't he going to need to re-torque the head bolts after x amount of hours?

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Went to a local mechanic today to take a look at the motor before I replace the gaskets. New gaskets are in and I just need time to work on the motor. He noticed the deination on the top half of the cylinder and said it looked like it was running lean and causing damage to the block from lack of lubrication, scorching the cylinder wall.

Another mechanic said if it has detination buildup on the cylinder, the timing could be off and it's time to rebuild.

From my previous posted image, the bottom cylinder has a silver buildup on the top half of the cylinder. Plus the cylinder is obviously "silver" and eating away on the powerhead. See pic below:

Basically, Mechanic A told me to replace head gasket, check compression, and it looks like it's running lean and might need need a carb rebuild or have clogged jet on that cylinder. If running fine after head gasket replacement, keep running it and keep close eye on motor temp and compression. I should probably mix the fuel a little richer since all the cylinders are running lean. (he looked at the plugs since they are all black and dirty.

So, if I had the cash, I'd probably rebuild it. Wife is so jealous of the boat she'd just assume strike a match and watch the boat burn before I invested another dollar in it so I guess I'm stuck with no rebuild for now and hope the motor doesn't get worse.

Any further thoughts on this issue? Again, many thanks to all those who have helped. I feel much more informed on my motor and I've learned a lot!

Also, do I need special hoses for the deflector hose or is there an OMC part number for the hose?

 

[Craig-]

Re: Spark issuse solved, now low compression in one cylinder

No mention of water by mechanics?

The silver is wear from loss of lubrication due to steam cleaning.

I don't see detonation damage, there is some slight pitting but that would be expected for the age. Plugs would also not be as you described if it were running lean and detonating. Don't run more oil than 50:1, even if it was running lean, that won't solve a lean condition. That actually could make it leaner. Lean is from lack of fuel for the amount of air being burned not lack of oil.

You should proceed as planned. The mechanics want you to spend money.
The water deflectors are a standard part, #0322411, replace all.

 

[CaneCutter79]

Re: Spark issuse solved, now low compression in one cylinder

You can't see the detination very well in the picture above. It looks like stuff is stuck to the top of the piston. I'll take another photo while I have the heads off.

I agree, I think water caused this problem. I should probably replace both head gaskets to prevent further damage on the other cylinders. The mechanic was a super guy and could tell I'm trying to do everything myself. He told me that I should rebuild the carb or inspect it to see if the clogged jet was causing the cylinder to run lean. He really was trying to help and not get me to "buy services" from him. He was impressed with my boats age/appearance, the current performance (considering) and wished me good luck. Pretty cool guy really considering how busy he was on an early Sat. morning. He said considering it's age and if it were his, he would proceed as you have noted (replace, recheck, test) and if the numbers didn't decrease, keep running it and to check frequently. As long as the warning buzzers work (he showed me how to check that too), everything should be OK.


So.......
If the spark plugs are black and carboned up, that is a result of too much oil/air and not enough fuel, thus running rich? Or is it too much feul and not enough oil that makes it lean? I'm getting myself confused....

Thanks!

 

[CaneCutter79]

Re: Spark issuse solved, now low compression in one cylinder

No mention of water by mechanics?

Actually I think he did. He just said it looked like it was running lean to him in addition.

From what I read in the repair manual, a smooth glass-like powerhead wall (like mine is now) can create compression loss. I guess the water created this damage? As long as water is not continuing to get into the cylinder, the motor should be fine even with a low cylinder from what you are saying correct?

The water deflectors are a standard part, #0322411, replace all.

I'm going to place another order from iboats to replace these and the bypass gaskets as well as the deflector hoses. Should I replace the cylinder head port hoses as well? They seem to be in great shape. Still holds factory paint and no dry-rot.


I found the deflector hoses on the Evinrude parts assembly drawing. I thought you were talking about the "cylinder head port hose" at the bottom. The water pass deflector hoses are inside the head cover. How do these work?

 

[itsaboattime]

Re: Spark issuse solved, now low compression in one cylinder

Cane, First congrats on tackling your motor troubles. When I first started reading this thread I figured it would end with you taking it to a repair shop.
Atta boy for doing it yourself and without breaking head bolts!!

Now, lets back up a bit. your spark test showed a weak spark on number 4 cylinder. You replaced the coil and your performance improved immediatly, right??
Looking at the pic of the head, I noticed ALOT of carbon built up on the head at #4 cylinder. I also agree that the head gasket is damaged and allowing water to enter that cylinder.

So, this is how I see it. The weak coil allowed carbon to build up in that cylinder due to not giving enough fire to burn all of the fuel/air mixture, making it run rich. You had your mechanic do a decarb. This loosened up the carbon in that cylinder and may have caused a weak gasket to pop and allow cooling water to enter the cylinder and "steam clean" the piston. This will also cause a lean and poor combustion in that cylinder. The fuel mix becomes diluted and can cause ring damage. Water isn't a lubercant. I believe you caught it before it could clean the head entirely. I bleieve there was more carbon there.

Now you have replaced the coil and will be replacing the head gasket taking care of both problems.
The main concern now is the low compression in that cylinder. Try this, while the head is off. Spray deep creep(sea foam in a spray can) all over that piston making sure the piston is covering the intake and exhaust ports. I believe, and sobody will argue with me I bet, that the rings are still hung up

I see no scoring or damage to that cylinder. I actually wish mine looked that good!!

Put it together and run it. Keep an eye on that cylinder. You have done it right. No mechanic needed.

 

[Craig-]

Re: Spark issuse solved, now low compression in one cylinder

Lean is not enough fuel in air/fuel ratio. Gas/oil ratio is not the same thing. Spark plugs will not look black and carbon crusted on lean cylinders. A lean condition results from fuel restriction or forcing more air through intake (not an issue in an outboard), usually clogged main carburetor jets. From what the pictures show, you don't have a lean condition.

The starboard head gasket is most likely in the same condition as port gasket and should be replaced. Deflectors control the travel direction of the water and should be replaced if bad and are usually replaced while you are in there as a matter of good practice. The leaking cylinder should be cleaned well, wipe up everything you can. Rotate crankshaft with heads off and wipe all cylinders with mineral spirits soaked rack, then coat with walls with a little 2 stroke oil. This should be done after you clean loose carbon, mineral scale and prepare the gasket surfaces.

 

[Craig-]

Re: Spark issuse solved, now low compression in one cylinder

1st photo of early detonation damage, may be argued pre-ignition, could be both.
2nd photo of severe detonation damage of motorcycle piston.
3rd photo of spark plugs general condition.

This is a good link about combustion.

http://www.abnormalcombustion.com/what-is-abnormal-combustion/

 

[CaneCutter79]

Re: Spark issuse solved, now low compression in one cylinder

OK so my plugs fall into the rich/oil categorie. What do I do to correct that issue? I've got new plugs too so I'll change them out also.

Should I try the Seafoam as suggested? I read that Seafoam damages gaskets/rings. I don't want to make things worse here...

Craig....how do you know so much about motors?

 

[Craig-]

Re: Spark issuse solved, now low compression in one cylinder

OK so my plugs fall into the rich/oil categorie. What do I do to correct that issue? I've got new plugs too so I'll change them out also.

Should I try the Seafoam as suggested? I read that Seafoam damages gaskets/rings. I don't want to make things worse here...

Craig....how do you know so much about motors?

Gap the new plugs correctly and run it a day on the water and pull the plugs and post plug photos, you can tune from there. Your tune is pretty good as it is, don't over oil.

The deep creep SeaFoam shouldn't hurt anything, you can use it to help break down the carbon buildup while the heads are off. Don't go nuts using it, shiny doesn't go fast.

Based on the photo you posted(attached), I think your rings are OK but you can't see them all the way around. I assume this is #4 cylinder. The black/brown towards top is from blow-by, but they don't look stuck and the blow-by should improve once oil isn't being washed away.

Experience and dirty hands a good part of my life.

 

[CaneCutter79]

Re: Spark issuse solved, now low compression in one cylinder

UPDATE
The saga continues...

So I get all the parts and finally get time to work on the motor and a bolt breaks off in the top cover of the cylinder cover. This one has two gaskets to replace, the top one and the main gasket.

I'm going to take the cylinder cover to a machine shop and let them extract the bolt vs. me trying to do it. I'd rather pay someone that I know can extract it without further damage.

Does this sound like the right approach?


So much for my fishing trip Sat. morning...maybe I'll get extra lucky and finsish up tomorrow night just in time to test the motor Sat. with a little fishing time.

 

[Craig-]

Re: Spark issuse solved, now low compression in one cylinder

UPDATE
The saga continues...

So I get all the parts and finally get time to work on the motor and a bolt breaks off in the top cover of the cylinder cover. This one has two gaskets to replace, the top one and the main gasket.

I'm going to take the cylinder cover to a machine shop and let them extract the bolt vs. me trying to do it. I'd rather pay someone that I know can extract it without further damage.

Does this sound like the right approach?


So much for my fishing trip Sat. morning...maybe I'll get extra lucky and finsish up tomorrow night just in time to test the motor Sat. with a little fishing time.

Awe that sucks. They were probably perfect inside too and never needed to be opened. Machine shop will get it out.

 

[CaneCutter79]

Re: Spark issuse solved, now low compression in one cylinder

The worst part is, I soaked all the bolts with PB Blaster several weeks ago. Most of the bolts were already really loose. I knew better and couldn't stop myself fast enough before it snapped. About the time I thought about PB Blaster and tapping, it snapped. It was that fast.

The bolt was corroded and rusted. Some of the other bolts that came out had a white chalky residue (galvanic action maybe?)

I took a tiny screwdriver and popped the gasket loose on the opposite end and white chalky powder is coming out. I'm ready to get the gasket cover off and see what's inside. Glad I'm replacing these gaskets too.


By the way, good call on the water bypass. They were deteriorating and pinched. They needed replacing.

 

[CaneCutter79]

Re: Spark issuse solved, now low compression in one cylinder

Great news! Took the cover to a local machine service. Awesome guy! He noticed the top plate had a thru-hole with no threads. He took out his pocket knife, pryed a little on the plate and the cover popped right off, exposing the broken bolt. He advised that I try a little heat and penetrating lube myself before bringing it to them for $50per hour service.

Took it home, applied heat, penetrating lube, tapped it with a hammer, applied vice grips, and cracked it loose. The bolt came right out!

I'd like to buy that guy a nice dinner!

Now.......hopefully I can get her all buttoned up this afternoon and test the compression. Then take her out on the water tomorrow morning for a little test run and enjoy some cooler fall weather and fish a little!

 

[rdenis]

Re: Spark issuse solved, now low compression in one cylinder

Great news! I may be hitting you up for some advice in the next few days depending on my compression and spark tests on my 79 115.

 

[Craig-]

Re: Spark issuse solved, now low compression in one cylinder

Great news! Took the cover to a local machine service. Awesome guy! He noticed the top plate had a thru-hole with no threads. He took out his pocket knife, pryed a little on the plate and the cover popped right off, exposing the broken bolt. He advised that I try a little heat and penetrating lube myself before bringing it to them for $50per hour service.

Took it home, applied heat, penetrating lube, tapped it with a hammer, applied vice grips, and cracked it loose. The bolt came right out!

I'd like to buy that guy a nice dinner!

Now.......hopefully I can get her all buttoned up this afternoon and test the compression. Then take her out on the water tomorrow morning for a little test run and enjoy some cooler fall weather and fish a little!

Cool fall weather? I went by a sign earlier that said 99 degrees! A little anti-seize grease on those bolts going back together.