Spark issuse solved, now low compression in one cylinder

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

It does run, I just do not want to damage it further.

What do I look for once I get the covers off? How do I change the rings? What if it's a warped cylinder? Sorry, I'm WAY New at going inside the motor. I mess with the outside stuff. I've cleaned the starter, replaced brushes, coils, plugs, etc. but when it gets in lower units and motors, I know nothing....

You are not going to change the rings, that would not be easy. Take the covers off, take and post pictures. You may find that just the gaskets are leaking.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

You are not going to change the rings, that would not be easy. Take the covers off, take and post pictures. You may find that just the gaskets are leaking.

Thank you sir. I really appreciate it. I'll do that. Just nervous about breaking a bolt. I'll use penetrating lube over a few days to help it soak in to prevent that. What is the torque setting for replacing the covers? You also need new gaskets right?

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Thank you sir. I really appreciate it. I'll do that. Just nervous about breaking a bolt. I'll use penetrating lube over a few days to help it soak in to prevent that. What is the torque setting for replacing the covers? You also need new gaskets right?

Go one step at a time.

Step 1.
With box end wrench, crack each bolt loose half turn. Do not use a big breaker bar or impact wrench. With a short wrench, you won't break a bolt by hand. If one doesn't easily turn, skip it and go on to next one. After you break loose as many as possible (hopefully all), spray with PB Blaster, let soak 20 minutes, turn a full turn with wrench and squirt again. If some are stubborn, soak over night, tap bolts with a hammer and soak again overnight.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Can you tell by looking if a head gasket it blown? Signs of oil leakage, carbon, etc.? Or is it so minor that you can't see it?

Just thought I'd ask before removing the it. Also, you need to replace the gasket regardless once you've removed the cover right? Any special gasket sealant required for that?

 

[Rscardina]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

you should see where its leaking ...with 0 on 2 cylinders it should be apparent.

NO NOTHING on the gaskets...actually I think the gasket says right on it "do not use any sealers"...

now get to pullin those heads and tell us what you find

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

HOLY SMoKES!!

I just re-read JB's Compression test instructions and just noticed an important aspect of the test that I didn't do..."remove all the spark plugs".


What did that do and how did it affect the readings? (please say it didn't damage anything further)


After researching old threads on here, I'm keeping my fingers crossed that the low cylinder is just a bad gasket or leaking gasket and not a ring/warped cylinder. For $12.50, I can replace the gasket and possibly fix the issue. (I hope)

Thanks all!

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

HOLY SMoKES!!

I just re-read JB's Compression test instructions and just noticed an important aspect of the test that I didn't do..."remove all the spark plugs".


What did that do and how did it affect the readings? (please say it didn't damage anything further)


After researching old threads on here, I'm keeping my fingers crossed that the low cylinder is just a bad gasket or leaking gasket and not a ring/warped cylinder. For $12.50, I can replace the gasket and possibly fix the issue. (I hope)

Thanks all!

Be sure to ground all plug wires when cranking it over for the comp test. You did no further damage one plug at a time, but ground them.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Just to make sure I don't mess up things any futher, can you just pull the plugs, reconnect to the coil wires and ground the plugs to the motor? Is that how you ground them?

Also, by not pulling the plugs, would that affect the readings? I hope to check things again this weekend.

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Just to make sure I don't mess up things any futher, can you just pull the plugs, reconnect to the coil wires and ground the plugs to the motor? Is that how you ground them?

Also, by not pulling the plugs, would that affect the readings? I hope to check things again this weekend.

As long as you keep them grounded somehow, or not engage ignition circuit.
You can remote crank with ignition key off or pull kill switch and key crank.
You risk starting motor by not pulling all the plugs and cranking with key. You also risk a fire with all cylinders open and sparks flying. Standard practice is to pull all the plugs, your reading should be fine the way you did it..
Did you crack any bolts loose yet?

 

[pmosier]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Switch the coil in question at the power pack, if it fires it's not the coil. Sorry I didnt read through the whole thread, but the coils dont seem to go bad as often as the power packs in my limited experience.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Since I'm pulling the heads and replacing the gaskets, should I replace the outer gaskets on the front side of the head cover as well (where the spark plugs are). See below...

I applied the 1st round of PB Blaster tonight. I plan on cracking the head covers Saturday to peek inside. Keeping my fingers crossed it's not a warped cylinder or bad rings.

I also noticed a leak below the flywheel but I can't locate it on the parts assembly drawings at Evinrude.com. Anybody know the gasket that goes below the stator and on top of the powerhead/block? You can see some of the leak in the pic below.

 

[deputydog1]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Generally compression checks are with all plugs pulled - you'll get a bit higher reading this way due to the starter turning the motor over faster (no compression to slow it down. Either way will work and the differential is the biggest thing. If all are close, they are in similar condition. If one is way off, it indicates a problem. I've seen aircraft engines with even compressions that were less than 40% of factory new compressions that ran fine for years.

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Since I'm pulling the heads and replacing the gaskets, should I replace the outer gaskets on the front side of the head cover as well (where the spark plugs are). See below...

I applied the 1st round of PB Blaster tonight. I plan on cracking the head covers Saturday to peek inside. Keeping my fingers crossed it's not a warped cylinder or bad rings.

I also noticed a leak below the flywheel but I can't locate it on the parts assembly drawings at Evinrude.com. Anybody know the gasket that goes below the stator and on top of the powerhead/block? You can see some of the leak in the pic below.

Covers can be separated from heads, gaskets are to be replaced. The other possible leaks under flywheel would require removing flywheel. Stay with step 1 for now, pulling the heads. The low cylinder condition and resolution will determine next step. You can clean and try to determine what the other leaks might be (grease, oil, melted something?). Removing the lower cowling will make removing heads easier.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I didn't have much time to remove the head covers today but I did get my own compression gauge and retested the compression the right way with a freshly-charged battery, all spark plugs removed, and the kill switch engaged to prevent fire.

Compression test numbers were almost exactly the same as before (within 1-2psi). I didn't apply oil in the cylinder with only 70psi because there is a lot of oil leaking out of both top & bottom cylinders on the left side of the motor. Looked like it had more than enough oil in it to me and the gauge itself had oil on the end as I removed the gauge.

SO the big issue I have consisently found is the motor is hard to turn over due to the one cylinder with low compression. If you remove all the plugs, the motor is not hard to turn over. If you plug-in the compression gauge in any of the other cylinders but the bad one, the motor turns over fine. Basically like this... (Vrr-Vrr-Vrr-Vrr) When testing the bad cylinder the motor turned over like (Vrr-Vrr-Vrrrr-Vrr-Vrr-Vrrr) Forgive my written description of sound but its a definate and noticable difference. After adding all the plugs back in and turning the motor over, it's a little worse and seems like it's got a bad spot in the motor. Odly enough, when the motor cranks, it runs fine and not mis-fires, no motor shakes, nothing. Runs fine out of the water (on hose).


I'm going to pull the heads tomorrow and post pics. I'm also going to pull the bypass covers and take pics as well.


A) What does the hard-to-turn cylinder mean when it's plugged with a spark plug or gauge
B) How do you do a leak down test?

I have to say, having this forum is such a huge comfort. Special thanks to Craig who's taken time to help.

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Squirting some oil in a low compression cylinder will temporarily raise compression usually because the oil can seal leaking piston rings.

The different sound when cranking with your bad cylinder(#4, lower port side) plugged is hopefully the head gasket leak. If you can see oil/fuel leaking from port cylinder bank, it would be due to head gasket failure or corrosion. Head gasket failure can also leak water into the cylinder and cause internal damage. The water is turned into steam which steam cleans the interior of the cylinder, piston top and spark plugs. This leads to lack of lubrication and resulting wear on rings, piston, cylinder wall and bearings. Salt water makes things worse.

Once you have head removed, you will see what is going on. Best case scenario will be just gasket failure with no water intrusion. Worst case would be catastrophic corrosion. Bad, but not worse case would be scored cylinder walls. I would not suspect catastrophic corrosion because only one cylinder is low. The other cases can be totally cured or maybe just improved by sealing the cylinder with new gasket. Stopping the compression and/or water leak, improving performance and running it until it gives up. Or spending a lot more money on a rebuild which I would not do to a motor of that age.

I'll be out on the water tomorrow and will look for your post in the evening. Good luck and don't break a bolt. If any don't budge, stop. PB Blaster soak, tap on bolt, soak and wait a day. Crack loose what bolts you can, not much blaster will get down to threads until you crack them loose, so crack then spray and give them some time to soak. Turn the heads up to horizontal with trim/tilt will help it to run down the bolts. Based on the look of your pictures, you shouldn't have that much of a problem getting them turning, if they squeak give them a blast.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I took the boat out this afternoon to check and see if I resloved the firing issue. Replaced coil, boat runs great. Motor ran 5,150rpm at 40-42mph GPS on a 15ft modified V tri-hull fish-n-ski. That's about the best I've been able to get out of the boat since I got it.

Motor ran great, no stalls, no overheating, and seemed to idle a bit better. The motor still struggles to turn over on the one cylinder even with a fresh battery. Once the motor is warmed up, the motor turns over much easier and sounds as it should. No air leaks, just pressure on the cylinder and hesitates to turn over on the one cylinder. Not enough to stop the starter but enough to notice it's not normal.

Retested the compression while motor was warm. I got 120psi in 3 cylinders and 80 in the low cylinder. Shot some 2-cycle oil in the low cylinder and she jumped up to 120. I thought "bad ring, not bad gasket" as soon as that happened.

Since the motor runs so good, no mis-fires, no motor "shimmy" or shaking, I thought, must just be a bad ring. So I pulled the heads and this is what I got. See links below to images.

I noticed a bit of silver in the oil I shot in the lower cylinder (the one that's low between 70-80psi). Is that a sign of a scorched cylinder wall or bad ring? (please say ring)

I am also trying to trace a bad gasket somewhere. I think it's either the intake gasket to the powerhead in front of the crank or its the main bearing seal below the flywheel. It's leaking a lot of fuel/oil mix lately. Worse than when I got the tune-up. Seems to get worse the more I run the motor. Could this be creating or affecting my low compression?

I have a lot of centimental value with this boat and hate to sell it. At this point:

A) What are my options
B) How much cost am I looking at to get this fixed by a mechanic?
C) Can the mechanic simply replace the ring only or will it drop in pressure again later?
D) I want to be able to keep the boat. SHould I just put it back together and keep an eye on the cylinder? I still need to fix this leaking gasket though that's leaking fuel/oil mix. That's dangerous and bad fuel economy.

Gasket leak at intake or main bearing seal

Removal of head gasket - lower cylinder is the one with low compression

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Silver color in oil in lower cylinder? Is that the ring?

Lower cylinder - exhaust port

Top cylinder - notice fine machine scratches in wall, lower one was smooth and no scratches at all

Backside of gasket cover

Removal of bypass cover on lower cylinder

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Last post with pics....sorry so many.

Cylinder Ring

Cylinder at full stroke

 

[Craig-]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

Wow, a lot to look at and it looks really good for it's age. No broken bolts, no corrosion, water passages are clear and just a bit scaled. You have had some water in #4 and the rings are worn. Maybe a very small water leak starting in #2 but no signs of damage in #2. I would expect 1 & 3 to look like #2 based on comp test results, possibly #3 a bit worse because the lower cylinders normally get wet sooner.
Needs head gaskets and I would replace the water passage deflectors (the rubber hose looking pieces) even though they look really good, they might be ready to crumble.
Doing rings on #4 piston is your call and cylinders would need to be measured to see if they are still in round tolerance. Ring job involves splitting the crankcase open, uncapping rod and pulling piston at the very least and can get much more involved. I would run it like it is with new gaskets, you won't be at 100% but you'll have stopped the water damage from continuing and your compression may improve on all four. You saved the motor, a lot of money, and it will run like a good used one.
The leak on top is hard to judge from pictures. There is a case (crankcase head) that holds the top crankshaft bearing and seal. The case has an o-ring that seals it to the block, it may be leaking and the crankshaft seal may be leaking. No really that big of a concern unless you lose a lot of crankcase pressure and reeds don't fully close. From what you describe running-wise, I would think the reeds are working OK. If you want to change the o-ring and crank seal, you can probably do it yourself, involves pulling flywheel and you need a puller for that. Since the bolts all came out, the flywheel will probably pop off pretty easy too. You would be able to inspect the stator and timer base as well.

Well done.

 

[CaneCutter79]

Re: Bad coil or failing power pack??

Re: Bad coil or failing power pack??

I would run it like it is with new gaskets, you won't be at 100% but you'll have stopped the water damage from continuing and your compression may improve on all four. You saved the motor, a lot of money, and it will run like a good used one.

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.

If you want to change the o-ring and crank seal, you can probably do it yourself, involves pulling flywheel and you need a puller for that. Since the bolts all came out, the flywheel will probably pop off pretty easy too. You would be able to inspect the stator and timer base as well.

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?