No compression on one cylinder 93 Johnson 88 spl

[SteuryLover]

Just got back from a ride today, after I took off from the harbor my power went down. After chugging around on what felt like 3 cylinders I pulled it out of the water and did a compression test. The top left cylinder has little to no compression. It will pump air when my hand is put up to it, but will not register on my compression gauge. So here is now my question. Where should I start to find the problem? What are the different issues that would cause this problem. I do notice that there is some what looks to be calcium around the head gasket. I let a buddy use the boat a few weeks ago. He left it in the salt water and used it for 5 days before flushing. Would this cause the problem. Thanks in advance for everyone's help on this.

 

[ray 6688]

Re: No compression on one cylinder 93 Johnson 88 spl

Hi
Is the bore and piston crown ok ?No scores pits?
Sounds like a blown head gasket.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

Im gonna pull the head off tomorrow. Just trying to find out what im getting in to. Thanks for the response.

 

[ezeke]

Re: No compression on one cylinder 93 Johnson 88 spl

If the head gasket is OK, pull the bypass cover on the weak cylinder and inspect the rings. You won't be able to see it all, but it may be enough. Don't try to reuse the head gasket.

It is very unlikely that a week in salt water without flushing, in and of itself, had any effect whatever on the cylinders.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

Just some more info, the plug from the bad cylinder was steam cleaned while in the head. Assuming water in the cylinder. Any info would be appreciated.

 

[ezeke]

Re: No compression on one cylinder 93 Johnson 88 spl

If the spark plug looks steam cleaned it probably is, so get some oil in the cylinder as quickly as possible and keep it saturated with oil until you can replace the head gasket.

Head gaskets usually fail due to overheating. This would be a good time to inspect, renovate and repair your whole cooling system.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

It happened today, I will pull the head in the morning. Should I also replace the exhaust gasket? I do own a manual for this motor but it always seems vague. Anything I should know or look out for? What are the chances I broke the piston? Thanks for the quick response.

 

[steven88venture]

Re: No compression on one cylinder 93 Johnson 88 spl

how long did u run it after it started messing up and did it ever bog down cause iv been around several v6s and if they blow the head gasket running down the lake the most of the time score the cyl ant they usually bog when they do. but u can tell when u pull the head

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

Well pulled the head this morning. The head gasket was clearly blown. There was small amount of rust in the top cylinder. There also seemed to be a very small amount of moisture left. After closer inspection , the internals are fine. The pistons look great, the cylinder walls have no scores and the motor turns freely. Boy am I lucky! No I get to replace the head gasket and and locate the reason it overheated in the first place. Any advice on this job is appreciated. Thanks for the help.

 

[ezeke]

Re: No compression on one cylinder 93 Johnson 88 spl

Start with a complete new waterpump.

The thermostat kits from Sierra (#18-3673) have everything needed to rebuild the thermostat system.

Be sure to inspect the water deflectors (Sierra #18-0892 or OEM 322,411)to be sure that they are in the correct positions. After an overheat, you probably should replace them.

If you find a lot of salt in the cooling circuit, Salt-Away will remove it.

When you replace the cylinder head, be sure to torque the bolts to spec with a reliable torque wrench, then re-torque after running.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

Great, thanks for the info. I do own a gallon of Salt Away, I guess I should use it more often. Looking at the block, there seems to be 2 small tubes. Are near the cylinder walls. Are these the deflectors? Are they simple to replace? Also I have the tightening sequence, but what are the 3 steps of tq when fastening? I have the total amount of tq that should be applied, but I also read they should be gradually tightened up to the specified amount. Thanks for the help!

 

[ezeke]

Re: No compression on one cylinder 93 Johnson 88 spl

Small sections of rubber tubing make up the water deflectors; two per side. Click the thumbnail for the correctly located deflectors on a damaged starboard bank.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

How are these replaced? I cannot find any info in my manual. Thanks for the help.

 

[iwombat]

Re: No compression on one cylinder 93 Johnson 88 spl

You probably also want to plane the head and make sure it isn't warped. Put sandpaper and a piece of glass and move the head in a figure-8 motion.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

Does anyone know the part # or the options for the head gasket? I am looking to buy it here on I boats but cannot seem to locate it.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

wombat, that's sounds like a great way to do that. What grit do you recommend? Thanks again everyone for all the help on this. It is my first head job on a outboard.

 

[iwombat]

Re: No compression on one cylinder 93 Johnson 88 spl

I'd probably hit it with 200 wet/dry and just make sure to look for even abrasion patterns on the head indicating it's not warped.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

Got it, I am very familiar with automotive heads. I am sure I am looking for similar issues. Any worries on the block side? Can I safely use 200 to remove all the grit from the block surface as well. I also see a good amount of carbon on the lower cylinder, assuming now is the time to clean the piston off. Any tips on product or process to get all that carbon off? Thanks for the time.

 

[iwombat]

Re: No compression on one cylinder 93 Johnson 88 spl

No worries on the block side. I wouldn't use sandpaper to remove old gasket, you'll never remove it evenly that way. Use gasket remover and a gasket knife (or putty knife). Get yourself a can of seafoam deep creep to remove the carbon deposits.

 

[SteuryLover]

Re: No compression on one cylinder 93 Johnson 88 spl

Alright sounds good, now if I could find the head gasket here on iboats I can get started.