Head removed

[SweeperForce]

Hello,
This weekend I decided to pull the head. I wanted to inspect the cylinder walls and pistons plus install a new head gasket. Cylinders look great, no scratches, scoring or any defects. However there is a lot of carbon on top of each piston.
What is the recommended way to clean them off?


Thanks,
Tom

 

[pnwboat]

Re: Head removed

The amount of carbon that it on the pistons is pretty much normal and is probably not an issue. You can use some Power Tune by Mercury or Engine Tuner by OMC and apply to the dome of the piston and let it set overnight. You can take a screw driver or something similar and gently pick at the thicker carbon deposits and get all the loose stuff off. After you clean all the carbon off, it'll look about the same as it does now after you run it for a season.

The area where carbon build up causes a problem is in the ring grooves. The rings must have several thousands of an inch clearance to move in order to seal properly. When you get excessive carbon build up in the ring grooves, the ring seizes and no longer seals against the cylinder walls properly and can cause scoring.

You can inspect the rings by taking the by-pass port covers off. Take a small screw driver and gently push on the rings. You should see the rings move just a hair. If there is no movement at all, and you can see a lot of carbon in and around the groove, then it's seized up. If this is the case, then use liberal amounts of Power Tune or Engine Tuner overnight and see if you can free the rings up.

I just check the compression a couples of times each season and if no change, I don't do anything. Just run it like it is.

 

[Frank Acampora]

Re: Head removed

Agreed! Those are normal carbon deposits (For a higher hour engine--Obviously we would not expect this on a newly rebuilt engine). You can fix it 'till it breaks. Leave it alone and run it as it is. Are you aware that a new head gasket for that engine is over 60 bucks? That's why on mine I re-used the gasket when I replaced two pistons.

 

[SweeperForce]

Re: Head removed

Yeah I was shocked over the price. I found them anywhere between $53 to $85
I didn't want any of the carbon to flake off and clog the thin exhaust passages. But if you fellows say its fine that's good enough for me.
I'll just put the head back on after I buy the new gasket. Thanks for the replies

Tom

 

[SweeperForce]

Re: Head removed

I managed to separate the head cover from the head. I wanted to inspect the water passage after the thermostat opens and check for any occlusions or obstacles. Now there is no gasket listed and the book says to use a sealant when I put it back together. Can I just use ultra RTV black?

 

[pnwboat]

Re: Head removed

Yes, any good quality automotive type RTV sealant will work just fine. Make sure the sealing surfaces are very clean and oil free.

 

[jerryjerry05]

Re: Head removed

Yes any RTV sealant is ok.
Black is my color of choice.
The blue or copper color looks ugly.
The deposits are normal.
If you do a de-carb once or twice a year it will get rid of that.
pnwboat suggested Mercury's Power Tune or Engine Tuner they are both the same product and work way better than Seafoam.

Since the heads off, take a propane torch and heat the top of the pistons.
You can't hurt anything as the torch doesn't get that hot.
Then before it cools spray PT or ET on the top of the piston.
The PT/ET will work on a cold block but works way better on a hot part.
The carbon flaking off would worry me.
Doing a regular de-carb will stop the excess.