Head Gasket
 

1988 175HP Merc OB.

Its been missing, coughing and stalling. Found water in #1 cylinder. I'm guessing head gasket is leaking. My big problem is getting a mechanic to work on it.

Has anyone replaced the head gasket. Is it a do it yourself job?

Re: Head Gasket
 

I'd say easier than a car,cause of the ease of getting to it.If the bolts are not froze/corroded etc.Hit them straight on with a nylon hammer, squirt some nut loose if You have too.Tighten a lil then back off,tighten, back off ,You got the rythem.Should be ok.Finding a Head Man if needed is the hardest part.Gotta good one if Ya wanna hit the Keys'
Scream'n Reels' [img]images/icons/cool.gif[/img]

Re: Head Gasket
 

Oh Yea being a '88 it's a 4 Beer Job ! [img]images/icons/wink.gif[/img]

Re: Head Gasket
 

I am not familiar with Mercs but can say OMC of that vintage it is a fairly simple job. Have you checked the compression to verify your assumption of the problem being a head gasket? Have you checked your wtaer seperator to make sure it isnt full?
Good luck

Re: Head Gasket
 

Pulled the head off last night. Came off easier than I expected. All cylinders and piston heads looked good, not much carbon and no scoring etc. But one of the cylinder heads had a few dings as if something was banging around in there. If it was a piece of ring wouldn't there be some scoring etc. When I bought the boat this past spring I was told that its rebulit two seasons ago. Hope what I'm seeing is old damage. I'll put it back together this weekend and check the compression. Wish me luck because I'm out of money.

Re: Head Gasket
 

IF it was rebuilt then it could be old damage from when the engine went. You can get away with reusing a head that has pot marks in it to a certain degree. My guess is it falls in the ok list, otherwise the dealer would not have reused the head. He had to warry his job when he was done.

Re: Head Gasket
 

Those dings are not good. Check the cylinder walls around the water jacket as they tend to corrode and you will have water intrusion (very typical). Take the heads to a machine shop and have them "shaved" basically grinded straight so they fit nice and tight on the block. New gasket and gasket material a must. I hope this helps but make sure the water has not eaten thru the cylinder sleeve and allowing water to enter.

Re: Head Gasket
 

Replaced head gasket and checked compression. It was good at 120lbs #1,3,5 and 125 2,4 ,6. Tried to start it and then the real trouble started. Hard starting and no idle AND infrequent but very noticable knocking noise as if there was metal hitting metal or something flying around in there I guess my season that never really started is over.

Right now I'm inclined to pull the power head, open it up and see what is going on. Any suggestions or advice would be appreciated.

Thanks

Re: Head Gasket
 

relax partner.....we have been there and boy its frustrating. You have excellent compression which is very positive. Get your self a mechanics stethoscope from Discount Auto for 4 bucks. Isolate the noise,..where is it comming from. Here is the tip of the day...check the flywheel magnets...they go loose and make a heck of a grinding noise. If its comming from the base of the powerhead it may be the lower bearing (not good) but remain positive...have a soda and systematically determine where the noise is comming from. The hard starting could be a problem with the carburators, carb gaskets, or reed valves. But first thing first....dude bet ya its the magnets. Email me some good news.

Re: Head Gasket
 

Hi Roland,

If I could get it to idle long enough to listen I would try the stethoscope. It's not a grinding noise but a very definite knock, sort of "clack". When I pulled the head it was nicked. Could I have a broken piece of reed flying around in there accounting for the poor starting and ideling and noise?

I'm asssuming that because I have good compression I don't have a ring or cylinder wall problem. Am I correct?

Before pull the power head off I'll check the reeds.

Thanks.