Head Gasket Problems

Joined
Jul 3, 2013
Messages
6
I am new to boating. Bought a 1988 crestliner with the OMC 3 litre engine. I took it out ant the head gasket blew. The mechanic told me head was warped and sent it out to be machined. I got the boat back and took it out for a test run and the gasket blew again within 5 minutes. Took it back to the mechanic and he looked it over and told me that the block may be warped and had to do some sanding or something to it. He told me that this should fix the problem. He also told me that it is expensive to machine the block as the engine has to come out along with the pistons etc. He did not charge me any extra for this sanding telling me it should be fine now. I took it out today to test it and again the head gasket blew. Not sure what to make of this. Can an engine block warp or is this mechanic giving me the gears. It's an old boat and may not be worth an expensive fix.
 

RogersJetboat454

Commander
Joined
Jul 9, 2010
Messages
2,964
Re: Head Gasket Problems

Welcome to Iboats.

Can an engine block warp.

Yes.
Between overheats, and the block shifting from regular heat cycles, it can change the trueness of the "deck" (surface on top of block that head gasket and head sit on). Typical remedy for this is to deck the block at a machine shop (milling machine precision cuts the surface back to true). Has this engine overheated at all? When you blow the gasket, is it actually damaging the gasket, or are you just getting water in the cylinders? Did the mechanic use a strait edge, and feeler gauges to check the surface of the deck for low spots?
 
Joined
Jul 3, 2013
Messages
6
Re: Head Gasket Problems

I've only owned the boat a short time. The temp guage didn't work at first so not sure if it over heated. once I replaced the sender unit it showed 160 ( not overheating ) If over heated it occurred before I bought it. The second time I took it in for the gasket the mechanic said that it appeared the problem had been ongoing for awhile as it caused a problem with the block. He assured me that after he sanded it or ground it whatever he did ( not machined ) that the problem would be fixed. I'm pretty sure he didn't look at the block the first time just the head.
 

RogersJetboat454

Commander
Joined
Jul 9, 2010
Messages
2,964
Re: Head Gasket Problems

Has the impeller been replaced?

Mechanics school 101, when a head gasket blows check BOTH the block and head(s) for warpage.
Like I asked before, is it certain that the gasket its self is failing (can you see a blow out on the gasket)?

Don't know about this sanding business. Some of the old timer mechanics can dress the block/head with a broad file, or piece of sand paper on a flat board, and get them close to true. But nothing beats getting the stuff milled to be sure.
 
Joined
Jul 3, 2013
Messages
6
Re: Head Gasket Problems

I Haven't seen the gasket , The mechanic did say that he saw a piece of the head gasket sticking out So I believe the head gasket blew out and not between the cylinders. I'm not sure what the impeller is but it has not been replaced to my knowledge. The engine was not overheating according to our temp gauge when we had it out testing it.
 
Joined
Jul 3, 2013
Messages
6
Re: Head Gasket Problems

Sorry I should also have mentioned that as the engine was running I could hear the sound of compression gasses escaping from the side of the motor
 
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