New to me 1995 4.3 OMC Cobra in Chris Craft

[JJBoatr]

A compression test is an easy way to rule out a head gasket problem. If you have coolant flow issues which are evident by the riser temp being high, your engine may have overheated to a degree that could have blown the head gaskets or cracked the heads. If you can spare the money amidst this growing disappointment go get a compression gauge and check all your cylinders. Make sure the throttle is full open and you remove ALL the plugs while performing the test, it will save your battery and wear on the starter.

 

[bruceb58]

Or do a cylinder leak down test. Way better test than a compression test. Just hard to imagine its a head gasket issue with a non pressurized coolant system.

 

[Alaboat]

Well I'll report back in a few days. I took the boat to a shop yesterday and they will diagnose in a few days. Before I took it in, I pulled all of the plugs and turned engine over several times to blow as much water out of cylinders as I could and reinstalled plugs. Hopefully it will not begin to rust.

 

[JJBoatr]

bruceb58,

I agree that it is hard to imagine but it is easy to rule out. I hope his mechanic has some good news for him.

 

[Alaboat]

No good news on engine. Mechanic said 0 compression on #1 cylinder and varied low pressure on other cylinders. He also found a big crack near starter and was experiencing same starter problems that I had experienced. He said probably cracked block from either overheating (which previous owner had experienced right before I bought it) or improper winterization (which previous owner said he never did since it was stored in climate controlled warehouse. Either way, his recommendation was not to go any further into this engine which would only cost more money.Even if it is was blown head gasket or warped heads, there is still the issue of big crack near the starter. Wonder what caused that? Anyway, his initial recommendation would be a VP reman which would be nearly 3K and doesn't fool with other remans such as Donavan. Any thoughts?

 

[JJBoatr]

Wow, sorry to hear the bad news. I bought a long block Chevy 305 for $1849 shipped from a company called "1800runsnew", google it. Seemed to be well built, ran great (past tense because I sold the boat), and they didn't require a core return which is a big plus in my book. Came with a 2 year warrantee even with me installing it myself. I believe they offer 4.3's as well. Problem with your situation is you don't know the extent of your overheating/freeze damage. You may also have internally cracked exhaust manifolds, the flywheel could be damaged from crack near the starter etc etc. I would tear it down and determine what you have that is still useable before buying a long block. This boat may be a lost cause if there is too much collateral damage.

 

[bruceb58]

Your engine is likely not a Vortec engine. Find one of those. You will need a new intake manifold though.

http://www.michiganmotorz.com/vortec...ent-p-283.html

Big crack near the starter may be trying to start it with water in the cylinders.