Cracked block or two blown head gaskets?

MFK27

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May 31, 2020
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1
Hi Everyone -

My husband and I recently bought a 2006 Malibu Wakesetter VLX with an Indmar 340 engine with 700 hours. Before buying, we test drove the boat for over an hour, checked engine oil before and after running, inspected the hull, have precious owner’s maintenance records, etc. Based on the following info, would probably hire someone to inspect the next boat we buy....life lessons

After using the boat for a little under 7 hours for wakeboarding and wakesurfing, we noticed the oil was milky. While in the water, we pulled out the oil and literally found 2-3 quarts of water. We then changed the oil and ran the boat again for 10 minutes back to the boat launch. Once we got it out of the water, we drained the oil again and found more milkshake/water. Based on our research we thought it might have been the exhaust manifolds leaking so we removed and found water in all cylinders (some more than others) We did a very basic test to see if the exhaust manifolds were cracked/leaking and the results indicate they were not. The extent of our knowledge about boat engines is limited, so we stopped there.

I should mention - the engine did not overheat but the engine was having trouble turning over once we hit the 7 hour mark (prior to emptying the water out of the engine).

Based on the symptoms I described, does this sound like two blown head gaskets or an internal crack to the block? The boat was winterized by a marina and we have the maintenance records to prove it. The marina who winterized is trying to tell us it’s two blown head gaskets (based on a compression test - where some of the cylinders apparently had ZERO compression) and another marina we went to for a second opinion does not believe that’s true and they are very confident it’s a crack in the block.

With that background info, how likely is it to blow two head gaskets simultaneously without an engine overheating/just generally? What is likely to cause that much water to enter the engine?

Really appreciate any perspective you can provide! Thank you.
 

alldodge

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Mar 8, 2009
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If (the big IF) it does have near zero compression then the head gasket would be blown.

From what I'm reading blown head gaskets would have the boat running real bad during the test ride. Oil was checked before and after and all looked good.

My thought is the block is cracked from improper winterization.

Suggest finding a certified mechanic and pay them to test.
 

Bondo

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Apr 17, 2002
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70,524
Ayuh,..... Welcome Aboard,...... Zero compression could be a head gasket, but that probably wouldn't put water in the oil,.....
A cracked block will put water in the oil, but not cause zero compression,.....

I suggest you need a 3rd opinion for a real Mechanic,.....
 

Lou C

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Nov 10, 2002
Messages
11,837
The problem with this question is that some engines with blown HGs will ingest water, some don’t. Some will have low compression some won’t. And there are other causes of low compression related to water ingestion such as rusty valve seats and stems. I had water in one cyl and a mist of water in another, with slow starting rough running that gradually smoothed out. I too thought it was exhaust manifolds but it wasn’t. I found exhaust gas in the cooling water and this can come from bad head gaskets a cracked cyl head or block. You probably won’t know for sure till you take apart but I would do a cooling system air pressure test and replace the manifold feed hoses with clear hose to check for exhaust gas bubbles in the cooling water.
PS my comp test results were close to normal not low at all, I found both HGs blown. Had heads checked both had cracks in the exhaust valve seats in the center cyls of the V6. I found two stuck valves when the heads came off. Block was fine. I replaced the heads with reman units 3 years ago and it’s still running well.
 
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jimmbo

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May 24, 2004
Messages
12,961
Any History of any other work done on the Engine?
 
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