Milky Oil, overheating and sheen in the water - AQ145A

Hi All,

Just recently got an 81 Gibson houseboat with a VP AQ145A motor. When I bought it, during a test drive we blew the radiator cap due to a failed raw water pump (it was the original VP impeller and all blades had been destroyed and clogged the tubes.). He knocked off 2500 bucks after some negotiations to compensate for a brand new motor.

I fixed the pump and cleared the tubes but ever since then I have had over heating issues. One suspect was the water intake. I'm going to connect a stainless steel hose directly from the copper tubing through the vent and into the water with a strainer on the end to take that out as a factor.

It was not till I changed the oil, that I started seeing a clearish sheen in the water coming from the exhaust. Checked the oil after running it a few times and it's now milky. Also I lost about a quart of oil. Suspecting a blown head gasket.

I've seen some threads mention the exhaust manifold sometimes being a culprit. How exactly would a bad (corroded) exhaust manifold cause water in the oil? When I pulled mine off, the insides had some pretty bad pitting. But only looked like where the exhaust was (on the wall between cylinder 3 and 4 ports there was a pretty good sized corroded hole). But not on any walls between where the water goes through the manifold separating the water and exhaust, or so that I can tell from looking inside.

Just ordered a new head gasket, and figured I'd do rings and rod bearings while in there. Just curious about the exhaust manifold. Any input is greatly appreciated.

Has anyone had similar problems? Any suggestions on things to check while tearing it apart?

Thanks!

Don't know about the overheating, but the current problem sounds like a failure in the oil cooler. Oil under pressure goes out into the raw water when engine is running and makes a sheen, water works its way the other direction into the oil when the engine is off, and make the oil milky when it is mixed in the next time you run.

Interesting, I just cleaned out the oil cooler when I checked the exhaust manifold. It was plugged pretty well with small rocks/shells etc. I will pull off the entire assembly once I drain the milky oil and let you know what the verdict is there. I just reassembled it with the same gaskets after...seemed fine.

I'm seeing ridiculous prices for a new cooler. ~ $766 dollars. Any recommendations on where to get a new one if necessary?

Welcome to boating.

Let me know what parts you might need. I have lot's of old V/P stuff.

If this engine's seawater pump was still using the original impeller..... I have several comments:

1...... I'm in disbelief! That's 33 years use.
2..... I'm amazed!
3..... The owner has shown a blatant disregard to maintenance! What else did he pay so little attention to????


I'd make certain that all previous impeller fin/blade debris had been found and retrieved.
The 145 uses a debris screen at the seawater intake on the heat exchanger.
Is this area clean and free flowing?
Has the water neck fitting and special beaded gasket been replaced?
Have the copper tube rubber rings been replaced?

I typically suggest to follow the incoming seawater path (no short cuts..... the entire path!) and examine all areas!
Check for any suction breach! The smallest breach here will prevent pump action.

Then follow the path from the pump to the H/E and beyond.
Check for debris, old impeller fins/blades, rust scale restriction, interior hose delamination (may not apply),etc.


These OEM systems work well. Something has changed, and is likely causing a restriction or a suction breach.



.

ericfragola said:

I'm seeing ridiculous prices for a new cooler. ~ $766 dollars. Any recommendations on where to get a new one if necessary?

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If you suspect the oil cooler, a good radiator shop can pressure test it for you. Most likely be able to plug or braze any bad tubes. If it turns out that the tube bundle isn't repairable, they show up on ebay quite often.

I've think you can by-pass the oil cooler instead of paying rediculous amounts for one. I think the AQ140 and AQ145 were the only VP OHC engine packages to have them. There are a lot of other models that didn't come with them so I don't think they are too necessary. It's just another part to fail.