highplainsdrifter

One of my 330hp 454's has water in it. I do not see water too much water in the oil that is in the pan, but when I run it, I see milky oil under the rocker cover when looking through the oil fill cap. That and the motor is not running well. Doesn't sound like something is broken, just runs poorly and is hard to start.

This is my current plan, let me know if I am on the right track or if there is something else I should do.

1) pull risers and check gaskets and general condition
2) compression test
3) pressure test oil cooler
4) pull heads
5) remove motor, disassemble and have block checked

Of course if one of the steps reveals a problem, I would fix that problem and then try running again.

The boat is new to me and was purchased as a winter project and I know nothing about the history of the boat. It was this way when I got it.

Thanks,
Russ

jdf4068

What is the engine temp. Sounds like condsate. Could be intake gasket leaking but your on the rite track

speicher lane

Compression test is step 1 and/or leak down test to zero in on the likely issues IMHO. That way you know how deep you are pulling apart in the final fix...

You are on the right track. Generally, a cracked block will be an instant milkshake in the oil pan but running poorly can be as simple as a pushed head gasket and water enters the system there

mike tkach

iTrader: (3)

i would perssure check the exhaust manifolds&risers first thing.

JohanSweden

I had the same problem with my Merc 496 MAG , water in the oil and the engine runs poorly.
I checked everything, leak down test, oil cooler.. The leak down test showed good results and I pressure tested the oil cooler with good results also.

Turned out to be the CMI exhaust, leaking tailpipes. I making new tailpipes for the moment, I hope it was the problem.




If you have after market exhaust like this you should check them before you tear the engine apart.
If you have original exhaust, check it anyway. But the aftermarket headers/tailpipes for $8k is not good quality as you can see..

oconnor marine

What year? Late 90's intake gaskets where an issue

highplainsdrifter

I did a compression test and all cylinders were 130-140 except 4 and 6 were 95 and 105 respectively.

It was hard to tell when removing the risers because the gaskets get tore up in removal, but it appears that one of them was leaking pretty badly because there was rust in the bottom of the manifold.

I have ordered a complete top end gasket kit that should be here tomorrow.

I am going to replace all the top gaskets and cross my fingers.

Thanks again for all the suggestions.