Where's the oil getting out?

wire2

wire2

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I ran my 5.7 Alpha 1 on muffs 2 weeks ago, saw a purple sheen on the expelled water. Oil level showed low, I put a quart in. Took it for a short ride, checked, oil low again. It was overheated 1 time 9-10 years ago, intake was blocked by weeds and no alarm back then.

So, I'm thinking head gasket?

Can I test for that by putting 5-10 psi into thermostat housing?
 
Don S

Don S

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Re: Where's the oil getting out?

You can pressurize the cooling system, but that's not your problem. There are no oil pressure passages going into the head except returns to the oil pan. No pressure at all. Even with a raw water cooled system, there is a least a couple of PSI to keep gravity from going into it.
I would bet the compression and leaksdown tests will be fine also. Think about worn valve guides on the valves if you are loosing raw oil.
 
wire2

wire2

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Re: Where's the oil getting out?

Good point, Don, thanks. I'll see if I can find any other signs.
 
wire2

wire2

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Re: Where's the oil getting out?

Update; I topped up the oil this am, (It was down 1 quart again but not milky) and took it out on the lake. VERY slow, only 36 mph, some backfiring. Back to dock, pulled the plugs, starting at 1. Some had a few tiny drops of condensation, but #8 gurgled ~ 1 cup of water out. I'll round up a gasket set and pull the intake, heads, next Friday. I expect I'll find 1 or both heads slightly warped from the previous overheat, and the #8 gasket area failed. As luck would have it, I have a spare set of aluminum heads on the shelf.
 
D

Desertsky

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Re: Where's the oil getting out?

Overheating can also cause oil to be sucked into the intake of one or more cylinders due ro warped or cracked intake areas. Have the heads checked for cracks as well as flatness.
 
wire2

wire2

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Re: Where's the oil getting out?

Desertsky said:
Overheating can also cause oil to be sucked into the intake of one or more cylinders due ro warped or cracked intake areas. Have the heads checked for cracks as well as flatness.
Click to expand...

Possibly, but oil being drawn into the combustion chamber would cause smoke, and there is none, even with the thru-hulls open.

I sought out an experienced engine rebuilder today, he feels it's most likely a crack in the rear of the block along a drilled oil passage, with oil at 30-50 psi being pushed into the block coolant area. His recommended test is to pull the intake, install an air fitting in the oil sender hole, put 60 psi air into it. Then spray soap/water on the inner block and watch for bubbles near the drilled passages. Friday.
 
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