LT1 oil consumption

[FTA1995]

hope you figure it out
Did you by chance get do a leakdown like Fred suggested?
Valve seals examined?
Coolant/ excessive fuel in crankcase?
If it came down to it, exhaust gas chromatography?

[Craig 94 TA GT]

I haven't done any of this yet - I barely had time to do the PCV valve. I will monitor consumption though, and change to non-synthetic oil. If there's still consumption, then I'll check out the compression/leak down.

I don't lose any coolant though...I am getting some crap in the coolant though. I've been having heater clogging issues and flushed the coolant twice. The first flush was using a Prestone flush chemical and power flushed the heater core. The heat was good for a couple weeks but started getting lukewarm at most. Then I flushed it REALLY well, including a garden hose in the radiator and the knock sensor completely out. Ran the car for several minutes with the crap cycling through. It was completely clear after then. I refilled 2 quarts of coolant and the rest water - after about 3 weeks, I'm losing heat again. It's not cold, but it's not nearly as hot during the flush. Opening the radiator cap shows some particles, but I don't know if this is normal. I have no idea if this means anything for the issue or not though.

[Al 96 Ram Air T/A]

I believe I've figured out what is wrong.

You have a very small quantum singularity between cylinders 2 and 4. It's swallowing not only your oil, but now consuming the heat from your cooling system.


I think it's time to call in Scotty...

[Craig 94 TA GT]

Dang, so is it really possible I have a hairline fracture in the gasket where oil is getting in the coolant??

The thing is though, I can simply flush the core without refilling hardly any coolant (just top it off from removing the hoses from the water pump) and the heat will be back for a little bit. But the oil as a contaminant in the coolant does make sense because the coolant looks to have something in it within some miles, with brand new clean coolant.

I don't lose any coolant though - is it possible for this problem to be one way only? This will definitely show in a leak down test, right?

[Joe 1320]

Dang, so is it really possible I have a hairline fracture in the gasket where oil is getting in the coolant??

The thing is though, I can simply flush the core without refilling hardly any coolant (just top it off from removing the hoses from the water pump) and the heat will be back for a little bit. But the oil as a contaminant in the coolant does make sense because the coolant looks to have something in it within some miles, with brand new clean coolant.

I don't lose any coolant though - is it possible for this problem to be one way only? This will definitely show in a leak down test, right?

I'm not liking the sound of that. is it possible? Sure. Could be a fracture in the head around a bolt hole that allows oil to get into the water jacket. could even be a crack in the block. One thing for sure, if you have done a complete flush and within a couple weeks your system is contaminated again, you're likely seeing a breech in the system somewhere.

[Craig 94 TA GT]

That would be really unfortunate. Everything was new or rebuilt with the new motor. Advanced Induction heads, which are "Pressure and Hardness tested to ensure the casting's integrity & ability to seal," new Fel-pro gaskets, and a completely re-machined block.

It would explain why I'm only putting down 34x RWHP and only running 12.4, maybe due to compression loss. I have a compression tester and I'm wondering if I should try to use that before a leak down test (which I don't have yet).

- Is there a cylinder or two that I should target in the compression test, where it's prone to leak oil into a coolant passage?
- If I buy a leak down test kit, can I simply use a Black and Decker Air Station inflator to pump the air, similar to http://www.amazon.com/dp/B000IE0YIQ/...SIN=B000IE0YIQ
which inflates to 160 psi? I don't have a standard air compressor.

Thanks for your help.

[FTA1995]

Thats interesting that you brought up the loss of cabin heat, that happened to me and i lost a bit of power too..... maybe oil sludge or contaminants building up in the heater core???? Could be a sign... I

[Joe 1320]

Here's a few tricks that might be worth attempting. Remove the spark plugs, get a compressed air fitting that threads into the spark plug hole. Apply the compressed air to each CLOSED cylinder. You'll have to rotate the engine by hand to make sure both valves are closed. Any air leaks will be heard escaping into either the intake, exhaust, water or oil passages. If you block off the TB you can also pressure test the intake mainfold.

A cooling system pressure tester can be used to do the same thing to your coolant system, only I would do it dry instead of with fluid. You don't want to force water into the oil just in case. In all cases, you want to listen for the hissing sound of where the air is escaping to.

The only thing left is a pressure test of the oil system.


I have seen the #7 and #8 cylinders rearmost headbolts work loose and the threads become a mix of oil and water. Why I've only seen it in those two cylinders is a mystery to me, but I figured that I would throw that out there as something to check.

[Craig 94 TA GT]

Thanks Joe - I don't know how I'll get my hands on an air compressor though. I'll see what I can find.

I think a cooling system pressure test is a good idea. I may have not filled it well since the flush, but I noticed something weird. When I opened the cap (20 minutes after a long drive, so it was still pretty hot), it had picture #1 level. Also, notice the small particles - I have no idea what these are. Maybe from the old hoses or original radiator. After about 20 minutes, the level fell to picture #2. 30 minutes, it fell even more. I topped it off and it's starting to fall off again. I guess I either didn't top it off well, or there's an internal leak now that the cap is off and the system isn't pressurized.

The weird thing is that the coolant itself looks fine - no sludge, nothing detectable. Oil also looks and smells fine - no chocolate milk. Noting on the ground either

[Joe 1320]

he coolant level will rise and fall according to heat. It expands when hot, contracts when cool. Wonder what the particles are?

[Craig 94 TA GT]

Ahh, thanks Joe, I didn't think of the obvious! That makes me feel better - I was already thinking catastrophe - nothing holding pressure meant leaking internally. I'm glad it's just expansion.

I have no idea what the particles are. I would assume the block machiner didn't clean the passages well, or the hoses are getting old, or it's just corrosion in the system with metal randomly flaking from parts. I did notice that when I removed the thermostat housing, it looked horrible. A wire brush and sandpaper had to clean it up - there was just gunk all over. I would assume other parts of the cooling system would be like that, and possibly causing the debris. I'm not sure though. Does anyone perform coolant analysis?

[Joe 1320]

There could be crap coming from everywhere in that cooling system. The expansion tank may have crud in there that gets drawn back into the system when the fluid contracts. fluid analysis might be good.

[Injuneer]

Maybe someone added the GM stop-leak pellets.....

[Craig 94 TA GT]

I think that might explain it. I added some leak stop stuff several years ago. Although I did a few flushes since then, it probably just accumulated in the radiator and throughout unreplaced items in the cooling system. That makes me feel better though - that it's probably not something completely unknown.