Consuming 4 liters oil per 600km!

[asavage]

Did crankcase ventilation change by changing the head gasket??

how can i know?

That was directed to Philip, not you. I do not think anything changed.

[after oil]

im real far behind on this. im afraid to work on my truck till summer when my wife dont work and we dont need two cars.
as is typical, a local mechanic says different than what you guys say. he says compression test will not reaveal for sure if the rings are bad. he says he did a test on a brand new chevy gasser. 200psi all cylinders. but when they took it apart found not a single ring was installed!
he suggessts leakdown test, but that it would actually be a waste of money and i should go ahead and tear it apart! perhaps ill rebuild the bottom end from my parts truck and just swap 'em later.

[philip]

-SNIP- He suggessts leakdown test, but that it would actually be a waste of money and i should go ahead and tear it apart!

A "leak down" is never a waste. A "leak down" will show pressured air ... leaking out through crank case (piston rings) or air leaking out inlet manifold and/or exhaust manifold (you would hear the lost air). Cyl valves. A little air lost is normal.

Now ... a lazy mech would poo poo "leak down" because he can make more money by going strait to your $$$.

[asavage]

A leakdown test only tests the compression rings, not the oil control ring, so your mechanic is correct in that a leakdown test wouldn't tell you a lot more than a straight-up compression test. But performing one or the other is a good idea to establish the baseline for future, as well as eliminating, say, a single scored cylinder. A compression test would tell you that that cylinder has low compression, a leakdown test would tell you how much leakage is from a cracked head, a leaking head gasket, a leaking valve, or via the rings/cylinder. You can do some juggling and glean some of that info from a compression test too, just not as accurately.

Yes, it's possible to have 200 PSI compression and no oil control ring. But in order to have 200 PSI compression, at least one of the compression rings must be installed.

Have you read the SD Comression Testing thread?

[after oil]

ok.. i'll have the tests done. al, can i borrow your compression test setup? i'll wait to have the leakdown test done, and ill see if someone else can do it besides the aforementioned mechanic. he's the same guy i went to with my head, but he might be the only guy in town that can do a leak down, i'll look into it

[philip]

ok.. i'll have the tests done.

Ya got nothing to lose here.

Cap off the crankcase pipe. Open the valve cover oil cap. With the engine at normal engine, idling, ... cover the valve opening using your palm for about 30-45 seconds. Now open away your palm.

Is there a sudden considerable POOF out of air (excessive crankcase loss)? Should be only a little.

A fluttering air with less than 1 lb of air pressure is correct.

[after oil]

thanks to al for the loan of his tester and adapters. i may have been able to get by w/o the adapter that he had made.
no. 1: 410
no. 2: 420
no. 3: 460
no. 4: 500

the back cover of the manual says standard is 427, minimum 356

what do i make of this?

[after oil]

Also, is there oil filling up near the rocker arms instead of falling back down through to the crankcase?

doesnt seem to be. there is some oil in there, though. i dont know whats normal.

now before i go and take the head off, should i do that leakdown test?

[asavage]

Are those number with all GPs out, and five to ten "puffs"? That 500 seems awfully high.

[after oil]

yes and yes

[asavage]

Off the top of my head, you might consider . . .

• Make up an adapter for my GP adapter to connect shop air to it.
• Bring a cylinder up to TDC, valves closed. Exact TDC is required.
• Remove oil filter.
• Use shop compressed air, pressurize cylinder to max shop air pressure (100 PSI or better).

Does the oil sitting in the oil filter base move? If so, you have an oil pressure galley leak to the combustion chamber. Possible leakage at head gasket interface (possibly somewhere else, but the oil consumption went up after you changed the HG, correct?).

[redmondjp]

Off the top of my head, you might consider . . .

• Make up an adapter for my GP adapter to connect shop air to it.
• Bring a cylinder up to TDC, valves closed. Exact TDC is required.
• Remove oil filter.
• Use shop compressed air, pressurize cylinder to max shop air pressure (100 PSI or better).

Does the oil sitting in the oil filter base move? If so, you have an oil pressure galley leak to the combustion chamber. Possible leakage at head gasket interface (possibly somewhere else, but the oil consumption went up after you changed the HG, correct?).

Al, I assume the emphasis on 'exact' TDC is an attempt to keep the crankshaft from rotating, balancing the broomstick, so to speak?

Another way to keep crank from spinning is to put a breaker bar on crank bolt with bar against a frame rail or the ground. I have used the compressed-air-into-the cylinder method several times to check for leaks on various vehicles, and I recommend the practice. In conjunction with a pressure gauge on the cooling system for cooling system leaks as well.

[after oil]

Make up an adapter for my GP adapter Wink to connect shop air to it.

i'll try to get on that tomorrow

Bring a cylinder up to TDC, valves closed. Exact TDC is required.

how do i know when the cylinder is TDC?

Remove oil filter.

stupid question: do i drain any oil first?

oil consumption went up after you changed the HG, correct?).

correct

Another way to keep crank from spinning is to put a breaker bar on crank bolt with bar against a frame rail or the ground

i can do that

[after oil]

Off the top of my head, you might consider . . .

* Make up an adapter for my GP adapter Wink to connect shop air to it.
* Bring a cylinder up to TDC, valves closed. Exact TDC is required.
* Remove oil filter.
* Use shop compressed air, pressurize cylinder to max shop air pressure (100 PSI or better).

Does the oil sitting in the oil filter base move? If so, you have an oil pressure galley leak to the combustion chamber. Possible leakage at head gasket interface (possibly somewhere else, but the oil consumption went up after you changed the HG, correct?).

i did it! or something very close. i am not sure where top dead centre is, but i guessed the pistion was there when a puff of air came out the glowplug hole. but i took the oil filter off first and did each cylinder, but the compressor i used only goes to 90 psi. i have access to a bigger compressor, but its a pain to move.

anyway, nothing conclusive happened

[asavage]

If you were able to get 90 PSI in each GP hole, and the valves for each cylinder were closed as you tested each cylinder, and no oil bubbled up out of the oil filter base during each test (with the filter removed) then I doubt you have a direct connection between the pressurized lube gallery and the combustion chamber.

What now?

Good compression (very good compression) but high oil consumption, commencing after having the head off.

Perhaps the shop left off all the intake valve stem seals?

A broken oil control ring would fit the symptom, but having the head off doesn't have anything to do with those.

Did the dipstick get damaged or replaced? I'm thinking perhaps a three liter overfill might get that symptom.

I think I am out of useful suggestions. I do not know how you could obtain 400+ PSI compression and have bad oil control rings at the same time. It is burning a lot of oil.