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Cant figure out why I am burning oil


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I put an engine from a parts car I got into my 280z. I just wanted something to get it back on the road for the mean time. Engine looked clean from the outside, but I dont know the history of the motor. I did a compression test cold and got roughly 140 across the board. I decided to drop the engine in and got in running. I had a fews bugs that have all been sorted out and the engine starts runs and drives excellent(super smooth). But I have burned about 1 quart or more in less than 50 miles of driving and idling in my driveway.

 

The things I have done are...

 

checked the PCV valve: found it was faulty replaced

replaced all the valve seals: engine seems to not be blowing as large of clouds of smoke

I disconnected the PCV hose and valve cover breather. made no difference with smoke out the tail pipe

checked the plugs, They all have deposit on them. But none of them are wet.

 

The only things I can think of that are causing this are broken ringlands, Stuck oil control rings, and worn cylinder walls.

 

I dont know any tests to check if these are the problem though. 

 

Also I just noticed my oil pressure gauge isnt reading past 1/4 the gauge as rpm increases. I am going to look into this to figure out the problem. Could just be a faulty gauge or sender. But thought I would add that incase it could be an underlying cause...

 

What idea do you guys have?

Edited by stravi757
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^^^ as stated and cylinder leak down test or you can use compressed air into cylinder ( make sure valves are in closed position ) to see if you can hear air coming out of your valve cover ( at oil cap )  . How many quarts have you added so far ?

Edited by Domzs
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That is what Im am doing currently. It looks like the smoke is going down a little bit since Ive drivne it more. But I am reluctant to to take it out since the car isnt registered. not too much smoke while driving but it will build up when you let it idle. still blowing alot of visible smoke out the pipe though.

 

I will run the leak down test and see if that tells me anything. And ill give it a couple more hard runs or run some sort of additive maybe that might be able to break the oil rings free(if that is the problem)

 

Otherwise I do have two spare short blocks ready to drop in....i just dont want to....

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Just ran leak down test. 

 

Cylinders 1-6-2-5 all read 7-8% leakage. Not bad...

 

Cylinder  3 (plug was black, just a little bit wet) read 15% leakage.

 

cylinder 4, 50% plus leakage.....Reason, Crack in head gasket through coolant causing fluid in radiator to bubble.

 

Since I replaced the valve seals, I did notice the smoke was down a bit. I havent checked oil consumption since then. I suppose the rest of the smoke is burning water...Yes water not coolant. I hadn't put any coolant in yet.

 

I do wonder why cylinder leakage is near double on #3  compared to all the other cylinders though. I still feel as if there is a blue tint to the smoke. Maybe that cylinder is still burning some oil?

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