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Discussion Starter #1
My 1983 Datsun 280zx NA is now blowing smoke (lots at startup) and then more noticeable while accelerating. The smell is terrible and leaks into the cabin. I tore this engine down to the head 3 months ago. New gaskets, R&R the head along with new valve stems. The works. I know blue smoke indicates burning Oil but I just had the head resurfaced, valve stems replaced, new head bolt, new gaskets all around. I swapped the PCV hoping it would help. Am i screwed? Oil levels definitely dropping. No performance issues that I can tell. In fact, it runs great. Haven't run compression yet. Any thoughts, ideas welcome. Thanks all.
 

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Discussion Starter #3 (Edited)
Here are the results of compression. Nothing too out of the ordinary here is there?

Cyl,Dry,Wet
6 - 151 - 160
5 - 152 - 160
4 - 149 - 164
3 - 149 - 165
2 - 149 - 160
1 - 151 - 160
 

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.02c Are you sure the head gasket had proper holes for oil drainback from valve area? Might explain oil level "dropping" if oil is held on top of head. Also, lots of oil up there might be sucked in around the valve stems, more so on acceleration as pistons sucking harder (faster) on down stroke. .02c Take the cover off to check top of head.
 

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Discussion Starter #5
My 1983 Datsun 280zx NA is now blowing smoke (lots at startup) and then more noticeable while accelerating. The smell is terrible and leaks into the cabin. I tore this engine down to the head 3 months ago. New gaskets, R&R the head along with new valve stems. The works. I know blue smoke indicates burning Oil but I just had the head resurfaced, valve stems replaced, new head bolt, new gaskets all around. I swapped the PCV hoping it would help. Am i screwed? Oil levels definitely dropping. No performance issues that I can tell. In fact, it runs great. Haven't run compression yet. Any thoughts, ideas welcome. Thanks all.
Here is a picture of the head. Nothing too crazy that I can see except for some oil pooling.
 

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Mr.Collinsworth:

Call me pedantic, but I can't help wondering about the read of the plugs.

And how old are the rings?

As a discussion point, I would note that good compression rings do not guarantee the efficacy of the oil control rings...

Just a thought...
 

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Certainly no oil retention.
The PCV was replaced. Have you checked if the hose is "clear" so crankcase pressure is being relieved so as not to force oil around the rings?
 

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Discussion Starter #8
Certainly no oil retention.
The PCV was replaced. Have you checked if the hose is "clear" so crankcase pressure is being relieved so as not to force oil around the rings?
Dumbestone, ill check on the PCV hose. Also, are you not seeing an issue from the pictures of the cyl head? Is the pooling excessive in your opinion or cause for concern?
 

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No pooling of significance. If the returns were blocked there would be a "flood" of oil. Only see nooks and crannies....normal.

I seem to remember some years ago a member posted about a filter/screen in the OEM PCV hose. ... True?
But your hoses look fairly new, judging by the clamps used.
 

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Discussion Starter #10
Mr.Collinsworth:

Call me pedantic, but I can't help wondering about the read of the plugs.

And how old are the rings?

As a discussion point, I would note that good compression rings do not guarantee the efficacy of the oil control rings...

Just a thought...
Attached are the plugs. Im not very good at reading these.
 

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Don't look bad. Not a sign of significant oil in the cyliner, IMHO.
Do look like you're running lean or ignition timing off, with the white "fluff".
The gaps don't look even.
 

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Well, difference of opinion is what makes the world go round, I reckon...

When I look at your plugs, I see:

The gaps are not consistent.

You're not running rich.

Evidence of oil; from the deposits on the grounds, to those around the edges of the nose, to those in the threads. Not "excessive", but there.

Which leads me to wonder:

Did you have the chance to check the fit of the valve stems in the guides? It is not unheard of for new guides to be reamed a bit loose; and were the valves assembled with stem seals on the intakes?

It's getting in from somewhere....

Were it I, the plugs would be thoroughly cleaned with a solvent and a brass wire brush, from tip to gasket until they look new. Re-gap all to the same value (just a scosh tighter, I think), apply the thinnest of touches of alum. anti-seize rubbed deeply on the threads (and removing any excess.. a "dry" coat as it were), and then mix them up before re-stalling. Run them for a few days, with road time if you can, and pull them all again for another read. Taking these last shots of them in order again would be helpful. Stick with this heat range.


$.02 from the cheap seats.
 

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Well, difference of opinion is what makes the world go round, I reckon...

When I look at your plugs, I see:

The gaps are not consistent.

You're not running rich.

Evidence of oil; from the deposits on the grounds, to those around the edges of the nose, to those in the threads. Not "excessive", but there.

Which leads me to wonder:

Did you have the chance to check the fit of the valve stems in the guides? It is not unheard of for new guides to be reamed a bit loose; and were the valves assembled with stem seals on the intakes?

It's getting in from somewhere....

Were it I, the plugs would be thoroughly cleaned with a solvent and a brass wire brush, from tip to gasket until they look new. Re-gap all to the same value (just a scosh tighter, I think), apply the thinnest of touches of alum. anti-seize rubbed deeply on the threads (and removing any excess.. a "dry" coat as it were), and then mix them up before re-stalling. Run them for a few days, with road time if you can, and pull them all again for another read. Taking these last shots of them in order again would be helpful. Stick with this heat range.


$.02 from the cheap seats.
I was just going to mention valve stem seals but ensys beat me to it. I had a similar, but not as bad, problem with a rebuilt Bronco engine. Bad seals let oil leak down while sitting causing a good bit of smoke on start up. Also, smoke was evident on hare acceleration. Replaced with good seals and the problem went away.
 

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I was just going to mention valve stem seals but ensys beat me to it. I had a similar, but not as bad, problem with a rebuilt Bronco engine. Bad seals let oil leak down while sitting causing a good bit of smoke on start up. Also, smoke was evident on hare acceleration. Replaced with good seals and the problem went away.
A leak-down test will show the bad oil seals. (See response #2 of this thread)
 

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A leak-down test will show the bad oil seals. (See response #2 of this thread)
I thought a leak down test would show leaking valves, not valve stem seals. My rebuilt engine ran great and had great compression but the valve stem seals were leaking badly. Oil was leaking past the bad seals puddling on top of the closed valves and into the cylinder of the open valves. That’s why there was a lot of smoke on starting.
 

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I thought a leak down test would show leaking valves, not valve stem seals. My rebuilt engine ran great and had great compression but the valve stem seals were leaking badly. Oil was leaking past the bad seals puddling on top of the closed valves and into the cylinder of the open valves. That’s why there was a lot of smoke on starting.

Tabaka45 you are correct! I must have been smoking:wink
If the valves are closed, as they should be for the test, none of the leakdown air is going to get to the seals.
 

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Did you have the head re-surfaced? Did you 'straight-edge' the block and head? Pinch the head gasket? You said oil level is dropping - what about coolant level? You could have a gap in between the head/gasket/block... a smidgen is too much. Did you have the head magna-fluxed?



So many variables brother.
 

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Also I forgot to mention that I have seen working on these motors, A faulty/bad fuel injector, usually one that is stuck open or is leaking from the o-ring, will deliver too much fuel to the combustion chamber. The excess fuel won't properly burn in the cylinder and instead comes out as white or gray smoke..gray sometimes mistaken as blue. But, you are burning oil apparently so, double check the cracks in the head - possibly in a galley.
 
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