Leak Down Test On Friday ...

[lookforjoe]

But there is shaft play in the turbo, up and down AND back and forth. Any play is a sign of a worn out turbo correct? I had the vacuum checked at the dipstick tube after my PCV system was "serviced" suspecting it hadn't been done correctly when the off idle smoke still persisted and was told it was well within factory spec, so they felt the PCV system had been serviced correctly. I had done a compression test a few months ago also and gotten a consistent 150-155psi across all cylinders at WOT.

No. Even new turbos can have some lateral/axial play. Does it have enough play to push the compressor wheel into the housing? any sign of scraping?

Since rebuild kits are only 70bucks on eBay (TDO4HL Flat Back for your turbo) I'd rebuild it anyway while you have the head off, if you've got over 150K on the car, after all, it's gonna go sometime. Of course, now would be the time to upgrade to a larger compressor :D

[mojojo]

Absolutely not.

Worn rings typically cause smoke at all times. Smoke from the tailpipe after sitting for long periods is from leaky valve stem seals.

...not forgetting to take in to account how worn the ring(s) are, they can eventually get to a point in which they will smoke at all times, but this 'behavior' has to start somewhere, and usually it's after prolonged periods of idling. The oil is passing by the rings at a rate in can not be burned completely and tends to build-up in the combustion chamber. Following, the initial off-idle rev forces the burning of the oil that has gathered, this is accomplished by the forces of thrust in the combustion chamber that force the rings in to cylinder walls sealing the cc.

Leaking valve guide seals usually show their face at initial smoke at start-up. The oil that gathers in the top-end soaks past the seals and is then burned once the engine starts.

Again, I'm assuming this would be a new symptom and not an ignored issue that has been prolonged to an extent that oil is sure to pass these points.

I've gained this understanding through factory backed training from two manufacturers, and real-world scenarios. This is me trying to diagnose over the internet. In the end, a compression and leak-down test is required to pin point issues.

[lookforjoe]

Valve stem seals cause the engine to leak internally.

For an external leak look at all the usual suspects. Is there a significant amount of oil under the spark plug cover? Double check those rear cam seals, if possible take a few things off so you can get a good look at them.

Not true. Exhaust valve seals, which are usually the ones that fail, leak into the exhaust ports, and from there into the manifold. The oil seeps past the old manifold gaskets, and soaks the manifold. On mine you could watch the oil vapor rise off the manifold, and of course it stank in the pass. compartment.

[mojojo]

Not true. Exhaust valve seals, which are usually the ones that fail, leak into the exhaust ports, and from there into the manifold. The oil seeps past the old manifold gaskets, and soaks the manifold. On mine you could watch the oil vapor rise off the manifold, and of course it stank in the pass. compartment.

I was thinking about this, especially after seeing your pics. I would have only assumed the exhaust valves be so hot to burn the oil, guess I was not considering the over-all condition of the seals.

[Ihatespeedbumps]

...not forgetting to take in to account how worn the ring(s) are, they can eventually get to a point in which they will smoke at all times, but this 'behavior' has to start somewhere, and usually it's after prolonged periods of idling. The oil is passing by the rings at a rate in can not be burned completely and tends to build-up in the combustion chamber. Following, the initial off-idle rev forces the burning of the oil that has gathered, this is accomplished by the forces of thrust in the combustion chamber that force the rings in to cylinder walls sealing the cc.

Leaking valve guide seals usually show their face at initial smoke at start-up. The oil that gathers in the top-end soaks past the seals and is then burned once the engine starts.

Again, I'm assuming this would be a new symptom and not an ignored issue that has been prolonged to an extent that oil is sure to pass these points.

I've gained this understanding through factory backed training from two manufacturers, and real-world scenarios. This is me trying to diagnose over the internet. In the end, a compression and leak-down test is required to pin point issues.

Yes, I think you correct, but not in this case. If were talking about ford 4.6L V8's this would absolutely be the case, but given the rarity of ring failures on these white engines, rings really are not the place to start. The valve stem seals are a known problem here.

Also, compression and leakage testing are the proper way to diagnose, but most members here don't have the luxury of that equipment.

Not true. Exhaust valve seals, which are usually the ones that fail, leak into the exhaust ports, and from there into the manifold. The oil seeps past the old manifold gaskets, and soaks the manifold. On mine you could watch the oil vapor rise off the manifold, and of course it stank in the pass. compartment.

Damn you had really bad seals. Thanks for correcting my error.

I will disagree about just the exhaust seals though. I've pulled the intake of many whiteblocks and found puddles of oil behind the intake valves. Out of curiosity, did you burn a valve with seals leaking that bad?

[mojojo]

Yes, I think you correct, but not in this case. If were talking about ford 4.6L V8's this would absolutely be the case, but given the rarity of ring failures on these white engines, rings really are not the place to start. The valve stem seals are a known problem here.

Also, compression and leakage testing are the proper way to diagnose, but most members here don't have the luxury of that equipment.

Well, I would be one not to assume an issue because it's oh-so-common to the car. I didn't say rings were the place to start, but only gave an example of my findings when I can further investigate be inspecting the internal components.

I am first to stress the importance of a compression and leak down test prior to diagnosing any running condition.

...thinking about my own methods, I have to realize I have a 'dealership tech' mentality. Meaning I always follow a certain path when diagnosing so that I can rule out the major effectors (in flow mechanical->ignition->fuel). But, at the same time I understand it's not always necessary to perform a mechanical test when one can observe in a fraction of the time, the fact that there's no fuel at the rail.

[lookforjoe]

[quote name='Ihatespeedbumps' date='01 March 2010 - 08:13 AM' timestamp='1267449223' post='1738725'

Damn you had really bad seals. Thanks for correcting my error.

I will disagree about just the exhaust seals though. I've pulled the intake of many whiteblocks and found puddles of oil behind the intake valves. Out of curiosity, did you burn a valve with seals leaking that bad?