Smoking investigation.

I have started to try and get to the bottom of the cars intermittant smoking problem.
When i left it idling the other day for about 10-15mins there was a cloud of blueish smoke coming out the back.
Today i decided to run the engine with the oil feed to the turbo blocked off and stop the turbo spinning from the inlet side.
I left the engine running for the same amount of time - no smoke!
So that tells me the motor is good?
I then proceeded to refit the oil supply turbo and run the engine with the inlet hosing disconnected - again no smoke! So that tells me the turbo is ok?

On removing the inlet hosing there was fresh oil in the inlet to the turbo and also on the outlet from the intercooler! Could the oil be being sucked in from the filler neck?

When i ran the engine with this hose disconnected there wasn't any oil/smoke coming out from the filler neck,(but of course there was no vacuum on it at that point)!
Should there be a restrictor in the breather between filler neck and turbo?

Any ideas would be great as i don't know where to go from here!

There isn't any filter just one way valves and different bores I think .You have a catch tank ? Later models have a filter in the cap ,no tank , I don't think they connect to the turbo can't remember .I've put a later type setup on mine now but before had the tank .
Always had a very oily intercooler pipe after cooler as well but no great amount of smoke at all .I had a crank pressure prob that pushed oil out the dipstick though but this was down to way too much oil as the dipstick was wrong .

There isn't a catch tank on mine.The filler neck top has a guaze in it and then one pipe goes to the inlet manifold via a one way valve and the other goes to the hose before the turbo - this is where i find oil,enough to run if i remove the hose and tip it up!

Get rid then
AFAIK the pipe to turbo intake is emission control only .I disconnected mine and put a mini filter on the end of the pipe .You could install a temp catchtank to the pipe and see just how much oil was being expelled .If a lot then ...............................

Hello mate,
My car has possible the same symptoms’ as yours. Smokes on idle after about 15mins (when hot I might add) but not all the time which is annoying. On occasions it has happily ticked over for 60mins and no doubt would have lasted longer but i got bored, other times only 8 mins?
I like you disconnected all the pipes you are talking about, and initially thought i had hit the nail on the head, however While stuck in another traffic jam. It started to smoke again.(note engine breather pipe to atmosphere)
I have changed the turbo twice, after advice from those in the know.

To positively identify the above next time it smokes disconnect the breather and leave it running. But again this will not give conclusive evidence as my car used to miraculously stop smoking too.

What i found helps is just keep some revs on, this prevents the vacuum from sucking in the oil/fumes who knows!
Anyway I now firmly believe my valve stem seals are Fubar. To that end
I am having a different engine fitted at the moment by DG.
But once i receive my old engine back, I will strip to confirm or deny said valve stem guides/seals. However I have driven my car for 3 years with this problem and it has run fine. Took it to Scotland and back without a hitch.

Today i am going to check/replace the oneway valve in the inlet manifold.Maybe this isn't always working correctly and under boost oil,(collected in the guaze in the cap), is being blown through to the inlet before turbo!??
Just a thought,i will also be fitting a temp catch tank as Lee suggested just to try and help the diagnosis.
I know the car is reliable and the smoking isn't causing a problem but it is just SO embarassing.Everyone looks at the car because they don't know what it is and then they get engulfed in a ckloud of smoke!!!

Don't bother with the catch tank it makes no difference.
Mine has this, I have removed it cleaned it/ was clean anyway) refitted, same symptons. If you beleve your car has excess crankcase fumes etc just disconnect, breather from the intake to turbo(leave open to atmosphere) and also blank of breather to inlet manifold. However i did this and it still smoked.

Yes the problem is apparent on idle but also after long periods of overrun where again the engine will be on max vacuum.
Saying that though at idle there is no vacuum in the inlet side as this is handled by the IACV!?
I suppose there will be on the hose ,(with one way valve),to the manifold but there isn't on the inlet to the turbo!
There is no sign of excessive crankcase gases.

If the problem is stem seals then i can't understand why it is intermittant.Surely if a few are knackered they will be passing oil all the time!?
Why you get your car back i suppose we will find out once and for all!?

Cheers,
Neil

I think you're barking up the wrong tree with the crank case vent unless it's actually spitting oil out. The TT DeLorean has its air filters directly on the turbos so initially we had the crank case venting to the outside world by a simple filter. However this would spit an incredible amount of smoke on overrun. I then plumbed up a DeLorean style vent cap (two ports) putting a the filter on the larger one, and an in-line non return valve (from a Delorean brake servo feed) and straight to manifold vacuum on the smaller. This means that the engine always has a vacuum leak of sorts, but being MAP based, doesn't affect fuel metering. So unless the turbos are actually boosting, the crank case fumes are drawn in and burnt in the engine and produce NO SMOKE.

I think it's a more simple case of burning oil, and the two main culprits are turbo and stem seals... IMO. Unless it's more catastrophic and you have worn rings and liners, but it would have to be a seriously abused engine for that to happen.

Saying that though at idle there is no vacuum in the inlet side as this is handled by the IACV!?

No, your IACV valve is managing the air flow into the engine, and at idle, it's at its minimum, so the vacuum will be at its greatest EXCEPT when at overrun when the IACV valce is closed.

It really helps not to think in terms of vacuum, but just in terms of pressure.

Zero is absolute vacuum, 14.7psi (1 bar) is one atmosphere (WOT without boost), a bar of boost is 2 bar of pressure.

Sorry, thinking about it more - are you getting clouds of basically WHITE smoke, or are you getting blue? If the former, then I'd bet my bottom it's the exhaust side oil seal in the turbo.

I'm convinced its not turbo,as i have been speaking with Dave Miles and he has exactly the same symptons.
He has changed turbos but the fault is still their.
I am going for stem seals as the smoke is blue it is burning it from somewhere,i don't think it will be bottom end- hopefully.

I have spent the afternoon stripping down the engine and tomorrow all i have to do is unbolt the head bolts and i will see?
Is there any test i can do on the stem seals before i remove,to confirm a fault?
Or is it just a case of changing them and trying it? If that is the case i may be tempted to put the Laguna engine in and leave it as at atmo,at least that way i may be able to get som,e money back on parts!

You on the hunt for some cheap camshafts by any chance Martin??

Not from a 2.8 even fire

Stem seals... no, not really. BTW I have some new head gaskets ready to go if you need them.

Thanks for the offer on the gaskets Martin,i will let you know.
As i said before if i can't find anything obvious i may drop the Laguna lump in!