Turbo smoke and other problems??
Discussion
Trying to get to the bottom of a problem with my CVH turbo engine. Full fresh rebuild about 2k miles ago, was running a brand new T04E turbo which lasted a week before it shat itself, horrendous smoke and oil consumption. I have a minor leak of exhaust gasses around the downpipe flange where liquid oil was being blown out. Replaced turbo for a slightly smokey but known good T3, still smokes terribly and doesn’t clear. Replaced again with another good T3 and still the same, oil return line on turbo is clear from any blockages, engine itself runs spot on and has good compression, all ports and plugs are dry with no fouling. Any ideas what this could be, I’m really stumped. I’ve seen healthy CVH turbo lumps blow filler caps and dipsticks out and still not for those that may suggest crankcase pressure being too high and mine doesn’t blow cap off??
I don’t think it’s engine related, there’s no oil in any engine ports or exhaust manifold before the turbo. PCV circuit seems fine, not sure about restrictor to turbo feed, I’ve not changed anything at all this has just all suddenly gone wrong. Like something is blocked somewhere and oil isn’t returning correctly for whatever reason
ProjectZS said:
not sure about restrictor to turbo feed
My limited understanding is that if it has a ball bearing it will need a regulated or restricted oil supply pressure to avoid blowing the bearing seals - if it has a journal type bearing it probably doesn't. The restrictor might just be an orifice in a connector or coupler and not obvious externally. It's the sort of thing that could easily be lost during a rebuild when replacing hoses or pipes.Oil is slightly overfilled, but not nearly enough to cause this problem, I’ve had more oil in it previously and it’s not done this. It is a journal type turbo, the oil drains directly downwards into a 45 degree pipe into the block, factory set up. No kinks in return pipe, this is the 3rd turbo it’s done this on now, 2 I knew we’re both good, doesn’t make any sense.
Have you done a leakdown test? If the original failure was down to e.g. a broken piston rather than turbo failure then no amount of new turbos would fix the problem.
When I bought my Fiat Coupe 20V (advertised very cheap with a "slight misfire") the first time I opened it up the smokescreen was like Days Of Thunder, road obliterated behind me. Turned out the previous owner had fitted a bleed valve and wound it up to the point of destroying the ring lands. It would run ok under part throttle/low boost though.
When I bought my Fiat Coupe 20V (advertised very cheap with a "slight misfire") the first time I opened it up the smokescreen was like Days Of Thunder, road obliterated behind me. Turned out the previous owner had fitted a bleed valve and wound it up to the point of destroying the ring lands. It would run ok under part throttle/low boost though.
Oil pressure does seem to be the most likely cause. I can't think of anything else that fits those symptoms.
Is it possible the supply side has been changed unintentionally and is now seeing more oil pressure - for example by being tapped off from a different point?
Any restriction on the return side would also raise the pressure. As well as being clear, it needs to be big enough to receive the total oil flow through the turbo without significant back pressure. If you crack the return line connector open a fraction, does oil seep out or spray out?
Is it possible the supply side has been changed unintentionally and is now seeing more oil pressure - for example by being tapped off from a different point?
Any restriction on the return side would also raise the pressure. As well as being clear, it needs to be big enough to receive the total oil flow through the turbo without significant back pressure. If you crack the return line connector open a fraction, does oil seep out or spray out?
Mr2Mike said:
Have you done a leakdown test? If the original failure was down to e.g. a broken piston rather than turbo failure then no amount of new turbos would fix the problem.
When I bought my Fiat Coupe 20V (advertised very cheap with a "slight misfire") the first time I opened it up the smokescreen was like Days Of Thunder, road obliterated behind me. Turned out the previous owner had fitted a bleed valve and wound it up to the point of destroying the ring lands. It would run ok under part throttle/low boost though.
As said in the original post, for it to be the engine to be causing the oil and the level of smoke on idle, it would HAVE to be misfiring, the quantity of oil in the downpipe is unreal, ligquid oil can be seen spraying from the downpipe join flange. When I bought my Fiat Coupe 20V (advertised very cheap with a "slight misfire") the first time I opened it up the smokescreen was like Days Of Thunder, road obliterated behind me. Turned out the previous owner had fitted a bleed valve and wound it up to the point of destroying the ring lands. It would run ok under part throttle/low boost though.
I know but with this is barely smokes whatsoever, in fact I can only assume the smoke When doing in this is the remaining oil in the downpipe burning off GreenV8S said:
I hope you mean oil return.
So this proves the problem is caused by the oil return - most likely, by backpressure when it is connected in the normal position.
No, the oil feed. I know disconnecting the oil feed to turbo is extremely rough, but simply to help diagnose it and the fact I have another 2 turbos which are in good condition, I tried this method to help eliminate the oil problem coming from the engine. When the oil feed to the turbo is connected it smokes very badly, when it is briefly disconnected and run straight into filler cap, the smoke almost entirely disappears. So this proves the problem is caused by the oil return - most likely, by backpressure when it is connected in the normal position.
ProjectZS said:
when it is briefly disconnected and run straight into filler cap
Oh, you mean disconnect the turbo end of the oil supply hose (and dump it back into the engine) so the turbo has no oil supply at all?That sounds like a bad idea but does confirm that the turbo is the source of the leak.
Have you checked the oil pressure on the return line?
GreenV8S said:
Oh, you mean disconnect the turbo end of the oil supply hose (and dump it back into the engine) so the turbo has no oil supply at all?
That sounds like a bad idea but does confirm that the turbo is the source of the leak.
Have you checked the oil pressure on the return line?
Oh I agree, it’s rough as, but got 2 spare good ones anyway, oil return seems to be working well, and oil return in block is clear That sounds like a bad idea but does confirm that the turbo is the source of the leak.
Have you checked the oil pressure on the return line?
Disconnect the drain and run it into a container...with the obvious proviso you dont run the engine until it's dry lol...
That way you can prove both oil supply and that you get a good visual on the drain in an ideal scenario. ie vertically down into an open container, with no bends, restrictions or crankcase pressure etc.
Really, it's a very simple and tried and tested engine setup, you should not be experiencing these problems and you should not need to be restricting the oil supply to the turbo.
So drain side and crankcase pressure/breathing would be likely suspects, if indeed the turbos are in good order.
That way you can prove both oil supply and that you get a good visual on the drain in an ideal scenario. ie vertically down into an open container, with no bends, restrictions or crankcase pressure etc.
Really, it's a very simple and tried and tested engine setup, you should not be experiencing these problems and you should not need to be restricting the oil supply to the turbo.
So drain side and crankcase pressure/breathing would be likely suspects, if indeed the turbos are in good order.
Boosted LS1 said:
Given what Stevie says what happens if you remove the oil filler cap?
In what way do you mean? There is no excessive crankcase pressure as far as I’m concerned, these have issues blowing filler caps and dipsticks out long before these sorts of issues I have neither of these symptoms either ProjectZS said:
There is no excessive crankcase pressure ... these have issues blowing filler caps and dipsticks out long before these sorts of issues
How much crank case pressure does it take to cause those other problems?How much back pressure does it need at the engine end of the turbo oil drain line to raise the oil pressure in the turbo far enough to push oil into the exhaust housing?
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