Hi,
I have just bought a 740 turbo diesel from a garage.
A couple of days later I opened the bonnet and the whole turbo side of the engine bay was black with oil.
I established that oil was leaking from the join where the metal pipe on the high pressure side of the turbo goes into the metal box at the top of the engine.
I took it back, and they changed some seals and said that they had checked and everything else was fine.
A few days later and the leak is starting to come back; not nearly as bad as before but no doubt it will get worse.
So there are a couple of issues:
(1) If oil is leaking from the tube I must be losing at least a little boost pressure as well. However this may not be significant.
(2) Where is this oil coming from? The turbo has oil leads in and out ( to cool the turbo) and I think there is also a scavenger pipe which comes from the rocker cover area to feed any oil fumes back through the engine (as with most petrol cars as well). If there is enough oil in the inlet area to blow out under pressure then this must be coming from somewhere, and also the rest must be going through the inlet, the engine, and the exhaust. It is almost as if oil is collecting in the bottom of the box on top of the engine (presumably a reservoir for high pressure air by the inlet) then being forced out of the join. To coat the engine bay there must be quite a bit of oil leaking out, which suggests that even more may be going through the engine. Conversely it may (as above) just be collecting in the bottom of the box, which could mean a lot less oil being lost.
I know that remote diagnosis is always difficult, but does this sound like a worn out turbo which will never be cured, or did they just not do a very good job when they changed the seals?
They also told me they had to wait a while for some silicone sealant to cure before road testing the car. Does this sound like a reasonable thing to be doing, or is silicone sealant a 'bodge'?
TIA Dave R