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Smoke from the exhaust on boost

Oh yes the fun and games removing the turbo [8|]
Been there done that and will probably be in there again as I should have replaced the catalytic convertor with a bypass at the same time and sent my turbo off for inspection and repair...
 
Sorry for the saga here but on investigating the inlet ducting and hoses, there is quite a bit of oil accumulating around the intercooler inlet and outlet so unless I'm missing something obvious the turbo requires a rebuild. From what I can see the rotor and bearings are fine but I guess the seals have gone. Here's hoping its not too much of a mission to remove.
 
When you say 'bearings seem ok'?...there should be no play whatsoever. I remember thinking mine felt ok until re-checking it after rebuild....:)
 
Fair amount of oil in the inlet can be from 2 sources, Air/Oil separator breather pipe which feeds back into the inlet. Or Turbo. I had similar issues several years ago and checked the compressor wheel for play, felt nice and 'tight' i.e. no play,but spun freely. However when I removed the turbo the turbine side had loads of lateral play in the bearing.
You can check the AOS by disconnecting the breather pipe from the intake, use a blanking cap, and run the pipe into an old coke bottle or similar strategically placed somewhere in the engine bay while you go for a 'spirited' drive. i.e build up the revs and boost. Oil build up in the bottle will almost certainly suggest crankcase pressure from ring blow by.
I ended up replacing the turbo and rebuilding the engine! Hope you're not in that territory as it's not cheap, but I enjoyed the experience.
 
Absolutely no radial or axial play that I can detect and nice free rotation but I guess the bearings are routinely replaced in any overhaul
 
Phil thanks for the advice on the AOS. So leaving the turbo aside, is the problem likely to be high crankcase pressure or can the AOS fail and cause oil in the inlet in which case I suppose its a cheap fix to replace or overhaul
 
Not sure how the AOS can fail as it's just a baffle tube with vent pipe (as far as I know, I've not opened one up), but I thought mine was leaking so replaced it last winter. It's a pig of a job, requires v.small hands to get the bottom bolt out! It may be worth removing it to give it a clean out, but unlikely to 'fail' unless it cracks and leaks oil everywhere. Alternative as has been suggested is to fit a separate AOS and run the engine AOS outlet to this (lots of folk do this mod, as have I). It's more of a performance mod than a solution to crankcase pressure issues. If you have a std car and want to keep it that way, I wouldn't do it.
 
I could be wrong but I seem to recall that the AOS has some form of coarse filter which can block with dirty oil/carbon build up and thus result in increased crank pressure. It's been a while so can't swear to this as fact

Pete
 
Nope the AOS is completely empty and just a void - worth checking the rubber hoses though that come off the AOS mine had split right underneath the intake manifold.


 
marojojoem said:
Sorry for the saga here but on investigating the inlet ducting and hoses, there is quite a bit of oil accumulating around the intercooler inlet and outlet so unless I'm missing something obvious the turbo requires a rebuild. From what I can see the rotor and bearings are fine but I guess the seals have gone. Here's hoping its not too much of a mission to remove.
Click to expand...
If they haven't been apart for a long time there usually is - might be worth cleaning them out and checking again after a 1000 miles or so,
Tony
 
I had the same problem with mine, grey smoke on boost, thought it was the turbo as some play in the shaft, had it rebuilt at Turbo Technics (lovely job) put all back together, still smoke on boost, turned out to be the AOS as suggested, had to take tubo etc out again to get at it, replaced with new one (an absolute pig to get out) job done.
 
It is possible to replace the AOS without removing the turbo. Just inlet manifold and heat plates. It's a real pig of a job though and you'll need to be a contortionist the get the bottom bolt out! I borrowed my wife's slender fingers for that job...
 
Hi I'm after a bit of support / encouragement. I have stripped away everything around the turbo so just a few bolts away from releasing the turbo for inspection / overhaul. Any tips for getting the bolts out from the exhaust, they all look pretty inaccessible, also which flanged joint am I unbolting, the one on the turbo or the flange lower down? So far its been a proper mission and doesn't look like getting easier!

The joint to the crossover pipe has been apart relatively recently so I'm hoping that will be the easier of the two.

Thanks in anticipation
Mark

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The turbo and the exhaust pipe (often called downpipe) attached to it come together as a unit.
The downpipe must be separated from the rest of the exhaust by removing the 3 bolts you can see and one bolt that attaches its 3 bolt flange to the engine block, which again is non-accessible from above. For this exact bolt I have found that a 13mm pipe socket was the best tool, and having access either from below, or from in between the left side member and the wishbone (from which you won't be able to see what you are doing but should be able to feel it and proceed blindly).
Proceeding from below however remains the least tedious solution.

If you are able to remove the bolt holding the downpipe to the block then you could probably award yourself a beer or two, as it is in my experience and opinion the most tedious bolt to deal with on the complete car, at least when the engine is still in. Good luck.
 
Thanks that's helpful, so getting underneath with enough clearance to get onto those bolts is the key. I will have a go in the next couple of days and report back!
 
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