I just got an S4 TII engine back from being rebuilt and finally dropped it into my 88 'vert and hooked everything up. After a bit of fiddling with the wideband, a few sensors, and the megasquirt, she's firing up very quickly and consistantly. Yay... except for the white smoke pouring out the exhaust. It seemed to be dependant on oil pressure/rpm, and did not smell like coolant.







In hope that it wasnt the rebuild (after all the time, $, effort and running around to get it into the car), i pulled the turbo apart, and sure enough there was a lot of oil in the heat shields and turbo manifold (none in the compressor). Further disassembly showed a bunch of scoring and abrasion on a section of the turbine oil seal bore in the center housing. I changed the center housing with a different one that didnt have this marking (but was older, smelt a little of burnt oil, and had a cracked turbine manifold on it when i got it), replaced the brass bushings, thrust bearing and turbine oil seal (the piston-ring thing around the shaft), and put the wheels and housings from the first turbo onto it. Then this whole thing went back on the car. She still smokes, but it doesnt seem to be quite as much as before.







What else could be the problem?







It was an Ito rebuild, so I doubt that its the engine internals. I checked the new center housing, and it had the oil restrictor still in place. The crank case is T-ed with the charcoal canister and a line to the intake, pre-turbo, and unplugging this line did not seem to affect the amount of smoke (although it was hard to tell, it was getting dark). The engine's been run for about 3-4 hours total, 1 hour after the rebuilt turbo went back on, so it shouldnt be any sort of fogging oil or stuff from the rebuild. It's also idling at ~1500 rpm, so the intake manifold is coming off again after work to check for leaks.







Could an oil injector be leaking, and how would this be tested?







Thanks, and pics of the center housings are posted here.

i think the dirty uglier of your center housings is the better one. clean ones no good.



also how does the shaft look? if the shaft is worn then it will also leak there.



hard part on a turbo rotary is to isolate where the oils coming from soooOoo



is there oil in the ic piping? sounds like a no, but hey



oil on the spark plugs? if yes, then its pre turbo...



pcv, try a different routing, does it smoke with the oil cap off?



oil injection, the vacuum lines for that are supposed to go pre turbo, but ive seen em smoke a lot there, try a couple things

yea, i used the dirtier one, and cleaned it up in a bit of WD40 (soaked overnight). The other one is junk, that mashed up bit is right where the turbine oil seal would be



There is no pcv solenoid, I just have the vac hose from the fill neck straight to the intake or left open, it doesnt make a difference smoking-wise.



There didnt seem to be oil in the intake, and when I pulled a plug it was dry except for some black in the center around the electrode extending onto the face of the plug, but I think this may be from running really rich (in the process of tuning as well).



The center shaft looked ok, it may have been a little worn tho, it was pretty shiny. Around where the turbine oil seal was looked fine tho.

cool, sounds like its the turbine seal on the turbo then.



also sometimes if theres a LOT of oil in the exhaust, it takes a LONG time for it to burn completely out.



one of the fd's lost a turbo once, and it took 3-4 weeks for the thing to burn all the oil out of the mufflers

as an update, after a couple days driving with the rebuilt turbo, it finally stopped smoking. Its still a little on the rich side, but street-tuning is going well so far. Warm-up is a bit rough, and the accel enrichments are still off a little, but its drivable enough to get to work every day.

cool

Rebuild engines smoke like all hell for a little after you first start them up. It's all the engine lube burning off.

New oil control rings can smoke a bit on first startup until they seat properly I'm pretty sure as well...

yea, a bit more driving seems to have taken care of the smoking problem, altho its still eating oil at a faster-than-normal rate. Just gotta keep a couple quarts in the trunk til break-in is over and see what it does then