smoking at decelleration

jpelfrey

New Member
After driving my 86 GN for a while at 55 - 60 mph, I see a cloud of blue smoke come out of the exhaust during decelleration. It doesn't smoke at start up, idle, or acceleration, only at decel. Car runs great, but the smoke is embarrasing. Any advise on where to start or possible fixes? Thanks!
 
The motor was rebuilt 9/06 at a reputable shop in Michigan soon before I bought it. I'm certainly not an expert on it yet. Here's what the job invoice lists for parts... New 208-209 camshaft, lifters, intake gaskets, valve cover gaskets, front cover gaskets, cam main and rod bearings, oil pan gasket, msd wires, egr valve, spark plugs, oil filter, exhaust flange gaskets, camshaft plug, hot wire kit, maf sensor, kenne bell fuel pressure guage. List of services...pull motor, Replace camshaft, frf motor and machine camshaft, replace all bearings. It most likely has @ 3000 miles since rebuild. It has a duttweiler intercooler and turbo and typical bolt ons. Not sure of exact type, sorry. It also has an ans turbo controller and knock sensor. I'm kind of learning my way with this car. Thanks.
 
I did not see any head work or mention of pistons and rings - sounds like you are sucking some oil past the valves - look in the up pipe
 
OK, I admit it...I have no idea what the hell I'm looking for. Never had the reason to work on it before, but I know how to turn a wrench. What is an up pipe and where is it located? Also, there's an annoying rattle in the wastegate and I unbolted the exhaust to see what was going on. First question...Should the lever be so tight you can't turn it by hand and should the round metal plug that covers the hole inside be so loose it spins easily? It appears that there's a crack in the weld that attaches the meatl plug part to the lever part. There's some condensation inside, is that normal? Just trying to kill a few birds with one stone. Thanks for the replies so far. Just remember that I'm an unfortunate novice, so please be kind. LOL.
 
The puck should spin freely. I don't know what you mean about the lever. Does the turbine or compressor wheel spin freely? Also, can you move either up and down or in and out? When does the waste gate rattle? From your original post it sounds like you may have bad turbo seals.
 
Up-pipe is the intake pipe between the intercooler and the throttle body. If there’s oil there trace it back to where it came from.

When the OEM turbo went bad on me I had the same symptoms as you described. As best as I can figure on deceleration the there is a vacuum created in the exhaust. If the oil seal in the turbo is damaged this vacuum sucks oil out of the turbo into the exhaust where it burns and creates smoke. Usually the oil seal/journal bearing is damaged by compressor stall (the fluttering noise when the throttle is let off right after boost (BTDT). My solution for this was a blow-off valve, which reduces the back pressure on the turbo.

The other suggestions of valve guide seals or rings could be the problem but valve guides will usually smoke at start up and rings will smoke at idle. Depends how good the rebuild was. I didn’t see any head work, head gaskets, pistons or rings on your list. It looks more like a patch job for bad bearings (lean detonation) and a wiped cam, not an engine rebuild, IMO. The fuel system was slightly upgraded to correct the lean condition. It is odd the head gasket didn’t go as they usually go first.

The waste gate lever should be able to flop back and forth. This was a common problem on the ATR downpipe (BTDT). The waste gate valve (round metal plug) should be relatively loose too. You probably salvage that downpipe although you may be better off with a new one, depends on your welding skills. Check out the downpipe parts from RJC Racing.

Condensation would be normal if the last time the car was run it didn’t heat up to normal op temp.
 
Thanks to all for the replies. I started to tear into it this morning and here's what I found. I found some oil in the up pipe. Not a lot, but I assume there should be none. The fins on the exhaust side of the turbo are pretty rusty, but spin freely and there's no movement in or out, up or down. On the intake/intercooler side, the fins spin freely but there seems to be some wear on the fins on the inside where it looks to be rubbing on the housing. There's a little movement up or down, but a lot in and out, @ 1/4". Also, I'm interested in a blow off valve if this will alleviate the problem in the furure. Please enlighten me on this if you will. I know I'll need a new turbo and I'm asking for some direction. I have a Garrett turbo with numbering/lettering on the side of OA/R 60 M24. Not sure which turbo will fit my needs. I'll probably order a new down pipe as well. If there's anything else that I'm missing, let me know. Again, thanks for all the help. I think it's truely awesome to have a group of people willing to share their experiences and advise with total strangers.
 
I'd like to stick with the same type turbo I have, just not sure which to order. I couldn't find the one I have on Garrett's website.
 
Here's what I came up with... Newer 208-209 camshaft, lifters, intake gaskets, valve cover gaskets, front cover gaskets, cam main and rod bearings, oil pan gasket, msd wires, egr valve, spark plugs, oil filter, exhaust flange gaskets, camshaft plug, hot wire kit, maf sensor, kenne bell fuel pressure guage set at 40 lbs (this was all done in '06). Additional info: Air research industrial division/garrett/duttweiler intercooler (PN 49200-2), K&N cone filter, ans controller and knock sensor, 43.5 lb. blue top injectors. Turbo 350 transmission, DTS axle w/373 gears, did have 411's, 275/50/15 BF goodrich g-force drag radials . This is all the information I know about the car. I live in Ohio and bought it last year from a guy in Michigan who claimed it's a 10 sec. car, high 9's on race gas/chip. I used to have an 86 T-type @ 10 years ago with some mods and this car is substantially faster. My goal would be to produce as much power I can without tearing something up internally. I'm pleased with the power it has now because I don't have much competition where I live, but we all could use more especially since I need a new turbo anyway. I'm telling my wife the same story by the way. Thanks for your help.
 
For giggles look at the corrugated metal pipe coming off the underside of the center turbo section.

My car used to smoke just like yours did. That pipe under WOT leaked.
 
I have the turbo off now, but I checked the pipe you mentioned all the way to the block, and it's as dry as a bone.
 
Back
Top