Turbo Chimaera smoking on overrun

[mattrosersv]

Hello all,

I have recently noticed that my turbo Chimaera has started chucking out a load of smoke on the overrun.

This is only noticeable on lift off after having a spirited foot to the floor type acceleration moment.

I can't notice any difference in performance

On the gas there is nothing remarkable going on with AFR

Car does not seem to be chewing through any oil or water.

Any ideas?? Turbo seals?

Cheers, Matt

[QBee]

Two things -

1. what colour is the smoke?
2. I use about a litre every 800-1000 miles in my turbo Saab, and am told it is the seals going, yet I don't have any smoke out the back.....

[mattrosersv]

Colour of smoke is light grey, but I am generally going pretty rapidly at this point so can't get a really good feel for whether this is fuel, oil or steam. At normal running/tickover there are no obvious signs

From the smell in the cockpit I suspect oil (I have a slight leak in one of the manifolds) - I am not running with live AFR adjustment before anyone asks.

I am going to pull the plugs, compression test and coolant sniffer test (I have one of those chemical test things).

From memory these are 2 x Saab turbos (Neal1980s old motor).

I **think** it might be popping a little more on overrun as well so was wondering if I have a slight miss at high revs/effort

Cheers,

Matt

Edited by mattrosersv on Monday 7th September 11:07

[900T-R]

Sounds like at least one of the turbos is expiring.

[neal1980]

Hi Matt,

Sounds like turbo seals to me. Mac had a similar problem and had the same symptoms.

Good news is the Turbo's were off a Subaru Impreza TD04's I was paying about £50.00 on ebay

You could probably get a seal kit for pennies!

Did I give you the spare turbo I had ??

[QBee]

I know nothing about turbos, other than fitted to Saabs.

But plenty of higher powered NA Chimaeras overfuel on the over-run, whether on the 14CUX or after market ECU, which is what causes the popping and banging, espcially decatted (and especially with a faulty exhaust). I have even had flames out of the back before i sorted out my exhaust.

I have followed one or two overfuelling Chimaeras, and seen a light blue/grey haze of unburnt fuel, both on hard acceleration and on the over run.

[900T-R]

Light grey smoke doesn't really point at rich running, though. When the turbo seals on my old 900 went, at first it was noticeable on the overrun, then if you left it idling for any period of time, ultimately it'd give anyone behind it the full James Bond smokescreen experience when standing at the lights.

[QBee]

Sorry for partial thread hi-jack, but it might help with the resolution.
Does anyone have any thoughts on why my 130,000 mile 56 reg Saab 9-5 Aero might be using so much oil? About 1 to 1.5 litres every 1000 miles. I have had similar Saabs before, never had this problem. No visible smoke, no dripping oil, no leaks visible. It is running fine, no strange noises, accelerates and drives well. I am using 0W40 fully synth oil as recommended. Baffled.
Turbo seals have been mentioned on the Saab forum and by my local dealer. But how can it be going into the turbo and not producing a cloud of white smoke?

[mattrosersv]

I expect it is effectively over-fueling at full bore - running 10.5 AFR at high boost iirc. I also have it set up to continue fuelling on ovrrun(can't remember the exact setting but it is configured on Megasquirt).

Seems a seal kit can be had for circa £30 - anyone done one of these - easy/complicated/special tools or puller require?

Neal, I think you did give me two turbos, one complete with turbo manifold, one without - I'll have to crawl around in my garage roof and hunt them out. Prob might be guessing which is causing the issue so will go with a couple of seal kits if diyable.

Thanks All!!

[N7GTX]

Same symptoms as mine. Turbo seals. A quick check is to see if the exhaust pipes are wet indicating presence of oil. Normally the soot is powdery black and dry.

[neal1980]

Plenty of guides online Matt, I did print one off just tried to find it but cant open it at work.

Search how to rebuild Td04 and theres a great step by step guide.

If you dont find it let me know will get it when I get home.

[mattrosersv]

Cheers Neal, I found a guide - looks easily doable......

[mattrosersv]

Sorry to be a pain Neal - Just trying to figure out which TD04s I have seems there are a few variants.

Any idea what year Impreza turbo they were off??

Cheers,

Matt

[neal1980]

1998 onwards I think Matt from memory.

There are bigger ones on the fancy subaru's sti etc but just get Boggo Impreza Model Td04 will be the same.

[mattrosersv]

Cheers Neal, I just found the serial number TD04L so as you say standard off the 2.0 UK cars I think.

[Richard 858]

Matt, I'd just supercharge it instead, that won't give you any problems

[Boosted LS1]

OP, you'll be pulling a lot of vacuam when you lift off. If an inspection of the turbo doesn't show oil in the wrong places then it could be valve stem seals.