Blue smoke from exhaust - RS Cosworth engine

Blue smoke from exhaust - RS Cosworth engine

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danny tattersall

Original Poster:

731 posts

255 months

Monday 18th August 2014
quotequote all
Hi to all, I’m trying to diagnose a problem with my Mk1 Escort, fitted with a RS Cosworth turbo engine, and would appreciate any suggestions. It has not been used on the road since returning from a rolling road session in October last year, where there was no smoke whatsoever from the exhaust despite undergoing a full power run at over 7000 rpm. I did not start the engine for a couple of months after the rolling road session but since then it now emits a significant amount of blue smoke from the exhaust once fully up to temperature, in particular when the engine revs are increased and then drops back to idle speed. There is no smoke on start-up and there is not as much smoke at idle speed (although the exhaust gases do smell of smoke).

I have tried doing some fault diagnosis myself and started by checking for play in the turbo compressor shaft and oil in the air inlet pipes from the turbo through the intercooler and the inlet plenum. There was very little play in the turbo and no oil whatsoever on the inlet side of the engine so, suspecting a turbo oil seal leak, I proceeded to look at the exhaust side of the turbo. Rather than disconnecting the exhaust downpipe from the turbo I undid the oxygen / lambda sensor blank on the downpipe and once again there was no sign of oil whatsoever. The next step was to do a compression check of the engine which resulted in readings of @ 135psi across all 4 cylinders. These appear a bit on the low side but are even and are probably correct as the engine is fitted with low compression pistons to enable it to run 35 psi of boost. My final check was to run the engine with the oil filler cap off and this revealed the fact that there was no back pressure whatsoever.

The engine is a Cosworth YB200 long stud block fitted and, amongst many other things, is fitted with with accralite custom dish pistons, GT30 roller bearing turbo with TIAL external wastegate, BD16 inlet cams, BD10 exhaust cams etc, Bailey breather system. The engine runs and idles smoothly, and performed well on the rolling road, but seems to have developed the problem ever since. I am at a loss where to start looking next so any suggestions would be welcome.

Thanks in advance,

Danny.

stevieturbo

17,229 posts

246 months

Monday 18th August 2014
quotequote all
Maybe a blocked crankcase breather or something ?

Was nothing at all changed during the lay up ?

How long have you driven it now with this problem ?

jontysafe

2,351 posts

177 months

Monday 18th August 2014
quotequote all
Check that you have the correct oil pressure at the turbo for a start. Some people have had to go smaller than the 1mm restrictor that's used normally.

The oil in a GT30 is gravity drained and fitting a GT30 on a 4x4 exhaust manifold leaves VERY little room for this to be straight down which it needs to be.

Mine smokes on the overrun and I know it`s not guides or stem seals as they are new. I`m currently rebuilding as I melted a piston being stupid. I will probably go custom tubular manifold to make sure the oil drain works properly and also free up some horses. The 2wd mani would do the trick but won`t fit in my car (Westfield).
I will probably get the seals on the turbo done as well.

danny tattersall

Original Poster:

731 posts

255 months

Monday 18th August 2014
quotequote all
Hi Stevieturbo, good suggestion thanks, I've thought about the breather previously but not checked it yet because I can barely see the thing due how little room there is in the engine compartment! The breather system is an uprated Bailey item and for whatever reason I didn't think that it would be susceptible to blocking. Nothing at all was changed during the lay up and the car has only been started and warmed through periodically. It has not actually been driven on the road since. Maybe checking the breather and giving it a run will sort it out but it isn't currently insured for the road. It is possible that the high rpm run on the rolling road forced some oil through and choked up the breather. Other thoughts include valve stem oil seals, although they would have been replaced during the engine build and I would expect smoke on start up.

Regards,

Danny.



danny tattersall

Original Poster:

731 posts

255 months

Monday 18th August 2014
quotequote all
Hi Jontysafe, I've not got the equipment to check the oil pressure to the turbo but it has an oil restrictor in the oil feed line and was fine previously. Am I correct in thinking that it the oil feed pressure is too high, or the drain isn’t working correctly, there should be signs of oil in the exhaust downpipe immediately after the turbo?

Thanks in advance,

Danny.

stevieturbo

17,229 posts

246 months

Monday 18th August 2014
quotequote all
A GT30 should have the restrictor built in.

And if you can confirm there are no visible signs of oil passing on the turbine area/wheel, then it's unlikely to be the problem anyway

danny tattersall

Original Poster:

731 posts

255 months

Tuesday 19th August 2014
quotequote all
I haven't looked directly at the turbine wheel but there are no signs of any oil immediately downstream of where the exhaust bolts on to the turbo. It could be that the exhaust is already so hot at that point that it is burning it off immediately?


jontysafe

2,351 posts

177 months

Tuesday 19th August 2014
quotequote all
That's what I think, it's not a huge about of oil and is just being burnt off.

Just out of interest and not related what intake and exh manifolds are you on? What ecu are you using and who mapped it?

littleredrooster

5,523 posts

195 months

Tuesday 19th August 2014
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danny tattersall said:
...but since then it now emits a significant amount of blue smoke from the exhaust once fully up to temperature, in particular when the engine revs are increased and then drops back to idle speed.
That would suggest that oil is being sucked down the inlet guides - worn guides and/or hardened stem seals. Easy fix if it's just the seals.

fatjon

2,144 posts

212 months

Tuesday 19th August 2014
quotequote all
stevieturbo said:
A GT30 should have the restrictor built in.

And if you can confirm there are no visible signs of oil passing on the turbine area/wheel, then it's unlikely to be the problem anyway
I bought a pair of genuine GT2826RS turbos from Owen Developments and they insisted that they had a restrictor in but on close examination the orifices were about 2mm and it smoked like buggery until I added a 1mm restrictor. This was not at grossly excessive oil pressure either.

danny tattersall

Original Poster:

731 posts

255 months

Tuesday 19th August 2014
quotequote all
Thanks for all the suggestions. If the problem was related to the restrictor I would expect it to have been evident from the initial build. As for the valve seals it does seem possible, although I think they would degrade over a longer period of time rather than no smoke whatsoever to significant amounts over a period of a couple of months.



Hi Jontysafe, as far as I know the inlet manifold is from a RS 500 and the exhaust is a 4 x 4 manifold modified to fit an external wastegate within the tight engine bay (Mk1 Escort). The ECU it is a Pectel Super 8 fitted with anti-lag, nitrous and water injection control plus control of the 8 fuel injectors. It was live mapped by Tommy Field Motorsport.

Regards,

Danny.

Edited by danny tattersall on Tuesday 19th August 20:43

hman

7,487 posts

193 months

Tuesday 19th August 2014
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Would say valve guides or stem seals as well.

jontysafe

2,351 posts

177 months

Wednesday 20th August 2014
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Not seen a 4x4 exh manifold flowing more than 420- 430bhp before without nitrous. That's where I'm at with mine hence going bespoke tubular. Are you 550bhp on the gas then?

danny tattersall

Original Poster:

731 posts

255 months

Wednesday 20th August 2014
quotequote all
Jontysafe,

I'm not 100% sure about the exhaust manifold being a 4x4 item. The engine is 550 BHP without nitrous and 620 BHP with nitrous, although it is currently disconnected as none of the insurers that I approached would insure the car with nitrous fitted. To be honest the car has far more power than is necessary in a shell that is so light and appears to be 'pub bragging rights'. The guy that paid to have the car built went over the top on the specification; for example it is fitted with 4 x Bosch 044 fuel pumps!! If you are interested in seeing a picture of the manifold I can take one and PM you?

Danny.

stevieturbo

17,229 posts

246 months

Wednesday 20th August 2014
quotequote all
danny tattersall said:
Jontysafe,

I'm not 100% sure about the exhaust manifold being a 4x4 item. The engine is 550 BHP without nitrous and 620 BHP with nitrous, although it is currently disconnected as none of the insurers that I approached would insure the car with nitrous fitted. To be honest the car has far more power than is necessary in a shell that is so light and appears to be 'pub bragging rights'. The guy that paid to have the car built went over the top on the specification; for example it is fitted with 4 x Bosch 044 fuel pumps!! If you are interested in seeing a picture of the manifold I can take one and PM you?

Danny.
4 x 044 pumps, when a single would do 600hp no problem ?

Seems a bit strange.

jontysafe

2,351 posts

177 months

Thursday 21st August 2014
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Hello Danny,

It's normally the 2wd manifold that's modified for external wastegate and that will flow 550bhp no problem. I would think this is what's under the bonnet.

My set up is specced to 550bhp with a facet lift pump and single 044 but I would probably plump for 2 044s if you are over 600 with gas. 4 seems odd.

Car sounds absolutely awesome though. Would love a blast with you, mine wasn't exactly shy at 430bhp and 700kgs (with fuel and driver).
Alas this will not be until 2015 now.

Just ordered supertech pistons, race bearings, wrc head gasket, bearing set, HP oil pump and new oil cooler for rebuild.