High oil consumption

[AndyP]

I don't drive my S2 all that often but when I do I always check the oil and it occoured to me the other day that I'm always having to put a bit in. So I decided to check the consumption to see how much it's using. The figures are not good, it's using a litre of oil in 6-700miles approx. So here's what I know:-

-It does not smoke on start up, hot or cold
-It does not smoke on the overrun
-It does smoke, light grey, under hard acceleration
-A compression check shows all is the same as when the engine was built, all cylinders within 3.5%.
-Plugs are a little black, but it's a dry black soot not an oily black. It does run a little rich on WOT
-The turbo, GT3071R, was rebuilt about 3000miles ago due to worn oil seals.

I'm thinking that the turbo is defective again, but can anybody suggest any other checks I can do before I pull it and send it off for another re-build?

[Colesy]

Breather system? Mine was completely blocked, cleaning it out reduced oil comsumption by about 90%!

[JP]

Check the breather system have you got a catch tank? I know if I go and hammer it about for a bit oil will collect in the catchtank if I don't have the seperator draining back properly. Without a catchtank recirculating into the intake of the turbo it starts to fill the intercooler.

Alternativelly if all those are fine if the air filter is too restrictive in WOT the compressor side seals allow oil to be sucked through into the boost run. That happened on my first GT30 with stock airbox.

[AndyP]

It has a seperator and a catch tank. The seperator drains directley back to the sump and the catch tank just has water and a bit of oil vapour in it. The intake pipe work is free from oil. Air filter is K&N and sized for 500hp, so should be fine.

[volcano rs]

It has a seperator and a catch tank. The seperator drains directley back to the sump and the catch tank just has water and a bit of oil vapour in it. The intake pipe work is free from oil. Air filter is K&N and sized for 500hp, so should be fine.

what oil are you using?

[Rusty]

Bet there's a small leak somewhere - mine has been doing this on and off for years and it's always been something leaking small amounts - One I can remember was where I removed the AC compressor bracket and a bolt was bottoming out on the thread by about 0.5mm and leaving just enough of a gap to leak (fixed by putting in a washer!) and the most recent was a poorly sealing gasket on the oil feed to the turbo (fixed with a new gasket). Both were leaking drops but over time, they add up. The other prime candidate is the oil pressure switch and I've even had a sump plug leak when the car is running but not when it's sat on the drive (that was an old Golf).

One thing you can do is to remove the line that feeds back to the inlet from the catch tank and run a small breather filter and block the inlet line. You can then get a better idea of anything going through the breather system without it getting ingested into the inlet.

[s2_bo]

Hope it's not the turbo again Andy.

If you take the breather return of the inlet and just vent under the bonnet you may get nasty smells in the car. That's what mine did anyway.

[AndyP]

what oil are you using?

Mobil 10W40

I'll return your call tonight

[AndyP]

Bet there's a small leak somewhere - mine has been doing this on and off for years and it's always been something leaking small amounts - One I can remember was where I removed the AC compressor bracket and a bolt was bottoming out on the thread by about 0.5mm and leaving just enough of a gap to leak (fixed by putting in a washer!) and the most recent was a poorly sealing gasket on the oil feed to the turbo (fixed with a new gasket). Both were leaking drops but over time, they add up. The other prime candidate is the oil pressure switch and I've even had a sump plug leak when the car is running but not when it's sat on the drive (that was an old Golf).

One thing you can do is to remove the line that feeds back to the inlet from the catch tank and run a small breather filter and block the inlet line. You can then get a better idea of anything going through the breather system without it getting ingested into the inlet.

It does have a very small leak on the cam cover gasket, but not nearly enough to explain the usage. I've had the MAF-Turbo hose off and that is dry so I'm sure it's not dragging oil back through there. I also swapped the intercooler recently and that only had a teaspoon of oil in it.

It definatley seems to be burning it from the grey smoke on WOT, I have a video at home I'll try and post it up tonight so you can see.

[AndyP]

[QUOTE=s2_bo;633213]Hope it's not the turbo again Andy.
[QUOTE]

I kind of hope it is as it should still be under warrenty, it's a pain it the a**e but an easy fix.

[Rusty]

What oil is recommended for the turbo? I've always run W50 or W60 on mine depending on whether it's going on track or not. Not sure if there are different recommendations for the GT BB turbos over the older tech KKK?

[terrybullwon]

Do you have a oil restricter before the turbo core?

[Jamo]

I suppose the real question is too try and list causes of oil loss under acceleration. Valve stem seals on the list?

[driftin jo]

I suppose the real question is too try and list causes of oil loss under acceleration. Valve stem seals on the list?

Valve stem seals leak more when you lift off at med/high rpm when there is lots of vacuum, oil is sucked past the valve stems into combustion chambers, look for a puff of smoke when you get back on the gas after lifting off to identify this as the culprit.

[AndyP]

Yes the restrictor is in place, I bought a complete hose kit for the BB turbo from 034. I have also tried running it on a 10W50 oil and it made no difference.

I'll try and get someone to follow me and see if it smokes when getting back on the gas.

Thanks for the suggestions