Astra vxr mk5 Burning oil opinions wanted?

[Andyb712]

​Hi all

So the cars burning oil and smoking and wanted some opinions on the cause

cars currently on a 130k

Rnd stage 3 remap 12 months ago fully rebuilt cylinder head, all new valves lapped in, nevlock stem seal retainers fitted cambelt waterpump new head gasket etc all done

new genuine gm turbo fitted but fitted with the modified step gap exhaust side oil seal

all of above fitted just prior to the rnd remap maybe done about 8-10 k since the remap smoking started in the last 1k or so

Running on 5w40 usually, also temporarily tried some 5w50 oil no change

Also tried a restrictor bolt no change

180psi across all 4 via compression test

Plugs look ok tan brown tips but slightly dry carbon fouled around the bottom end of each threaded portion maybe running slightly rich

Cylinder 1, 2 and 3 ever so slightly wet on the piston crowns when looking through spark plug holes with a torch, cylinder 4 bone dry

Symptoms are no smoke on cold start in mornings etc usually only once hot, idling at traffic lights 8/10 times a plume of smoke when pulling away, occasionally when excessive idling it starts pouring out even when not touching the throttle it clears as soon as I pull away

Occasionally I get a very slight puff of blue smoke when reapplying the throttle after overrun

car runs fine and pulls well no misfires or error codes

from my own research I've come up with a few possibilities

Damaged stem seals either torn the top off one or possibly melted on the exhaust side even though I fitted the nevlock retainer ones and they are very highly rated apparently they can still fail

worn valve guides? not 100% sure on condition of them as it was a refurbished head I purchased I just swapped the nevlock retainer seals and relapped the valves as it had been sitting a while but the valve guides did look ok no hairline cracks etc and had next to zero play in them with the new valves just not 100% sure if they were new or not

blow by or sticking oil control rings haven't done a leak down test yet only a compression test

I have checked for blocked breathers etc all clean and not blocked I wouldn't say their is excessive pressure from the breather system but there is a moderate amount

And then lastly the turbo next to zero end float but their is a little side to side play in it but next to no difference from when I checked it when it was new 12 months ago

A few turbo companies do say the standard turbo does not fair well with mapping but most say it's the oil seal that lets go first and I had the uprated step gap seal fitted and it was a brand new genuine borgwarner turbo fitted just before the remap

car is running a 3 inch cobra double decat non res 304bhp

any tests I can do to rule out the turbo or stem seals based on symptoms I'm having

I'm leaning towards the stem seals but just don't fancy going through all that work again if it's the turbo causing it or vice versa changing the turbo and it's the stem seals

So basically lads anyone hazard a guess or solid answer as to which one is the cause based on the symptoms its showing?

Anymore info needed just let me know, to say I'm frustrated and stressed out with it is an understatement

Just pray someone here can offer some insight

[GreenV8S]

I'm not familiar with that installation but you've identified the obvious candidates: excess blow-by via the PCV system, valve stem seals or the turbo.

You challenge will be to find a way to eliminate any that you can. Any possibility of disconnecting the turbo from the intake manifold for a quick test at idle to see whether you can eliminate that? Can you disconnect the PCV connection to the intake manifold (and block the opening at the manifold) and rule out the PCV system?

[Zener]

And just to add to the above ^ a compression test or leak down is no indicator of functioning oil control rings usually due to carbon clogging/deposits rather than wear and tear , very common nowadays with these low friction/thin ring packs

[LukeSi]

My friend had similar, valve stem seals cured it.

[Andyb712]

Cheers for the replies all done some more digging and found the lowest part of the the crankcase breather pipe was clogged/furred up with gunk/mayo

Basically the pipe between the engine block up to the cam cover

The lowest part where it bolts to the block with two 13mm bolts was really clogged up and restricted

Cleaned it out and the problem has improved massively

No more smoke at idle whatsoever, however it is still smoking slightly after being driven aggressively then into the overrun once reapplying the throttle between 1k-2k again a slight plume out the the back

But again its intermittent not everytime

The new symptoms are making me lean more towards the turbo now

The idle issue made me think stem seals or valve guides

Were as the throttling up from overrun makes me think turbo

Any thoughts anyone?

[GreenV8S]

Andyb712 said:

throttling up from overrun makes me think turbo

Valve stem seals or turbo (or both).

[Andyb712]

GreenV8S said:

Valve stem seals or turbo (or both).

Given the fact I've already changed both in the last 10k lol

Care to to hazard a guess which one is more likely to have failed 1st prematurely?

[GreenV8S]

Have you actually disconnected the PCV system from the intake to rule that out completely?

[Andyb712]

GreenV8S said:

Have you actually disconnected the PCV system from the intake to rule that out completely?

Its doesn't not have a pcv system as such

Basically one large hose connected from the back of the cam cover to the air intake just after the maf housing and into the turbo air intake

And then another small hose connected to the back of the cam cover and then the throttle body with a small one way valve in between

At idle the throttle body/intake manifold produces a vacuum to suck the crankcase gases out of the cam cover, then on boost the one way valve shuts to stop boost pressure from escaping the intake manifold and pressurising the cam cover and the large breather pipe takes over

But yes I did disconnect both hoses and ran them down the back of the engine bay to test and it made no difference

[GreenV8S]

Andyb712 said:

Its doesn't not have a pcv system as such

Basically

What you're describing *is* the pcv system.

If you have taken that out of the equation and still have a problem, you'll need to investigate other possible causes. Is it possible to produce the symptoms with the car stationary? If so, is it practical to run the engine with the turbo disconnected from the intake?

[Megaflow]

You say stage 3, how much power is that?

If it is a significant increase of stock I’d be concerned about the peak cylinder pressures being too high for piston rings with 130k on them.

[Andyb712]

GreenV8S said:

What you're describing *is* the pcv system.

If you have taken that out of the equation and still have a problem, you'll need to investigate other possible causes. Is it possible to produce the symptoms with the car stationary? If so, is it practical to run the engine with the turbo disconnected from the intake?

What I meant was is it doesn't have a pcv valve in the normal sense like most modern engines ie a replaceable part as such

Its more like a vacuum pressure relief system rather than an actual valve

Lots of people on the the vxr forum over the years asking about pcv valve location to no avail

I did try to disconnect the turbo boost pipe work from the fmic to the throttle body but unfortunately the car just won't stay running even when attempting to apply throttle to keep it running

So basically no smoke on the drive even if left idling 20mins or so not even a slight plume

So basically only when driven hard then overrun then reapplying the throttle produces a plume which soon clears after hitting boost again

Edited by Andyb712 on Friday 18th September 16:17

[Andyb712]

Megaflow said:

You say stage 3, how much power is that?

If it is a significant increase of stock I’d be concerned about the peak cylinder pressures being too high for piston rings with 130k on them.

304 Bhp up from 240 and off the top of my head around 325 lbft of torque rnd motorsport did say when they mapped it that it was a surprising healthy engine given its age

They said it could have easily made another 15-20 Bhp but the standard gm/borgwarner actuator was holding it back and it would have been better with a turbosmart actuator but they didn't have time to fit one on the day

Who is to say it's not had a replacement engine at some point before I bought it

Plus RND are renowned for making safe reliable maps

It only goes to 16-17 psi overboost and holds around 14psi

Seen some people at stage 3 on the vxr forums reporting that it holds around 20 psi and reporting overboost in the mid 20's

And reporting lower power figures than mine even with much higher levels of boost

Edited by Andyb712 on Friday 18th September 16:19

[GreenV8S]

Andyb712 said:

So basically no smoke on the drive even if left idling 20mins or so not even a slight plume

So basically only when driven hard then overrun then reapplying the throttle produces a plume which soon clears after hitting boost again

I think you're approaching the point where you need to start inspecting things to look for damage/wear. It may be possible to narrow it down a little further.

Do you also get the smoke when you drive gently for a while and then go into overrun and then onto power? In other words, is that initial boost necessary to see the problem?

[Andyb712]

GreenV8S said:

I think you're approaching the point where you need to start inspecting things to look for damage/wear. It may be possible to narrow it down a little further.

Do you also get the smoke when you drive gently for a while and then go into overrun and then onto power? In other words, is that initial boost necessary to see the problem?

Yes mate if driven carefully no smoke, only seems to be after very strong boost and even then it's not on the let off phase just on the throttling back up