Worn rings or valve stem oil seals?

[expolicev70t5]

My car now has 283K on it and I don't see any smoke when driving, however I have noticed I am using about 1/2 litre of oil every 1000 - 1500 miles and if I go down a long hill on overrun when I get to the bottom of the hill and accelerate away I am getting a plume of burnt oil smoke which then clears as I drive off. there is no smoke on tick over and non on start up , any one know which problem I need to address? is it likely to be worn valve stem oil seals or worn piston rings? or something else that ive not though of. I did think PCV at first however there is no hue from dipstick when warm.

[htomi]

Did you do the glove test? What's the change interval? What type of oil do you use?

[expolicev70t5]

Is that the latex glove over oil filler cap? No I haven't done that

[expolicev70t5]

Did you do the glove test? What's the change interval? What type of oil do you use?

for the glove test am I right in thinking you put latex glove over oil filler hole whilst engine is warm and running and if it inflates there is positive pressure meaning PCV system blocked?

[Timo.]

283k ?? Good effort

[Orca2]

Compression test it . If any cylinders come up as low on test drop a little oil in the cylinder and retest . If the compression figure increases its the rings or the bores. If not it's the valves.

[expolicev70t5]

Compression test it . If any cylinders come up as low on test drop a little oil in the cylinder and retest . If the compression figure increases its the rings or the bores. If not it's the valves.

Any idea what sort of figure I should be looking for if good compression? having never done a compression test before I'm not too sure of figures I'm looking to attain.

[expolicev70t5]

283k ?? Good effort

Yep 283000 miles just had new turbo and Do88 intercooler so seems to pull very well but now seems to puff a bit of smoke after overrun hence the thread

[Timo.]

Had stem seals leak on a vr6 corrado many years ago.

After spending £1200 allegedly getting them replaced (included new clutch) it still puffed away after overrun.

Not the worst thing to be wrong. I wonder if the cost of fixing is worth it?

[expolicev70t5]

Had stem seals leak on a vr6 corrado many years ago.

After spending £1200 allegedly getting them replaced (included new clutch) it still puffed away after overrun.

Not the worst thing to be wrong. I wonder if the cost of fixing is worth it?

Doing glove test tonight to see if its PCV system, spoke to a mechanic friend of mine and he thinks its the rings as there is no smoke apart from after a down hill run, if this is the case I have 2 options, 1 have bottom end rebuilt with new bearings and rings or 2 source a replacement engine. Im going to compression test it at weekend and have a look in bores for scoring with endoscope at weekend.

[htomi]

Yes, that's the one. Place the glove around the oil filler. If the glove inflates its a sign of a clogged PCV system.
Also you can take off the plastic engine cover and check for oil there. Means the same as above, PCV clogged.
While you're there check the top part of the PCV pipe. The L shape one which goes under the engine cover. Some had a small crack and was leaking slowly.

[expolicev70t5]

Yes, that's the one. Place the glove around the oil filler. If the glove inflates its a sign of a clogged PCV system.
Also you can take off the plastic engine cover and check for oil there. Means the same as above, PCV clogged.
While you're there check the top part of the PCV pipe. The L shape one which goes under the engine cover. Some had a small crack and was leaking slowly.

Well last night I did the glove test to check the pcv system. The glove didn't inflate so I guess that's good but it didn't look to get sacked down either as I had seen on you tube video's. Will check compression and bores at weekend

[htomi]

Best of luck!

[LeeT5]

My car now has 283K on it and I don't see any smoke when driving, however I have noticed I am using about 1/2 litre of oil every 1000 - 1500 miles and if I go down a long hill on overrun when I get to the bottom of the hill and accelerate away I am getting a plume of burnt oil smoke which then clears as I drive off. there is no smoke on tick over and none on startup , any one know which problem I need to address? is it likely to be worn valve stem oil seals or worn piston rings? or something else that i've not thought of. I did think PCV at first however there is no hue from dipstick when warm.

Ok....lets get this back on track.

The symptoms you describe (highlighted in bold) I had the exact same symptoms!! same amount of oil consumed and smoke from exhaust after going down hill off throttle. Exactly the same!

When I checked my PCV (not by doing the glove test - which doesn't always work if you don't get a 100% seal on the filler cap...clumsy method) but by warming the engine up to temp and allowing it to idle for 5 minutes. Pop the bonnet with the engine still running at idle and pull the dipstick out about 3". If you see puffs of white smoke coming from the dipstick tube then your PCV system is blocked.

After i replaced my PCV system, the puffing white smoke stopped and the engine definitely drove better (maybe a placebo effect but none the less, it drove much, MUCH better!) it certainly sounded different!

The smoke after going down hill has also diminished, not totally, but it's improved.

I also, very close to PCV change, had my BSR map removed and a custom map fitted. Not only did this solve ALL my mild manner idling, rough running and harsh throttle issues, but the car drives better than ever AND less unburnt fuel from the exhaust (seen a greyish plume on hard acceleration) only ever so slightly visible now.
I know that the BSR map causes excessive over fuelling (not when it should) and this would suggest the bores were being washed with fuel that was unburnt, not so now.

I can only speak from personal experience and of course my symptoms may differ slightly.

Valve stem oil seals may also be the primary cause of the excess smoke on overrun, but what I can say is I'm no longer consuming so much oil. I've always checked my oil religiously once a week and since replacing the PCV and remap, I hardly ever top up.

[expolicev70t5]

Ok....lets get this back on track.

The symptoms you describe (highlighted in bold) I had the exact same symptoms!! same amount of oil consumed and smoke from exhaust after going down hill off throttle. Exactly the same!

When I checked my PCV (not by doing the glove test - which doesn't always work if you don't get a 100% seal on the filler cap...clumsy method) but by warming the engine up to temp and allowing it to idle for 5 minutes. Pop the bonnet with the engine still running at idle and pull the dipstick out about 3". If you see puffs of white smoke coming from the dipstick tube then your PCV system is blocked.

After i replaced my PCV system, the puffing white smoke stopped and the engine definitely drove better (maybe a placebo effect but none the less, it drove much, MUCH better!) it certainly sounded different!

The smoke after going down hill has also diminished, not totally, but it's improved.

I also, very close to PCV change, had my BSR map removed and a custom map fitted. Not only did this solve ALL my mild manner idling, rough running and harsh throttle issues, but the car drives better than ever AND less unburnt fuel from the exhaust (seen a greyish plume on hard acceleration) only ever so slightly visible now.
I know that the BSR map causes excessive over fuelling (not when it should) and this would suggest the bores were being washed with fuel that was unburnt, not so now.

I can only speak from personal experience and of course my symptoms may differ slightly.

Valve stem oil seals may also be the primary cause of the excess smoke on overrun, but what I can say is I'm no longer consuming so much oil. I've always checked my oil religiously once a week and since replacing the PCV and remap, I hardly ever top up.

Thanks Lee, I did glove test and also checked dip stick method glove neither inflated or got sucked in, there was no smoke from dipstick hence I came to conclusion PCV was ok ( I did disconnect one or two pipes to check in them and they were all clear). My car has done 183000 miles, I no longer think its valve stem oil seals as there is no smoke on start up and non when the car is left idling hence I came to the conclusion its the rings oil being pulled past the scraper ring with the negative pressure on over run, I have consulted with a mechanic friend of mine and he is of the same opinion. At present the car isn't mapped as I had held back from mapping it unit I had sorted any issues. The car hunts at idle from time to time and I get a MAF code, I have replaced with brand new the following items MAF with a new Bosch one and replaced boost hoses, Intercooler (as this was extensively bowed across the bottom) map sensor, coil packs, tcv oh and a brand new K24 turbo from AET as old one started to smoke badly most of which was fitted over the last 2 months. In fairness the down hill smoking issue only seems to have started since fitting the new turbo which is giving me a lot more performance compared to the old tired unit it replaced. The car still hunts from time to time and occasionally seems to flutter at about 60 to 70mph where it almost feels as though the turbo is cutting in and out, I then seem to get an over boost code and limp mode, Im guessing I have an air leak somewhere? If I reset the code it will be have for a week or so before same happens again, now to top it all off I went to get the tracking done last weekend as I noticed it had started to wear the edge of the front tires, only to be told the steering rack had excessive play and needs replacing.

I'm getting to end of my tether with the car at moment as its due MOT in June, so I have bought a C70 2.4t GT cabriolet to use in the mean time whilst I decide how to progress with the V70

[LeeT5]

What fault codes are you getting?

It does sound like an air leak, with the sporadic hunting.

[expolicev70t5]

Codes are P0100 Mass air flow sensor, P806 clutch position sensor and P0234 turbo/supercharger over boost, oh and yesterday I got a couple of new codes ping up P0027 powertrain and cant remember other one but description was about bank one o2 sensor reading so guess I need a lamda sensor too now

[LeeT5]

Ok, the hunting at idle from time to time and a MAF fault code is 100% air leak, more than likely on the boost side.
Overboost fault codes are normally caused by an air leak.
The MAF fault code your getting is caused by an internal leak on the boost side of the vac lines. More likely, one of your 'one way valves' is leaking and allowing boost pressure into the MAF to turbo hose. This will cause unmetered air back into the MAF flow and cause the MAF fault code.
Ironically, I had identical symptoms, so I know I'm not barking up the wrong tree here!

It would help greatly if you could get Volvo codes rather than generic codes but the fact your symptoms are the same as mine were and your getting intermittent hunting and MAF fault codes, says you need to replace BOTH the one way valves.

For the record, as I've already documented in my 'project thread', that these valves caused me a 2psi boost leak! So replacing them should make a dramatic difference.

If you want more details, all the info is in my project thread, inc pictures of what they look like.

Regarding your O2 sensor fault code....that'll be caused by the air leak mate and not because you need an O2 sensor.

[expolicev70t5]

Ok, the hunting at idle from time to time and a MAF fault code is 100% air leak, more than likely on the boost side.
Overboost fault codes are normally caused by an air leak.
The MAF fault code your getting is caused by an internal leak on the boost side of the vac lines. More likely, one of your 'one way valves' is leaking and allowing boost pressure into the MAF to turbo hose. This will cause unmetered air back into the MAF flow and cause the MAF fault code.
Ironically, I had identical symptoms, so I know I'm not barking up the wrong tree here!

It would help greatly if you could get Volvo codes rather than generic codes but the fact your symptoms are the same as mine were and your getting intermittent hunting and MAF fault codes, says you need to replace BOTH the one way valves.

For the record, as I've already documented in my 'project thread', that these valves caused me a 2psi boost leak! So replacing them should make a dramatic difference.

If you want more details, all the info is in my project thread, inc pictures of what they look like.

Regarding your O2 sensor fault code....that'll be caused by the air leak mate and not because you need an O2 sensor.

Interesting I would have never associated o2 sensor code with an air leak. I had assumed that was a separate issue. I do remember reading your thread some time ago and you replaced the one way valves with Mercedes-Benz ones as they were a fraction of the cost if I remember rightly

[htomi]

Additionally, while you're investigating the air leak, I would suggest to replace the TCV too. Go with the factory Pierburg unit.