Blue smoke after idle

[JordyHolland]

Dear Volvo fanatics,

A few months ago I have done large maintenance on the engine of my 1994 Volvo 850 2.3 T-5. We have replaced the Turbo, PCV system, valve stem seals, and many more parts.

The first time startup, we encountered excessive blue smoke from the exhaust. Turned out, a cap from the turbo was still in the oil outlet of the turbo, clogging the oil drain line and pushing oil through the intake and exhaust of the turbo. Cap removed afterwards, car was running fine, no excessive smoke anymore.

After this, I've encountered a cloud of blue smoke every time I'm accelerating after idling for a short while, even after 10.000 km since the maintenance. The turbo pressure tubes are always oily from the inside, also the turbo intake tube contains oil. On the bottom of the intercooler, there is oil where the intake throttle body hose is connected (OEM RIP kit).

I've searched a lot on Volvo pages and it always comes down the following issues:

- Valve stem seals (replaced during maintenance)
- Bad Turbo (replaced during maintenance)
- PCV system (replaced during maintenance)

We figured, the turbo probably is beaten up by the clogged oil drain, so we mounted a new turbo again. Same problem. Vacuum lines are all replaced too, and also correctly placed.

What can possibly be causing my car to smoke during/after idling? Could it be my catalytic converter that has seen too much oil? Any other possible causes?

Thanks in advance!

[scot850]

There are several possible causes and you appear to have addressed some of them.

First question is to do with the parts you used in the repairs/maintenance.

When you say you replaced parts did you you all new parts including the turbo?

Is the turbo from a known good supplier?

When you replaced the valve stem seals, what brand did you use?

Did you remove the cylinder head and have the valves ground and stems checked for wear? If not it could just be the valve stems are worn and new seals will not fix that. The issue of oil smoke after idling or coming off or going on the gas are usually signs of the stem seals leaking.

It is possible that the cat got a lot of oil in it but after 10,000km I'd expect most to have burnt off by now or you would have a clogged cat.

How many kilometers/miles on the car engine?

When you did the PCV system service did you replace all the parts or re-use the oil catch can?

When you did the PCV system did you make sure that the drains from the catch can were 100% clear, especially the lower one?

Having said that I'd expect the seals to blow more than the oil smoke but it is possible.

Lastly for now, have you had the engine compressions checked to make sure you don't have excessive piston ring wear or damaged/stuck piston rings?

Neil.

[JordyHolland]

Hi Neil, thanks for your answer!

Here's some answers on your good questions:
Indeed the parts are new, not second hand or re-used.
The turbo is from Mellett, UK, a well known brand.
I am pretty sure the valve stem seals were original Volvo parts.

I did not remove the cylinder head, we used specialized tools to replace the stem seals without removing the cylinder head. However, as the car did not smoke at all before the maintenance, I doubt the valves themselves are worn.

Could a clogged cat be the cause of the smoke? Too much back pressure in the exhaust causing oil to push into the turbo intake? Is it normal that there is a puddle of oil in the turbo intake hose? And oil in the bottom of the intercooler? And that the turbo pressure hoses are oily?

There are 368k km / 230k miles on my car.

The PCV is all new too, catch can and the drain tubes. Drains were 100% clear, we removed the engine from the car so that was clear to see

I did not do a compression test, but i doubt it is the piston rings, since there was no sign of smoke before maintenance.

I hope you can help me solve this issue,

Jordy

[Sveedy]

You didn't mention a glove test, which could tell you if you still have too much crank case pressure, even after doing the PCV. If you do, then I would suspect worn rings. 230k is getting up there....

[misha]

Why did you replaced valve stem seals if you didn't had a sign that they were bad?

I don't quite understand the need for valve stem seals replacement if the car didn't had blue smoke from the exhaust at all.

[scot850]

Annoying as another post I made has disappeared!

In that I mentioned a suggestion to do a glove test as suggested by Sveedy above. Put a rubber or latex glove over the oil filler with cap removed. Start the engine and see if the glove rises, does nothing or get sucked inward. If either of the first 2, then rev the engine slightly and see if the glove expands or gets sucked down. Any expansion is a crankcase pressurising.

As misha says, why did you change the valve stems, but I understand it is while in there and preventative maintenance. I believe the number of burnt valves on these is contributed to by leaking oil onto the valves and then they overheat.

Were the turbo, intercooler and pipes oily before repairs? If not it is back to what misha says to a certain extent, but my twist is, if it wasn't bad before and now it is, something you did has made it that way. So first thing is to check back over what you did.

Turbo and pipes do get oily with age a the seals start to leak on the turbo and pressure from the engine and PCV system can push oil into the system.

As to the cat being blocked/contaminated then that is possible. But I would expect after a good run and you are not getting a stink out the back and the engine is otherwise running ok, then it is not the issue. If the amount of oil smoke continues at the same rate then it is a continuing leak issue.

If not already done, then a cylinder pressure test is next with engine still warm. Check dry (no oil added to cylinder) and wet (with maybe a teaspoon full of oil in each cylinder) and see if there is any difference. The reading compared between cylinders and within the cylinder dry to wet will maybe point a way forward.

I had a 760 turbo that did the same thing after a heat re-build. Turned out the dealer knew squat as the cylinder head leak was not the issue but stuck oil rings. That ended up with a re-bore and new pistons.

The car ran great but over time the air filter and turbo system filled with oil.

Neil.

[JordyHolland]

You didn't mention a glove test, which could tell you if you still have too much crank case pressure, even after doing the PCV. If you do, then I would suspect worn rings. 230k is getting up there....

Hi Sveedy, i didn't mention a glove test indeed, however i did do it. When idling (warm engine), the glove isn't sucked in and not blown up, when revving it is sucked in. PCV seems to work normally.

[JordyHolland]

Annoying as another post I made has disappeared!

In that I mentioned a suggestion to do a glove test as suggested by Sveedy above. Put a rubber or latex glove over the oil filler with cap removed. Start the engine and see if the glove rises, does nothing or get sucked inward. If either of the first 2, then rev the engine slightly and see if the glove expands or gets sucked down. Any expansion is a crankcase pressurising.

As misha says, why did you change the valve stems, but I understand it is while in there and preventative maintenance. I believe the number of burnt valves on these is contributed to by leaking oil onto the valves and then they overheat.

Were the turbo, intercooler and pipes oily before repairs? If not it is back to what misha says to a certain extent, but my twist is, if it wasn't bad before and now it is, something you did has made it that way. So first thing is to check back over what you did.

Turbo and pipes do get oily with age a the seals start to leak on the turbo and pressure from the engine and PCV system can push oil into the system.

As to the cat being blocked/contaminated then that is possible. But I would expect after a good run and you are not getting a stink out the back and the engine is otherwise running ok, then it is not the issue. If the amount of oil smoke continues at the same rate then it is a continuing leak issue.

If not already done, then a cylinder pressure test is next with engine still warm. Check dry (no oil added to cylinder) and wet (with maybe a teaspoon full of oil in each cylinder) and see if there is any difference. The reading compared between cylinders and within the cylinder dry to wet will maybe point a way forward.

I had a 760 turbo that did the same thing after a heat re-build. Turned out the dealer knew squat as the cylinder head leak was not the issue but stuck oil rings. That ended up with a re-bore and new pistons.

The car ran great but over time the air filter and turbo system filled with oil.

Neil.

Hi Neil, it's been a while.

The rubber glove does nothing when idling, and is sucked in a little when i rev the engine. That seems normal.

The valve stem seals was preventive maintenance indeed, because the engine was out of the car anyway, which made it a little easier.

The turbo hoses were oily before, however not THIS oily. There's always a puddle, also in the turbo hose that goes over the engine (RIP kit). Also, the MAF sensor seems a bit oily.

The cylinder compression test is a good one indeed, maybe that's something to try. However, i expect this to be okay because it began smoking right after maintenance.

I still suspect that there's oil leaking in the intake hose somehow, because the intercooler and hoses are very oily. Also, the smoke is only coming when revving after idling with a hot engine, and NEVER at startup (which you would expect if it was valve stem seals, right?). With low revs after idling, no smoke. A little higher revs (driving away at traffic lights), theres a big cloud of blue.

Jordy

[abscate]

The test for valve stem seals is to coast down a hill, with high engine vacuum, then step hard on the accelerator while watching the rear for heavy smoke.

If you didn’t use the set of Volvo stem seals it’s very likely your new stem seals are still leaking.

The part number below saves you about 40 Euro from the price

Valve stem seals (20) $7.03/each (FCP Euro)
Valve Stem Seal Kit = 272424 $76.24

[JordyHolland]

The test for valve stem seals is to coast down a hill, with high engine vacuum, then step hard on the accelerator while watching the rear for heavy smoke.

If you didn’t use the set of Volvo stem seals it’s very likely your new stem seals are still leaking.

The part number below saves you about 40 Euro from the price

Valve stem seals (20) $7.03/each (FCP Euro)
Valve Stem Seal Kit = 272424 $76.24

Thanks for the tip!
I am currently in Austria and just coasted down from 1800m height while engine braking. After that, a cloud of smoke did come out, however not that much. I have the feeling that more smoke comes out when I'm idling the engine while stop-and-go city driving.

I have indeed not used the original Volvo stem seals, could this be that big of an issue?

Thanks in advance!