C70 T5 smoke problem

[SteveSarre]

Hi Viking,

Do you have a couple of vacuum check valves (one way flow valves)?
Are they working, and are they fitted the correct way round?

HTH
Steve

[Vikingt5R]

Originally Posted by SteveSarre

Hi Viking,

Do you have a couple of vacuum check valves (one way flow valves)?
Are they working, and are they fitted the correct way round?

HTH
Steve

Hi Steve,

You mean these valves? :




A few months ago I disassembled those valves to change their tubes that were in poor condition, I checked the operation of the valves and there was one of them that was wrong because it allowed air to pass in both directions, at that time I did not change it because I had no replacement and I thought it wouldn't be too important ...

Is it possible that the whole problem of my engine is caused by one of those valves in bad condition?or in the wrong position?


Thank you very much to all of you, I think we are closer to finding the solution !!

[SteveSarre]

Hi Viking,

Yes those are the valves.

Thinking about it a bit more, I am not sure that they would cause your smoking problem (I would need a bit more time to re-read the posts), but they are easy to test, and easy to fix, and easily overlooked.

I will try to post the link to where I last bought them from on ebay. The replacements are not exactly the right size (because on the original Volvo ones one side has a smaller diameter than the other) but they are good enough.

Steve

[SteveSarre]

Hi Viking


If possible you want to check the external diameters before you buy, but I have used something like this

https://www.ebay.co.uk/itm/142920614766


HTH
Steve

[SteveSarre]

Hi Viking

Is the seal on the oil filler cap in good condition?
Volvo part number 940096

That seal gets old and hard, so may not be sealing correctly.


If it doesn't seal well then air will be sucked in there, instead of being sucked at the dipstick.

https://www.ebay.co.uk/itm/282884880480

HTH
Steve

[Vikingt5R]

Hi Steve,

Thanks for the links, I will make an order for the valves and I will replace them because as I said before, there is one that does not work correctly, as it is very cheap, so I will change them.

Regarding the seal oil filler cap, when these smoke problems began in my engine, I did a few kilometers to see if the smoke gradually disappeared, while I have used the car with smoke problems, I have seen that around the oil filler Cap was leaking oil ...

The oil filler cap seal I put on new (aftermarket) about 2 years ago, so I thought it would be leaking oil from the cam cover, even though I had another new seal in my garage, I decided to change it.

So now I have the oil filler cap with the new gasket. This was the last thing I did in my car before the Covid-19 passed, so until this virus passes, I will not be able to check if the gasket was leaking oil ...

So if my gasket was in bad condition, could it be to blame for the smoking problems from my engine?

[SteveSarre]

Hi Viking

Sorry - I don't know what is causing your engine to smoke out of the dipstick tube.

You said
"disconnect the narrow ptc tube (comes from the intake manifold) and connect it directly to the fat ptc tube (comes from the PCV valve)"

I don't think there is a PCV valve. There is a PCV system.
PCV = "Positive crankcase ventilation"

There is a large plastic box below the intake manifold. I would call that an oil trap or a PCV tank.

There is a PTC nipple on the air hose near the turbo
PTC = "Positive Temperature Coefficient"
It should not be blocked, and looks like a simple hole. I think the wires to it warm a metal tube. I don't think it matters very much if the electrical supply to that is working or not. Maybe someone else can explain what it does.

Robert DIY has some videos on the PCV system
https://www.youtube.com/watch?v=FIRoc0VxLd4

https://www.youtube.com/watch?v=eEZzqyu2a6c


Also
https://www.youtube.com/watch?v=G46aNGJM94I

Does your car have an idle air control valve? (see 2:53 on that last video) I think it will have one if it has a throttle cable (eg 1998) and does not have an electronic throttle module (1999 or 2000). Do you know if that is working? If you take it off the car, and twist it from side to side, you should see the inside mechanism rotate. They sometimes get clogged up, but you may be able to clean it (with carburettor cleaner). That may have some effect on the vacuum at idle, which may affect the smoking.

What happens if you put two gloves on (one on the dipstick and one on the oil filler opening)?

Hope that helps,
Steve

[Vikingt5R]

Hello,
I know well the pcv system and the ptc valve, the problem I have is that I am from Spain and I don't speak English well so I have to use Google translator ... so I can't express myself correctly ...sorry



My engine is the first T5 version that mounts by trhotle cable yes.

It is clear that I have a problem with the vacuum in the PCV system when working at idle, and it has to be from some lost air / pressure leak somewhere in my engine.

I hope to find the solution soon so I can explain what the solution is

Thanks a lot

[SteveSarre]

Hi Viking,

No problem. I hope the coronavirus situation in Spain improves soon.

I think it is worth looking at the idle air control valve.

Steve