PCV question

**Wasp** · Saturday 14th March 2015, 00:11

I wonder if someone can advise please? I replaced the entire system today without issue but I still have smoke from my dipstick tube. Only driven 5 miles or so since if that's relevant. No constricted pipes,no problems. I wonder if I can draw on your expierience. All supplied by FRF so no issues there and vehicle is a 1996 850 T5. Thank you.

**Timo.** · Saturday 14th March 2015, 09:21

I cleaned my PCV last year. It wasn't blocked in the slightest as I was getting a little blow back through the dipstick. I distmantled. Cleaned with carb cleaner thoroughly, put it back together and it had made not the slightest bit of difference.

Maybe there is always a bit that comes out??

**960kg** · Saturday 14th March 2015, 10:51

Just because some smoke comes out the dipstick tube doesn`t mean anything!...

The reason it smokes is because it is easier for the smoke to come out the dipstick tube as you have removed the dipstick and it exits the least line of resistance.....there is not enough vacuum at idle to remove the fumes via the PCV system.....also the sump pressure works on a very slight + side at idle.

ALL engines have sump pressure as the engine is only a pump......most have two pistons up and two down which equals the pressure more but of course our engines are 5 cylinder so not quite equal sump pressure at a given time!....

**Dream3r** · Saturday 14th March 2015, 11:16

In the later cars Volvo added a vacuum banjo as part of the pcv pipe to fit this I believe. Might well be wrong, it's a working theory.

**LeeT5** · Monday 23rd March 2015, 11:13

Originally Posted by Dream3r

In the later cars Volvo added a vacuum banjo as part of the pcv pipe to fix this I believe. Might well be wrong, it's a working theory.

Your not wrong at all.

The banjo that bolts to the underside of the manifold is the vacuum one as it has a one way valve built in to it. The other is free flowing as coolant passes through it.

On earlier systems as on the 850 there are three 'check valves' and IMH they need to be replaced as over time they fail and also get blocked.

One is between the solenoid valve (not to be confused with the TCV) and the vacuum tree.
The other two are between the fuel tank purge valve and the intake manifold, and the Fuel tank purge valve and the Air intake hose from the air filter to the engine.

This picture should help:

http://www.matthewsvolvosite.com/ima...se-routing.jpg

**Dream3r** · Monday 23rd March 2015, 11:26

The part numbers are the same for the banjos? (#973950) Admittedly, it wasn't me who put it in-to the head so I can't say for sure but if you look in VIDA they are the same.

**LeeT5** · Monday 23rd March 2015, 11:35

Originally Posted by Dream3r

The part numbers are the same for the banjos? (#973950) Admittedly, it wasn't me who put it in-to the head so I can't say for sure but if you look in VIDA they are the same.

I know that mate. I raised this point with Volvo UK when I was fitting my PCV, but they weren't interested.
Fact is, the banjo bolts removed from my car were both the same except one had a valve in it, the other didn't.

If you fit the vacuum valve banjo to the coolant side of the PCV on the right hand side of the head, then due to the fact you do not know the coolant flow through the pipe, you will most likely induce a blockage and cause flow to stop. This, of course, will have an adverse affect on the engine and likely cause it to overheat.

I made this point quite clear on my Project thread #61.

After I spoke with the master tech at my local Volvo dealer, he agreed that he wouldn't fit the banjo vacuum bolt and would reuse the oe banjo, or 'Hollow screw' as they are more commonly known.

If you want pictures of the vacuum bolt and my explanation, this go here:

http://www.vpcuk.org/forums/showthre...-Project/page4

**Dream3r** · Monday 23rd March 2015, 11:45

Interesting! I might have to double check that is right on my car then. It's not the easiest of bolts to get to either ffs!

I was actually thinking about this on and off since the PCV, alas no overheating though.

**LeeT5** · Monday 23rd March 2015, 11:51

On P1 and 850 models the hollow screws are exactly that...hollow! Both of them.
It's only on P2 models did they introduce the banjo with a valve, however, I do think it's a clerical error on Volvo's part that the numbers are the same and a clear oversight from a non technical boffin that, no doubt, changed the numbers on Volvo VIDA system. Put the bolts next to each other and they are physically the same size, same thread etc. So you can see how they could have made a mistake.

**Dream3r** · Monday 23rd March 2015, 11:55

I'm sure we had the right stuff in the kit then, got it from Simon @ FRF. The left over banjo is the non-return one so we should be good. I'm replacing the inlet manifold in a few weeks so will stick it in then.

**LeeT5** · Monday 23rd March 2015, 12:10

Originally Posted by Dream3r

I'm sure we had the right stuff in the kit then, got it from Simon @ FRF. The left over banjo is the non-return one so we should be good. I'm replacing the inlet manifold in a few weeks so will stick it in then.

To be fair to Simon, he's only going to supply you what VIDA says is required in the kit. So if VIDA says you'll need two blue banana's then Simon will supply you with two blue banana's!!

My point is, I believe (as did the master tech) this is incorrect. You only need one banjo with the valve, not two. You reuse the old banjo and make sure you fit two new copper washers to each banjo union.