240 General: Positive Crankcase Ventilation Clean Up.

[Paul240480]

Positive Crankcase Ventilation

It is common for this system to clog up if neglected. The result will be oil leaking through the rocker cover gasket, or worse. The first time mine blocked up, the oil dripped onto the exhaust manifold. If yours has got to this point, budget for a new rocker gasket too.

There is a flame trap inside one of the pipes, Volvo decided this was no longer needed & as part of their service schedule, I understand they removed the flame-traps during. Mine was not 'dealer serviced', so I found mine still in place when I first did this job in 05.

So, first we need to identify the bits in question.

1)
This is one of the pipes; this is attached to the air intake manifold with a brass connector. The pipe pushes onto the connector & the connector is threaded into the manifold. A 15mm spanner is required to undo it.

If you follow this thin pipe down it will take you to the flame trap holder Pic taken off the car so you know what you are looking for.

2)

It is quite dark down there & there are lots of other pipes so take your time & familiarise yourself with the location.

There is a 'fatter' pipe coming from the flame trap & holder which connects below the big rubber 'bellows.

3)

The aim here is to remove these three parts, the 'fat & thin pipe' & the flame trap holder, for either cleaning or replacement. We shall also clean up the 'venturii plate', bear with me....

The pipes are all push fit, but do bear in mind that the plastic holder will be brittle, especially that thin 'nipple' for the thin pipe. Believe me when I say it is easily snapped off!

So now we are ready to start. You can undo, with your 15mm spanner the brass connector & separate it from the thin pipe. If it is at all blocked up, spray some carburettor cleaner into it to clear any gunk, if needed a straightened paper-clip can be poked through it to clear stubborn gunk.
The connector:

Looking into one end, after being cleaned:


Now look into the 'hole' in the air intake manifold, where the connector threads in:

If needed shine a torch into it & make sure it is clean & gunk free. If not, use something like a straightened paper-clip to hook any dirt out.

Next, directly below the air intake manifold is a big rubber bellows. We shall remove this. First note it's position, & mark with tippex on the bellows and where if sits on the body, so that it goes back in the same place:

There is an arrow on the bellows, if you can find that, you can note it's position, & use that as your marker.
Undo the two jubilee clips on the bellows & gently ease the bellows out:
Here I have removed mine & put tippex on the arrow, so you know what to look for on yours:


You should be able to see the flame trap holder more clearly now, with the belows out of the way:

(The 'plate' here in the 'bowl is the venturii. Yours may be clean like mine is now. It may have a layer of thick oily sludge on it, if the system is blocked up. Mine certainly had in 05. Clean it out using paper towel & carb' cleaner. Be gentle with the plate it needs to remain in it current position).


Now, you should be able to reach into grab the flame trap holder & disconnect the fat pipe from it. Then you can pull the holder itself off, & finally carefully remove the thin pipe from it.
So now you will have these two bits & the thin pipe:



I'm afraid I didn't photo the fat pipe (brain gone), but you can now pull gently free from here:

If you cannot get a good grip on it, you may want to remove the vertical metal support for the air intake manifold, 4 bolts, two top, two bottom IIRC. The manifold will be fine.

Now it is time to clean the pipes out, if re-using. Carb' cleaner, again & maybe suitable items to poke any solid matter out. In 05 my 'fat pipe' was blocked almost solid!


Moving onto to the plastic flame trap holder, you will see it it actually two pieces push-fitted together.
You need to separate them. A screwdriver may assist as a lever if well stuck.


If yours still has it's flame trap in position it will be in here:


Look in the end & you will see one of these, that is the flame trap, it is a little sieve.



I popped a new one into mine as demo'. If yours is there, it will more than likely be black & blocked.
To remove it, get a small 'self-tapper' screw & turn it in by hand to one of the holes in the flame trap.


Then you can grip the screw with a pair of pliers & wiggle the trap out.


As mentioned the trap can be ditched. The holder itself, will no doubt benefit from a good clean up.

Now it is already to go back together, as is always 'famously' said, refitting is a reversal of the procedure!

If you are fitting a new thin pipe, it is a good idea to have a long length, so you can feed it down through the manifold & easilyy attach it to the two re-connected parts of the flame-trap holder:

If re-fitting the old cleaned out pipe, it is just a bit more fiddly. You may find yourself working by 'feel'. Note my shiney cleaned out Venturii plate

You can now re-fit the brass connector into the manifold & (if new cut the new pipe to size) & push on to the nipple on the connector. Then fit the fat pipe to the flame trap holder & then firmly push it home into it's 'hole'.

Quite a tight fit, this one do make sure it is 'well in'.

If you removed the vertical support for the air intake manifold, you can now replace it.

Then, check that Venturii plate for any crud that has fallen during the work & clean it out again if needed, then re-fit the big rubber 'bellows. Remember to align it to your mark. It is a bit fiddly to get the upper & lower 'collars' to fit right, so take your time & make sure they are neatly in place all the way round. Then tighten up the jubilee clips. We want a good seal here, no air leaking.

Fire up & go for a spin. If your system was blocked you should notice a much free-er revving engine. Should be a tad smoother too.

Finally, make checking this a once yearly 'job'.

I think that covers this one. If I've missed anything, or if you have any 'cunning tips', or if anything needs adding / correcting please feel free to post it.

Thanks.

[Mike_Brace]

I'm glad you have managed to write this one up Paul. It is quite a fiddly one to do and diffficult to illustrate. It is possible to do with removing the bellows but as the venturi will always benefit from a gentle clean it is worth doing at the same time.

If the manifold support bracket is removed do make sure it is refitted tightly. I have had several instances over the years of the bolts coming out and then the manifold coming loose causing all sorts of running problems due to air leaks.

Mike

[ALLOA]

Excellent guide Paul. I tend to do this one on an annual basis as well. As I have 'hands like shovels' I find that I need to remove the bellows!
Out of interest did you find that any of the 3 rubber mounts that secure the plate assembly had sheared? I have had this on most of the GLTs that I have owned. I'm not sure what causes it.


Best Regards

Scott

[chesters6]

HMMMM none of your engine is remotely like my carb version looks very alien!
from recollection i have a thin pipe from the carb base and a thick one going to the carb air inlet ,yes just photo'd it to be sure .
how do you clean out the parts below those parts you removed its a nightmare to see never mind get to .
PS in your top picture the pipe to the right looks a bit dodgy is it the brake servo pipe? if so it may be worth looking through mine looked like that and it had almost closed inside at the connection point to the head

[Paul240480]

@ Alloa, yes I have replaced the fore most support before, due to it breaking. I think it is just an age related wear & tear issue. The other two AND the one I replaced are now all showing signs of wear. I guess the vibration takes it's toll too.

@Chesters, I could write all I know about your engine on a postage stamp & still have room for an essay! Lol. That said, those two pipes look very PCV,-ish. Mike will no doubt confirm or otherwise

That pipe on mine does look a tad tired, it has done for too long! I think it is a vacuum pipe for the clutch. I'll know if it gives out cos the clutch pedal will be very hard to push down. Thanks for the nudge, I'll get myself a new one

[honestjoe]

@Chesters, I could write all I know about your engine on a postage stamp & still have room for an essay! Lol. That said, those two pipes look very PCV,-ish. Mike will no doubt confirm or otherwise

You injection boys crack me up!!.....pssssst...Robinsons "old tom" strong ale..8.7abv..nectar!!..cheers paul..hj.

[BrianH]

James this 'sorry tube' could be the connection to the vac. tube to the brakes. It will fail internally. Beware!

BrianH

[wooble]

Originally Posted by Paul240480

That pipe on mine does look a tad tired, it has done for too long! I think it is a vacuum pipe for the clutch. I'll know if it gives out cos the clutch pedal will be very hard to push down. Thanks for the nudge, I'll get myself a new one

It's the vac tube for the brake booster, if it collapses or pops you'll lose your power brakes, which could be hairy if it happens approaching at a junction! You'll still have unassisted brakes, but it would be something akin to stopping an old land rover from speed (I.E. practically sanding on the pedal with both feet!)

[Paul240480]

Wow, thanks folks, I'll make that a priority then

[chesters6]

Originally Posted by wooble

It's the vac tube for the brake booster, if it collapses or pops you'll lose your power brakes, which could be hairy if it happens approaching at a junction! You'll still have unassisted brakes, but it would be something akin to stopping an old land rover from speed (I.E. practically sanding on the pedal with both feet!)

been there landrover wise ,it must be the only off road vehicle where if you get the rims wet you lose brakes for two days because the shoes get wet compared the volvo ones are brilliant wet or dry