Flame trap 1990 740 b200e
 

Hi
Before tackling some of the oil leaks on my newly acquired 740 I am trying to clean the Pcv system. I am having trouble accessing the flame trap to extract it.
Is this a case of manifold off or has anyone any tips?

I’ve attached an image of what I can see from the front. I have removed the breather pipes from the flame trap/ breather box.

Cheers

Matt

The flame trap is only on non turbos like yours, it is a little white plastic tub a couple inches long and has a gauze filter of sorts inside it, if you have taken the hoses off the PCV box then you will have the flame trap off already.

The PCV box is the black box attached to the block, it looks like a right pain in the backside to remove on yours. You will need a new O-ring for it too as the original one will be brittle and flat not sealing anything. The O-ring is available from Volvo and the part number is 949659 it is very cheap and not worth doing the job without it.

The PCV box will need soaking in something like petrol for a couple of hours and blowing out with a compressor to get the carbon build up out.

Thanks for the reply.. yea it’s the PCV box I want to clean. The flame trap and pipes weren’t too bad at all.
If I can whip out the large rubber ball that’s jubilee clipped
on the right hand side of the photo that would give me quite a
Bit of room but I’ve no idea what it is!

My 940 has a B200F engine. I cannot comment on the B200E engine and have no idea what that “large rubber ball” is, but I have found that the easiest way to access the PCV oil trap on my engine is to remove the air intake ducting between the air filter box and the throttle body. I hadn’t touched it since acquiring the car in 2005 although I had been diligently changing air and oil filters and cleaning the IACV. When, following advice on this forum, I eventually decided to clean the throttle body and removed the air box and ducting I realised that access to the PCV system and oil trap was relatively easy. The most awkward part of the procedure is removing the pipework and flame trap above the oil trap as they are partly hidden between the induction manifold and the cylinder head. I have read somewhere, cannot remember where, that care needs to be taken when actually lifting the oil trap off to ensure that the pipe which sits under it and goes down into the sump is not disturbed and lost into the sump as it is a sump off job to recover it. On my engine that pipe has a collar on it’s top end (the visible end ) which prevents it from falling through. After removing the oil trap securing bolts I gently removed the oil trap and that pipe just stayed in place.
So, again following forum advice, at each oil and filter change I check/clean the IACV, throttle body, flame trap and oil trap.
Dave has suggested a mod. for the location of the flame trap by fitting a longer pipe between it and the oil trap so that the flame trap is further up and more easily accessible. I intend to try that when I next clean the PCV.
Whilst you are doing this check that the small bore vacuum hose from the flame trap to the throttle body and the pipe and drilling into the throttle body are not blocked. The first time I cleaned mine I found them well blocked.

That "sock" or as you call it, a large rubber ball links the fuel distributor to the throttle body. If you don't get it back perfectly the engine won't run properly, if at all.

There is a conversion kit that lifts the flame trap above the manifold or you can make one yourself, basically just a longer rubber hose between the oil separator (PCV box) and the flame trap - well worth doing!

As for the existing oil separator, how badly blocked is it? A long hose attached to the oil separator and spray carb cleaner in the top of the hose can often do enough cleaning through it. Other than that i'd suggest removing the inlet manifold for access to the PCV box - make sure you have a new inlet manifold gasket ready to fit after though.
That way you only have to disturb the top of the "sock" where it meets the throttle body.

You don't need the flame trap itself , It was deleted by volvo well over 20 years ago !

Thanks for the advice guys.

Laird Scooby.. are you basically saying to pour carb cleaner straight in to the top of the plastic oil separator?

How would I then extract the contents from it? Wouldn’t all the crud then find it’s way down to the sump?

Apologies if I’m way off here

Not quite - spray carb cleaner from an aerosol, it will dissolve the gunge and yes, return it to the sump but when you next do an oil change will be removed, meanwhile the filter will catch it.

Obviously you don't want to use gallons of the stuff, the solvent based carb cleaner will evaporate off and/or be diluted by the oil (and then evaporate on first use once the engine temp is above a certain level.

If you think about it, the crud/gunge that's in the oil separator is only oil that has been thrown up there in the past and stayed there for whatever reason. Lack of oil changes is the most likely/common reason for this as dirty oil is more likely to contaminate the oil separator in the first place.

I can understand why you misinterpreted what i was saying but hopefully that clarifies it. The other alternative is an afternoon spanner twirling to remove the inlet manifold for access (some people can manage without but their fingers are nimbler than mine!) then removing the oil separator and either cleaning or renewing it, complete with new seals.

Keeping the flame trap clean and regular oil/filter changes help to avoid the situation in the first place, especially after you've got it clean the first time - often it's found you have to clean it all again a month or so after the first clean and again at each oil change until it stays reasonably clean.

No that’s absolutely crystal clear now, I really appreciate it. I’ll give that a go and then an oil change, which was on the cars anyway. I intend to do all the belts and the 3 shaft seals behind the belts so don’t want to waste my time doing that if there is still too much pressure in the system.
How long would you recommend before doing the oil change?

It would definitely be a manifold off job as the separator is pretty much surrounded at all angles, I can’t even touch a bolt let alone get a socket on one.
I’ve watched all the videos and guides to it but none of the engines have a similar set up to mine. They all seem to have clearer access.. typical of my luck!!!

Cheers

Matt

I can see your plan now Matt which leads me to give a bit more advice. Add ~0.5L of Carlube ATF-U to the engine oil and run it for about a week before doing the oil separator and rest of the PCV system.

While you remove the manifold and sort the oil separator, have the oil draining and a new filter ready to go on as well.

Once you've done the oil separator and refitted the manifold, topped the coolant back up (you'll have to drain the coolant to below head level before removing the inlet manifold) and secured the cooling system again, refit the sump plug and fit the new oil filter, put another 0.5L of ATF-U in then top up with a good quality 10W40 semi-synthetic oil to the correct level.

I'd suggest cleaning the PCV system again after a month or two (but not the oil separator as that should be ok) and whenever you do the PCV system, don't forget the vacuum stub on the inlet manifold, it has a tendency to clog on K-Jet equipped engines.

As a normal thing, i'd suggest oil/filter changes at 3k miles until the oil is staying clean between changes then bring them up gradually to your preferred interval but i wouldn't suggest going more than 6k miles for the oil/filter change interval.

I always add ~0.5L to the sump before topping up with 10W40 on both my beasts, it also helps keep hydraulic tappets working as they should which is handy on my other one.

Have a look at one of my old threads about my last B230E powered 740GLE, that also had K-Jetronic and you can see the mod i did to the breather system to lift the flame trap in post #13 - well worth doing! :thumbs_up: