Exhaust (?) gas leak at rear of inlet manifold - 200 SE

[Stephen Edwin]

200SE. Two litre engine. The Lamda sensor warning came on. I reached a known lay-bye in a short distance. By then the temperature gauge was going up. As I stopped there were exhaust (?) gases coming from the bonnet. There is no noticeable loss of coolant. The engine is not running noticeably rough. I was near home so after resting the engine I drove carefully home.

The apparently exhaust gases seem to be coming from the region of the rear of the inlet manifold, where there is a hose coming from the air inlet pipe. That hose is not attached to anything. I'll have a proper look in daylight. Is this of itself enough to identify the fault/cause/cure? Please?

It's a curious setup to my mind, to have exhaust gases on the inlet side? Unless a head gasket blows. But then I'm well out of date.

[minesa240x3]

Sounds a bit like one end of the engine breather hose has come off?
When the engine is hot it will blow hot gasey type mist out.Or it could be the actual oil seperator top hose that has popped off.Both are situated down by the inlet manifold.Very awkward to see the oil trap breather box as it's very tight to the engine block and hidden underneath the inlet manifold.Try looking above the starter motor but at the side of the engine block.

It would affect the lambda sensor as not only would it throw pressurised air out but the other end it should be connected to will be drawing in fresh air.

Keep us informed please.
Regards Brian.

[loki_the_glt]

The hose is probably part of the crankcase ventilation system and has coem adrift somehow. The best thing is to look at the entire engine in daylight, tracing the pipe's run and concentrating on where it might go, based on its length and shape, then focus on those areas. IRC there's a black flame-trap affair under the intake manifold with a pipe that runs to the manifold.

[Stephen Edwin]

Thank you both. It looks like a Positive Crankcase Ventilation issue?

It does look like the hose above the manifold near the rear of the manifold has blown off under pressure. It should be joined with another hose coming up from that oil separator and a small hose going sideways. Actually the small hose may still be joined to the upper hose, I've looked only with clean hands so far ...

I'm assessing that the flame trap is blocked causing the hose to blow off. My usual Volvo parts supplier tell me they have in stock the flame shield ... a round white plastic honeycombed item ... part number 1389657. It would cost me ... £2.88 .... <Smile> ... I understand from the Bentley manual the trap should be cleaned or replaced at 20,000 miles anyway, so I may as well replace it, and buy a spare.

That shield they say is all they usually replace. They say it goes inside a "nipple" that does not usually need to be replaced. Does that fit with experience please?

So, do I need to order in anything else from them to be sure of being able to do the job?

[wooble]

You don't need to replace the flame trap, it's been in the Volvo dealer manual to remove and discard it for years now, its only purpose is to stop backfires potentially causing an explosion of crankcase gases (when did you ever hear of this happening on any car ?!).

All you need to do is remove and thoroughly clean the black plastic holder it sits in, and the two hoses coming off it. The plastic can get brittle with age, oil and heat so be careful with it .The small hose to the intake manifold may well require replacing as it's probably clogged solid with tar, it's worth unscrewing the brass nipple it connects to on the intake manifold and cleaning that out too with a piece of wire.

When I bought my current 240 the flame trap had not been serviced in over 100k miles. The flame trap, small hose and intake manifold nipple were clogged solid with tar. The car was leaking 1 litre of oil in 150 miles due to crankcase pressurisation, and the underside and tailgate were coated in oil spray. After cleaning up the PCV system the leaks were reduced to almost zero.

[minesa240x3]

Spot on Wooble exactly what I would like to have put.
All my 240's have had gunged up thin pipes so I just replace the whole length.Also as said the small brass connector blocks as well so thin piece of wire after removing it works well.I also got less oil leaking on my F reg after cleaning it all through.
The bit of plastic that has the small pipe joiner sticking out becomes very brittle I know.Mine broke off while on holiday and it ran terrible until I found out just what it was.

Regards Brian.

[Stephen Edwin]

Further thanks for the further advice. Ta.

Is the tube down to the oil separator likely to be blocked also? And, is there much likelihood I'll have to clean out the oil separator?

I'm just trying to prepare myself ...

*****

By the way. I bought this car two years ago via eBay, from a then forum member near Beccles. I had the rear arches done. I had to replace an exhaust mounting. I fixed a few very minor irritant points. I've got a couple of odd jobs still to do, including a door lock solenoid. Basically it seems to be a nicely working example of the 200 estate. My mileage is extremely low, but none the less the car has been no bovver to me so far. Kushtie.

[Clifford Pope]

Wooble's post says it all, or very nearly.

In my experience the black oil separator box is another suspect, and is so awkward to remove that no-one ever does so it gets neglected and gradually clogs up with tar.

It is theoretically possible to remove it without disturbing the inlet manifold, and quite easy if you saw off the plastic lug at the top which secures the wiring loom.

it's not worth trying to flush it out - the oil will be caked hard inside. It's purpose is to catch oil mist and allow it to condense and run back into the crankcase. As it clogs up it becomes less and less effective, so even more oil mist gets drawn round the breather network, which clogs everything still more.
The separator doesn't just need a clear airway through - it needs the large air reservoir to work properly.

[Stephen Edwin]

I'm tackling this in stages. Fortunately I rarely need the car. Today I dug out the old honeycombed flame trap.

I find the lower tube, from the oil separator, is a very loose fit on the plastic holder. I'm wondering actually if half the holder is missing, and if that tube has been force stretched over the holder and is giving up the battle? It might even be not the right tube?

Basically, the insert was on view inside a holder on the underside of the holder. There was no lower part for the holder. Should there be two parts of the holder please? Should there be any hose clips?

Starting up I'm not getting exhaust spewing in to the engine bay.

The Lambda light hasn't gone out but that might respond to a short test drive ... ?

I'm thinking in terms of replacing all three tubes, the holder and the brass connector. Depending on the cost. I might have a go at cleaning out the oil separator ... or I might not.

[Clifford Pope]

One end of the flame trap fits into a special hose that is wider at one end.

It's definitely worth removing and inspecting the oil separator if it has never been done. Be very careful unplugging it from the engine block. It fits into a tight rubber grommet, but the box and the grommet become fragile with age, and it is easy to break them and drop the bits into the sump.

Also there is supposed to be a hose attached inside the sump, so that returning oil runs down to oil level, and is not blown back up again.