940 2l Turbo Oil Leak / High Pressure
 

Hi All,

Just picked up my first Volvo, a 1991 940 2.0l Turbo Estate and although I am impressed with it, I have a wee problem.

I knew it had a bit of an oil leak, which I thought was going to be a nice and easy fix.

It was spraying a little oil out of the oil filler cap. Nice and easy... change the seal. Yes, but unknown to me, there seems to be high pressure in the system, and that was the weakest link so the oil was spraying from there. Nice new seal, so next weakest point got it.

The turbo return pipe that goes into the engine itself happened to be the next weakest part, and when driving normally it is piddling out. Not so good.

Friday afternoon at 5.30, as the garage was closing, I managed to get a mechanic to have a quickie look over it, and he said he thought it was the breather box being blocked.

As a temporary 'fix', as I had to get the car home the next morning... um, 800 miles away.... the best he could suggest was leaving the dipstick out to release some of the pressure. Well, as you might well guess, it was better than nothing, but far from ideal. Took the journey nice and steady and avoided any hard acceleration.

Managed to get through 8 litres of oil on the way (sorry bikers -I'm one too). Engine bay a bit of a mess as oil squirted out of dipstick hole, plus some was still coming from turbo return pipe, and covered the whole of the underside of the car and the tailgate.

So the question I am posing, is does it sound like the breather box, and if so, what is it, and where is it? Any help/suggestion in how to remove and clean, or whether it just needs replacing.

Many many thanks in advance.

Rob

crankcase breather can cause oil leaks, as the pressure in the crankcase will rise. normally the weak point is the front oil seals, but if it was really badly blocked, then i expect that it could cause other seals to blow too. certainly sounds like the pressure in the crankcase is too high. does the dipstick rise if the engine is run with it down fully, as i'm told that that is an easy way to know if the breather is not functioning right.

you can either replace, clean or possibly remove the gauze in the breather box, which will be clogged with oil. replacement is easy, or soak it in petrol before drying and refitting. i think i have heard of people removing them, but they're there for a reason, so i wouldn't!

Hope you get it sorted

Richard

Hi Richard,

Thanks for the quick reply.
Was reluctant to leave the dipstick down for risk of blowing any other seals. Will it be ok to do that??

I have identified where the breather is now (I'm not the greatest of mechanics!), so will take it apart tomorrow and check the pipework too for any blockages.

Will report back after doing that. Any other suggestions/help from others still welcome and appreciated thanks.

Rob

don't really know if it would damage any further seals, but i believe that it is known to lift out of its tube slightly if the pressure is high.

hope you sort the problem out.

Richard

Hi Richard,

Thanks again for your reply.

Had a look at things today.

Took the breather box off and gave it a thorough clean. Also all the pipework to it. The little pipe from the manifold to the fire trap (?) was blocked solid!!

Having done all that, I took the car for a good spin, but there still seems to be a fair old pressure there. The oil filler cap, with the new seal, is still blowing some oil out onto the top cover.

Also, the turbo return pipe as it goes into the block is still blowing oil out.

I took the turbo return pipe off to find that the o-ring was more of a u-ring. Being in the back of beyond and with the car in bits I was unable to get a replacement today, (although no bank holiday in Scotland today), but have used a temporary gasket seal. Taking it for a gentle spin, it seems considerably better (still a wee bit) for the turbo return pipe seal, but again, it is still blowing from the oil filler cap, (as done nothing further to alleviate the pressure).

Any other places anyone can think of that I need to check etc that could be causing the high pressure?!

The dipstick doesn't appear to be rising up at all, even with a good welly on the first test drive.

Many thanks in advance.

Rob

The vacuum system is fairly simple, air is sucked from the crank case via the flame trap (breather box) to the inlet side. The coiled metal filter is normally replaced with a plastic holey one as they are impossible to clean, but taking it out is probably better than oil spraying out everywhere. The breather box may also be blocked, but check the pipes are clear. Normally it is just the coiled filter.

Standard test is to lift loosen the oil filler cap and try to lift it gently with finger tips only. If it is ok then there should be a slight suction that you can detect by the lifting force, then goes when you lift it higher, and then suddenly comes back on when it is lower.

Thanks for the reply Tony.

I have checked the filler cap test, and it seems to be as you describe. The very first time I took it off, there was a fair bit of splattering of oil. After that I did as you suggest, and it was ok.

I am still getting leaking from the oil filler cap on a run with the car even taking it steady. Confirm that there is a brand new seal on here.

I'm just trying to check that I have cleaned the whole system, but am a little confused with all the engine variants and what is on what car.

I have the 2.0l Turbo, which has B200 stamped into the block itself (can't see if it is FT etc - just says B200). It is a 1991 on a J plate.

Looking on;
http://www.swedishautoparts.com/940/...FLAME+TRAP+KIT

I can confirm that I have definitely totally cleaned the;

PCV Oil Trap
PCV Hose Nipple
Hose from PCV Oil Trap to PCV Hose Nipple and on towards the air filter
Hose from PCV Hose Nipple to inlet manifold (was TOTALLY blocked!)

I cannot find what is described here as the flame trap or the plastic filter with it. Does my model of engine have this??

The leaking is occuring even when barely spinning the turbo up or putting minimal load on the engine. Obviously more leaking with more revs and higher engine load.

Hmmm?! Ideas.

If there is vacuum and a new seal then surely must be the cap, are the retaining clips bent or the cover distorted? That is all that should matter at tickover.

Maybe the rings are leaking and pressurising the crank case.

The coiled filter may not be on these cars, I might have been thinking of a 360, sorry if I got that wrong.

all redblocks (so far as i have heard) have the flame trap, which is where it blocks (according to what i have read). will hopefully be clearing mine this evening so will try to get some pics to show you what it is.

Richard

Volvo removed the flame trap on the turbocharged redblock engines in the 1990s.
They replaced this:http://www.volvoclub.org.uk/faq/Imag...meTrapLate.gif with this :http://www.volvoclub.org.uk/faq/Imag...rapFitting.gif

They discarded the honeycomb shaped screen as it was constantly clogging (although the narrow tube on it's replacement also clogs).

Interestingly, if you check in Vadis, it shows the original 3-part flame trap.
But if you order the part (no.1332660) you will get the above (right).

It is worth getting one as a spare (I have) as the narrow outlet has a habit of breaking off as you are removing it to clean.