Oil leak, head gasket?

[Cylinder 8]

Hi all, my 940 (B230FK) has had a nasty looking oil leak ever since I bought it just over a year ago. Both sides of the block look quite wet (driver's side is much worse) and over time it runs down and coats the underside of the gearbox, but the oil level doesn't really drop, the leak just looks worse than it is. I've already replaced the distributor seals, front camshaft seal, valve cover gasket and oil trap. None of these have made much difference. I really want to sort it before I upgrade the turbo and put everything under more stress, and noticed today that the oil seems to be collecting at the joint between the head and the block:





I'm starting to think the head gasket has broken between an oil gallery and its edge, although the gasket was apparently replaced and the head skimmed about six years ago. Is there anywhere else I should be looking before I take the head off to check?

[360beast]

Wash it all down with some brake cleaner and see where it comes back.

[Laird Scooby]

Have you checked the PCV system and cleanied it? Have you renewed the oil filler cap since you've owned it? What about oil/filter changes? What oil are you using? Have you already increased the boost?

[Cylinder 8]

Thanks for the suggestions, there isn't much access to clean it all off (especially on the exhaust side) but I think it might be my best option.

The oil trap is new and all the PCV hoses are clear. It's had regular oil and filter changes using Magnatec (I think it's 5W40). It's currently running 9PSI on the original turbo but it was leaking just as badly as standard. I have noticed some oil running from the cap actually, there isn't much but I'll get a new seal for it and see if that helps.

[TonyS9]

Standard boost will tend to cause oil leaks on these if you use it alot. There is no check valve in the breather and the dump pressurises the crank case. Oil pretty much comes out everwhere when you close the throttle. On my B230FT (14psi) 360 there are oil drops all over the engine bay. My standard 940 B230FT is pretty oily too.

On the oil trap did you replace the O-rings. On the disti did you replace the actual rotating oil seals (not just the o-rings).
For the valve cover you have to seat it + tighten it really evenly.

[Laird Scooby]

Originally Posted by Cylinder 8

Thanks for the suggestions, there isn't much access to clean it all off (especially on the exhaust side) but I think it might be my best option.

The oil trap is new and all the PCV hoses are clear. It's had regular oil and filter changes using Magnatec (I think it's 5W40). It's currently running 9PSI on the original turbo but it was leaking just as badly as standard. I have noticed some oil running from the cap actually, there isn't much but I'll get a new seal for it and see if that helps.

Did you check the small bore stub on the inlet manifold? That has a habit of clogging up and will cause the problem you've got.

Don't get a new seal for the oil filler cap, you'll make things worse. Get a new cap as you were advised to! It's part of the breather system and should be renewd periodically.

Also try running it on the correct oil, semi-synth 10W40, not something that is thinner than a bank managers blood!

[Cylinder 8]

Yes, new o-rings went on with the oil trap. I replaced both o-rings on the distributor, I didn't realise there were other seals as well. The engine seems more oily at the front than the last time I checked, I think I'll have another look at the front camshaft seal as well.

[TonyS9]

Originally Posted by Laird Scooby

Don't get a new seal for the oil filler cap, you'll make things worse. Get a new cap as you were advised to! It's part of the breather system and should be renewd periodically.

Also try running it on the correct oil, semi-synth 10W40, not something that is thinner than a bank managers blood!

5/40 just means it has a narrower voscosity range than 10/40. 5/30 uis perfectly suitable for the UK, although track use with boost I'd probably go with 40, but these things are robust as hell, I don't think it really matters.

Also, how is the cap part of the breather? AFAIK its just a plug, it either seals or doesn't. I'd suggest testing it before replacing it.

[Laird Scooby]

Originally Posted by TonyS9

5/40 just means it has a narrower voscosity range than 10/40. 5/30 uis perfectly suitable for the UK, although track use with boost I'd probably go with 40, but these things are robust as hell, I don't think it really matters.

If it doesn't matter, Volvo would recommend running the engine on water as a lubricant wouldn't they? Don't forget these engines were designed back in the 60s as the original pushrod/OHV B18/B20 engines and were running 20W50 back then! Tolerances were tightened over the years so they now happily run on 10W40 but go thinner, unless you're in a cold country and you're likely to get oil leaks.

Using 5/30 in the UK, you'll have leaks and knock your ends out - i'm just glad it's not my engine!

[TonyS9]

Originally Posted by Cylinder 8

Yes, new o-rings went on with the oil trap. I replaced both o-rings on the distributor, I didn't realise there were other seals as well. The engine seems more oily at the front than the last time I checked, I think I'll have another look at the front camshaft seal as well.

Most likely its the boost that causing it, I tried a check valve but it seemed to fail pretty quickly, then it started affecting the brake resevoir briefly on the track dumping brake fuid out, but another check valve did seem to fix that. The 'faulty' check valve seems to work with a blow test, and I have another in series, but still have problems.

The standard tuning cure is to vent the crank to atmostphere into a catch can. I was trying to avodi that, but not successfully yet.