940 smoking/burning oil

[bob12]

Originally Posted by griston64

See notes re oil

[ATTACH][/ATTACH]

That and the chart is identical to my Owner's Manual for a 1990 740.

Bob

[Laird Scooby]

Originally Posted by griston64

See notes re oil

[ATTACH][/ATTACH]

Is that including the bit about 15W40 and 20W40 Mark?

Also Volvos original choice of words is potentially important - "Synthetic or semi-synthetic may be used ......." as long as it meets API/SG etc.

The key word is may, i suspect their thoughts were people would default to mineral oils which usually have larger molecules than semi-synth and larger still than fully-synth.

Semi-synth is therefore a good all-round choice as while it provides for extended oil changes, it still has a mineral base so the molecules are larger. Fully-synth will extend the oil changes further and is likely to stay in grade longer with constant sustained high speed driving and/or town use/short journeys but having smaller molecules is likely to be more conducive to oil burning.

Hence Volvos recommendation to use 15W40 or 20W40 in engine prone to oil burning.

I'm a big believer in using the oil that was used (or most likely to have been used) when the car was first used. While fully-synth oils were available throughout the life of the 7/9xx range, they were barely available when the B20 pushrod OHV engine morphed into the B21 OHC engine that the 240 used and was later improved further for the 7/9xx range.
As such, it could be considered the engine (in its basic form) is actually a 1960s design and then, even semi-synth was borderline witchcraft!
Fast-forward to the 90s and the chances are, Volvo used semi-synth from new. This would have produced different wear patterns in the engine to mineral or fully-synth oil. As such, using semi-synth would seem to be the most logical and best option.

I note Robs comments about using fully-synth, not knowing when he got the car (how new) or any of its history (did he rebuild the engine for example?) it may be he's used fully-synth and never had a problem. If memory erves, i think he also runs on LPG in which case the engine oil will stay cleaner between changes so less wear will occur when it's due for a change.

The big thing is consistency. Chopping and changing oil brands and types won't do the engine any favours long term and in my experience, semi-synth seems to be what all my 740s were happiest on.

A nte about part-synthetic oil. This is mineral oil with synthetic additives, no more, no less and certainly not a 50/50 blend of mineral and semi-synthetic oils which may or may not have additives as well.

[Laird Scooby]

Originally Posted by bob12

That and the chart is identical to my Owner's Manual for a 1990 740.

Bob

DItto my 1988 760 Bob.

[bob12]

Yes Dave, I have always used semi synthetic 10/40W but, I'll have to ask my mechanic what he's been putting in since I delegated oil and filter changes a couple of years ago. Whatever it is it hasn't created any problems currently. Bob .

[Jelle9990]

The intercooler came out today and there were very little amount of oil in it! I cleaned the intercooler and chargepipes with petrol and now it should be even cleaner than it already was(was very surprised how clean it was!)

I assembled everything and fired it up, let it warm up and reved it and saw the same big cloud of white smoke...

Soooo.... the valve seals might be toasted?

Or the turbo seals are? Is that a hard task to replace or can I do/check it my self?

[Jelle9990]

Does the T3/T4 turbo fit straight on the original manifold?
https://www.ebay.com/itm/372964639358

[Jelle9990]

Never mind the question above, don’t know how to delete a post(noob)
I looked further in to it and saw it wasn’t water cooled like the one I have(just saw a lot of videos of b230’s with T3/T4 but that looks like a bigger conversion....

Is there any way I can 100% confirm it’s either the seals or turbo? Or is it 100% the turbo? Like rolling down a hill in gear, take a drive without charge pipe or something like that?

I’m not sure but I think I have a Garret t3 maybe? is that worth rebuilding or should I swap with another?

[Laird Scooby]

Originally Posted by Jelle9990

Never mind the question above, don’t know how to delete a post(noob)
I looked further in to it and saw it wasn’t water cooled like the one I have(just saw a lot of videos of b230’s with T3/T4 but that looks like a bigger conversion....

Is there any way I can 100% confirm it’s either the seals or turbo? Or is it 100% the turbo? Like rolling down a hill in gear, take a drive without charge pipe or something like that?

I’m not sure but I think I have a Garret t3 maybe? is that worth rebuilding or should I swap with another?

Fairly certain the 760T used the Garrett T3, you can buy replacement cores quite cheaply, i don't know if this is the correct core but gives you an idea :

https://www.ebay.co.uk/itm/For-Saab-...AAAOSwftZbfROd

Might be worth a look?


*** EDIT *** Sorry, was thinking of another thread about a 760T!

[griston64]

Originally Posted by Laird Scooby

Fairly certain the 760T used the Garrett T3, you can buy replacement cores quite cheaply, i don't know if this is the correct core but gives you an idea :

https://www.ebay.co.uk/itm/For-Saab-...AAAOSwftZbfROd

Might be worth a look?

What year is the car as most 940's used a Mitsubishi turbo

[Jelle9990]

It’s and 93’ 940 with B230FT with 4 gears with overdrive(m46?) but the middle of the turbo clearly says garret and the front says b.c AIR-48m