As many will know I have been fighting wicked oil usage on my 945t (91, b230ft 145k, 5 spd) for a couple of years now...with little success... for those NOT in the know...

1. no external leaks (i mean NONE)
2. new turbo - no evidence of extesive oil from it
3. no oil in the intercooler
4. PCV system cleaner than a really clean thing
5. One way valve installed in the PCV system to the manafold
6. Compression tests just fine
7. Tried just about every oil going (dyno/synth whatever) makes no difference to the usage
8. Tried auto-rx, comming tothe end of the rinse cycle, engines quieter, but no difference to the oil usage (well maybe down a tad...could be my imagination)
9. car pulls like a train...
10. oil usgae is 1ltr /350 miles if my wife driving it (shopping trolly on wheels, little sustained boost, low revs round town) 1 liter /200 miles if I drive it (boost, higher revs, longer runs)
11. NO smoke at idle (for 20 mins...) Smoke under SUSTAINED full boost and (im told by following driver) down hills (high vacume) smoke under boost seems to trail off, like it gets a dose of oil...then not a lot more...

at this point my thinking is...

Inlet valve seals, high revs put more oil in the head..so more burnt. High boost AFTER vacume pushes the oil in the manofold thru the engine, perhaps work guides/seals also allow some boost into the cam area leading to added blow by into the cylinders... High vacume sucks oil past the seals...

Now the question is:-

1. Do the seals with the head in place.
2. Have the head pulled and rebuilt
3. Get a second hand head and rebuild.
4. Fit new engine
5. Sell car and buy something else (960...850 t5 etc)

basically i have my own veiws about the pro's and con's of this wouldbe interested in others views and vieews on my diagnosis.

well thanks for the replys guys...i think...seems the jury is still out...

ok we have oil control rings, valve seals, turbo or rear seals (camshaft)..

like the boroscope idea - any idea how i lay hands o none?

I dont think its the cam shaft (this engine is seriously clean..i would spot it im sure..but thanks for the experience)

plugs all look about the same (bit on the oily/carbony side but not wet oily...)

the inlet manafold inside is filthy..sort of backing up valves perhaps, but maybe they just get like that after 150k...

so if its oil control rings feeling is it would effect one or two cylinders and show on the plugs??? - if so i dont see the evidence...

turbo..perhaps, not ruling it out...but thought inlet side leaks were more common.??

valves...would this crud up the inlet manafold? if so is it worth takign it off, deep cleaning then keeping an eye on it - never pulled one what are the risks (know exhaust ones are meant to be a pig...)

any more for any more?

Dear the kick inside,

May this find you well. If the oil control rings are clogged, that presumably means oil is being left in the cylinders, and is being burned. If that's the case, the inside of the exhaust pipes should be thick with carbon or tarry residues. One presumes that at some point, the catalytic converter would be completely clogged.

It might be worthwhile to inspect the inside of the exhaust system. It might also be worthwhile - and not hugely costly - to find an outfit that can measure the emissions. If excess oil is being burned, it should show up in the exhaust stream.

In effect, you're running a gas-oil mixture. At 1 quart of oil/200 miles, that's a 40:1 ratio, assuming 20 miles/gallon Ώ quart of oil versus 40 quarts of fuel]). My chainsaw takes a 40:1 gas/oil mixture.

If so, the exhaust should be richer-than-normal in hydrocarbons. The rate of oil use is so high, that I doubt enough oxygen can be supplied, completely to burn completely the gas-oil mixture.

If the emissions test finds that HC levels are above normal, it would support the thesis that the oil control rings are clogged.

Are you the car's first owner? If not, do you have oil change records? If not, do you know where the car lived, and where it was serviced?

Those records - likely showing long intervals between oil changes - might also be of diagnostic value.

I'm not sure how oil control rings get broken, unless the oil was reduced to a sludge, and so clogged the rings, jamming them such that piston movements flexed them to the breaking point.

Their breakage should have produced at least a few metal fragments, which would find their way into the oil pan. Perhaps a magnetic drain plug would show the presence of any metal particles.

Hope some of this is useful.

Yours faithfully,

spook

hi spook,

thanks for the input....

"the inside of the exhaust pipes should be thick with carbon..."

well its pretty black and carbony, and i have completely replaced it within the last 3000 miles...

" the catalytic converter would be completely clogged" - doesnt have one that got removed when the new exhaust went on, thought a partially blocked exhaust could be the casue of all this - i metered the presure iun the exhaust and it seemed high...(and yes its legal to do it where i live...)

"to find an outfit that can measure the emissions" - thats done once a year at the annual test, car flew thru (could be lambda sond works very well - could be that i got a gas emmissions sheet on my 850, but interestingly didnt on my 940 fro mthe same place, same guy - perhaps he was being nice to me...)

"that's a 40:1 ratio" - yep its running 2 stroke! - doesnt smell like one though...which suggests the mixture is burning efficiently at any rate - and thinking about it PERHAPS suggests it isnt the turbo where the oil would burn ineficiently and stink to high heaven you would think...


"If so, the exhaust should be richer-than-normal in hydrocarbons. The rate of oil use is so high, that I doubt enough oxygen can be supplied, completely to burn completely the gas-oil mixture." dunno about that..dunno HOW good lambda sond is at that....

"HC levels are above normal, it would support the thesis that the oil control rings are clogged" - or oil being burnt thru the engine (say leaking valve seals)????

"Are you the car's first owner?" - nope, not by a long way

"If not, do you have oil change records?" nope, but i DO have an incomplete service history, mostly volvo genuine and she did go a little long on some services, but not massively so...

"If not, do you know where the car lived, and where it was serviced?" - sort of, see above...

"Those records - likely showing long intervals between oil changes - might also be of diagnostic value. " yeh, she went long but we arnt talking 20k between services and i suspect (looking at the history) she may have had quick oil changes between with no reciepts (I say this cos their is evidence of things like brake disks/tyres etc at quick fit shops..but still majour services at main dealer and bloody expensive they were too!)

"I'm not sure how oil control rings get broken, unless the oil was reduced to a sludge, and so clogged the rings, jamming them such that piston movements flexed them to the breaking point.

Their breakage should have produced at least a few metal fragments, which would find their way into the oil pan. Perhaps a magnetic drain plug would show the presence of any metal particles" - no evidence of metal in there and she pulls really well, compression is ok i would have thought broken rings = cylinder damage - (compaired to my 70k 2.5 20 valve 850 which SHOULD be about as fast)

dont get me right i quite like the gummed rings theory, if its right then perhaps auto-rx may yet sort it...(that would be nice....) and the car does show some signs of basic neglect (the gear box oil was original at 140k i would say - manual box, and orrible oil!), the brake fuid needed changing...etc...

Dunno like i say im after ideas and ways to prove them cos this has cost way to much already and I feel in my bones its something simple, it simply doesnt 'feel' terminal - partly cos the engine runs so well...

I've read all the good answers and what-ifs and if it were my problem I would replace the valve seals "on the car". It is a job that isn't too involved given the right tools. Some compressed air in the cylinder you are working on will hold the valves in place while the tappets etc. are removed to get to the seal area. (If you do it yourself watch for the rotating engine when you presurize the cylinder.)

Given all the analysis already done it seems this is the easiest, least expensive way to prove or disprove the valve seal theory.

I'm not really familiar with gas turbos but I know my diesel turbo dumped a lot of oil into the intake manifold as the turbo-charger reached it's end of life. If it were the turbo and you have an intercooler, I'd also expect to find a lot of oil settled low in that 'cooler.
--
'96 965 with 16' wheels at 119K. Had '85 745 Turbo Diesel for 200K.

yeh my thoughts exactrly on the turbo (unless its just venting oil on the exhaust side)..no oil in the intercooler and the throtle plate (butterfly) which lies imediately in front of the manafold is clean...


thing is opion has been given that if the seals are shot at 150k the stems/guides may also be buggered...and simply no point replacing the seals...and i understand (aka am lead to believe) that you cant check this without pulling the head...

oh choices choices...

I tend to think valve seals.They are relatively cheap to replace on the car-try this first.If this doesn't fix it,then guides-this will require pulling the head.While you are doing this,it should be relatively easy to inspect the oil conrol rings.Hope it's just the seals,though.Leaking seals can produce just the symptoms you describe-and all are probably leaking equally,so looking for one or two extra-dirty plugs doesn't help.Seals failure is age-related.Assuming they are all the same age,they could all be leaking the same.Hope this helps.
sredwine 94 940T 150K

Greetings,

Where is the oil going? I am puzzled by this with my 940, but I do have a suspect.

For about a year I had a leak on the front of the engine. Could not identify exact cause since it was behind the timing belt cover. I thought it was the intermediate shaft seal. The amount of leakage was enough to leave a few drops on the driveway each day. This past June I decided to replace the front shaft seals and the timing belt since it was almost due. I discovered the leak was from the front crankshaft seal and the aluminum carrier plate to engine block gasket. The clue to my current problem was that the lip on the crakshaft seal had become embrittled (discolored, and cracked easily on removal). Drove the car for a month (about 1200 miles) with no drop in oil level on the dip stick. Engine was completely dry and tight.

The car is not normally driven above 55mph. In July my son took it on a trip of about 750 miles at speeds up to 70mph. When he came back the engine had lost an entire quart of oil. (It had never lost or used this much oil before) Got underneath and inspected. No sigins of oil on the bottom of the engine or the front where the leak had been. In 2000miles since that trip about a pint of oil has been added. There have been no drips on the driveway. The engine produces no smoke. What I have found is a small amount of engine oil and gunk buildng up on the transmission case and support member since it was all degreased in June. (my second clue).

What I suspect is happening is that the rear crankshaft seal is embrittled like the front and that the oil is slowly leaking out at high RPM, flowing out across the transmisson and being lost out on the highway. I am keeping a close eye on this but I am not really motivated to pull the transmission just yet.

Mike


'94 940 B230FT 102k-miles, '02 S60 41k-miles

With all you've reported, it HAS TO be going through the "new" turbo.
I'm assuming it either has a manufacturing flaw, or it was really a rebuilt unit and clearances are not what they should be.
If there's any warranty on it, this should be replaced free of charge.
I've seen a few cars do this, and I agree the consumption is excessive, especially with no leaks. The engine CAN burn this much without making too much smoke- the fuel injection system is carefully monitoring mixture and compensating, probably burning a bit LESS fuel as the O2 sensor records high HC levels. So in a sense, the car is running on oil a bit.
I think confirmation would come from the spark plugs- if they are all equally clean (or equally dirty!) then it's not something like bad rings or valve guides. If you DO have one or two filthy plugs, then obviously the engine has an oil control problem- otherwise, it's in the turbo.
Good luck with it.
--
Rob Bareiss, New London CT ::: '87 244DL/M47- 234K, '82 245T/M46-182K, '89 244DL/AW70- 212K Not too distant past: 86 244DL 215K, 87 244DL 239K, 88 744GLE 233K, 88 244GL 147K, 91 244 183K

If it does not smoke when revved up after 20 minutes of idling I think you can assume there are no problems with valve guides/seals.

As you have eliminated so many other possibilities my money is on broken or stuck oil control rings

Even total failure of the piston oil control rings will not influence compression readings if the compression rings are OK.

Not Volvo specific advice, but based on 40 years of experience on engines of all types.

Colin.

1990 740SE B200E/M47, remote C/Locking.

ok i buy that...(hell i would buy tower bridge right about now)...

any way i can DIAGNOSE that rather than just gettign the engine pulled apart..or an new engine dropped in...see much the same was pronounced that lead to the new turbo..not that im doubting you, just looking for a little objective measurement in the equation...

my logic on it not smoking at idle was that eh inlet valves are o nteh high side of the camshaft (the engine being at an angle if you follow) so low revs = lower oil presure = oil draining away so seals not actually under much oil and also relatively low valcume....but at higher revs, higher oil presure so more oil up there, then bang off boost into high vacume (some 20% or so higher) and all the oil up there gets sucked down...but i may be blowing smoke here (well i am from the car, possibly also the theory!

i appreciate the input so...if its blown control rings are we talking gummed up, worn or broken - wouldnt broken effect compression due to wall damage?

btw oil weight doesnt seem to make much difference tried 0w40 m1 and 10/w40 various stuff...no change...but then again that only the cold weight i guess...

oh and the inside of the inlet manafold looks grim...but the throttle butterfly is clean on the outisde (one thing that made me think valves..)

40 years takes some argueing with though...

Dear the kick inside,

May this find you well. At the risk of trespassing on your goodness, with regard to point No. 1, have you examined the underside of the car, after a good run? I presume your inspection for sure covered the top of the engine.

Oil pan bolts tend to work loose over time, allowing oil to seep past the gasket. To tighten, use a criss-cross approach, and do it in stages, to compress the gasket equally, until snug. Then, go 1/8th turn more.

Also, if you are not the first and only owner, did previous owner(s) keep the "flame trap" clean? If not, oil may be seeping past the rear main seal. However, the actual rate of leakage is so high, that were the car to sit in one place, there would be oil visible on the ground.

The amount of smoke you report the engine emits does not seem sufficient to account for the loss of a litre/350 miles. To burn that amount of oil, you'd be laying a smokescreen. Somewhere, fluid is leaking out.

Your comment that loss rate is nearly double under boost suggests that the pressure is forcing oil out of the engine, rather than burning it.

I'd check underneath, very carefully. If necessary, put the car up on a stout rack (one used for trucks/lorries) and then accelerate to 100k/hour, and tromp down to engage the turbo. Then, see if there's any sign of oil leaking (pouring) out underneath.

Could be that a pipe/tube is split, and when boost is applied, pressure causes it to open-up and to leak oil; when boost subsides, the gap narrows or closes.

Hope this helps, but not to raise yr. blood pressure.

Yours faithfully,

spook

nope i have intermately examined the underside...its been degreased, cleaned and spit and polished...

there is NO external oil leaks and i do mean NONE...

no i really do mean it its dry under there... its parked on my drive every day NO oil spots none nada....

I have concrete ramps built into my drive so have great access under the car and have crawled under it with a 500w hallogeon light...its DRY

I agree with you seems like a lot of burning...for not much smoke..but thats what happens...

as for the oil use going up i 'THINK' that it revs dependant rather than just boost...my thinking is perhaps more revs = more oil at the TOP of the engine thus more oil being pulled past the seals???

seriously i have spent THOUSANDS trying to sort this and it really isnt leakign out....

If you can get access to a boroscope that might help you to determine the problem. A boroscope is basically just a lighted sight glass on a flexible stalk. You pull a plug, insert the scope and take a look around. You can see roll the engine to see the valves when they're open, and you'll be able to make some conclusions by noting the presence or lack of oil deposits on the valve stems.
But, I think Colin is probably closer to the mark. Stuck oil rings are a problem I've seen and experienced quite a few times.
Richard
--
86 740T/87 745GLE/96 960 Wagon