Club 80-90 Forums

I take it thats in bar ? , if so then its down , way dowwwwwnnnnnn

sorry 8 bar is minimum , looks like wored rings , which is not too bad ,
you could try an engine wash out but could make it worse , or you could just keep putting in thicker oil and keep on driving it

99576 Miles on the clock
Oil change july 2008 with 10/40 semi synth, was hot as drove in drive and attacked.
would think the engine would burn oil when pulling if rings where completely shot but still only burns on over run, did it again today and not all the time only on long down hill run's with not throttle.

Those compressions then are not truly representative or I'd agree with T'Onion, rings are sticking or very worn.

I've used an additive called a mono-molecular oil before with good result on low compression engines, when it hasn't mattered much what happened - and worked.

Not an oil viscosity bulker, not a PTFE additive, but makes a very thin (one or two molecules thick) oil/metal bond with the surface. To do that, it has to shift carbon, and this then frees up rings. Can be a downside if engine compressions dependent upon a large carbon seal on piston top-land, but overall tends to improve compressions and reduce oil burn...

I'd try again first with open throttle and engine cold, might give a clue... spin it over for a few seconds with all plugs out first, just to splosh a bit of oil a round if it's been standing...

Putting the oil down on horz opposed engines isn't always that effective I would think.. due to layout. Also, wnat to mill the engine over a bit with the oil, before taking compressions... did you squirt it in with a oil can?

10/40 semi synth

i'd be putting 10/40 regular oil in not semi synth , could be that it a wee bit to thin and working its way passed the oil scraper on over run

Yes i did use an oil can 3 pump's in each but didn't turn over before taking reading's.
Think i will try compression test again at the week end on a cold engine with throttle open and all spark plug's out. Then try regular oil.
A little scared to try and free up rings yet as this is the wifes daily drive so will need a plan B if i make it worst.
Thanks for the help so far and i will keep you posted

Ta..

Dont know if it has been said before, but a smokey overun can be caused by worn valve guides, the vacuum in the cylinders pulling oil down into the engine. This wont always show up in a compression test if the valve is sealing well.

Morganman wrote:Carried out a compression test today after a trip out results as follows:-
1 = 7.9 dry 8.5 with oil
2= 8.1 dry 8.5 with oil
3 = 8.0 dry 8.5 with oil
4 = 8.0 dry 8.5 with oil
all with throttle closed as no helper around all a little low but no great changes between cylinders should I be worried about rings?
or is it looking more like valve leakage.

Mondeo story:
Cracking car except slight smoke after overun. Low water temp put down to sensor. Suspected valve stem seals but assessed good buy even if £500 short engine required. Gave the man £300 and drove home. Changed valve seal using evil down the plug hole device so no head off. Only slight improvement. Discovered no thermostat fitted. Replaced stat and changed oil using recomended cats pee viscosity. Left home on trip to Dorset on clear road cruising at 70MPH with oil temp at normal. Lifted off at Winchester and noticed dense smoke screen in rear mirror. Completed journey using neutral in overun situations due to fear of retribution on part of following traffic or getting nicked. Waited until dark before setting off home. Changed engine avoiding whole front subframe drop - Haynes - by removing head first. Disovered less than ideal piston/bore fit. Fitted short engine and have now had about 5 years good service out of it.

Or to put it simply: Yes I suppose it could be the bores!
Cheers
Ken

Dont know if it has been said before, but a smokey overun can be caused by worn valve guides, the vacuum in the cylinders pulling oil down into the engine. This wont always show up in a compression test if the valve is sealing well.

Yes 'twas I think mentioned back up the thread awhile and compressions indicate soemthing awry with piston bores (worn/glazed) etc.

However, might be worth checking you are not running a high oil level...

anyway, see what the 2nd set of compressions come out like next w/e

Compression test result after carrying advise:-
ie open throttle, all plugs out, cold engine, 4 pumps of oil on wet test and turn over a few times before test.
1=9.9, 10.1
2= 10.5, 12.0
3= 10.2, 11.2
4= 10.4, 11.9

These look better cylinder one being a little low but not a great increase after oil inserted.
Like your views,
Also no one has confirmed yet if stem seals are fitted on this engine?

1=9.9, 10.1 (2%)
2= 10.5, 12.0 (14%)
3= 10.2, 11.2 (10%)
4= 10.4, 11.9 (14%)

AV. of 150 psi (10.25 bar), yes more like it

These look better cylinder one being a little low but not a great increase after oil inserted.
Like your views,

Also no one has confirmed yet if stem seals are fitted on this engine?

I think conclusion was not, and if that implies valve guides are worn it might also imply that the seats or seatings are not as good as they should be