30 replies to this topic

[wezg]

Hello all can anybody shed any light on this...?

Has anybody ever come across this odd oil burning problem..

We stripped down and fully resealed a 998 A+ and reinstalled it. We also replaced the stem seals with MPI Viton stem seals

Its now completely leak free but is using a considerable amount of oil( more than 1ltr every 500 miles ) but shows No signs of smoke.. Also passed its MOT emissions test no problem

So did the usual checks.
Spark plugs all grey/brown
No external leaks
No smoke on cold start up ( maybe a tad of black due to being rich with choke on.)
No smoke on hot starts
Exhaust has nice dry black carbon on it
Pistons dry with normal black carbon build up
Test drive.. No smoke on hills under load and running well
Compression test with good results ranging from 173-189psi.
Carried out a leak down test got good results 14-19% leakage when hot also showing same pattern as compression test
Owner is very happy with performance and its not using excessive amounts of fuel

Any ideas?

Thanks
Wez

[sonikk4]

What about on the over run?? It does sound like a ring issue and I mean the oil control rings.

If you have not touched the pistons then does sound like it could be the culprit. Either that or the bores are glazed.

[wezg]

Engine is still smoke free on overrun.. And thats with a passenger in the car looking for smoke so not just try to use mirrors..
The engine has done 70km since it was over bored so not really that high a milage.
We put the camera down the bores aswell and no scores to report but maybe a slight lack of cross hatching is visible..thats my only concern that I have found..
I just cant see how its using so much oil yet producing NO smoke.. Is it possible we have the perfect burn situation..?

Wez

[Spider]

If it's not dropping the Oil, it can only be burning it.

 

You need to burn a fair bit of Oil before it becomes visible smoke, generally more than what you're burning.

 

It maybe some gum in the rings, you can try cleaning them by changing the Oil to a good 10W40 Diesel Engine Lube Oil to clean them, then go back to a good 25W50 and see how it goes, however, like Sonikk, I'm inclined to feel the bores are glazed.

[wezg]

Moke i have to disagree with burning more oil than this for smoke.. I have a sprite that burns oil.. Lots of blue smoke on cold start up..fair bit on over run aswell so I know it has an issue..Yet i have not had to top up the oil over 3000 miles...

This car is using over a litre of oil every 5 hundred miles..
I would expect to see some smoke at least..

Never known glazed bores to also leave engine running very well indeed.. Normally compression ratios drop badly with glazed bores..

Edited by wezg, 26 June 2019 - 09:21 AM.

[mini13]

Its obviously the oil pixie then...

[Rorf]

Have heard of people stealing petrol and batteries but oil is likely the next one

[MiniMadRacer]

Have you checked the radiator water lately, thought that is a hell of a lot of oil to be passing into the water.

[Steve220]

Pull the breather hoses and see how much oil is in there.

[wezg]

No oil in the water.. Breathers are clear and no vapour or puffing when disconnected either..we have joked its the fairies..!
Just got me baffled.. Would have thought there would be some form of evidence.. Either smoke..fouled plugs...damp oily tailpipe...puffs of vapour from the breathers... But nope nothing... Just wondering if anybody has had any similar happen and how was it cured..?

[Dusky]

Something doesnt add up.

1 liter every 500 miles, but you have only done 70 km?

[dyshipfakta]

Something doesnt add up.

1 liter every 500 miles, but you have only done 70 km?

some 000s missing I presume.

[RooBoonix]

Something doesnt add up.

1 liter every 500 miles, but you have only done 70 km?

That's what I was thinking. If has only done 70km then the rings have nowhere near bedded in yet so oil consumption may be high...

[Dusky]

Something doesnt add up.

1 liter every 500 miles, but you have only done 70 km?

That's what I was thinking. If has only done 70km then the rings have nowhere near bedded in yet so oil consumption may be high...

Thats what Im hoping on ^^

[Minigman]

Had a similar engine issue last year with a newly built engine. I was driving it too gently and I did have puffs of smoke on the overrun. I just drove it harder for the next 500 miles and everything bedded in and the oil consumption stopped almost entirely. Don’t thrash it with high revs, but do put it under load to get those rings bedding in properly. I did my bedding in in short 3 second bursts. Foot flat to the floor and then letting off again. Wait 30 seconds and then repeat. Did the trick. Next engine I’m running in is going to get punished from the 1st mile!