oil consumption after rebuild?

[angelr4]

Hello to all!


Last summer I performed a rebuild on a badly damaged 1972 Fulvia Berlina 1.3 engine. As a cause of sticking valves (?) I found it to have a broken piston crown ,broken valves, ruptured combustion chamber...so the repairs were: Second hand cylinder head, with new inlet valves and all valve guides, cylinder rebore with new pistons, as one of them was badly scored, and new con rod bearings, just in case (they were in fairly good shape).
After that, the engine ran fine, but gave off some white smoke, mainly on acceleration, just like burning oil. I assigned this to the engine not being run in yet.
After about 1100 kms, the problem remained, white smoke clouds mainly when accelerating. Engine still ran OK, absloutely no coolant consumption, oil consumption about 2 liters/1000 km, oil pressure a bit low (I rely on the gauge, I haven't measured it with a proper instrument yet). Measured compression, equal on all four cylinders. I did a leakdown test and it showed neglible losses (about 1%). By checking the spark plugs visually, it was clear that cylinder No1 had the problem, as only this plug had some hard deposits.
I removed the head, and it was more than obvious, only cylinder no 1 seemed to burn oil, as all deposits were accumulated there, and the first piston crown had a very light oil spray on it. After removing the valves and springs, all I could find was a slightly loose fit of the No1 inlet valve in its guide. Note that oil seals was modern type (elring brown ones) fitted on all 8 valve guides. I took the head to the firm who reconditioned it, and they also accused the inlet valve guide. So they replaced again all eight valve guides, plus fouw new exhaust valves.
Yesterday I put them all back, only to discover that the engine smoked even worse! Did not check anything yet, as I was too frustrated...

My main question, apart from the obvious suggestions of what else may had gone wrong, is, has that engine any oil passage nearby the first cylinder that may have cracked? Any other ideas? Thanks in advance, and sorry about the length of my post!

[gamma a.i.]

Oh my my; I wish you had posted this on 1 April

not being an engine man... 1st thought is "1 piston ring"...but I am not an engine man.

still, I hope to hear what it is finally determined to be the cause & the solution ; because I also own a (blue) smoking-fulvia !

[lucasgeheniau]

Strange, blue smoke is engine oil.

I have had white smoke, when braking and then accelerating.
That turned out to be brake oil. Because of a leaky seal at the end of the main brake cylinder, oil dripped in the servo. Month after mont etc, so sometimes the brake oil was low. I thought it was from the wear of the brake pads only. (the level in the servo was rising slowly.)
At last, when braking, the oil entered the vacuum hose to the inlet manifold, which resulted in white clouds when accellerating.

Two litres of engine oil every 1000 km. is high, even just after rebuilt. I can only think of a broke oil scraper ring on cylinder 1.
It can be broke when mounting the new pistons.

[lancialulu]

Faulty pistons with too wide lands for the rings or soft rings. I had this with an old but not high mileage fulvia 1.3 and I changed the rings and all was cured. The old ones were soft.

Tim

[angelr4]

Thanks to all for your replies!

My first thoughts were in fact related to piston rings, but wouldn't that give lower, or at least different compression and/or leakdown values on 1st cylinder, before I even stripped down the head?

lucasgeheniau, I will check the brake servo, but i think it's OK. At the same time as the engine repair, I did a brake fluid change and fluid level didn't drop down too much.

lancialulu, pistons and rings are new. "Soft" rings would also cause compression losses, I think. Moreover, why should this happen only on the 1st cylinder? Maybe that much difference in manufacturing tolerances? I admit I didn't measure piston ring gap and vertical clearance in piston grooves. They are supposed to be just right when new .

There is no high pressure oilway nearby cylinder No1 that could have been damaged and leak oil, am I correct?

[NMLancia]

Compression rings are not the same as oil control rings. You can have good compression and yet still burn oil. Why only No.1 ?.
I dont know but it could be those rings failed to seat, always check all tolerances when building a motor, even of new parts!

[Huib]

My prime suspect would also be the oil control ring on #1. Maybe damaged during mounting. 2 liters of oil per 1000km is a lot for leakage through the guides.

About the colour of smoke:
white: water (coolant) or brake fluid. When it is caused by brake fluid there is usually enough smoke to hide an aircraft carrier
grey: petrol. Mixture too rich
blue: oil

When the guides leak, there is a puff of smoke at the start of acceleration after deceleration. When the rings leak it is during the whole acceleration.