Oil Consumption After Rebuild (Re-ring)?

[Nessism1]

Compression rings are forced into the cylinder wall by combustion pressure. NOT oil rings. Oil rings are forced into the cylinder wall by the wavey expander (spacer) spring. I'm starting to think that driving hard won't help the oil control rings seat. That's simply a function of surface roughness on the cylinder wall and the parts wearing together.

 

[Exhaustgases]

A great example of an over costly disposable engine. My lawn mower engine is built better in some respects. Someone mentioned Vega engine, right on. How come all german auto engines are pot metal now? Cheap cheap.

 

[Cujet]

Compression rings can greatly affect oil consumption

 

[Donald]

Why didn't the short block come with the cylinders all set for pistons to be installed.

I actually thought a short block came with pistons installed. Just no heads?

 

[MichaelCT]

Why didn't the short block come with the cylinders all set for pistons to be installed.

I actually thought a short block came with pistons installed. Just no heads?

It's an used bare block, factory new short block assembly won't make financial sense in my location.

In relative figures, I paid 135 for the parts and labor, going with a new block would probably be 200-250, while complete new engine installed is ~350.

 

[someonesomewhere]

I was told in the past to leave the unit in a lower gear and do some hard throttles and quick decelerations when you are moving, not from a dead start. This was in a stick car or motorcycle. Might be an old school way that is not relevant today, but it has always produced strong motors that did not burn oil.

Same. Usually in reference to old small blocks, but at a base level, the principles are the same, generally.

 

[MichaelCT]

Compression rings can greatly affect oil consumption

Did some further reading today and apparently the second ring does both compression and oil control, primarily the latter.

And the second ring gets less combustion pressure so they can cause oil consumption under lighter loads.

The article was mainly discussing ring gap tolerance issues but I feel the same principal fits my situation as the rings are yet to fully break in.

 

[Donald]

It's an used bare block, factory new short block assembly won't make financial sense in my location.

In relative figures, I paid 135 for the parts and labor, going with a new block would probably be 200-250, while complete new engine installed is ~350.

So was there any machining done to the cylinder walls? Or pistons were pulled and your old pistons with new rings were installed?

Many would have bored and gone with oversize pistons.

 

[MichaelCT]

So was there any machining done to the cylinder walls? Or pistons were pulled and your old pistons with new rings were installed?

Many would have bored and gone with oversize pistons.

The replacement block came completely empty, my original pistons were used with new rings.

The (replacement) cylinder walls were pretty clean and looked just like my old block. Given the difficulty with honing Alusil, it wasn't done.

While BMW does offer + 0.25mm pistons, the replacement block was in spec so it wasn't warranted, and one still will have to deal with honing Alusil after boring.

 

[Donald]

The replacement block came completely empty, my original pistons were used with new rings.

The (replacement) cylinder walls were pretty clean and looked just like my old block. Given the difficulty with honing Alusil, it wasn't done.

While BMW does offer + 0.25mm pistons, the replacement block was in spec so it wasn't warranted, and one still will have to deal with honing Alusil after boring.

I am not in Asia and my only rebuild was a 1965 Mustang 289. But have not really heard of people buying a bare block.

What would Dave's Auto in Utah do? He would probably hone the cylinders as he seems to have every piece of engine rebuilding machinery including a SIM tester. Don't know that I have ever heard of a shop with a SIM tester. Possibly because few shops have one or because I work on mainframe computers all day and not gasoline engines.

 

[MichaelCT]

Some updates:

The car has done another 350 km, with about half ran pretty hard intentionally and the other half being normal street and highway driving.

On harder runs, the oil level remained relatively stable (~61-62mm raw reading), and the dash indicator always stayed at 1/2.

I also found some info on the raw values and dash indicator, the threshold between 3/4 and 1/2 oil level seems to be 65mm.

Upon coming to a stop after normal driving on two occasions (at the same parking spot), the raw value read ~ 65-66mm, and I noted that the coolant temp was at 105C (this is the economical cycle target temp; hard runs are around 90C).

At another time, the dash indicator actually went back up to 3/4, I didn't have a scanner with me that time but I were to guess, it was probably just over 65mm.

All of the above mentioned readings were taken with the engine running and after fully warmed up (the dash won't display an oil level reading if car wasn't running or still cold, only "Oil Level OK" message if cold raw reading is above 60mm), and after shutting off, the raw values were always at or around full (~74mm).


Ideally, if my original reading at 30KM was fluctuating from engine temp, then I might not have much oil consumption after all. Otherwise, I am still happy for not losing noticeable levels of oil after another 350 km.

Will update again at higher mileages.