smoking oil

[Cabriolet]

this will be the third rebuild in as man years on this engine.
the rings,bearings,timing belt and waterpump have 16k.
the head was refreshed 8k ago. it was flattened (lapped on glass till flat.) new seals

now when i push the car up to 80+ the oil consumption is crazy, DD at low speed no oil loss. but doing 75-90mph ill lose a qt/2hours.

getting off the freeway after driving fast today the engine was shaking and sounded like a WRX boxter engine. (no power loss tho)
popped the oil cap at my dad's and smoke was pouring out.

about 2k miles ago i did a compression test and it was very good.


before i rip the engine out tomorrow and rebuild a whole new engine for her, any ideas?

[Cronopoulos]

Looks normal, mine doesnt use any oil but it smokes like that.

[jlevie]

The last time the engine was rebuilt were the cylinder bores within the wear limit? Likewise for ring grooves in the pistons. Were the cylinders cross hatch honed?

[Cabriolet]

The last time the engine was rebuilt were the cylinder bores within the wear limit? Likewise for ring grooves in the pistons. Were the cylinders cross hatch honed?

Yes the cylinder bore was still very good and still cross hatching. The block only has 132kthe miles and 114k was as automatic.

[Cabriolet]

Compression is 50psi in cylinder 5. Engine has been pulled

[jlevie]

Yes the cylinder bore was still very good and still cross hatching. The block only has 132kthe miles and 114k was as automatic.

That isn't what I asked. The only way to tell if the cylinders are below the wear limit is with bore gauge and the measurements must be made at 120 deg apart and at the top, middle, and bottom of the bores.

Any time the rings are replaced, if the cylinders aren't worn, they much be cross hatch honed. If you don't do that the rings will take a long time to seal, if they ever do.

[Cabriolet]

All 6the of the top rings were shattered. Cyl5. Has both top rings broken and gouged the cyl wall. All the honing is gone.

[jeffnhiscars]

Im still wondering why this very engine has been "rebuilt" 3x in 3 years....and now this

[bmwstephen]

eric, is your exhaust blowing out white smoke as well?

[Cabriolet]

round 1 i rebuilt it, bc the car was new to me, needed a manual swap, and had oil pan and water pump leak.
round two my head bolts stretch, typical VR issue.
this round my top rings broke on the 4 of the cylinders broke and cylinder 5 had both top rings break.
the rings appear to be way too big. and that may have taken off all the honing.

not blowing smoke at all

[kronus]

did you gap the rings when you put them in?

[Cabriolet]

did you gap the rings when you put them in?

I did not. I thought buying stock rings in a stock bore would be fine. Well it wasnt. Live and learn.

[kronus]

Yeah, I learned this recently when a buddy warned us to do it before bolting our lemons engine together. The rings expand under heat and if there's not enough gap they have nowhere to go and wreck the bores.

[jlevie]

New rings always have to have the gap checked and they frequently need adjustment of the gap. Like measuring bores and journal diameters so you can use the correct bearings and having in-spec cylinders cross hatch honed, checking the ring gaps is an essential part of a rebuild.

[Cabriolet]

well the rings appear to all be within spec.
could i have just gotten a bad batch of rings?