Excessive oil use - replacing piston rings without removing engine?

[Rob]

To set the scene:

My rev3 turbo engine was running a big SARD turbo when it came from its donor car. I presume it is still on stock internals.

I get absolutely no oil smoke on start up, in the turbo hot pipes, on the floor under the car or anywhere else.

I see no oil smoke in the mirror when driving (ever) but a mate told me on a run a year or two back that it was putting out a little blue smoke on full throttle.

The engine does like a bit of oil, I have to top it up every few journeys as it will go from full to half way on the dip-stick in this time.

The engine feels very strong and performs as I would expect.

I am guessing that there is excessive wear to the piston rings and this is what is causing these symptoms. As I only suffer one symptom, a leak-down test would only be a waste of money in my opinion.

I very much doubt I could change the piston rings from removal of the sump and crank without removing the engine could I?

If it is possible it would save a bit of cash.

Thanks

Rob

[Lewis Jay]

Yes you can it with the engine still in.

Head off, sump off, pop em out the top.

[ashley]

It would be a proper bu88er trying to compress the rings into the bores from below, you'd probably need to remove the oil squirters as well for access...way easier to drop the engine imo

Worth doing a simple compression test....?

EDIT- as above, if you remove the head as well then yes, but I'd still go for dropping the engine I reckon, would be quicker I reckon.

[mrdb]

new rings will need the bores honed/deglassed also or your waisting your time....

[Rob]

Thanks chaps.

I was just wondering if it would be simpler to do it in-situ and save some money, but it seems that it might just over-complicate it.

If I did the job myself then that would be the only way I could do it as the car is parked on a public road at all times.

If I disassembled it before the rings actually failed, would I need to hone the bores? Presumably you only need to hone on a rebuild when the ring fails and it scratches up the bore?

I guess I could do a compression test as I do have a compression tester.

[bobhatton]

Sounds like the ring lands have gone on a piston or two, its a bit more that just rings

[Rob]

Sounds like the ring lands have gone on a piston or two, its a bit more that just rings

I think you are right but rather than the rings having 'gone' they are a bit worn, as like I described, the engine performs very well still.

[mrdb]

rings wear to the bore, so the bores need a hone to provide a rougher surface for a few 100miles so the new rings can seal properly. if bores are left un honed(smooth) rings will not bed in to bores and it will cause bad compression, oil burn etc.........

[Rob]

rings wear to the bore, so the bores need a hone to provide a rougher surface for a few 100miles so the new rings can seal properly. if bores are left un honed(smooth) rings will not bed in to bores and it will cause bad compression, oil burn etc.........

Thanks for the explanation, I had misunderstood the honing process as I thought it was to smooth out blemishes rather than to roughen in order to bed new rings.

[JJ]

As a few have said, can do it with just a set of ramps...

Remove turbo / head assembly, remove twin sump... can remove the rods and pistons and inspect issues.. Pistons / rings...

All nuts and bolts, generally straight forward

[Rob]

As a few have said, can do it with just a set of ramps...

Remove turbo / head assembly, remove twin sump... can remove the rods and pistons and inspect issues.. Pistons / rings...

All nuts and bolts, generally straight forward

Hi JJ

Oh right, well that might be worth considering. Thanks

[Fourveesix]

Its impossible to insert the pistons into the bores from underneath, they have to come out the top because the pistons are wider than the webs in the crankcase unfortunately.

Id remove the engine entirely and strip it (if it is indeed the engine that needs attention) and put it on a stand, because how on earth can you clean the bores properly with the crank still in place?

If you hone the bores, the media goes straight into the crankcase, the chances of keeping it out of bearings is minimal, youre bound to get contamination and youll be back to square one in no time.
Add to that the fact that to clean the bores effectively after honing theyll need scrubbing with hot water and detergent to remove the abrasive media from the honing crosshatch, then clean each bore with ATF and clean paper towels until they come out free of media or the rings will not bed in and youll have an oil burner again.

You sure its not the turbo ingesting oil thru a worn seal rather than the engine itself?

Leak down test and compression tests needed i think.

[Rob]

Thanks for all the replies.

I have decided to just use the car and not worry about it too much. I check the oil every other time I use the car, so I won't be letting it get low.

I may also change from Mobil 1 oil to something else as I have read that it burns off more than other oils?.....