Oil Consumption conundrum

Starting to think about next steps to address high oil cons (1-2 litres per 1000 miles) in my GRiSO......or just keep topping it up. There is no smoke on cold start up, no smoke on long hill throttle shutdown, in fact just a general and constant vague smell in the exhaust . Compression on cold engine is bang on at 205 psi each cylinder (WOT). It runs perfectly all the time & it's always burned oil....doesn't seem to get any worse or better

When I stripped down and did the rollers 10K miles ago there were oil deposits on valve stems and lots on piston crown - I pulled the inlets and put new seals when I shimmed them; left exhaust alone - wish I checked deeper then.

[You must be registered and logged in to see this image.]

Oil level is always at minimum or below (it goes down fast), plenty of oil pooling in air box & around inlet rubbers but not excessive (IMHO - unless it's going as a mist and not all dropping out), no leaks anywhere else. I'm thinking it's consuming oil through either rings not broken in by PO, oil control rings or valve stems/guides or engine is throwing unusual volumes into crank breathers and inlets. I could do leak down test and check any big variance (would there be much if compression is good?) there but beyond that it's just strip down and check including ripping cylinders & pistons out to check....

Any thoughts ?

Paul

Looking at that piston it looks as if the piston is getting well washed. My guess is your suggestion that the original owner babied it or maybe it's had a friction modified oil put in it at some point.

Rip the top end off, run a boron ball hone through the barrels to break the glaze, re-ring it and replace all the valve guide oil seals then take it out and beat on it like a red headed step child.

Pete

Any chance you have the newer (short) dipstick in it?

I did that  , but would not Paul's problem of excessive consumption happen w/o regard to dipstick?

Bill

I was just thinking if it were overfilled it might seek it's correct level pretty quickly.
I've seen car engines do that. No idea if our grisos would, but it doesn't cost anything
to check. I'll go back to my scotch now

Pete's got the answer, no band aid fix for this one.

Thanks Pete et al; what I thought I'd have to do...new ring pack & hone it out...........winter project it & deep dive checking all the valve guides & replace all stem seals.....look for red-headed step-children......and it's not the dipstick !

Do you run a exhaust with a cat?
The cat can cover up all sorts of smoke and smells.

No Smoke when following you Paul.

Most bits ready now (rings, gaskets etc) but struggling to get 95 mm flex hone locally. For a quick couple thrusts back & forward could use a second hand one (bishop & actress joke)...but none of them around either

But main thing is USA websites recommend 240 grit Aluminium Oxide over Boron Carbide for Nikasil glaze busting - does that sound right ??

[You must be registered and logged in to see this link.]

In the UK it would be worth a few £ to get Langcourt Engineering to have a look and if necessary deglaze your cylinders. I have used them many times for air cooled 911 cylinders - real experts in nikasil and other coatings.

Thanks for that -will keep them in mind !

Click & Clack (American car advise radio show that used to run on NPR - public radio - and VERY popular) found that you can have pretty massive oil burning without any visible smoke. Once you started seeing smoke in the exhaust you were well past a nasty problem.

Breaking in procedures seem to create as much of a dust up as oil threads but I'm starting to put more stock into the version where you run it up to redline and back down (force a lot of pressure on the rings both ways) using dino oil. After 200-250 miles you drop that oil, fill with dino again, run nomally for another 1K or so, drop that oil and switch to synthetic. The idea is that rings break in rather quickly and if you baby it they don't and they just don't work like they should.

Did this with my problem child XR650L on the last rebuild and things seem to be working well for a change. Naturally this is only data point. And Internet advice no less; so approach with a healthy dab of salt.

Don't break in your motor like my brother... :-)

rboe wrote:

Click & Clack (American car advise radio show that used to run on NPR - public radio - and VERY popular) found that you can have pretty massive oil burning without any visible smoke. Once you started seeing smoke in the exhaust you were well past a nasty problem.

Breaking in procedures seem to create as much of a dust up as oil threads but I'm starting to put more stock into the version where you run it up to redline and back down (force a lot of pressure on the rings both ways) using dino oil. After 200-250 miles you drop that oil, fill with dino again, run nomally for another 1K or so, drop that oil and switch to synthetic. The idea is that rings break in rather quickly and if you baby it they don't and they just don't work like they should.

Did this with my problem child XR650L on the last rebuild and things seem to be working well for a change. Naturally this is only data point. And Internet advice no less; so approach with a healthy dab of salt.