K Series oil in cylinder

[Mechanical Moz]

VVC160 engine rebuilt last year, bottom end had new Goetze liners & rings, new Rover main & big end shells.  Head was stripped, cleaned, valves lapped and built back up with new MGR seals etc.  No problems at first, although the oil consumption was higher than my old 60k mile factory VVC engine.  New engine uses a couple of hundred ml per 500 miles compared to virtually nil of the old engine.

Last time out at the Anglesey track day in October I noticed some oil smoke for 30 seconds to a minute or so after cold start.  Only just got round to looking at it so I thought I'd stick a cheapo USB borescope in the cylinders to have a look.

First of all removing the plugs revealed #1 plug (far right below) to have signs of oil fouling.

Looking down the plug hole with the borescope and on #1 piston there are drops of oil on the crown.  The engine hasn't run since it was turned off after driving from Anglesey back to Liverpool in October, in other words after a very long run.

Here is #4 piston for comparsion (#2 & #3 look the same as #4).

I tried to look at the cylinder walls using the little angled mirror attachment but it isn't great.  Although it was enough to show droplets of oil on the wall of #1, wheras #2,3 & 4 had no droplets I could see.

I'm assuming it can only be one of two things, oil control ring stack on #1 piston or valve stem seals/guides on at least one of the valves for that cylinder. I tried measuring the valve guide wear when building up the head as per the Rover manual and I thought it was OK but I wasn't convinced I was getting an accurate measurement.  Stem seals were all new.

I'm well used to the start up smoke from the rattly old A series in my classic Mini and the smoke from start up on the Caterham is noticeably worse.

Is there a way of determining which is the cause and how long might I live with it without causing further trouble?

[Tom_Arundel]

Looks like a ring/ bore problem to me. You could compression test it and maybe as a last resort try some Ajax.

[SM25T]

Could it be the valve stem oil seal ?

[oilyhands]

If it were rings, you would see an annulus of oil around the outside of the crown, my guess is that it is more likely a bad stem seal or two, the MG/land rover ones are now made in China and the material hardens in use which limits their effectiveness, the ID is often oversized as well, the portion that fits the guide is also oversized so they dont seal against the guide stem very well either.

Oily

 

 

[Mechanical Moz]

Thanks, have BM you about replacement seals.