Hi there.
I am doing a minor overhaul of a 300k km VW engine due to high oil consumption and oil leaks at the cyl. head.
I wanted to replace the valve stem seals, cam shaft seals and the head gasket. Since the cyl head had to come off anyway, I decided to replace the piston rings also.
After teardown of the head it was quite ovious that cyl 2,3,4 have had the most oil burn due to coke build up on the intake valves, but also at the piston crown...
Now to the interesting part
Resurface of cyl head on the surface grinder: Only 25 microns had to come off in order to make it flat again! That's pretty amazing. But due to a deep mark from the head gasket I needed to remove 20 more microns.
Some cyl heads wants to warp quite a lot - 500 or 600 microns is not that uncommon!
Then the piston rings: The top rings was worn 0.4 - 0.5 mm (ring gab) Those could not hold up to factory spec.
The 2nd compression rings was hardly worn at all and could easily hold up to factory spec. But there where some coke buildup in the 2nd ring groves and on the rings too.
The oil control rings: some build up of coke and varnish but far from clogged up. Oil drain holes in pistons where just fine
Big end shell bearings: No measurable wear at all, just a few tiny scratches, and some stains from the oil maybe.
Sludge: None.
Varnish: Yes, quite dark in color but just a thin coat. Actually the valve sprigs had the thickest layer of varnish.
Since I got the car at 220k I've been feeding it shell helix 0W-40 at 15k drain interval
So far I'm quite impressed by that little engine. I belive it can do an other 300k, but the rest of the car will probably turn into rust before 600k
I am doing a minor overhaul of a 300k km VW engine due to high oil consumption and oil leaks at the cyl. head.
I wanted to replace the valve stem seals, cam shaft seals and the head gasket. Since the cyl head had to come off anyway, I decided to replace the piston rings also.
After teardown of the head it was quite ovious that cyl 2,3,4 have had the most oil burn due to coke build up on the intake valves, but also at the piston crown...
Now to the interesting part
Resurface of cyl head on the surface grinder: Only 25 microns had to come off in order to make it flat again! That's pretty amazing. But due to a deep mark from the head gasket I needed to remove 20 more microns.
Some cyl heads wants to warp quite a lot - 500 or 600 microns is not that uncommon!
Then the piston rings: The top rings was worn 0.4 - 0.5 mm (ring gab) Those could not hold up to factory spec.
The 2nd compression rings was hardly worn at all and could easily hold up to factory spec. But there where some coke buildup in the 2nd ring groves and on the rings too.
The oil control rings: some build up of coke and varnish but far from clogged up. Oil drain holes in pistons where just fine
Big end shell bearings: No measurable wear at all, just a few tiny scratches, and some stains from the oil maybe.
Sludge: None.
Varnish: Yes, quite dark in color but just a thin coat. Actually the valve sprigs had the thickest layer of varnish.
Since I got the car at 220k I've been feeding it shell helix 0W-40 at 15k drain interval
So far I'm quite impressed by that little engine. I belive it can do an other 300k, but the rest of the car will probably turn into rust before 600k
