Pie_n_Chips

Hi guys I'm a regular over on the UK board and as technical knowledge is a little thin on the ground over there I thought i'd post up here

OK the history is I've had a top end rattle for some time know on my S, with the cam chain tensioner being replaced around 3 months or so ago. Now my car has always used oil with upto 300ml topups every 200 miles not being uncommon. But recently since my decat I have noticed the oil coming out of the back after a hard run, not good. So the dealer has it in and we try and get a claim under extended warranty for a failed oil stem seal.
Here are some pics of what we found

Pistons 4>1 showing visible signs of oil burning


Close up on no 4


Cylinder Head


No 4 shell


No3


Crank journals


Now these pics would seem to suggest oil starvation at some point, but the car has always been an S2k club car and the oil levels are checked with every tank of gas.
The garage in their wisdom didn't run an oil pressure test before stripping the block The bores are as smooth as a babys butt with no visable signs of abnormal wear/scoring.
All rings are intact.
My initial thoughts were low oil pressure from the pump, would cause the wear on the shells, but that still doesn't explain the excessive oil consumption/burning

Any additional thoughts input would be appreciated guys

thanks

Slows2k

The carbon on the piston crowns is normal, same goes for the cylinder head.

The rod bearing don't look the greatest, it's possible some dirt embedded into the bearing.

Got any pics of the bores/rings? Have the measured the bores for taper/out of round?

Pie_n_Chips

The only one I have is still with the pistons in situ, so it's not very helpful


These is also slight wear on the the cam journals would this be normal on a 60k car?


Carbon build up on the back of the valves


As far as i'm aware they haven't measured the bores, i think they're just hoping for a short block replacement rather than find the exact course TBH

FormerH22a4

I burn a lot of oil and will go get a head repalcement first. I'll update the board on what they find.

cdelena

The bearing wear does not look good and I could only agree that it looks like a oil pressure / starvation problem at some point.

With bores and rings that look good I would look closely at the valve guides as a oil consumption suspect. Was there compression / leak-down tests run before the decision to tear it down?

Pie_n_Chips

Only a compression test was done prior to stripping and that showed all 4 cylinders to be OK. Will await a decision from the warranty company before we decide to strip the head further to investigate guide wear.

Just as an aside how would you check for guide wear??

StuartL

*falls off chair*

Pie_n_Chips

Come on then mr expert how?
wiggle the buggers or what? or would it be quite obvious?
Would a visual inspection be enough?

camuman

pretty sure a leak down test would tell you....maybe thats why he fell off the chair. ussually, when a motor is exhibiting oil consuption, you look for where its goin and where its coming from. a leak down test is a given before tearing a motor apart. there a dollar something each and maybe 50-75 bucks to install from a shop, just do them and save yourself the worry that it might be them.

Pie_n_Chips

Ah well the dealer stripped the motor so..........