*****FIND PART TWO OF THIS THREAD HERE https://www.evolutionm.net/forums/ev...e-pistons.html ************

ok so here is the not so quick and dirty.

low mileage used 2.0 motor with drop in pistons, rods etc. standard valves, non-ported head with ferrea valve train (dual springs etc) and revolver cams. been only 2K (hard) miles since rebuild.

found my car was burning way to much oil recently, and would on occasion give the white smoke on startup. i did a compression test some time ago found C1 to be a little lower than the others but not more than 10%. i decided to do a leak down test last night with the following results.

C1 - 20%
C2 - 06%
C3 - 08%
C4 - 05%

i could only hear leaking from the oil filler opening. didn't hear anything from tb or tail pipe. also did a coolant leak test by plumbing 90 psi straight into cylinders and coolant level did not rise.

spark plug from C1 had enough oil on the threads to make a small pool where I put it down. plug from C3 had oil as well but not as much as C1.

off came the exhaust manifold. saw the valve guides were dripping wet in C1 and slightly wet in C3.

off came the head. saw no signs of detonation on pistons, tuned by a professional, but scuffing on the top of cylinders is present in all. now this may have been from before the drop in job as i know some scuffing from factory is normal, but i am not sure (didn't see the condition of bores before).

questions:

1) would the higher leak down percentage be caused by the leaking valve guides or just poor ring seal in C1?

2) would most of my oil consumption (half a quart in 500 miles) be from the leaking valve guides or will some of it be from bad ring seal. i also did have some misc leaks from cam seals (maybe even crank seal) not enough to ever drip on the ground though.

3) how bad does the scuffing look? i was planning to just repair the head and keep running the bottom end. yes my finger nail can get caught slightly on the scuffed areas.

Hope you guys can point me in the right direction. Thanks

PICS:

C1



C2



C3



C4




V1





P1








P4





H1

 

how much is half a quart in liters ?

 

still too much ... it's almost the same 1 US quart = 0.946 L

so.. 0.473L

it might be burning more than that, i drive it very irregularly so its hard to keep track.

 

how many total miles are on the car? Not just mileage since the rebuild?

 

I don't really think that is too much for a rebuild engine. according to factory specs, 1L - 1000km is OK.

Depending on how I drive, I get a little less than that, and if I don´t push it, not no cunsumption at all.

 

if you mean on the motor prior to rebuild then 5900miles. motor is from another car.

 

ok lets see.. i check my oil it's half way between the marks.. i drive say 100 hard miles and it would be almost at the low mark. seems excessive to me.

 

no one care to comment on the state of cylinders? i am being told it is a clear indication of det?? the pistons overheating and expanding too much scuffing the walls, and if i could see the piston walls on the intake side there would be pitting on them....??

 

I don't know if it's a indication of detination or not. But I do know that with forged pistons you have to run a larger piston to cylinder wall clearance because they expand more.

 

I have seen that kind of damage 20 times or so. DSM guys in this area arent very good tuners. There were lots of failed builds around here. It is from detonation. Its also clear the oil burning is likely coming from head. The oil control rings dont ride over the damaged area of the cylinder walls.

 

so if the majority of oil burning is from the head, then would the recommended course be to repair the head and ride the short block out? 20% leak down doesn't make much power difference.

what about high lift cams like the revolvers i run. would they tend to cause valve guide issues, and can this be remedied by a fully built head?

wish i had more answers than questions.

 

There would be life left in block at stock power levels. But for high power it would be pointless. Too much heat will be passing the rings on the cylinder with 20% leak down.

 

bump

 

If there was det on the motor, would it not be seen on the pistons or the valve bowl of the cylinder head? To me this looks like the piston to wall clearances were not done properly and the piston scuffed the cylinder wall just slightly on expansion.

This engine was always monitored properly with det cans.

 

Can you take a picture of the piston at the top so I can have a good look at the edge of the crown,
If they are out of the block now do the same and the top side of the crown, also the head where the squish is.

Mark