Advcie on N/A engine
Turbo Mini Forums

In the summer i did a compression check on my engine and it came out with 100,100,100,70. This seemed really low i was expecting 140-160.

So i have biten the bullet and tyaken the head off for the first time. As it was running rich everthing is pretty carboned up.

but when i try and move the pistons from side to side they move more than i would have expected (i am no expert though).

If the movement is the reason for the loss in compression i would have expected to be burning loads of blue smoke permently, but it was running clean except for starr up (valve stem seals i imagine)

Any opinions on piston movement and the loss of compression you would expect/oil burning is much appreciated.

thanks
Dave

If the cylinder head has been changed from what was originally fitted to the block u may have the wrong size chambers in the head i.e.too big

Metro turbo weekend driver,Mini turbo in the making again!

Hmmmmmmmmmmmmmmm..........................................
it seems to me you are asking a question on a PUG!:

The movement on the bores may be OK!
BUT how many miles has this unit done ?
forget the valve stem seals TOTALLY
the give away is in THAT bore! on test thats the PROBLEM, WHY?
strip the unit and you may find a broken ring or a largre score in the bore ????
but before, hows the head gasket ???
check it out carefully!!!! inspect
it may be blown
i doubt it though.






BENROSS:

Edited by BENROSS on 23rd Jan, 2005.

not much help now but for future reference after doing a compression test squirt a little oil into the cylinders (trough the sparkplug holes) if your psi readings improve then normally this indicates a ring problem, if they stay the same wet plus dry then normally indicates head or gasket fault.

no longer a series, but still 1.3 turbo.

been and had a look at it today, lots of scoring in bores 1 and 4, the pistons feel very loose in the bores aswell. its a 1330 but mileage etc is unknown i think (dave may know)

he did say the readings went up when he oiled the bores, head gasket is fine aswell.

looks like fooked rings i reckon, time to start the turbo conversion now then dude....lol

if its not too scored/fecked, clean it, crack test it and take it to 1380, rebuild with a turbo strapped on. If its been thrashed, when you get it out, heave the crank out (you'll have to anyway for the rings) and check the centre main bearing cap and block *edges* as it is quite possible that you'll find a tiny lip where the bearing shells have hammered into the block - not so good. Fecked rings suggest (amongst other things) C/R too high (too *small* chamber/skimmed head/block) or just plain been thrashed. Whats the head casting number and are the pistons dished or flat tops?

Muppet i met at a mini meet had fed a turbo to a flat topped piston 1380 and was suprised when he shattered his pistons...

Good luck!
Ed.