4AGZE Compression rate

[craigy]

Hey Guys,

I've been having some issues with a GZE which i recently installed into my sprinter. I've put about 4 litres of oil through it in about 2 weeks!

I checked compression and it comes up as follows:

cylinder 1: 190psi

cylinder 2: 190psi

cylinder 3: 170psi

cylinder 4: 190psi


The pressure seems excessive to me. The 4AGE manual says a naturally aspirated version should be about 159psi, with a tolerance of 10psi.

Just wondering if anyone has the cranking pressure for a standard late model GZE, or an idea why the compression is so high?

I'm pretty much convinced that the rings/bores are damaged in cylinder 3, i poored oil down the cylinder and rechecked the compression and it came up to 190psi.

Also a part number for GZE pistons, when i pull the engine apart again i want to see if the pistons have been replaced with the correct items.

Any info/ideas would be muchly appreciated.

cheers
Craigy

[30psi 4agte]

Ill have to do a double check but i think from memoy my low comp turbo engine has 225 psi comp in each cyl.

So that would make yours very low ad prob causing probs.

Do a search on this site for GZE piston part no. It has been covered and is a very helpfull thread !

[bathurst-91]

lol i have a gze and its comp is as follows 150 130 140 125, still runs perfect...

[30psi 4agte]

hmmm mabe my memory is wrong

[feral4mr2]

the 8.0:1 c/r gze according to my manual is 121psi to 156psi with no more than 14psi between the cylinders.

The 4AGE manual says a naturally aspirated version should be about 159psi, with a tolerance of 10psi.

i'm certain it's higher than that for a 9.4:1 c/r 4age, but i dont have my manual handy to check.

[1JZ-Rolla]

How good is your compression gauge? I'd be less concerned about the actual readings, and only worry about the variation between cylinders, unless you trust the calibration of your gauge 100%.

[Hen]

With those oil figures have you checked to see if your sump plug is still attached?

Any signs of where the oil is escaping? Blowing smoke, leaking from sump gasket or front or rear main seals?

Hen

[craigy]

I havent checked the sump plug, perhaps a chicken plucked it out......i hear they make good hard shelled eggs with a good piece of iron in there diet.

seriously though, i dont have any oil leaks. And it blows A LOT of smoke under boost. Which suggests to me thats it is rings/damaged bore.

My only other thought was valve stem seals/guides, but they shouldn't leak under pressure.

[kingmick]

how high do you usually rev it in those two weeks? they tend to top up when reving them had and you get oil going into the intake from the breather. Is it a bigport or smallport? as the bigport dosnt have the extra external oil drain so they top up more under revs.

By your pot readings No3 is down a bit so it could have stuffed oil ring or rings.
These sort of things can be hard to workout without going over it in person.

The smoke white or grey under load?

much smoke on first start up of the morning?stem seals would be hard pressed using two litres of oil in a week.

cant hear and rattle noise from cylinders?

was the plug from No3 oiled up?

your dipstick being pushed up after driving?
is there much blowbly out of the dipstick tube when free reved?

by the sound of reading and the oil use{unless some very spirited driving}you have glazed,broken oil ring or ringland in No3.

Sorry cant be much help over the net.

[Hypo]

When doing a compression test if you haven't disconnected your fuel pump will the fuel increase compression that has been fired into the cylinders?

Apologies if this is a moronic question.

[The Witzl]

perhaps your turdo has decided it would rather spew oil than boost.

[Hen]

Also are you sure its oil smoke that you are blowing on boost? That map pours out plenty of chuff when you plant the foot, especially if the changes for the bigger injectors have been made conservatively.

Hen

[kingmick]

perhaps your turdo has decided it would rather spew oil than boost.

i must have missed the turbo bit?

thought it was a gze! if turbo yes it could be but it must be like the bat mobiles smoke screen with that much oil

[Hen]

It is a GZE with SC still firmly attached.

[progkamol]

I have a GZE but never done a test and not even driving it yet ... should finish building up end of this month and I'll run a test on it as well ... Hey, not so sure about this but you said you recently installed the GZE??? I was told by few fellows on the forum that after the engine swap or etc you should drive normally without reving the sh!t out of the motor for like 5000km or so??? ... again not so sure about this but that is what I am going to do ... Could that be a problem??? ... someone please advice