C20XE Compresion Question

[Nurb608]

Ok,

I just finished carrying out a cold compresion test on my C20XE, results as follows.

Cyl 1 - 155PSI
Cyl 2 - 150PSI
Cyl 3 - 000PSI :(
Cyl 4 - 000PSI :eek:

I then ran a wet test on 3 and 4 to further diagnose, this was done cold too as there wasn't much chance of me getting the motor up to operating temp without waking the kid. New results...


NO CHANGE :sick:

Going off what i've read, does this mean I am looking at an issue with the valves or does the wet test have to be done with a warm motor?

By the way, should have stood back a bit further on the wet test, oops.

Any help on this would be greatly appreciated, no idea on this kind of stuff.

Cheers.

[SSS_Hoon]

im fairly sure that both compression test need to be done while the car is at op temp.


How did u actually do the test though?

3 and 4 like that could mean that the head gasket is blown inbetween the 2 cylinders also.


SSS_Hoon

[Nurb608]

I used a compresion gauge in each of the cylinders and cranked it over until i got the max pressure on each cylinder. I know the reading will be out by a little on a cold motor but pretty sure the initial test can be done cold.

[auzvectra]

i have always tested on a cold motor. did you wait a while after u put the oil in for the wet test?
n what grade oil did u use?
yes sounds like headgasket is gone between 3 n 4.

[auzvectra]

also it doesnt sound very high in 1 n 2 neway, could be fine, but even the astr has 180, the gsi has 220??

[Nurb608]

Yeah, waited for the oil to settle. I think for the C20xe it is meant to sit between 160 - 200 on a hot motor test. I'm hoping it's just a head gasket but the log book for the car only goes back to 135K, the motor is now at 180k

[auzvectra]

hmm, ok. might just be low due to being cold then ;).

[Nurb608]

Thats what i'm hoping for :D

[vectraguy01]

doesnt sound good at all, hope its a easy n not expensive fix!

[mr corsa]

could try a leak down test if you know any one that can do it

[Nurb608]

could try a leak down test if you know any one that can do it

Anyone in Melbourne that can do this and is mobile as the car isn't going anywhere :(

[mr corsa]

duz it blow bubbles in the radiator res when running ?

[Nurb608]

can't say i've noticed any

[mr corsa]

can't say i've noticed any

water level normal

[Nurb608]

yeah, all good. I'm guessing you thinking the water isuue associated with the non coscast head?

[poita]

should be around 150-200 across the cylinders, countering for engine temps at the time

[Nurb608]

OK, so next question is, what do ineed to know to remoce the head to replace the gasket, should i replace anything else (within reason) whilst i'm doing it?

[mr corsa]

OK, so next question is, what do ineed to know to remoce the head to replace the gasket, should i replace anything else (within reason) whilst i'm doing it?
tricky job if your askin questions like this

[Nurb608]

Well it's just something new to learn.

[auzvectra]

the most important bit is to make sure u set the timing right after ;), and at tdc b4 u start ;).
u need a new head gasket, n head bolts.
new exhaust manifold gasket, but u may be able to leave it on. best to do the cam seals, n the tappet gasket as they leak all the time neway.

[auzvectra]

other then that ir's pretty simple, just make sure u have all the tensions 1st.
all the cam bearing caps are numbered, and the came are diff too, but i think u only need to take 1 cam out to get the head off.

[Nurb608]

Cool, can buy a kit from the U.K. with all those gaskets and new head bolts. If i'm resetting the timing, would it be worth doing the timing blt and water pump at the same time as the logbook shows the servicing is about 60K behind and not sure if the previous owner did this.

[auzvectra]

yeah for sure ;).

[poita]

yer defin do it.
would be a heart breaker to do the current bits, then the water pump fails ;)

[Nurb608]

Thanks guys, this will be...err....interesting :)

[Nurb608]

Ok. What else do i need to take off to take the head off? The cam gears and belt? The black plastic backing that is joined to the head and bottom end?

[mr corsa]

exhaust manifold
inlet manifold dissconet fuel lines
before you take the head off line up tdc before removal of head

[Nurb608]

Sorry, bad photo. The exhaust manifold is aff and the inlet manifold is off. The y are bothe just sitting there. Looks like i need to take the timing belt off and the black bit that sits in behind the cam gears. How do I know where TDC is and how do I get tehm around to there before I take it off?

[auzvectra]

turn the motor over with a 17mm socket on a breaka bar from the bolt on the centre of the crank.
there is a mark at about 2 o clock behind the harmonic balancer and a timing mark on it, make sure this is lined up and the marks on the cams are at the top aswell, or it will 180 deg out ;).
if ur not sure bout the timing but, i would sujest some help when putting it back togetha!
there will also be some coolant lines, 2 behind the alternator, and a few at the other end of the head above the gearbox.

[Nurb608]

Cheers! If in doubt i will grab my brother or semi brother in law around to make sure. If that fails, i'll book you in when your down doing the remaps :)

[auzvectra]

haha, tru. not that i'll have much spare time :p.

[mr corsa]

so you gunna machine the head and stone the block ?

[Nurb608]

so you gunna machine the head and stone the block ?

Well i was thinkin, while the head is off, might aswell get some work doen to it. any references for people in Melb?

[Nurb608]

OK, been lazy. Finally got the head off and found the head gasket had been demolished between 3 and 4, i'm hoping thats the issue. I've taken a pic and you can clearly see that 1 and 2 have been getting oil. Can also see that 3 and 4 haven't for a while. Before I put this all back together with new gaskets, water pump and timing belt, is there anything else I should check?

Cheers.

[auzvectra]

well u wanna throw a strait edge on the head n make sure it's flat ;). or take it to a head shop n get to have a quick look at it n see what sort of condition they think it's in.
you may need to get it shaved if it isnt flat.
also put the head on the bend upside down flat, and pour metho into the combustion chamber around the valves, till it's almost full. then see if any leaks down the ports thru the valves, if it does it will need a valve grinde or atleast a reseat.