4age Very Low comp on cyl 3 and 4

[Julz01]

Hi Guys

Just had this happen to me today completely out of the blue on the way to work, Prior to this my car has been running fine for the last couple of weeks besides a dodgy fuel filter which was limiting the revs.

essential both cylinder 3 and 4 are not running, the car is on running on only 2 cylinders as when I disconnect the spark from either cyl 3 or 4 or both at the same time it doesn't change the running of the engine. Where as if cyl 1 or 2 is disconnected it stalls out.

So I have done a compression test and it has pulled cyl 1= 160 psi cyl 2 = 150 psi cyl 3 = 50 psi cyl 4 = 50 psi

also did a wet compression test and cyl 3 = 70 psi , cyl 4 = 60 psi according to the comp tester it could be the valves.

I also removed the cam covers to just double check that cam hadn't snapped or logged and rotated it by hand and its moving.

so just want to ask some opinions on what it might be , guessing its the valves but don't understand how both cylinders could let go at the exact same time, and car was been driven normally at the time it let go.

any advice would be appreciated also if any VIC guys could recommend a good mechanic that has 4age experience that would be good.

thanks

[banana_socks]

Head/gasket gone between cylinders? Check for coolant in the oil, or bubbles in the coolant.

[oldcorollas]

Hi Guys

Just had this happen to me today completely out of the blue on the way to work, Prior to this my car has been running fine for the last couple of weeks besides a dodgy fuel filter which was limiting the revs.

so it was running lean at higher revs?
that could blow the HG..

[Julz01]

when the fuel issue occured it was running out of revs at 3k , so for the whole time it was doing it I drove it normally but did not rev it hard

[pandaah]

do a leakdown test in number 3 at TDC with number 4 spark plug out. you might find you hear the air pissing into number 4 cylinder then youll no for sure

[andrew_mx83]

was it pinging with the fuel issue?

HG or detonated pistons by the sound of it...

[briney]

Head/gasket gone between cylinders? Check for coolant in the oil, or bubbles in the coolant.

this bloke is onto it i reckon.

[feral4mr2]

Head/gasket gone between cylinders? Check for coolant in the oil, or bubbles in the coolant.

i agree. you wont get bubbles in coolant or coolant in the oil when this happens. but it should sound like a wrx.

[jazae86]

Out of interest, does the motor have a multi metal layer head gasket or a standard Toyota head gasket?

Jason

[TRD-12A]

either way head needs to come off

[andrew_mx83]

either way head needs to come off

nailed it.

[Julz01]

yea will be taking the head off soon to have a look, got no idea what sort of head gasket was in there, thanks for the help guys

[Talasas]

Lean conditions can burn valves as well so make sure you check your exhaust valves closely. I had this happen due to poor fuel flow as well.

[Julz01]

still havent gotten around to this, but going to be doing it soon, anyone got a recommendation of what thickness head gasket would be good to run on a NA 4age was thinking TRD 0.8 one

[oldcorollas]

stock are 0.8? (apparently 1.2 is stock) and 7A are MLS? or something like that... ie stock equiv of TRD