4age starting problem

[bmak]

Recently I changed the head gasket in my hatch & it started & ran fine afterwards.

The next day it had no fire at all. Checked cam & ignition timing, fuel & spark all the usual things and everything seems fine. Could get a few pops out the intake & eventually it started by holding foot flat & it ran on a few cylinders for about 1 min until it cleared up. So i redo timing etc. and it runs & drives perfect.

But the next day same thing apart from when it cranks there is a loud tap from cam cover area so i pull it off & everything is tight & looks ok. It eventually starts & the loud tap stops and in runs fine again.

Today no start again & the loud tap. I'm thinking valve sticking & the tap is cam hitting follower. But still it only sounds like one tap so I'd expect it to still start on the other cylinders.

I guess the next step is to check cam clearance while its cold & maybe comp check.

Any other ideas?

[Ben Wilson]

I'd be guessing that perhaps the head gasket is leaking - Is the oil milky, coolant oily or dropping?

[oldcorollas]

Today no start again & the loud tap. I'm thinking valve sticking & the tap is cam hitting follower. But still it only sounds like one tap so I'd expect it to still start on the other cylinders.

crank it with rocker covers off? see if any are sticky

[bmak]

yeah ive cranked it with covers off & all looked ok. I'm about to do comp check. All water & oil is fine.
Bit wierd for a valve to stick now but i cant think of anything else.

[bmak]

I haven't done a comp check yet cause it started & i want to do it cold.
I got a mechanic to listen at the motor as it was cranking & eventually fired & ran rough for 30 sec or so & they are pretty sure the loud tap is pre detonation probably caused by over fuelling.
So now i have to look into why its getting so much fuel. Ive already tried disconnection the cold start injector.

[oldcorollas]

sticky injector?
see if they all click, take off one lead at a time and see if it helps starting... if one cyl is bad, swap around that injector and see if problem moves etc...

overfueling? hmm.. wouldnt it just not fire if it was way overfuelled?
unless an injector is dribbling overnight, so that a cylinder is full of fuel when you go to start??

leave overnight, pull plugs and look inside the chamber for fuel?
or leav eignition off, power fuel pump, pull plugs and see if fuel dribbles in?

[bmak]

it wont fire at all starting normal but full throttle it will eventually fire & carry on a bit with lots of nasty rattles.

I was thinking stuck injectors too. Already disconnected cold start & that didnt help so if it doesnt start tomorrow i'll cut fuel pump & see what happens.

Any sensor problems make it rich enough not to fire at all?

[Grega]

you running stock fuel pressure or more than normal?
also is timing set correctly with T1 and E1 jumpered? 10 deg IIRC

[bmak]

Everything is standard apart from shaved head.
Cam & ignition timing has been rechecked number of times.
I was thinking of removing the cold start injector as even with it disconnected it can still be leaking.

[Ben Wilson]

Try cranking it without plugs, if anything is leaking into the cylinders, it should show up.

[bmak]

Looks like I've found the problem.
No. 6 cam follower was about 5mm short of the cam lobe today. Cant see any reason for it & once i got it started it freed itself up. When it warmed up i could rotate the shim & bucket easily so it it cant be that tight.
It wasn't removed when i changed head gasket.

So now how do i free it up? Just take a long drive & maybe next time it cools down it will be fine or should i pull it out & clean it up a bit?

[Ben Wilson]

Could you move it by hand?

If so, I'd be thinking you've got a bent valve there. Otherwise, I'd be pulling it out and having a good look in there.

[bmak]

I doubt a valve is bent as its taking less than 30 secs after the motor starts before it comes unstuck now.
I'll give it a decent drive this weekend and hope for the best i think.

[Ben Wilson]

In farness, 4AGs are cheap, give it a go

[nb86]

the loud tap could certainly have been piston to valve contact. normally this is impossible on a 4age but with a shaved head, who knows?
deopends how much they took off. if a valve was sticking badly it could have been bent on the first startup. if you drive it, it will free up but the car will start blowing smoke when the stem seal begins to leak. this would be my suspicion.