Question to those who have taken m20 head off

[mirek]

Bought the car with a broken timing belt, busted rocker arm, and a few bent valves. Took the head apart, sent it to a machine shop all valves, stems, seals were replaced and set, and apparently pressure tested :\ Put the car back together, new water pump, timing belt, all belt, new HG, and it ran rough. Did a compression test to find 180 180 180 180 30 180. Looks like one of the valves is burnt

So I need to take it apart again, if the timing belt doesn't need to be changed, what can I do this time to do this quicker, i'm going to leave the intake manifold on this time since I just had it powder coated and leave the TB on as well.

So far I've taken off all the plugs, airbox, everything on the drivers side, and the distributor, plugs, wires, fuel rail and fuel connectors. Can I remove the head without removing the fan, rad,?

Any help would be appreciated.

[bimmer_E30]

Bought the car with a broken timing belt, busted rocker arm, and a few bent valves. Took the head apart, sent it to a machine shop all valves, stems, seals were replaced and set, and apparently pressure tested :\ Put the car back together, new water pump, timing belt, all belt, new HG, and it ran rough. Did a compression test to find 180 180 180 180 30 180. Looks like one of the valves is burnt

So I need to take it apart again, if the timing belt doesn't need to be changed, what can I do this time to do this quicker, i'm going to leave the intake manifold on this time since I just had it powder coated and leave the TB on as well.

So far I've taken off all the plugs, airbox, everything on the drivers side, and the distributor, plugs, wires, fuel rail and fuel connectors. Can I remove the head without removing the fan, rad,?

Any help would be appreciated.

no u cant , u have to remove the fan clutch+fan then Timing belt.

[kenika65]

always replace the timing belt when removed.

also start by taking the valve cover off and checking valve clearance on your dead cylinder you might have a valve over tightened causing it to stay open,,,

What you want to do is take the valve cover off and turn the motor by hand until the dead cylinder is at tdc then check to make sure you have clearance between the valves and rockers. if you have more question on how to do this then ask but just so you know if you just had the head rebuilt and just put it together then i highly doubt you burnt a valve in such a short period of time.

[Al Canuck]

always replace the timing belt when removed.

also start by taking the valve cover off and checking valve clearance on your dead cylinder you might have a valve over tightened causing it to stay open,,,

What you want to do is take the valve cover off and turn the motor by hand until the dead cylinder is at tdc then check to make sure you have clearance between the valves and rockers. if you have more question on how to do this then ask but just so you know if you just had the head rebuilt and just put it together then i highly doubt you burnt a valve in such a short period of time.

Uh oh Mirek, are you gonna shoot this guy down, too?


Kenika65, I wouldn't spend too much time trying to help Mirek with this. He already publicly lambasted me on our local forum, for suggesting he buy a new timing belt. Also, he's 110% POSITIVE he has a bad exhaust valve, so need to actually diagnose it! Why do a leakdown test, when you're SOOOOO certain it needs a new valve?

Some people's children......:(

[jlevie]

While this could be a problem with the head or valves, since it was just worked over by a shop I rather doubt that the cause is a valve. And decent shop would have noticed a problem bad enough to produce those compression results. I'm wondering if that cylinder might not have a bad piston, perhaps holed by a valve.

i might be tempted to re-use the timing belt if the engine has not been run since the head was re-installed, but otherwise a new timing belt is indicated (they're cheap).