[stevo]

Well, I am replacing the head gasket on my friends 92 GST (6bolt). When I pulled the head i notice that the intake valves on cyl 2 or 3 (cant remember off top of head) were slightly open. Not on both of them though. Just one of them. I thought there were all supposed to be open/close the same amount. Here are some pics, tell me if it is supposed to be like this.

This is of cy. 2 and 3. Notice how the intake valve is slightly open on one.

Also, when i towed the car from this "mechanics" house, i noticed that cyl. 1 and 4 looked as if they had been grinded clean. Is this going to effect anything? He only did it on cyl 1 and 4 since they were up (due to timing marks aligned).

Thanks for the help. I am sure you will have some questions, so ask away.

 

[Sean485]

Yes, the two intake valves on each cylinder should open at the same time, but before you suspect bad valves try taking the rocker arms off and see if all of the valves close. If they do all close then my guess is that one of the lifters simply lost oil pressure causing the valve to close. But then again i have been wrong before.

The piston looks ok, it looks like he just tried to get some carbon off of it, i woulden't really worry about it, its not a big deal.

 

[stevo]

Yes, the two intake valves on each cylinder should open at the same time, but before you suspect bad valves try taking the rocker arms off and see if all of the valves close. If they do all close then my guess is that one of the lifters simply lost oil pressure causing the valve to close. But then again i have been wrong before.

I thought that all 4 intake valves were supposed to be open the same amount on cy 2 and 3 at the same time? On cy 2, one is open more than the other and on 3 they are closed.

It will not effect anything?

 

[Sean485]

No, although 2 and 3 are up/down at the same time they are at different stages of the cycle, on the down stroke one is just finishing with intake, and the other is just finishing with the power stroke. When they are both up one is doing the compression stroke, while the other is finised with the exhast stroke, starting the intake.

The main thing is that the two intake valves on cyd 1 open at the same time. The two exhast valves should also open at the same time. This goes the same for all the cylnders. I hope i helped and didn't just really confuse you, maybe someone else can explain it better.

 

[stevo]

Yeah, understood. But on cy 2 one of them is open more than the other. Is that a problem?

 

[Sean485]

Yeah, understood. But on cy 2 one of them is open more than the other. Is that a problem?

It's not supposed to be like that, but check to see if one of the lifters collopsed, they operate on oil pressure, and they should stay pressurised, but if one of them looses pressure it will close the valve. Try taking the rocker arms off of cyd 2 and if both of the valves close then it should be fine. The only ways that the two valves on the same cyd don't open at the same time is 1) Lifter collopsed(most likely) 2) camshaft is broken between lobes(higly unlikely) 3) bent one valve and not the other valve(also unlikely)

Try that and let me know what happens.

 

[stevo]

Thanks, ill take a look at it tomorrow. Thanks for the help.

 

[1 fast POS]

Rotate the cam until the lobes on the cylinder in question are straight up. This way both valves should be closed. As previously mentioned in this thread the valve that is closed all the way may just have a drained lifter, so the sure fire way is to pull the followers out on the cylinder in question and make sure the valves seat. And Sean485 pretty much summed everything up.