3.4 DOHC engage clutch engine dies

[Lee150]

1991 Chev Lumina 3.4 DOHC 5 speed man. when the engine is warm engage the clutch and the engine dies it doesn't stall it dies it's like turning off the key rev up to 2000 and you can get it rolling goes through the gears without any problems, when the engine is cold there is no problem getting it to engage at low idle
Engine starts easy idles smooth .Have just started checking things out any suggestions would be appreciated

[pocket-rocket]

I know the only thing I've ever heard of that will stall an engine when pushing the clutch is worn thrust bearings in the engine. What happens is the pressure from the clutch pressure plate pushes in on the crank. Normally the crank isn't moved in that direction, but after years of sitting on the clutch at stop lights, the pressure takes its toll and the crank will walk in and out. Next time you try it, have someone sit at the crank pulley side with a drop light and see if the crank moves out when the clutch is engaged. If it does, it's thrust bearings and the engine needs to come out for new bearings. This is why you will not find me sitting on the clutch in gear while waiting for a light to change. I normally won't clutch it until the light for the opposite direction goes from yellow to red. It's also bad on the clutch as well.

[Schurkey]

Yeah, except he says it happens when he ENGAGES the clutch. The crank would already be accepting the thrust from the pressure plate, and the thrust load would be reducing as the clutch engages/pedal is released.

I'd be wondering about the IAC and TPS. Maybe a small vacuum leak as the engine accepts load when cold and the injectors are a bit richer.

[pocket-rocket]

Good catch. That's what working in a factory all day and getting 4 hours of sleep a night will do to you.

[Lee150]

Okay so I haver the Turner Pro software and a cable and have run a couple logs just to see what is going on and it shows multiple sensor failure which I don't necessarily believe because when I'm logging the numbers hic up about once every second. ( as in the rpm goes from 0 to 900 constantly at idle, engine is running smooth) The one output I have is FP volts 14.3 program indicates to high Bat. volts starts out at 14.6 but comes down to 14.5' so voltage problem here? two questions (1) what is FP volts (2) could I email the file and somebody with knowledge have a look at it

[Smittro]

Except the LQ1 does not have thrust bearings..

There is only one flanged main bearing to control crank shaft end play..

[pocket-rocket]

Except the LQ1 does not have thrust bearings..

There is only one flanged main bearing to control crank shaft end play..

What else do you think I would mean by saying thrust bearing? It's a bearing and controls how much the crank is able to move end to end (thrust, in a sense). I've also yet to hear anyone else on this board call it anything other than a thrust bearing, so I think it's pretty unanimous.

[Smittro]

What else do you think I would mean by saying thrust bearing? It's a bearing and controls how much the crank is able to move end to end (thrust, in a sense). I've also yet to hear anyone else on this board call it anything other than a thrust bearing, so I think it's pretty unanimous.

I was'nt trying to be a dick, my bad..

[pocket-rocket]

I was'nt trying to be a dick, my bad..

Nor was I. Just stating my own personal observations from being around here and engines for some time. I'm still curious to find out the actual name for it if it's technical name isn't thrust bearing. You know, like core plugs being called freeze plugs since they aren't meant as a frozen water protection device, but rather for the sand core casting process.