Engine dies when clutch is depressed?

First thing I thought of was the thrust brng deal also. Have you had any one look at the front pulleys for you while you push inthe clutch, yet? Even though the motor was mated with a automatic for so many years, this is still a possibility. I had a similar problem last summer.

 

Like Kustomman said if there is no pilot bearing installed then when you press the clutch in the disc and input shaft would be free to flail around until it hit something like the pressure plate or throwout bearing. might be a good thing to check over. make sure the input shaft is the right length and engages the pilot bearing properly also. throw out is right one for ****** and pressure plate also. input shaft bearing is not wobbled outand the throwout bearling slide shaft lets it slide free and does not bind. Just a few thoughts

Mark

 

Yes, it has a pilot bearing

Engine dates to 1979, bellhousing, starter plate and trans were matched from junkyard, codes are from 68-71 V8 Maverick/Mustang, clutch kit is for same. Flywheel is aftermarket with correct balance.

 

But when you depress the clutch pedal, you are disconnecting the motor/crank from the trans itself. The input shaft should not be connected. That leads me to believe the trans has nothing to do with it. Check to see if the crank walks then report back. Other than that and too much clutch travel, I can't think.

 

Could the clutch disc be in backwards, I've seen it before. Easy mistake. Usually chews up the flywheel bolts, and noisy....OLDBEET

 

Let's just ***ume my crank is walking. How screwed am I?

 

IF the crank is walking, you definitely need new main bearings. While you're in there do all the bearings. Hopefully the thrust face on the crank isn't chewed up and only the journals need turning.

Tracy

 

^^^^^ Truth, but I still can;t see that being the cause or even likely. But I'm no master and 90% of the time I'm wrong. For your sake, hope I am.

 

are you able to spin the engine by hand with the clutch depressed /
also is the balancer walking when doing so/ do you have the right poilet bushing installed

 

sure sounds like the transmission is lockedin two gears

 

That sounds promising.

 

I have been following this thread for a while trying to get the full report on what has been done and what the results are. So far it has not been reported if the clutch ever has a point where it disengages, so I am ***uming it does not. So here is my take on this.

The flywheel and the pressure plate are bolted as one to the crankshaft, the clutch disk is a movable plate that spins between the flywheel and the pressure plate. When in the closed position they act as one unit, when in the open position they act individually. The problem occurs when the clutch pedal engages the throw out bearing and pressure is placed upon the fingers of the pressure plate there is a noise and the idling engine stalls. If there is a screech or grinding noise it usually means that there is an interference problem with some thing that is spinning.

You have to dismiss locked in two gears as this would stall the engine upon start up with out the clutch depressed as the input shaft turns in gear or out. Most modern engines only have minimal end thrust so pressure from the throw out bearing would be absorbed by the pressure plate movable fingers and hardly push the crank forward unless the crank thrust bearing was destroyed and it would leak oil like a well.

Now as long as this is in neutral this thing runs fine. Upon depressing the clutch it makes a noise and the problems start. It is at this point where two moving parts meet and where the problem probably occurs. The only thing that really move forward to back is the pressure plate fingers. Now they ride against the throwout bearing, which is centered on a sleeve, between the throw out and the disc center there is air gap to allow for bearing travel before hitting the center hub of the clutch disk. If the bearing or pressure plate fingers contacts the disc hub you have a clearance problem.

The after dropping the trans the first place to check is to see if there is a rub mark on the center of the clutch disk. In most applications the flat side of the disk goes to the flywheel side, the shock spring pack is offset to the trans side. At this time look at the relation ship of the pressure plate fingers to the clutch disk center, there should be at least 1/2" clearance. If the fingers are hitting the spring pack you will see a rub mark and would indicate that you have the incorrect clutch or pressure plate.

If there are no marks on the center of the disk the next place to check will be on the out side of the pressure plate. No knowing what style of pressure plate you installed, some pressure plate designs have counter balance bobs attached to the out side of the pressure plate fingers. The balance bobs move rearward as the fingers of the pressure plate are depressed and may be hitting the side of the bell housing especially if it is severely tapered. This action usually gives of a dull grinding noise and produces shaving of aluminum in the bell housing pan. It is characterized by the fact that the engine runs free until the clutch is pressed, grinding starts, engine slows, let the clutch back out grinding stops, engine returns to normal. If you have this type of pressure plate take a flash light and shine in the trans input opening to see if the balance bobs are shinny, scuffed up or you can see score marks on the inside of the case. My guess is that this is the source of your problem. Wrong pressure plate.

Keep us posted as to what you find.

 

How can that be if it is happening when the clutch is pushed in. Pushed in elimates the transmission.

 

Mybe the clutch fork is walking around and letting the T/O bearing bind up enough to stall at idle. I had this happen, but it kept breaking the T/O in half and not stalling the motor.

Tim

 

Listen to ****. I'm really curious to find out what's causing this problem.

 

The crank is definitely walking, I'm 90% sure. With the engine off, I can pull the clutch fork by hand until the TO bearing hits the pressure plate, then feel it "clunk" as the pressure plate moves forward towards the engine (without depressing the fingers), so I'm ***uming the whole balancer/crank/flywheel ***embly is moving and would account for the problems while the engine is running. Yikes.
I'm still curious as to why the motor has not grenaded and still holds good oil pressure? I'm wondering about the loose clutch fork suggestion. Would a binding TO bearing really cause the engine to die so violently? And to Mr. Spadaro, thank you for your detailed post! I did not see any su****ious marks on ANY of the clutch parts, flywheel bolts, etc, when I pulled them. The brand new TO bearing was TOAST. Thanks for all the help.

 

i think your pressure plate is bent. i know this seems odd but i had a friend that had the same problem with an old austin mini. after numerous attempts and replacing all kinds of parts it turned out to be the pressure plate

 

I've tried 2 different brand new pressure plates with the same results...

 

You need a HAMB hands on weekend. Buy some beer and bugers and get as many HAMBER"S to your place this weekend. You can't fix it, we can't decifer the problem without a hands on look. HAMBFEST is the way to roll.

 

Burgers

 

Ok, next approach, The throwout bearing is an interrupted load carrying bearing. It is very difficult to toast this bearing unless you run it with continual load and a lack of lubricant. You did not fully explain what toasted meant but I am ***uming that it is physically damaged.

If that is the case and there are marks all over the bearing. It would now lead me to believe that the bearing is binding on the fingers of the pressure plate. You should check the length of the transmission throw out bearing collar. The bearing centers on this collar, if this collar is too short for the throw necessary to disengage the clutch, the bearing will slide off the end and wedge it self between the pressure plate forks and the end of the collar. Because you said there is a slight click during the clutch stroke this could be the bearing slipping of the collar. If your throw out bearing is attached to the clutch fork it kind of realigns it self when you release the clutch. The transmission throw out collar should extend thru the pressure plate forks.

From the flat edge of the trans face, measure the depth of the throw out collar and then from the bell housing surface measure the depth to the pressure plate forks. The measurement distance on the bell housing side should be slightly shorter than the length of the throw out collar. If you have a measurement discrepancy greater this would indicate that the throw out bearing is potentially falling off the collar and the source of the trouble. I still don't think the crank moves enough to be the cause of the problem.

Keep us posted.

 

I'm having a similar problem.... Did this ever get worked out?

 

Bad or no ground . It grounds thru the clutch linkage when you start it and when you push the pedal it no longer grounds and the ignition cuts off. I fought the same thing for ever and come to find out it was grounding thru the throttle linkage.

 

Joecool is on the right track. Guy brought me a Dodge truck that had the lights go crazy, bright to dim and back
continuously when clutch was depressed and engine would cut out to the point off dying. He had recently
changed engines and did not install the ground strap from engine to firewall or the one from eng to trans.
I put both ground straps on and all was well. Weird.

 

Interesting old thread. Someone call Curtis, he was last seen here just before Christmas 2017.

 

Hope he fixed it. Had the opposite happen on my 57, engine would die when clutch was at top of stroke, turned out IGN wire fell down onto clutch spring and was pinching when spring relaxed.

 

I actually had this problem, the solution was obvious after a bit of visual poking around. The clutch linkage was hitting a wire that caused a short.

 

.................................These are the kinds of things that will drive you absolutely NUTS!

 

From far away over here, it sure sounds like a serious thrust bearing prob on the crank.
Odd story of mine that is prolly not a whole lot related, but could generate ideas--
One Jeep pickup my son drove to college for a while started stumbling and dying every time he pushed in the clutch. After some puzzling investigation, I finally found that a few bellhousing bolts were loosening up, letting the bellhousing shift around a bit. That didn't seem to be THAT importantly related, but it apparently had a sensor or ign trigger that read the flywheel.
I tightened the loose bellhousing bolts, and the prob went away.
So, a trigger of some sort moving out of alignment when a wandering crankshaft moves out of alignment??
I hope the crank end-thrust isn't letting the crank chew on the main bearings...

WHY BE ORDINARY ?

 

I bought a '54 Chevy with a 327 with a 3 speed manual installed. It had a difficult to depress
clutch pedal with a clicking/grinding noise when pushed in. I pulled the transmission out
(it didn't have a "******" ;>| ) and found the throw out bearing off the fork and jammed
between the pressure plate fingers.
Likely a careless install of the trans. allowed the t.o. bearing to slip off the fork clamps.
Don't know how they could have got it back together that way. The fork pivoted on a ball
stud in the bell housing. They must have got it off the ball and knocked the t.o. bearing off
the clips on installation. Shade tree screw up I guess.