Engine won't turn over when warm

[GOLDCYLON]

My cars pervious owner bypassed the switch because he was tired of having been towed to GM and the switch was replaced three times. He said the problem also occured after driving the car for a while. He would stop somewhere and then no start when he would get into to start driving it again. Always when the car was hot. Very simular to the OPs problem.

A large percentage of us have already done this becuase the switch is a POS. I am glad to hear a few members here have not had a problem. My arugment is its only a matter of time as it will happen at the most inconvient time in the most inconvient place and you be saying damn GC warned me. Im sure age of the componet, mileage and AZZ time in the cockpit all factor in here as to why the switch fails. Or you can just bypass it and when you car doesnt start you know what you can rule out. A no brainer if I ever saw one.

[John Boothby]

This may sound stupid, but this is what happened to me. I have only heard guys complaining that the car will not start with a bad switch. My car starts all the time, however, the last time I took it in for an oil change the mechanic turned the key over with the car IN GEAR without depressing the clutch and the car lurched forward. He said I had a bad safety switch. I always start the car in neutral and depress the clutch. I assume the switch is to prevent the car from starting in gear. Mine still starts even in gear if you depress the clutch or not. So, do I have a bad switch? Like I said, stupid question.

[scottfab]

Originally Posted by John Boothby

This may sound stupid, but this is what happened to me. I have only heard guys complaining that the car will not start with a bad switch. My car starts all the time, however, the last time I took it in for an oil change the mechanic turned the key over with the car IN GEAR without depressing the clutch and the car lurched forward. He said I had a bad safety switch. I always start the car in neutral and depress the clutch. I assume the switch is to prevent the car from starting in gear. Mine still starts even in gear if you depress the clutch or not. So, do I have a bad switch? Like I said, stupid question.

Not at all a stupid question. In fact timely.
Sounds like someone bypassed that safety device.
Hard to know who would be liable if someone got hurt when the
mechanic turned the key.
Another reason to leave safety equipment in place and functioning.
As for me, I leave air bags working and the clutch switch alone.

[GOLDCYLON]

99% of all the manual cars Ive driven if you try to start the car in gear the car will lurch forward. There is no liability issue... Just a mechanic who has no business working on your car. If you start any manual car it could be in netual with your foot on the brake for safety. You can have the clutch enganged or not its a matter of choice. I perfer to have my clutch depressed with the car in netural because thats how I learn to drive a standard. The clutch is always depressed unless you are planning on moving or remaining in neutral

Equating an Airbag to a clutch switch when one of the pair strands your car is simply not worth the debate. Your mileage may vary

[Kevin]

i don't see the clutch switch as a safety issue.

[GOLDCYLON]

Originally Posted by Kevin

i don't see the clutch switch as a safety issue.

100% concur

[scottfab]

This car comes with a "start defeat" safety switch.
There is no other purpose for it.
I'm not convinced a good lawyer could not make a good case for
negligence in a wrongful death suite.
And since we've discussed it on this forum there is a paper trail to at least those involved in the thread.
Chances for someone getting hurt? Probably low.
Chances for a suit happening in this economy if something does happen?
I'd say fair.
I for one am leaving my clutch switch in place.
I suggest anyone new to the car do the same.
There is no way I want someone later saying I recommended removing it.

[Paul Workman]

Originally Posted by GOLDCYLON

My cars pervious owner bypassed the switch because he was tired of having been towed to GM and the switch was replaced three times. He said the problem also occured after driving the car for a while. He would stop somewhere and then no start when he would get into to start driving it again. Always when the car was hot. Very simular to the OPs problem.

A large percentage of us have already done this becuase the switch is a POS. I am glad to hear a few members here have not had a problem. My arugment is its only a matter of time as it will happen at the most inconvient time in the most inconvient place and you be saying damn GC warned me. Im sure age of the componet, mileage and AZZ time in the cockpit all factor in here as to why the switch fails. Or you can just bypass it and when you car doesnt start you know what you can rule out. A no brainer if I ever saw one.

Question: Do you know whether or not the previous owner turned the key and then pressed the clutch, or visa-versa (like should be done to avoid arching at the contact points)?

P.

[Blue Flame Restorations]

Someone educate me, please.

When factory new, with the switch in place, should the car require the clutch pedal to be depressed before the starter will even turn?

My starter will turn without the clutch pedal being depressed and I assumed that the switch had been by-passed.

[Paul Workman]

Originally Posted by scottfab

Not a bad idea as long as the FET is clamped with a zener to protect it from the inductive kick of the starter solenoid. (similar to class D amps).

Hmmmm..... Well, that might work, but would have consequences. Due to the fwd bias threshold, in a situation where the starter is already "a bit finicky" (w/regard to minimum voltage requirements). I don't know if I want to put a healthy diode in series with the output. Maybe the simple "filter" capacitor (like they do on distributor/coil ignition) to absorb the "kick" might be sufficient, ya think?

Originally Posted by scottfab

There will always be this pressure on the thrust bearing either before start or after. Failure will not be due to pressure on the bearing but the spin of the bearing dry which would happen regardless. (IMHO)

I believe Marc is referring to the force imparted on the TO bearing to release the pressure on the clutch disc, which acts on the crankshaft via the flywheel when the clutch pedal is engaged. NOT pressing on the clutch would prevent this force from acting on the end of the crankshaft and the thrust bearing. Bypassing the clutch interlock switch would allow the motor to start w/o end thrust. Starter load would go up slightly as the transmission would be turned w/o the clutch being disengaged. (Prolly not so much on a DD, or even one driven once a week. But, once a month or less, and in the winter months especially? Makes sense.

Originally Posted by scottfab

A noted and well know author and owner of a ZR-1 once said of the GM designers, "these are highly skilled, highly paid engineers that focused on these designs for years. They know more than shade tree mechanics." (paraphrased) That statement comes to me every time is see someone on this forum struggle with some of the more notorious failures. Fact is we've had decades now of experience that those engineers did not have. Improvements are not only needed but necessary for the good of the car. However, I've always made my mods "backoutable" just in case it's important to the next owner. (very likely after I'm gone)

People aren't perfect, and bean-counters force engineering compromises to be made. Truth is where you find it, beit in some college level engineering course, or discovered by a "shade tree mechanic". Serendipity is a heck of a good teacher, I find!!

Back to the OPs question: All this said, I DON'T think it is the interlock switch anyway. I agree w/ scottfab. I suspect a connection issue (either internal to the starter or at the battery terminals or ground terminal). If it were the interlock, connecting jumper cables to the battery wouldn't result in it starting.

That said, electrical problems often will only show up when devices get hot. So, a cold starter might test OK, but after being heat soaked, things might turn up that weren't there before!

P.