Engine won't turn over when warm

[Crusin]

I presently own a 1990 ZR-1. After driving for a while and trying to start, the engine doesn't turn over . As soon as jumper cables are put on the battery, the engine starts right up. Had battery and alternator checked out okay. Problem persisted. Had battery changed and starter rebuilt. After driving 60 miles or so turned off and tried to start later and still got the same problem with no start. Had key checked and is okay. I would appreciate some suggestions. Thank You

[GOLDCYLON]

Bad clutch switch or your starter is suspect. My money is on the clutch switch as the culprit. A lot of members have bypassed the switch as to not get stranded. Look in the solution area and that should walk you through the process.

Heres a link below on how to run the bypass

Welcome to the forum. GC

http://www.zr1.net/forum/showthread.php?p=98493

[Crusin]

Thank You for your suggestion, I will have that looked into.

[rhipsher]

Need to make this one a super sticky. Its like Deja vu all over again.

[Brad Sewell]

I would also check the starter ground and the negative battery terminal for corrosion and clean the connection points on the frame

[Kevin]

if you haven't done it bypass the clutch switch. did many years ago and never had another problem with that

[scottfab]

Battery......
If you put cables on and it starts right up then it's battery.
I assume by "cables" you mean a jump.
The car is very sensitive to a marginal battery.

Also, I'd leave the clutch switch in place. It's a safety feature.
They only burn up if you don't have the clutch fully pushed
when you turn the key.
Many get in the habit of turning the key as they press the clutch
and this put a hurt on the switch (arcs inside)
I've never had an issue with my clutch switch in 15yrs of driving.

[Paul Workman]

Battery......
If you put cables on and it starts right up then it's battery.
I assume by "cables" you mean a jump.
The car is very sensitive to a marginal battery.

Also, I'd leave the clutch switch in place. It's a safety feature.
They only burn up if you don't have the clutch fully pushed
when you turn the key.
Many get in the habit of turning the key as they press the clutch
and this put a hurt on the switch (arcs inside)
I've never had an issue with my clutch switch in 15yrs of driving.

ABSOLUTELY!!! I was just about to say this very thing!

A while back I posted a schematic for a relay to do the heavy lifting, leaving the clutch switch to simply activating the relay - vastly reducing current draw through the switch. However, in retrospect, the problem with the arching is simply moved from the switch to the (mechanical) relay. So! I think I'll re-design the circuit and put a MIL spec solid state (FET) in place of the relay (read: no arching ever).

That said, Marc Haibeck made the comment once that he bypassed the clutch switch because pressing on the clutch puts a good deal of force on the thrust bearing in the LT5, a bearing that can be very dry, depending on how long it has been between startups. So... There's that to consider.

This discussion is warming to a tech article for the Registry, methinks!! But, in the mean time, I agree - we should be a smashin' da clutch afore turnin da key, doanchaknow!!

P.

[Crusin]

I would like to thank you all for your suggestions in regard to my current problem with engine not turning over when hot. Keep on Motoring Guys. CHEERS:

[scottfab]

However, in retrospect, the problem with the arching is simply moved from the switch to the (mechanical) relay. So! I think I'll re-design the circuit and put a MIL spec solid state (FET) in place of the relay (read: no arching ever).

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).
Then, like any mods, it's a matter of documenting it well and in a place you'll find it if something goes wrong down the road. (or for the next owner) One of the biggest lessons I learned on custom mods was to document well. There's no amount of "oh I'll remember what I did here" that works :(

That said, Marc Haibeck made the comment once that he bypassed the clutch switch because pressing on the clutch puts a good deal of force on the thrust bearing in the LT5, a bearing that can be very dry, depending on how long it has been between startups. So... There's that to consider.

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)

This discussion is warming to a tech article for the Registry, methinks!! But, in the mean time, I agree - we should be a smashin' da clutch afore turnin da key, doanchaknow!!

P.

Best overall solution would have been in the initial design. That is the NO (normally open) clutch switch in line with the high current starter solenoid is bad. Better would have been a NC switch in the gear lever at neutral. No one would be moving it while turning the key.

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 incase it's important to the next owner. (very likely after I'm gone)

[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]

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]

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


100% concur :cheers:

[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]

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]

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?



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.


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.

[GOLDCYLON]

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.

No idea Paul that was like 7 years ago. But he had to get the car towed three times back to GM. One can assume he was capabile of driving it and starting it. Each time they replaced the switch. He finally got tired of being stranded by it and bypassed it.

[GOLDCYLON]

This car comes with a "start defeat" safety switch. There is no other purpose for it.

Other than to piss off the owner when its fails I disagree there is no there is no good reason for it.

I'm not convinced a good lawyer could not make a good case for negligence in a wrongful death suite.

A hollow arugment... any good lawyer can argue anything. My case in point the woman who burned their laps when they dropped hot coffee on it served by McDonald. But Hell I degress

And since we've discussed it on this forum there is a paper trail to at least those involved in the thread.

Beware Lawyer spybots ?

Chances for someone getting hurt? Probably low.

Concur

Chances for a suit happening in this economy if something does happen? I'd say fair.

See my McDonalds comment anything is possible

I for one am leaving my clutch switch in place.

Well ok then

I suggest anyone new to the car do the same.

Well Ok then again

There is no way I want someone later saying I recommended removing it.

Go Boldly

[Brad Sewell]

Back to the OP: this was the most useful information I found when I was chasing my no-start. Good luck.

http://www.zr1netregistry.com/ZR1_troubleshooting.htm#Start

[Kevin]

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.

on the off chance that someone other them me gets into my car with my car in gear, hits the key, and the car jumps a few feet forward and kills someone, I'm fairly sure I can find a good lawyer to fight that case. I suggest anyone new to these cars disable the clutch switch. There I said it. It's not like the car will fire up and go roaring around town at twice the speed of light if someone happens to hit the key while the car is in gear with the clutch switch bypassed and the clutch out, it's going to lurch forward and die. With the car in neutral and you hit the key, the car is going to start and sit there.

[rhipsher]

Other than to piss off the owner when its fails I disagree there is no there is no good reason for it.



A hollow arugment... any good lawyer can argue anything. My case in point the woman who burned their laps when they dropped hot coffee on it served by McDonald. But Hell I degress



Beware Lawyer spybots ?



Concur


See my McDonalds comment anything is possible



Well ok then



Well Ok then again



Go Boldly Im scared now. I'd better put mine back on immediately.:(

[GOLDCYLON]

This is NOT a Clutch Switch Bypass but rather a method to reduce current in the purple wire that may pass through the Clutch Switch. You can also bypass the clutch switch with installation of the Relay if you want.

Starter Relay Modified (http://www.zr1.net/forum/showthread.php?p=134105)

Note: I wired the relay a bit different as follows.....
Pin #30: Purple wire to starter (3/8 inch connector).
Pin #87: Red wire battery positive 12v 3/8 inch connector (connected to battery positive multiple connection post).

With this wiring method, Pin #87a is Not hot at any time and not used. (Look at the schematic printed on top of the Relay).

Thanks for clarifying the bypass Cliff :cheers:

[John Boothby]

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

The mechanic will not touch the car again. He was recommended by another (non ZR-1) corvette owner.

[VetteMed]

I'm proud to say my clutch switch is bypassed. TO hell with the lawyers, and those who fear them.

[Kevin]

I'm proud to say my clutch switch is bypassed. TO hell with the lawyers, and those who fear them.

hey, I can be happy or right...



(i'm married to a lawyer)

[scottfab]

Other than to piss off the owner when its fails I disagree there is no there is no good reason for it.


Don't know that it was put there to piss us off. I personally have never had a problem with the switch but then early on in 97 I understood the problem and began to fully depress and engage the clutch switch before starting the engine to avoid damaging the switch.

A hollow arugment... any good lawyer can argue anything. My case in point the woman who burned their laps when they dropped hot coffee on it served by McDonald. But Hell I degress

Agreed. Someone actually sued the large company I worked for about a decade ago for not explicitly saying in the manual that you could not dry your cat in their microwave. True story. And yet a "good lawyer" would get a large settlement if negligence can be proven to a jury. In this case they lost.

Beware Lawyer spybots ?

????? They do find stuff on discovery. Depending on which side of a suit you're on this can be a good thing or bad. They just love it when a trail of behavior can be found. It can prove forethought and intentional indifference which cranks up the punitive damage $.
I don't fear lawyers. I fear being stupid. As defined "ignorance" is not knowing something. Stupidity is knowing and still doing the wrong thing.
WITNESS: your honor I resent this line of questioning. The attorney is trying to make me say that I saw the defendant rob the store. He couldn't have robbed the store. I did. ooops
(edited later - I am referring to no one but myself. I did a similar thing to the above once)

I am not a lawyer or married to one but I do keep my mind open when my lawyer friends have spoken. At least enough to know what to do should I hit a pedestrian or how to leave a plausible deniability statement in my prose. (I do this thing XYZ but I do not advocate it for anyone).

It would be interesting to post a "poll" on this as to how many member have bypassed the switch. Maybe there are a "lot" of them. Maybe not.

[GOLDCYLON]

It would be interesting to post a "poll" on this as to how many member have bypassed the switch. Maybe there are a "lot" of them. Maybe not.


LOL using your arugment Scott why feed the lawyer bot? ;)

[Kevin]

i'm still trying to connect the dots on how bypassing the clutch switch is dangerous

[scottfab]

i'm still trying to connect the dots on how bypassing the clutch switch is dangerous

While I would never bypass the switch (cya)
It is dangerous in that it's conceivable someone by accident
(or on purpose to set up a suit) could claim that GM installed
this device to preclude an accidental crushing of someone's
leg or cause the car to lurch out in traffic etc etc.
And then by intentional negligence it was circumvented.
There is a big difference in negligence and intentional negligence.
A REAL BIG DIFFERENCE.
Imagine the worst case scenario. A child (maybe a grandchild) is in
the car somehow (got in without permission). The child sees the key and puts in in and turns it. The car is pushed into first gear and offers little resistance to movement and there for runs over and crushes a neighbor
kid. The neighbor kid's parent is a knowledgeable lawyer........
The stage is set to loose everything you own not to mention the grief anyone would have for being responsible.
Like I posted earlier the chances of happening are VERY remote.
But then why store gas next to a furnace?

Having said my position. I do acknowledge we all have the right to do changes to our car that we feel make it better.
I'm done with this thread.
Long live the ZR-1.

[Crusin]

Thanks for your suggestions. I agree the Safety Switch is for Safety. I bypassed the S/S and problem went away, but I am waiting for a new switch to be delivered. Better to be safe than sorry.

[Z51JEFF]

Thanks for your suggestions. I agree the Safety Switch is for Safety. I bypassed the S/S and problem went away, but I am waiting for a new switch to be delivered. Better to be safe than sorry.

Where exactly did you find the switch if you dont mind me asking?I spent more than a year looking for one and stumbled on a new one on Fleabay about 2 months ago.

[Crusin]

I was informed by ZIP Corvette Parts that they would be receiving new ones in 2 months. I recently phoned to inquire if this was indeed correct and informed No it wasn't that they won't be getting new Safety Switch's for a manual transmission. Guess I will have to look again to obtain one myself. CHEERS!

[scottfab]

I was informed by ZIP Corvette Parts that they would be receiving new ones in 2 months. I recently phoned to inquire if this was indeed correct and informed No it wasn't that they won't be getting new Safety Switch's for a manual transmission. Guess I will have to look again to obtain one myself. CHEERS!

Keep us informed. I'm sure many will be waiting see what you come up with.

[Tyler Townsley]

GM redesigned this ckt in the 92 MY. Any one have a manual that deplicts the changes. It might be easier to convert to that setup. I suspect its some kind of relay configuration (which could give us the 'correct' relay to use.)

Tyler

[scottfab]

GM redesigned this ckt in the 92 MY. Any one have a manual that deplicts the changes. It might be easier to convert to that setup. I suspect its some kind of relay configuration (which could give us the 'correct' relay to use.)

Tyler

Yes as memory servers the newer design draws less current though those contacts. However, if you remember to stat the car with the clutch peddle pressed in all the way the contacts do not arch and last indefinitely. Oh and of course leave the key turned a bit longer than you would other cars after start to avoid having the MAP sensor tube from coming off :)

[Z51JEFF]

Keep us informed. I'm sure many will be waiting see what you come up with.

12 months ago Keen Corvette Parts was in the process of having these produced,dont know how close they are to having them on the market.

[Z51JEFF]

Corvette Express found one for me about a year ago but at $150 plus markup it was close to $200 by the time it was shipped to me.If you need one bad enough you might look them up,this place is in Vacaville Ca I think,your welcome.

[Crusin]

Thanks for your reply Jeff. I will check them out to see if they have any available. CHEERS!

[Paul Workman]

Back to the starting issue for a moment...

FYI, A couple years back there was some chatter about the contacts inside the starter solinoid being a problem at about 40k miles (on average).

This is the relay that connects the battery to the starter windings - 100s of amperes involved, and is what is what starter "rebuild kits" consist of.

The contacts consist of a copper ring and two copper terminal posts. The copper ring (looks like a washer) is on a shaft that is slammed against the two copper terminals when the starter solenoid is activated to connect the battery to the starter windings.

At issue is arching. The result of arching is pitting and carbon tracing severely pits and etches the copper ring as well as blasting molten material from the surface of the copper terminals. Over repeated usage, the electrical connections deteriorate to the point where the starter will "click", but because current sufficient to turn the starter is not flowing, the engine will not turn over.

One can buy rebuild kits for the starter on ebay for under $10; consisting of a new armture & attached copper ring, as well as the two terminals.

(Note: One word of caution regarding some of those kits: The (plunger) pin on the armature may not be exactly the same length as the stock one. However, the copper ring of the stock armature can easily be resurfaced with some emory paper wrapped around a small (block of wood). Then, replace the terminal pieces and adjust them so that the ring contacts them both at the same time, and reuse the stock armature. (12,000 miles since I did mine and still going strong!))

This may have nothing to do with the issue at hand, but for anyone pulling the plenum for some reason, and hasn't R&R'ed the starter solenoid contacts, then would be an ideal time to do so!

FWIW,

P.

[Crusin]

Thanks for your opinion Paul. The issue was solved after I bypassed the Neutral Safety Switch. I am now in the process of trying to find a NSW for a manual transmission. CHEERS!

[scottfab]

Corvette Express found one for me about a year ago but at $150 plus markup it was close to $200 by the time it was shipped to me.If you need one bad enough you might look them up,this place is in Vacaville Ca I think,your welcome.

wow, $200 for a switch. I'm sure glad that I have always pressed the clutch all the way down before turning the key!