C3 Wont start when Hot

[don justham]

My 1970 starts fine will run for a while and then when its turned off won't re-start. Turn the key and it just clicks. Let it sit for an hour or two and then it starts fine. ANy ideas would be appreciated. Thanks

[John H.]

Re: C3 Wont start when Hot

Assuming your battery cable connections are clean and tight, sounds like the chronic heat-soak "cooked solenoid" issue; some folks report improvement with the commonly available heat insulation wrap sold at speed shops, some just need a new solenoid.

[Tom S.]

Re: C3 Wont start when Hot

Sounds like solenoid to me. If it is a numbers matching car I would pull the starter and have it gone through.If not you can get a good exchange.The heat on these was and always will be a major problem.Its the nature of the beast, a friend had one new in 69 and it was a problem then.

Tom

[Joe L.]

Re: C3 Wont start when Hot

Don-----

The only sure-fire solution to this problem that I have ever found is the installation of a slave solenoid. Kits with instructions are available from auto supply stores and, I believe, some of the Corvette parts vendors, too.

I had this problem with my original owner 69 virtually from the beginning. I tried EVERYTHING to solve it. The only thing that worked 100% was the addition of the slave solenoid. That ended my problems once-and-for-all.

[Kieran A.]

Re: C3 Wont start when Hot

Don,I had a 1978 L-82 that did the same thing. We ended up putting a remote starter solenoid (from a Ford!) on the framerail to keep it away from the heat of the exhaust manifold. I never had a heat soak problem again. Of course this was a last resort after checking the cables,connections and the battery. The car was used as a daily driver also. I later read that GM Delco issued a lighter return spring for the starter solenoid to help alleviate this common problem. Maybe Joe Lucia could give you the necessary part number if needed. Regards,Kieran #11373

[Joe L.]

Re: C3 Wont start when Hot

Kieran-----

The spring part number is GM #1978281. However, it's discontinued. No matter, though. That spring was one of the MANY "solutions" that I tried. It was one of the "solutions" that produced "0" benefit; that may be why GM discontinued it and went back to the original spring.

The slave solenoid (Ford-style) is the only permanent solution that I found. The real problem is heat-induced resistance in the "purple wire" that energizes the on-starter solenoid. The slave solenoid, in conjunction with a heavier gauge wire from the slave solenoid to the "S" terminal, insures that full voltage is supplied under all conditions. It works like "magic" and I've found it to be 100% reliable. After its installation, no more worries, at all, about hot restarts. And, I've tested mine many times in Death Valley, CA in July and August.

[Jim T.]

Re: C3 Wont start when Hot

Don not all C3's have this hot start curse. My original owner 70 still driven today has never had a hot start problem even in Dallas,Tx hot summers when I lived there. My 68 did have the problem you are experiencing. I put in a new Delco battery that had more cranging power and the problem went away.

[Mike Cobine]

May be the connector on the firewall

I'm not convinced it is the wire completely. The reason is I have found that many when this occurs do not have full voltage at the bulkhead connector. I think the problem may really be on the firewall in the connector than the solenoid or even the wire. This is why "fixes" to those areas do not cure anything.

I had a Suburban that did that often. I believe there is a fusible link between the two halves on the purple wire. Beleive it or not, Chevy stuck several in between the halves and they are NOT fun to change. I hotwired a wire from the inside around to the outside to connect and the starting problem went away.

I had a similar problem with a Chevy van. Some strange quirk of fate in a gas station 400 miles from home with the Corvette on the trailer took out the fusible link between. Hotwired the connector and never had a starter problem again except for a starter that ate itself. That is how I had the idea to look there on the Suburban.

[Patrick H.]

Re: C3 Wont start when Hot

I had it happen to me when the ground strap from the motor to the frame wasn't quite tight enough. That was an interesting one, but thankfully easy to see when I went underneath to look at the starter.

Patrick

[Les Jacobs]

Re: C3 Wont start when Hot

I too had a grounding problem..at the battery clamp. When cold it was tight enough to start and run. When hot, there was a high resistance path from post to clamp. So not only would it not start when hot..but if running, a sudden heavy electrical load (lights) could kill the engine. Cleaned and tightened the connection and the problem disappeared. If only they were all that easy.

[Paul L.]

Re: C3 Wont start when Hot

The solution to heat soak in my 1979 was rather expensive and certainly not NCRS. But I was tired of being stranded for an hour or so after a nice drive and a stop for ice cream. I purchased a Chevrolet high-torque mini-starter. The problem never re-occurred.

[Bill Braun 33186]

Re: C3 Wont start when Hot

I had the same problem with my 67 big block but solved it by making sure the starter cable was as far away from the exhaust manifold as possible.

Problem never recurred.

Bill 33186

[Rob Edwards]

Re: C3 Wont start when Hot

The point about all wires being intact and tight is well taken. We had terrible hot-start issues with the '62 and when we put it up on a lift it quickly became obvious that the riser valve was cracked, and the hot exhaust gas had burned off most of the (+) battery cable, there were only about 20 strands left intact. Amazing it started at all, let alone the safety issue of uninsulated cable coming directly off the battery. With the exhaust fixed and a new cable, no starting issues, even when the gauge is at 210 from heat soak after a long run and 5 minute shutdown.