C3 Corvette Starter Heat Soak

Friday, October 6, 2017

I've been having problems when I try to restart my Corvette once the engine is hot.

Yesterday, I took the car for a spin around town and, after a stop at the local Sunoco, I went to start the car, only for the starter to barely turn like if the battery was almost dead. What's interesting is that while it struggles for a few seconds, eventually it spins somewhat normally and the car starts right up.

The dashboard battery gauge proved that the alternator was doing its job by showing the battery was being charged, so I believe that's not the culprit as I think the loads being imposed on the battery while trying to restart the car, are strong enough to require the alternator to recharge it, as shown by the gauge. After a minute or so, the needle settles back down to a normal positive voltage.

In order to chase this issue, I removed the battery to have it tested at the local auto parts store, where it showed a 95% charge and it was given a clean bill of health for both voltage and cold cranking amps.

The battery, by the way, is barely two years old, and—it's been my experience—that you can get approximately five years of life out of a car's battery.

Since my Vette is not a daily driver, I think that getting six years of usable life out of the battery may be possible and reasonable. Anyway, the battery does not seem to be at fault here.

After getting back home, I wiped the battery down, but first I decided to inspect the battery terminals and clean them. While at AutoZone, I purchased a pair of side-mount terminal bolts since the original ones looked pretty tired and corroded. I assume they were original to the car.

Removal of the terminal bolts is easy. All I had to do to remove them was apply light pressure on the threaded side of the bolt and they slid out of the cable end.

While I had them out, I took the opportunity to clean the plastic cable end covers the best I could, considering that the battery is located behind the driver's seat which makes access to it a bit challenging. Thankfully, removing the driver's side T-top helps.

After cleaning the cable end covers, I sanded the cable ends to remove some of the corrosion and ensure good contact, plus I coated the area with dielectric grease to keep any future corrosion at bay. I then installed the new terminal bolts.

Since it appears the issue is not battery- or alternator-related, I will have to do a little more research to see if the issues I'm experiencing point to a defective starter, even though the one in the car is barely a year old, but since it is a remanufactured AC Delco unit, you never know.

Again, this problem only happens after the motor reaches normal operating temperature so I am starting to believe that it may be the dreaded "Heat Soak" problem that I've heard affects GM starters of the 1970s and 1980s, although I have to say that I don't remember having these type of problems back in the day.

Since I do not have a lift and am in the process of starting to rehab a house I just purchased in DeBary, Florida, plus all the associated moving expenses and work in order to be ready to move all of my stuff to the new place before the end of the year (when my current lease expires), this project will have to be continued in a few months.

Sunday, October 10, 2017

I went ahead and reconnected the battery and the car started right up. I let it idle until it reached operating temperature, but wasn't able to recreate the issue, so I am thinking that the motor may need to run a bit longer for heat to build up and cause this issue, which by the way, I have no idea if it affects the starter solenoid or something else.

It was suggested by two mechanics that I replace the almost-new AC Delco starter with a newer GM unit with a reduction gear. That sounds great but such a purchase would cost around $300 which is money I rather spend on the new (to me) home.

Once I am able to crawl under the car I will see about cleaning all the electrical connections and ensure the ground is properly connected as someone mentioned it could be contributing to the issue I am experiencing.

I may also install a heat shield, or cover the starter with a heat mat, or both!

Stay tuned for an update in a couple of months.


I was finally able to figure out what was causing the hot-starting issue, and it had nothing to do with the starter. The culprit was discovered once the alternator gave up the ghost. Once I installed a new alternator, the hot-starting issue went away completely!

My guess is that the alternator was starting to fail and not charging properly while the car was running, hence the intermittent nature of this issue, but regardless of the actual cause, I am glad that this issue has been finally resolved.

Thanks for following my 76 Vette Blog!

Product Links... (#sponsored)

• How to Restore Your C3 Corvette: 1968-1982
• 1968-1982 Corvette Restoration Guide, 2nd Edition
• 1976 Corvette Service & Overhaul Manual
• 1976 Corvette Assembly Manual

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