Slow chugs from starter with warm engine but not cool engine?

Question

Suburban 1998. Starts pretty good at first, but after a 30 minute drive it is sounds like trouble.

A good start usually has a quick series of short chugs, each getting stronger until less than a second goes by the engine is running.

A troubling start can sound like a couple longer/slower chugs, both sounding about the same, and then the third chug starts it.

I don't drive this vehicle often. I never do hear the solenoid click, but that doesn't mean there isn't one. I don't think there is any grinding sound -- certainly no high pitch screeching sound.

I have not yet watched for dimming/brightening of the lights during a bad start because I only recently realized the pattern. (good start when cold, bad when warm) The battery is less than a year old, but I will probably have it load tested anyway this weekend.

After the engine has been off for awhile, I can start the vehicle 6 times in a row and sounds like a good start each time, of course it gradually gets weaker (I assume that is due to battery drain).

Why do you think it would work better on a cold start, and not a warm start?

Answer 1

This sounds like a classic case of "heat soak". In most Chevy V-8's the exhaust pipe runs very close to the starter. The starter absorbs the heat, the heat increases the electrical resistance along with expanding the metal parts. The combination of the two can result in sluggish starts when the engine is hot. The symptons get worse as the starter ages. The factory solution was a heat shield that usually gets tossed or rusts away with the first starter change. Heats shields are available in the aftermarket from speed shops or performance outlets. You may also consider wrapping the pipe with an insulating wrap typically used on exhaust headers. A new starter may temporarily fix the problem depending on how hot the starter gets.