Starter

[Riley012]

I have a 1982 k20 chev pu. This winter there has been a few times when my starter would not engage, I put my sunflower heater under the starter for about an hour or so and it would engage and the truck would start. When this has happened the temp was around 15 to 20 below or colder. Can anyone tell me what mite be the problem or is it just the cold weather. It seems to be fine when the temp is a little warmer. Also I do plug the truck in. Thanks:

[Dvldog8793]

Very possible that it is corrosion on the connections for the starter or in the starter. If corrosion is present and the temps go south that makes things worse. Extreme temperature change cycles can also loosen connections over time. If you remove the starter make sure to re-install using NEW bolts torqued to the right value.
Good luck

[trbankii]

When you say "won't engage" - what do you mean? That the starter spins without turning the engine over? Or that the engine spins over but won't start?

[Riley012]

When it's very cold it won't do anything till I put a heater under it for an hour or so

[DmaxMaverick]

Check for batt+ voltage at the small pole on the starter solenoid, with the key turned to "start", at a time it won't turn. If it has no power, then the problem is not the starter, or solenoid. If there is power, and it still does "nothing", then read on.....

Sounds more like an issue with the solenoid. If it doesn't move, the starter motor doesn't get power. This isn't too uncommon, even in less cold temps, when they wear out or have been contaminated. If the plunger has been "greased", it's possible the grease is locking up at that cold. The solenoid should be clean and dry, inside and out. Fortunately, they are inexpensive to replace. Unfortunately, you'll need to remove the starter to do it.

Note:
It is much easier to mess with the starter with the passenger/front wheel removed, and often the fender liner/flap as well. This gives a clear shot at the starter, bolts, electrical and all, from the wheel opening.

[trbankii]

When it's very cold it won't do anything till I put a heater under it for an hour or so

No offense, but it would help if you gave clearer descriptions.

"Won't do anything" - No click? No nothing? Dash lights don't come on?