Hot start Options

[Pursang]

I've heard about this problem before. You've been driving on a warm day and, at some inconvenient stop, the starter won't engage. Dead. Nothing. Nada. Battery is fine but no action from the solenoid. Bump start works and you get back to your home just fine. Next day the car starts as if nothing was wrong. People with more knowledge than I, and they are legion, tell me that this is a common problem with the teener. Thanks for that but I would like to know what the root cause problem is. My car has been run on hotter days for longer periods and this is the first time I've experienced this failure. Is it a wiring problem, a weak fuse, a tired old original part or what? Inquiring minds want to know. Thanks.

(74 2L)

[toolguy]

Adding a 'slave' relay is a good method to save your ignition switch contacts from arching and extend it's life. . It does not fix a defective solenoid with a Hot Start problem. . . It does however give you a better {shorter} path for the yellow lead that operates the solenoid. . This would be effective if the yellow lead, which comes from the ignition switch, has a low voltage /amperage resistance problem.

Electrically, Heat is a resistance multiplier to current flow, and when the solenoid and the battery cables get really hot, there is a higher current resistance and less current can get thru to operate the starter.

Yep, the solenoid can easily be taken apart, It has large contacts inside which are most likely heavily pitted [another resistance location]. . these can be sanded or filed to extend their life. . I've successfully remade the copper contact parts when they were beyond a simple filing. . . The other common big resistance issues for hot start problems are in the battery cable itself, it's connections on both ends, and the Ground Strap at the transmission. Often, corrosion from the battery terminal travels down the battery cable and are present inside the cables insulation cover. .

All the small resistances add up, sometimes individually they aren't much, but in a complete circuit, they are accumulatively over the threshold for the starter to operate when hot

Go with simple first, check the connections and cables before you pull the starter and solenoid. The following is a general sequence to locate the problem source, but multiple issues may mask the real problem. . .
If the solenoid does not click [try to operate] when you turn the key, look for an issue in the large yellow lead, it's connection or the ignition switch. .

If the solenoid clicks but the starter does not turn, investigate the main battery path. . remove the yellow lead, and jump the main battery terminal at the starter to the terminal where the yellow lead was. . You have now bypassed the ignition switch and the starter should turn. .

If it does operate, a slave relay may be your solution. . . If the starter does not operate, look into the solenoid contacts and cable connections. . . . .
You can still have resistance problems within the solenoid. . you didn't fix the issue, you overcame the lower operation limit of the solenoid. . Hope this make sense. .