93 Buick Regal 3.8L

Probably a corroded or loose ground connection...

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Check out your fuel delivery system. If the battery were bad, you would (most likely) encounter a problem in cold conditions.

check the ignition modude "usually under the distributor cap". they're heat sensitive before they fail.

When hot, do you hear a "click" sound? If so, the starter solenoid is energizing, but not transferring power to starter.There are 2 large terminals on starter, one is for battery power into the solenoid, and the bottom on(the shorter one that is hard to see) is the actual output to the starter.

If it is clicking, it is bad.If it is not clicking, but has voltage to the small terminal to ground, the coil inside of the solenoid is bad,either way, replace the starter solenoid.

Inside the relay, there is a copper disk that connects the two copper bolts you can see from the outside of the relay. Copper corrodes pretty easily from the arcing and sparking of making and breaking contact. This will eventually lead to a condition where the relay works sometimes and sometimes doesn't. However, since you changed the starter and nowadays that means the relay as well as they are usually sold as a unit....

There is also the neutral start safety switch (for automatic transmission) and a switch at the clutch pedal (manuals). The neutral start safety switch can be checked by starting the car in neutral instead of park or bypass it temporarily.

Does the exhaust pipe run near the starter?

When in a financial pinch, I have disassembled the solenoid, reversed the copper washers, and reassembled.I also reversed the square posts so the pitted part was down, and the new part up, to contact the reversed washers.I also made certain that the washers made square and total contact with the posts.Dis-assembly required drilling out the rivets and replacing them with screws and nuts.

It lasted many years after the ad-hoc repair,as good or better than a new one.

You can test the starter by using(intermittently) a jumper cable from the Large battery terminal to the lower terminal on the solenoid.Make sure the car is in park and the brake is set, and that the ignition is turned off.

Be very careful when doing this, because the post is very close to ground, which will generate a large spark if you hit it.

If starter energizes with the jumper, the problem is the solenoid or the park/neutral safety switch.Good luck.

When the ambient temp is higher, if you connect the battery positive to the relay coil(small terminal from the ignition switch) does it crank?

If yes the problem lies in your wiring - Battery-fusebox-ignitionswitch-starter motor

If no the problem is in either the battery to starter motor (+ve) connection, or the starter - engine block - battery return connection.

I suspect a loose/corroded connection in one of those paths so that when it is cold/moist you have enough continuity to start, but when hot and dry you do not.

You need to trace it out, a multimeter would be handy to check the resistance of the various paths, and remember the solenoid is only energised via the ignition switch with the key in the 'start' spring loaded position - ie it will not stay there by itself - you need two people to check it....

Hi,

You said you replaced the starter, Was it new or used?.

Quite often a so called good used starter can have the same problem, especially under load.

If that is all ok maybe have the battery load tested.

Regds

jim

is anybody considering wether or not it has a security codignition and the risistance in the system may be affected when it gets to a certain temp range. I', not an engineer, just an old mechanic who still reads.

Good thought. Going back to post #10 he would discover that he had power from the ignition switch, but not at the #85 terminal at the starter relay.

Thanks to all for the suggestions, but I think we have a Winner Anti thanks.