The engine turns over and starts fine when it's cold or cool, but won't turn over once it's hot. I'll turn the key and get a single "whurr" as if the engine just spun 1/4 revolution and then jammed up.

Diagnosis:

1) Connections

- Power and ground connections at the battery, starter, and alternator all seem fine and the battery does charge well when the engine is running.

2) Battery (Optima Red Top)

- I measured the static voltage at the battery to be 13V with lots of ground continuity to the strut tower.
- I had the battery checked at a local parts shop and it's putting out 718 CCA (rated for 720) at 70°F.
- I monitored the voltage at the battery during a hot start and it drops from 13V to 11V when the engine locks up.

Right now, I'm left with believing that it's a heat-soaked starter issue...but there's a kicker! If I have a jump start from another vehicle when my engine is hot, it'll start up just fine.

Any idea what could be the culprit here? Any help would be greatly appreciated!

 

My brother had a problem similar to yours except the starter wouldn't do anything when it was warm. Turned out to be the theft system on the alarm (aftermarket).

 

The starter is doing something in my case and there is no security system on the car - OEM or otherwise, so that wouldn't be my issue. Thanks for the idea though!

 

Easy as! put in a new starter then.

 

What's saying that there is anything wrong with my current starter? For example, if the problem is something like heat soaking the starter solenoid, it would just happen again to any other starter I choose to install.

I would like to find the source of the problem so that I can address it properly.

 

Is it heat shielded from header heat

 

The headers are wrapped, but they do come pretty close to the starter. I thought that maybe insulating the starter might be a good idea as well but wanted to ask on here to see if anyone else had encountered similar problems.

 

Any added heat needs to be kept away from starter & solenoid

 

I understand that, but is that what's causing my issue or is there something else I should be looking into?

 

Kind of sounds like the starter is not throwing out the gear to engage the flywheel, It is most likely a starter issue. Get an auto sparky to check it. Replace it, heat shield it. Even look at a reduction starter, they are much stronger.

 

I'm pretty sure the gear is being ejected correctly since the engine does turn over 1/4 revolution.

 

Have you done the big 3? Is it a factory starter, or one of the newer style "high torque" pieces with two long bolts?

 

The engine is in my RX-7 so I don't have a traditional power setup. My current wiring scheme is as follows:

4 gauge wire from battery + to starter
4 gauge wire from starter to alternator
4 gauge wire from alternator to fuse box

The starter is an OEM LS1 unit (PN# 10465385).

 

*Bump*

Anyone have any idea why jumping the car helps it start hot?? I can't get my head around this!