Engine won't start when hot!

[FLavionics]

I have a 38 Fleetwood Expedition with a cummins ISB 6.7L 360 HP Diesel.
The first time this happened we were along way from home. It was a hot day in Texas and we pulled into a rest stop for a few minutes. When I tried to start the engine nothing happened meaning it would not crank or turn over. . It seemed like the batteries were dead. I made the switch that parallels the house batteries for this situation but no help. Panic set in. I tried switching the battery switches on and off. I got my volt meter out and went across the batteries and had the wife turn the key and much to my surprise it started normal.

I decided I would not turn the engine off till we were set up in our camping spot for the night. After we were all set up with the engine still hot, I tried a restart and nothing. I decided not to touch anything till the next morning to see if it was temp related.

The next morning the engine stated fine. We spent the next three weeks repeating the same scenario.

I always wait till the engine cools down less than 194 deg before shutting down. This last time I continued to try and start noting the engine temp. This time it started after the engine cooled to about 170 deg.

I was wondering if this could be a normal operation not to start with a engine hot but I had a conversation with another Fleetwood owner with the same engine and they never experienced this issue.

Any thoughts?

[twinboat]

Not normal.

Two things can be effected by the heat, that can cause your problem. The solenoid on the starter motor and the starter relay back near the engine.

Its going to be tough figuring it out, unless you can duplicate the problem, while testing.

One other thing to check is that, although rare, some starter motors have over crank protection switchs on them. That could be bad. It marked as the " OCP ", in the picture.

[Bob_C]

That's known as a hot soak condition.....after it cools down, works fine.....I replaced the starter......

[SKP Kirk]

I once had a gas chassis RV with that same problem. I replaced the starter and added a heat shield and never had the problem again.

[FLavionics]

I crawled under the rig last night to check the wiring and also got the P/N of the Starter. (Delco Remy 8200571 29MT) From what I can tell, this starter is not equipped with over crank protection switch.

The starter of course has the solenoid attached to it and also another relay which I am assuming is the "Stater Relay" twinboat spoke off.
Attachment 302037

If that is the case it sounds like the best plan of action would be to replace the starter assembly.

According to the cummins wiring, Power comes directly from the battery to the starter. If I can duplicate the problem, I should be able to check for power at the Starter solenoid and relay while the wife turns on the key.
Attachment 302032

Except for the fact it will be extremely hot under the engine at that point, it [U]should [U]be easy enough.

Plan B would be to take a gamble and just replace the starter... Its not as expensive as I thought it would be. I would think buying OEM Delco Remy would be worth the extra cost than a after market?

[FLavionics]

Not sure why the attachments wouldn't show so ill try again.