Does anyone have any more ideas on this?

I have recently been having starter problems on an '84 300SD! The starter was replaced 1.5 years ago with a Bosch rebuilt unit. Two days ago I had to replace it again. Due to my remote location, I ended up with a "Delco-Remy Bosch-type" replacement, which lasted a total of 6 hours!

This is really bugging me. After the replacement, every thing started great with excellent spin up and engagement. Two times later, still no problems noted. Then nothing. No solenoid click or anything. After putting a meter to it, I am left with questions.

Has anyone heard of a glow plug relay causing starter solenoid shorting problems? The reason I ask is while measuring the solenoid voltage at the small terminal strip, I read 12V in run, 13+ in start with the gp relay disconnected. When reconnected, there is 5.5V in run and 13+ in start. Since this is also tied to the crank input of the gp relay, it is suspicious. However, when the starter was replaced, the operation of the glow plug system was normal.

After doing a search, I have noted that several people considered heat to be a problem. My starter failed in approx. 90 degree heat. However, I noticed that most of the responses recommended going with a "heavy duty" starter. Since there was no response as to whether this fixed the problem on most of these, I can only assume they took the advice and have had no further problems.

Did I receive a "Delco-Remy Bosch-type" defective starter or is there the possibility of further problems?

I appreciate feedback, especially from those who have encountered a similar problem. Please tell me what ultimately resolved your problem.

Thanks!