Mine dogs slightly when it's hot. Just enough for me to notice, really. Never caused a problem (yet - original starter in a 1991 truck).

 

Better get some heat tape on the exhaust or starter soon then. Thats how it started with me then the bearings fried up, best bet is to catch it quick.

 

What is happening is heat absortion into the starter, I have seen it a million times. I would always recomend a heat shield on starters. This is a common problem in heavy machines and older chevy trucks. check for an exhaust leak around the starter.

 

I have maybe found part of the problem, the original routing of the negative cable had it going to the top of the starter where it bolts up to the transmission. I cut the cable and moved it to the power steering pump bracket and thus far it cranks better. I guess time will tell but it's been a week and it's started right up after 30 min of drive time so thus far it seems to be fixed. Not sure if this will help anyone but might give that a try.

 

I'm having the same problem with the 5.8L 1990 f-150. Replaced starter 3 times with no success and also the cables. Battery checks great but when this sucker gets hot she drags really bad. Wrapped the pipes (replacement y-pipe) with heat wrap and used a starter heat wrap and nothing has changed. I'm starting to think it might be mechanical? removed the connector at the distributor to disarm the timing advance and same ol'. suggestions anyone?

 

Any other answers for this? Dealing with the exact same thing here.

 

If anyone finds out what is causing this problem then let me know please. Only thing I can tell you is what's it's not. I'm going to try to see if the engine itself is to blame soon.