Starting, slow and then fast???

[Anonymous]

Went to start my 250 2V yesterday after it was already warm. Sounded like the battery was dead and would hardly turn the engine over at all. Turned the ignition off and on a couble of times would barely turn over at all and eventually the engine fired up and started. Let run for about 30 seconds turned off and then tried again. Engine then turned over very fast and started easily.
I had this problem previously, what could it be?

 

[rbohm]

8) the starter is starting to go. heat soak causes extra resistance in the starter windings, and when the resistance in the starter gets too high it wants to quit working.

 

[Anonymous]

Thanks its worth a look.
Ive had it reconditioned a short time ago. When you say heat soak do you mean it may be getting too hot near the headers?

 

[rbohm]

8) that and its proxemety to the block. when the engine sits with no coolant flow, the coolant transfers its heat to the iron block wich then radiats it to the underhood air. the starter being next to the block absorbs this heat, and the windings get hot and dont flow electricity like they do when they are cool, thus the higher resistance in the windings. if the brushes are goind bad, or the commutator has grease or other stuff on it, it also adds resistance, and the added heat makes the starter run much slower than normal.

 

[twentyover]

Potentially stupid response, but are you sure your block is cleanly grounded to the chassis? Running a block ground strap (or head ground strap?) May be your getting intermittent good ground and poor ground, creating a large voltage drop between the block and the chassis at high current loads

 

[addo]

If it's the Bosch starter, likely the commutator hasn't been properly undercut, and has now glazed/shorted.

 

[Anonymous]

Dont know about the block to chassis earth (Ill check) but my mechanic made up a fairly makeshift earth (four or five wires jioned) together) going from the battery terminal to the front of the car body. Would this do it. I think I may have the original thicker one somewhere