928 Coke Car: Starter not engaging. What to do?
 

Hey guys,

At my last track day the Coke car started having issues with the starter. It got progressively worse throughout the day to the point that now, I cannot start the car. The starter motor spins fine, but it's as if the solenoid doesn't engage with the flywheel. Sometimes it engages for a little bit, but not long enough to start the car. It's an original-style starter (not a lightweight) as seen in the pic below.

Doing a search showed that the common failure mode is that the starter stays engaged, which is the opposite of my issue. Another failure mode is the motor itself won't turn - which is not the issue here either.

I'll be diving in later tonight, and was wondering if anyone has had this issue and how it was resolved? Can I service the solenoid? I have an old starter where the motor wore out. Can I Frankenstein the two?

Thanks for your help!

https://cimg8.ibsrv.net/gimg/rennlis...8b30c6555c.jpg

When I said a few of us would be at Road America for track support, I don't think we planned on push starting you 4 times a day :p

That's why I 'm trying to sort it out now. You guys will be drunk off your asses or hungover. Either way, you'll be just as reliable as the current starter. :p

Total WAG, grease cooked out of it by the heat from the headers and there's too much resistance for the bendix to do its thing? Perhaps a heat blanket would be good prevention in the future (?)

Sounds reasonable. I was wondering if it was heat related too. Never clean/opened a started. But you did, right? How hard is it to get in there to clean/re-grease?

Is there a way to "bench-test" these things, safely?

I got as far as cleaning the armature and R&R'ing the brushes but didn't mess with the bendix.

Seth has gone deep into the starter, details starting in post #9 of this thread:

https://rennlist.com/forums/928-foru...er-refurb.html

AO, you can mix and match starter pieces no problem. Swapping solenoids should not be a big deal. See my thread that Rob referenced.
However, opening the solenoid is a different animal. You have to unsolder the solenoid coil leads. I chose not to do that.

Good Luck! With both your starter and hungover pit crew...

I'm on it! Thanks guys! WIll post the outcome later tonight/tomorrow.

Have you tried striking it with a hammer...
https://cimg3.ibsrv.net/gimg/rennlis...0d1d2e2646.jpg

LOL! Not yet. But when I get it on the lift... :icon501:

Striking!? Tapping! Tapping! It does work- on everything from MGB's to John Deere equipment in my experience. (YMMV of course)

You have to ask: At what point did it become such an issue that Bosch/Porsche had to create a special sticker to address the problem???

Disconnect your 14 pin connector and touch pin 14 to the jump post and see if that gives it enough voltage to engage. Might want to ensure it's in neutral tho.

Google provides answer. Apparently very common and very "verboten"
https://cimg9.ibsrv.net/gimg/rennlis...ca106ea8da.jpg

https://cimg1.ibsrv.net/gimg/rennlis...df1af54a6b.jpg

https://cimg3.ibsrv.net/gimg/rennlis...4e998787c5.jpg

https://cimg4.ibsrv.net/gimg/rennlis...a6d6a28ea7.jpg

Down the rabbit hole: If there is no sticker, is it okay, or even REQUIRED, to strike with hammer?

"Everything which is not forbidden is allowed"

"The jocular saying is that, in England, "everything which is not forbidden is allowed", while, in Germany, the opposite applies, so "everything which is not allowed is forbidden". This may be extended to France—"everything is allowed even if it is forbidden"—and Russia where "everything is forbidden, even that which is expressly allowed". While in North Korea it is said that "everything that is not forbidden is compulsory"