Author Topic: Yet another hot start issue (no crank when hot)  (Read 2883 times)

rikaro

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Yet another hot start issue (no crank when hot)
« on: December 14, 2014, 04:15:19 AM »
I've did quite a few searches but I never really get the time to get the car sorted.

The car sometimes does not start after a warmed up drive during the summer. It doesn't crank at all. If I wait 15-20 minutes when it would magically crank and start.

I was thinking of replacing the starter but I was wondering if anyone had run into a similar problem. I've done some search and most people's hot start issue still cranks but just idles roughly.

I do also have a rough idle during cold start. I believe this is an entirely different issue.

Any help would be greatly appreciated.

DesktopDave

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Re: Yet another hot start issue (no crank when hot)
« Reply #1 on: December 14, 2014, 09:55:20 AM »
Might be the starter switch. Next time it doesn't crank, check terminal 11 of the diag connector for +12v when someone turns the key to start. If there's no voltage there, jump +12v from the battery to term 11 and see if the car cranks.

How's the battery, anyway? When you have the problem, is it a lot of clicking relays, or does the car just go totally dead? Either case could be a dying battery, bad ground strap, or a hard short somewhere.

You also might want to look at relays K5 & K7...they're supposed to "unload" when the starter engages to crank the car. If they're not opening up, the car's other electrical systems will not be disconnected, dramatically increasing the load on the battery.
« Last Edit: December 14, 2014, 10:03:26 AM by DesktopDave »
'08 Karmesinrot 128i 6MT
'86 Zinnoberrot 635CSi (M30B32/G265/3.46 torsen LSD)

Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

rikaro

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Re: Yet another hot start issue (no crank when hot)
« Reply #2 on: December 14, 2014, 02:13:28 PM »
Hmm interesting. I'd read a lot and everyone suggested that it could be the starter or a bad ground since it only fails to start in hot temp after a drive.

When I turn the key, you can still hear the fuel pump click. I didn't bother looking into the battery since there's no click when I tried to crank. I guess I'll have to look into that as well

DesktopDave

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Re: Yet another hot start issue (no crank when hot)
« Reply #3 on: December 14, 2014, 05:13:57 PM »
I'd suspect it's not the starter...they usually fail completely. In my experience, if it's temperature dependent, I tend to suspect electrical troubles.

Batteries are funny things too. They can show healthy voltage, but fail to deliver the amps you need. Any auto parts store can get you a load test, although I will try two or three stores since they're often just trying to sell you a new battery.
'08 Karmesinrot 128i 6MT
'86 Zinnoberrot 635CSi (M30B32/G265/3.46 torsen LSD)

Sold: '97 Montrealblau 318iS, '91 Brilliantrot 318i, '91 Brilliantrot 318iS

rikaro

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Re: Yet another hot start issue (no crank when hot)
« Reply #4 on: December 15, 2014, 05:30:05 PM »
It sucks because it dies whenever I'm in the middle of something else.

I guess I'll look into:
-k5 and k7 relay
-battery
-ground

thanks Dave!