Car doesn't start/turn-over properly when warm?!?

[tyke350]

On a few occasions when I've been out in the car for a good run (so all is nice and warm) I've got back in the car after a few minutes only to find it doesn't start. The starter motor turns over very very slowly but not enough to start her up, which would suggest a flat battery. However, once it's been stood for say 15mins (and cooled down a bit?), she either starts as normal or the starter motor turns slowly but then speeds up and starts her up.

What's strange is this seems a bit random, as normally the car starts up fine even after just a few minutes shut-down.

The battery normally reads 13.4-13.6 amps when running, but the times when it hasn't started it's down at 12.2-12.4 amps.

The dealer has checked the battery and found nothing wrong with it, so am hoping someone out there may have some suggestions?

Something which may be related - not long ago the car died on me while in slow traffic, turns out is was the 100amp alternator fuse that went, which has since been replaced by a 150 amp fuse. When this happened the battery ran flat, so could this be the cause of the problems (even though the battery has been checked).

Any suggestions much apreciated!
Thanks

[Toady1]

why did you replace the 100A fuse with a 150A one? thats asking for trouble if you ask me!

Could be that the starter is getting quite hot. Does it have any heat proofing around it? if not try that.

[tyke350]

Toady1 said:

why did you replace the 100A fuse with a 150A one? thats asking for trouble if you ask me!

Could be that the starter is getting quite hot. Does it have any heat proofing around it? if not try that.

The dealer told me replacing the 100Amp fuse with a 150 Amp(although may have been 125?) was standard as the 100amp fuses are always going and a known problem.

Will take a look at the starter motor, but has been ok for the 1st year of ownership, problem only came about after my 100amp fuse/flat battery issue.

Thanks
Matt

[Toady1]

mmm? best see what other 350 owners have done with their fuse as its not really something id do, surely the loom and charging circuit was designed to be protected with a 100A fuse. Im not yet a 350 owner so can only help you with the mechanical experience i have (profession) but it does sound to me like the starter is the problem, we used to get it on the gensets if the engine cells got too hot. Have you checked the earth strap too?

[VARLEYHYD]

The starter motor seems to be reliable, but some folks have experienced, poor starting when hot. I am not sure why it can fail but to replace its airbox off. Its off a 5series BMW, part numbers- Bosch 0 001 108 063, BMW 1 312 104 8.

[Targarama]

Could just the battery getting a bit tired. Has it ever been replaced? Maybe there is a bit more resistance in the starter circuit when things are hot which a strong battery would not worry about.

[tail slide]

VARLEYHYD said:

The starter motor seems to be reliable, but some folks have experienced, poor starting when hot. I am not sure why it can fail but to replace its airbox off. Its off a 5series BMW, part numbers- Bosch 0 001 108 063, BMW 1 312 104 8.

Graham you're a mine of info

But time to come clean, yours was a kit of parts?

[tyke350]

Thanks for the suggestions, will chase this up with the dealer next week!

I'm thinking it's more likely to be the battery as it was only an issue after the 100amp fuse went and the battery flat for a while, although the dealer tells me they've checked it and all seems good!? If it was the starter motor it just seems a bit of a coincidence that it happens soon after the 100amp fuse blowing.

Appreciate your responses
Matt

[VARLEYHYD]

tail slide said:

VARLEYHYD said:

The starter motor seems to be reliable, but some folks have experienced, poor starting when hot. I am not sure why it can fail but to replace its airbox off. Its off a 5series BMW, part numbers- Bosch 0 001 108 063, BMW 1 312 104 8.

But time to come clean, yours was a kit of parts?

Yes; it has been a kit of parts

Just keeping my hand in though,
couldn't resist changing a set of pads & taking 'daftlad' John's discs off at Oulton on Wednesday.

G

[astonman]

Sounds like what we used to call a lazy starter.Had the same thing on an Aston DB6 and C type Jag replica.If its ok after its cooled down completely its the starter not the battery,if in doubt change the battery ,its not for nothing but its cheaper than anything else.

[tail slide]

VARLEYHYD said:

Just keeping my hand in though,
couldn't resist changing a set of pads & taking 'daftlad' John's discs off at Oulton on Wednesday.
G

There's no holding you back.

I'll send you next year's speed champ events list

[tyke350]

Thanks for all the advice on this, will be speaking to the dealer this week to hopefuly get it fixed!!

[stats007]

tyke350 said:

The battery normally reads 13.4-13.6 amps when running, but the times when it hasn't started it's down at 12.2-12.4 amps.

I think you mean volts not amps. The higher voltage is down to the alternator running.

[tyke350]

stats007 said:

tyke350 said:

The battery normally reads 13.4-13.6 amps when running, but the times when it hasn't started it's down at 12.2-12.4 amps.

I think you mean volts not amps. The higher voltage is down to the alternator running.

Volts indeed, just testing!
thanks