Author Topic: Overheating starter motor ??  (Read 217 times)

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Minijohn

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Overheating starter motor ??
« on: October 29, 2021, 05:19:10 pm »
Has anyone had a problem where the starter overheats due to it's proximity to the exhaust?

My car has a Michael Speeder twin tailpipe exhaust which comes within about 10mm of the starter solenoid.
I'm having all sorts of problems starting which I think may be being caused by the heat as I've tried everything else - new battery, cleaned starter, new brushes, new solenoid etc

I'm going to make a heat shield to attach to the exhaust to see if that cures it.


bertvb

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Re: Overheating starter motor ??
« Reply #1 on: October 29, 2021, 08:42:02 pm »
Just for info:
I also have the Michael Speeder exhaust (single tailpipe). No problems for me, but I have a bit more than 10mm of clearance.

Maybe you could test it with some tinfoil?

Abarth982

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Re: Overheating starter motor ??
« Reply #2 on: October 30, 2021, 08:32:51 am »
Not meant to be a daft question but ...  Are the symptoms the same when the engine is stone cold?

Minijohn

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Re: Overheating starter motor ??
« Reply #3 on: October 30, 2021, 09:18:06 am »
Yes. What usually happens is the car is OK during the journey and when I stop/restart it's fine.
It's the stone cold that's the problem, as if the heat from the previous journey has really sunk into the starter.

Incidentally I found an exhaust system for sale which said not suitable for cars with electronic starter.
I presume that means the electric solenoid type rather than the earlier pull type.
Maybe it takes up more space or it's heat affects the starter.

I think I'll cut a corner off the silencer and weld a plate over the hole to give a bit more clearance

Thanks
« Last Edit: October 30, 2021, 05:04:18 pm by Minijohn »

Minijohn

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Re: Overheating starter motor ??
« Reply #4 on: October 30, 2021, 05:06:36 pm »
I've now removed the silencer and reshaped the part closest to the solenoid to give over 2" clearance.
Now to see if that's cured it............

Abarth982

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Re: Overheating starter motor ??
« Reply #5 on: October 30, 2021, 05:47:09 pm »
Will be interested to see hoe you get on with the additional clearance.
Must admit that I was expecting you to say the opposite, ie difficult to start when hot after the heat has soaked into the starter, not cold when it should have all dissipated.
What exactly are the cold starting problems, starter not turning fast enough to fire up the engine/not engaging thereby failing to spin the engine?

bertvb

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Re: Overheating starter motor ??
« Reply #6 on: October 30, 2021, 11:50:41 pm »
I don't think the heat from the exhaust is the problem if you can start with a hot engine.

Have you checked battery voltage when the car is cold? Can you measure any electrical losses (voltage drop) to the starter?

I assume that starting a hot engine works because a hot engine has les frictional losses to overcome when turning.

Minijohn

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Re: Overheating starter motor ??
« Reply #7 on: October 31, 2021, 12:19:58 am »
the cold start problem seems to be the solenoid won't pull the bendix into mesh - hence why a whack with a hammer is needed.
Even then the starter was sluggish as if the battery was low, but a new battery didn't cure it.

My theory on heat is that the heat from the exhaust maybe siezes up the solenoid as it cools down, making the next cold start a problem.

I'm going to see how it gets on over the next few days - fingers  crossed.




Abarth982

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Re: Overheating starter motor ??
« Reply #8 on: October 31, 2021, 12:34:06 pm »
I sold my 126 a year or so ago so can't remember where/what engine to chassis earth straps there are but I'd certainly check/clean them as when cold it'll need far more amps to turn it over than when hot ...
   

Minijohn

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Re: Overheating starter motor ??
« Reply #9 on: October 31, 2021, 10:58:49 pm »
there's just one engine earth strap - near the alternator.
I've replaced that, cleaned the ends etc and also tried using a jump lead as an additional earth strap, but no difference.
The car's been OK since I modified the silencer box (fingers crossed)

Thinking back, I've been having cold starting problems since I put the twin  exhaust box on the car, .
I replaced the battery, not much better - so I decided it must be the starter motor.
I replaced the solenoid and brushes - still no better, so I fitted a re-con starter motor.
It then seemed OK and for several months the car was off the road while I converted it to RHD. I started it occasionally but it was never taken on a run and got properly hot.
Then 3 months ago I taxed it and have been using it quite often since.

I'm fairly confident the exhaust was the problem, just need a couple of weeks to monitor it.

Minijohn

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Re: Overheating starter motor ??
« Reply #10 on: November 19, 2021, 12:45:16 pm »
Well I've finally solved it.
I've been waiting for the problem to occur when I'm at home and could do some proper testing.

So to go through the sequence, ignition on, warning lights OK, turn key to start, warning lights dim slightly, nothing happening at the starter motor.

I ran a jump lead from the battery positive and touched the starter terminal, bypassing the solenoid.
The starter motor turned over, meaning my problem lay with the solenoid.

I then removed the small wire from the solenoid & did a voltage check when the key is turned - only 9.3 volts? Voltage check on the battery was 12.5 volts.

I then traced that wire to a junction below the fuse box.
Voltage going in (from the key switch) - 12.5 volts.
Voltage going out - 9.3 volts.
A quick spray with WD40 (I didn't have any contact cleaner) put back together - 12.5 volts in and out.
Re-attach the wire to the solenoid & it fired up first time !!!

 

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