starter motor issues - heat soak?

[3jcelica]

Ok the starter is on my race car it keeps dying not sure whether it is heat soak or not. Generally the starter is sticking on mid race, first time I found the solinoid wire was burnt out, second time the solinoid wire is burnt and the power feed wire is burt out (not good as it is connected directly to battery).

In the first case I could hear the starter still engaged when I came off the track, the second case, I susspect it was engaged for some time before the wires burnt as the gears have been ground.

I have had some heat issue due to the turbo manifold being close to the starter, but manifold is now heat wraped, and heat shielded, starter has a heat shield with an air gap.

I have a simple momentary switch for the starter, feeding relay and then to starter.

My thought is perhaps the relay is failing due to under bonet temps or vibration, or just stuffed. This would be an easy fix with new relay, rubber mounting and fuse, or

the starter solinoid is engaging when heat soaked, I have normally seen the opposite i.e.heat soaked startermotor solinod wont engage or motor won't engage.

Any thoughts?

Roger

[Shakotan_Aaron]

ive never had the main power from battery connected threw a relay? im not even sure how you would do that or why. i wired the solenoid on a new wire strait from the ignition barrel. this was in my 4a ke70 and i never had a issue ever.

i would be looking over the wiring as it seems really strange that the starter would engage after the engine is running. if the solenoid wire has been burnt out then that suggests that these either a short or a lot of constant current flowing. id run a new start circuit. wire strait from battery to main power on starter, push button on dash > solenoid. everything is heat shielded or wrapped then heat soak doesn't make sense?

[3jcelica]

Ae71,

Just to clarify the solenoid feed is on a relay, the main power feed is straight from battery. As you suggest I will run a feed directly from battery to switch to solenoid and get rid of the relay. I orginially put the relay in as ther current was to low to kick the engine over but that may have been due to the original starter wiring.

They only reason I can think of the starter re-engaging is either wiring short as you suggest, this could happen in the relay or relay wiring or heat expanding and making the starter contact and therfore flowing current down the solenoid wire.

Roger

[beerhead]

Test the barrel with a multi meter. Could be the internal spring for the starter contacts is old and the vibration of the car is flicking on the starter.

[TRD-12A]

i wouldnt remove the relay just reposition it inside the car i would probably run a different switch more heavy duty push button, i would say the wires are burnt out because its been engaged while your racing defanitely very bad!!!! have you tried a different starter motor?

[3jcelica]

Beerhead,

It has happen to two starters, the lates was new, but am pulling this one down to see if I can see anything,

TRD12A,

Thanks for the input, relay inside car sounds like a better idea. Have rewired to day with a heavy duty push button, 8g wire without relay instally to see whether it is now needed. If I find the need for a relay definetly inside car this time.

Roger

[3jcelica]

Lastest testing with a new starter, solenoid wired through switch to battery (removed relay out of the circuit). Bring the engine up to temperature (82 deg) switch of the engine and the starter is not engaged, but the motor is spining. I cut the solenoid wire motor still spining, have to use the isolation switch to stop it.

To me it is seems as if the running heat is making the motor contacts some how?

Roger

[oldcorollas]

checked out if there is crud in the solenoid switching contacts?

[3jcelica]

Pulled the solenoid apart, not to bad inside certainly nothing to worry about. I tested with a multimeter open circuit when in normal position, closed circuit when pushed back. All operating as it should.

Threw it back in the car and noticed it now works correctly but is taking time to disengage i.e. a couple of seconds after releasing the switch it is still spining.

So I now I think it is a heat effected solenoid spring resulting in the solenoid not returning after engagement properly, and therfore solenoid engaging mid race as the spring loose it force due to heat.

More heatshielding required I think. Currently maniold is wraped with a heat shield ontop of the manifold, starter has a heat shield on it. Perhaps a heat shield under the manifold and more wraping down the dump pipe is required

Roger

[oldcorollas]

if sprign has been heated so much as to lose it's force.. has it permanently softened? worth replacing now?
air duct from under up toward the starter?

[allencr]

...the starter is not engaged, but the motor is spining. I cut the solenoid wire motor still spining, have to use the isolation switch to stop it.

I'd think that it's pretty much impossible for the solenoid to be making contact & feeding the motor without the drive being engaged. Sure the terminal doesn't spin & touch when tightened? Also, if the solenoid's spring had current going through it, that could make enough heat to untemper it, otherwise an external heat source would probably melt the aluminum on the starters drive end & the bellhousing before it could get hot enough inside to bother the spring.

[3jcelica]

allencr,

tend to agree with the aluminum melting before the spring gets tempered. Just can't think of anything else myself, made sure the main feed was well away from solenoid so they can't contact.

The plunger has to move for the contact to be made and the motor to spin, just can't think of any forces in action other than heat. Note the last time it did this (yesterday in the garage) the starter motor was not engaged, just the motor spining.

Oldcorollas,
New starter motor will be going in once I think I have the problem sorted, hopefully a reduction gear starter, duct from just under the crossmember up to the starter is a good idea that I think I will implement thanks.

If you think all this sounds strange, so do I, starters so simple, two wires but starting to be a pain.

Roger

[oldcorollas]

the heat shield on the starter/solenoid......

can it move around with vibration? if it was to contact the two exposed bolts on the solenoid, the starter could spin without the solenoid engaged.... but more likely to earth to the body of the starter perhaps?

i've had a shield dislodge before... although it just resulted in some "special" arcing

[3jcelica]

Ok after putting in a reduction gear starter, another heat shield and redoing the wiring. The problem turns out to be the wiring. I took my car out last weekdend and ended up with a dead short to the battery, caused by the starter wire feed losing its insulation due to heat.

So it looks like my starters have been dying due to wiring failure under heat then shorting between the solenoid and power feed.

Am now rewiring it for the third time, my manifold has been wraped in the best wrap money can buy (ceramic wool with reinforced wire), the route is almost straight down toward the cross member (away from heat source), the only other thing I can think of to stop the problem is two layers of dual wall heat shrink over the cables, and thermal wrap the cables similar to the manifold.

Can anyone think of anything else to make the cable less susceptible to heat?

[river]

Hi,

Bolt a heat sheild cover over the wires.

seeyuzz
river