Anyone fitted a remote solenoid to combat heat soak starting problems.

[Paul H]

Unfortunately the cabling was not long enough for Vince to fit the new solenoid in the preferred  6 o'clock position, and he said it's not a good idea extending the heavy duty cables , because over time the joins can deteriorate and cause a volt drop , which would affect the efficiency of the  starter motor.

So a new solenoid has been fitted in its original 12 o'clock position  ,and he has replaced the fried insulation on the cable from the solenoid to the starter with new insulation , and sleeved the whole cable with Vitcas Glass Fibre Sleeving capable of withstanding temperatures up to 550°C ,the same stuff I put on my HT leads . He has also sleeved all the smaller cables connected to the solenoid with the same sleeving .

He has also added a better heat shield between the starter motor and engine /exhaust manifold, and I have now given  the starter motor a thorough testing ,by getting the engine bay really hot several times ,leaving it for 20 minutes and it cranked fine ,firing the engine instantly .It also behaved when I took it to the Malvern kit car show on Sunday, and stopped a few times on the way home for a pint ,then some grub and it cranked fine when I got back to it . So hopefully it's all ready for Charlies road trip to Norfolk in a few weeks' time ( touch wood  )

If it fails to crank again when it gets hot , I will  run some heat resistant ducting to channel cool air onto the starter motor , not via the radiator cooling fan as was my original idea , because that would just blast hot air onto it from the radiator , but via a separate manual switch controlled fan drawing in cool air from the front of the car.

[Chris]

The set up that is on my RV8 is a Ford two speed ,twin 10'' fans that has a good fitting plastic cowl that is fitted
to my old copper radiator and has a belt & braces override switch that is not of the ignition .
I know it isn't really necessary, but in my case the temperature switch is fixed at two temperature settings, I could
easily change this to a variable type.
Have had this set up for thirty years to date and have never had any overheating or heat soak issues with the
starter motor and that being a Prince of Darkness version ( Lucas 3M 100 for those in the know ).
It is of a copper wound armature & field coil type with steel carcass / pole shoes, the front being Aluminium with a steel drive. The solenoid is at a 5 o'clock orientation has a steel case with copper windings, definatly not the lightest starter but it has yet to fail me in very hot or cold conditions, that's in this country with a few hot summers that we have had .
Today most electrical stuff like this is manufactured with mostly aluminium that is ok but never as good as Cu, that's my experience but Aly is cheaper for the people who produce these products .
After a run out my proccedure to dissipate unwanted heat is to flick the override switch whilst reversing into my
garage and letting the fans run for a couple of minutes with the engine switched off, open the back door of the
garage to allow the heat to dissipate a bit .
That's about it ,
Hope I haven't bored any body to death,

Chris.

[Paul H]

I fitted a high performance Kenlowe 16" fan 5 years ago which i run through  an inline stat ,off a permanent live feed , which as you say keeps it running until the rad has cooled sufficiently .

I decided to fit a manual override switch after i got stuck crawling along in a huge queue for many hours on my way down to Dorset a few years ago during a heat wave ,just to keep a decent air flow through the engine bay.

When i get the car back, i might look at running  some heat resistant ducting to the starter motor to channel air from the rad cooling fan,so i can just give it a blast for 5 minutes if it still decides  not to crank 

I wont be able to access the forum for the next 10 days as we are  off on a break today .

[JON1D]

That makes sense being protected by the sump guard. My fan blows a lot of heat from the engine bay when switched on. Not all 16 inch fans are the same. Going with a Bosch or Spal fan you would notice a huge difference in cooling over unbranded fans and a cowling. If your thermostat fan controller is set correct, there is no need for a manual switch. My fan is not wired off the ignition switch so will run after engine switch off to stop the rise in temperature that occurs and reduces the chance of heat soak.

[Paul H]

If i was to put the solenoid at the 6 o'clock position, ie at the bottom ,it wouldn't catch any road debris Jon because my sump guard ( not shown in the photo) completely covers the underside of the engine from chassis rail to chassis rail . It would also put the solenoid  furthest away from the exhaust manifold and radiated heat from the block which curves over it .

My sump guard has louvres situated underneath the starter motor to suck hot air away from the "Hot Zone " on the move , so If fixing the fried cable and fitting a new solenoid at 6 o'clock  doesn't work, the only thing left to do is fit a fan to blow cool air onto the starter for 5 minutes before i try starting it ,which could be hooked up to my manual override switch for the radiator cooling fan 

I wonder if anyone has done this ?

[JON1D]

The location at 6 o'clock of the solenoid should be 12 o'clock as you are rotating it 180 degrees that should keep it out of road debris and away from the heat source. Heat is a killer for electrical components so the added heat shield should improve the longevity of your starter. The heat over time cooks the copper windings and the resistance between the windings isolation reduces. I have remote solenoids Ford type and a Toyota one that failed last year after 30 years. I had a starter motor fail with slow crack after rolling road set up as it eventually cooked it with the amount of heat generated in the testing over a few hours of constant restarts.

[Paul H]

Sorry , the solenoid is shown in the new 6 o'clock position.

[Paul H]

Fried cable insulation and solenoid in current position.

[Paul H]

Thanks for getting back to me guys.

The starter motor on my AK is a Tilton high torque geared mini super starter 54-0001,which Vince fitted  3 years ago to overcome cranking issues when hot and sleeved all the cables connected with the starter motor with high temp heat shield sleeving and it's got a 780 Ah battery ,which only drops to 10.8 Volts during cranking, so that's all good .
 
So as I can't work on the cobra at the moment due to health reasons, and I can't get the car high enough to gain access anyway, I took the car over to Vince again for him to look at the starter motor heat soak  issues, and has discovered that the starter motor solenoid is failing to close the contacts  and throw out the mechanical lever to engage the drive gear once the heat from the engine seeps into the starter motor solenoid  . When he bridged the contacts with a screw driver, the motor spun, but did not throw out the lever, so the engine did not crank , which proves the actual starter motor itself is fine even when hot ,so either the solenoid windings in the solenoid are getting too hot ,increasing the resistance thus creating a volt drop or the contacts are burnt out.

The other thing he discovered is the insulation on the short heavy duty cable from the solenoid to the motor is badly fried, and exposing the conductor which means it's been getting extremely hot, which means its resistance is increases , thus causing a volt drop across the cable , so the motor is not spinning. This is probably due the  fact that the solenoid is in quite a cramped hot zone between the engine/heat shield  and sump guard . So, he's going to index the starter motor round 180 degrees and fit a  new replacement solenoid which is currently at the 12 o'clock position ,around to the 6 o'clock position furthest away from the hot block and exhaust manifold and out of the "Hot Zone "  and put heat shield sleeving over the cable with the fried insulation . (See photo )

Can anyone see any problems with us ding this ?

 We do not think  fitting a remote solenoid will work because  its a dual action  solenoid on my Tilton starter ,which not only closes the contacts to allow power to the motor, but it also moves a mechanical forked lever to throw the drive gear out into the fly wheel ,so it needs to be the proper solenoid fitted to the actual motor itself.

I will try and attach some photos.

[Tony]

Several years ago I started getting problems starting the engine. The starter on my 6.3 SBC AK used to crank very slowly or sometimes not at all and I would just get a click when I pressed the starter button, usually around 5 to 10  minutes after I turned the engine off and the heat had built up under the bonnet. Once i let it cool down it would start ok.

I tried wrapping the exhaust manifold and fitting a heat shield between the manifold and starter motor ,but the problem remained . I replaced the battery with a high amperage version, checked all the earths, battery connections,  and cable sizes etc and finally resorted to fitting a Tilton high torque geared mini starter which seemed to fix the problem for a few years ,but the problem came back last year  .

Apparently the heavy duty contacts inside the solenoid on Tilton high torque geared mini starters are prone to burning out ,and not making a good contact ,if they are too near the exhaust manifold, which it is on my AK, due to the windings expanding inside the solenoid and requiring more current to activate .

So has anyone solved this problem by fitting a remote solenoid somewhere high up away from the heat, and if so where did you fit it ,what Make /Type/Amperage solenoid have you fitted ,how easy was it to do and has it cured the heat soak problem.

I might be wrong, but I seem to remember many years ago Tony Merrick saying this was a common fix .

Paul

Good memory Paul!
I fitted a high amp relay to the bulkhead on my AK, just above the starter and used the ignition switch/button to just energise the relay. I also took a high amp cable from the alternator to the relay then to the original starter solenoid, so, the ignition switch energised the new high amp relay, which then allowed 12v from the alternator to the solenoid. In my case, and I expect most, it's heat soak in the cable from the ignition switch to the solenoid that breaks down, rather than the solenoid itself. Of course, other opinions are also valid. 

[KevinW]

I haven't done this, but on original cars there was a remote solenoid on the firewall. That was using an old traditional starter motor ofcourse.

Here is an example  - on the second pic you can see the solenoid at the rear of the engine bay on the left of the pic:

https://fordauthority.com/2019/02/this-1965-shelby-427-competition-cobra-could-sell-for-4-million/

[Paul H]

Several years ago I started getting problems starting the engine. The starter on my 6.3 SBC AK used to crank very slowly or sometimes not at all and I would just get a click when I pressed the starter button, usually around 5 to 10  minutes after I turned the engine off and the heat had built up under the bonnet. Once i let it cool down it would start ok.

I tried wrapping the exhaust manifold and fitting a heat shield between the manifold and starter motor ,but the problem remained . I replaced the battery with a high amperage version, checked all the earths, battery connections,  and cable sizes etc and finally resorted to fitting a Tilton high torque geared mini starter which seemed to fix the problem for a few years ,but the problem came back last year  .

Apparently the heavy duty contacts inside the solenoid on Tilton high torque geared mini starters are prone to burning out ,and not making a good contact ,if they are too near the exhaust manifold, which it is on my AK, due to the windings expanding inside the solenoid and requiring more current to activate .

So has anyone solved this problem by fitting a remote solenoid somewhere high up away from the heat, and if so where did you fit it ,what Make /Type/Amperage solenoid have you fitted ,how easy was it to do and has it cured the heat soak problem.

I might be wrong, but I seem to remember many years ago Tony Merrick saying this was a common fix .

Paul