'68 new problem start relay sticking problem

[jerthemost]

a few days ago after installing a new radiator and 2 9" elec fans my start relay solonoid started stciking. after it cools down it is ok. changed it out with new borg-warner and today in town first time since changed out it did the same thing again with the brand new relay. something strange is going on.

could a pulled down battery cause that if voltage drops below a certain point? fans coming on at same time as starter could drop the voltage considerably i suppose. they draw 80 watts or about 6 amps each. i willl wire in a relay to lock out fans when starting and try that.

any thoughts on this would be appreciated.

 

[ackjlo]

Is your battery in the trunk ?? I encountered this problem when I moved my battery to the trunk. I replaced the cableswith 0/1 welding cable and that cured the problem. Lower voltage and higher amps weld the contact points in the solenoid.

 

[JonK]

Inside the solenoid is basically a set of points, they make contact to send juice to the starter when you turn the ign. and break when you let go. You may need to rig a test light to the starter cable side of the solenoid that you can see from the drivers seat and see if the light goes out when you let go of the key. Then I'd move it to the prong for the incoming signal coming from the ign. switch and see if it stops when you let go of the key. May be a bad ign. switch also.
Jon

 

[jerthemost]

not bad ignition switch

it's not bad ign switch. pulled that wire off relay and relay contacts still making contact. after it cools down for few minutes they open back up again. i am an old retired electrical and mechanical engineer so i understand about contacts and voltage drop wire size etc.

this is obviously a case of contacts sticking from getting too hot. it only does it when starter has to turn over several times before cranking. the mystery is why the contacts seperate after it cools down. i have worked with a million realys and contactors in my years and seen many with welded contacts but never one that sticks when hot then seperates when cools down a bit.

everything under the hood is hot, can't touch the coil. can barely stand to touch the hood to open it it will be so hot. part of this is our extreme heat i know here in houston but these cars were driveable in heat 43 years ago.

i checked how much the 2 fans drop the voltage and is only 3 tenths of a volt so that is not the problem. does anyone know how much current the average starter draws and how many amps the relay contacts on a a brorg-warner realy are rated for?

i am looking into buying a heavier duty relay.

 

[MitchGT]

you can also try putting some insulation on the starter. the heat from the exhaust radiates right onto the starter, and can make it hot. Heat = resistance, which would need more power to turn the starter over, which might cause your relay issue. Does the car start fine when cold, and develop the problem when hot?
I did it on mine, and it started much better on hot days....

 

[ackjlo]

The relay isn't the problem

Either the starter is drawing excessive amperage, make sure you have a solid ground, between engine and chassis. Or as I stated before you need larger cables. I'm just saying, BTDT

 

[jerthemost]

acts up when hot

the problem usually happens when it has been driven or runs a while and gets heated up. when the car is cold i set the chock (electric) and it starts immediately. after it has run a while it takes several turns of the starter to start. that is usually when it happens. there is one exception partly, a year ago it stuck on a cold start but had carb and choke problems at the time so it did not start immediately, took several grinds to start. that was a different starter too by the way.

so it for sure seems to do it after turning starter over several times and the starter gets hot. i will recheck all cables but i think cables are big enough just may not be tight enough. i had a problem on my first car a '55 ford. after rebuilding the engine the battery would not recharge, i was a teen then and it kept stranding me in the woods, my gf wasn't happy about that. found the problem after i traded it off, we had put the ground on a head bolt and when it heated up the connection got just loose enough not to charge even though it showed chargeing.

so ground is critical and so is heat. what is a good way to insulate the starter. we are having 100+ days here in houston and the heat of the concrete and asphalt is even worse.

and what about a new better quality starter? i have also found some start relays rated for 200 amp continuous, maybe one of those. i cannot find the amp rating of the bwd relay i have but guess is no more than 100amp iff that much.

i have found a few cases on forums where others have had same issue but no solution. eleminate heat though should for sure make a difference.

 

[MitchGT]

I bought some aluminized heat shield, cut it, and clamped it around my starter. you can get some from summit racing, or maybe a local auto parts place.
My long tube headers are only an inch or so away from the starter, so it's easy to see how the starter can get so hot. Anyways, as soon as I did that, my hot start issues went away.
You could also get Ceramic coated headers, but that is an expensive way to solve the problem...

 

[jerthemost]

progress report

installed my second new borg warner brand relay and it seems to be doing ok at least for now. went to town yesterday in 100 + heat, a waitress said it was 108. no sticking relay even though i had a heck of a time starting the car after it got hot. so keeping my fingers crossed. i did install an emergency disonnect knife blade switch on the battery ground side though.

i drilled a hole in the end of the blade and put a tie wrap through it to make a loop you can grab to ****** the blade portion of the switch up to keep from having to touch the hot switch. that was mostly for the wife.

it's been so hot here everything is too hot to touch. i literrally burnt my finger opening the trunk the other day.