Team Camaro Tech banner

Heat Soaked Starter Myth

14K views 32 replies 17 participants last post by  X-77 keith 
#1 · (Edited)
Some threads lately that refer to heat soaked starters and the use of remote Ford style relays, sometime referred to as solenoids. It's a big relay.

On GM starters this also works as a relay. Key turned on>solenoid kicks in to engage drive gear into flywheel or flex plate>contact disc connects batt power to the starter motor.

Ford style uses a remote mounted relay that when ignition is in start position it simultaneously provides batt power to the solenoid and the starter motor. This is usually done by installing a jumper from the Batt terminal to the S terminal. No reason to run a separate wire from the relay to the starter.

GM Batt Pos goes directly to starter.
Ford Batt Pos goes to relay and from relay to starter.

Both styles accomplish the same thing. When ignition is in start position you get full Batt power to the starter motor.

Installing a Ford Style relay on a GM starter will help IF the Contact Disc is not making good enough contact in the solenoid to provide full Batt power to the starter motor. This is a band aid. It's not fixing the problem.

If you have a starter issue blamed on this mysterious "heat soak" you really have an issue with the starter or the wiring.

If you have full Batt via the Purple wire to the S terminal it is most likely the contacts in the starter solenoid are bad. This can happen over time due to arcing each time the starter is engaged. Pull it a part and clean the contact surfaces or replace the solenoid.

If you don't have 12v to the S terminal. Ignition switch, NSS switch or the wire itself are bad.

So a guy adds a Ford Style relay. The purple that was on the GM solenoid now goes to the Ford relay. When ignition is in start position the relay is closed and Batt power goes to the solenoid By doing so he has bypassed the solenoid to get power to the starter motor. He has not addressed the root cause.

The common goal for both styles is to get full Batt power to the starter motor.

The Myth

"when the engine is hot it won't start. when it cools off it starts"

Degraded wiring and bad contacts are being affected by the heat caused resistance.

So cure the problem don't just treat the symptom.

There is a place for Ford Style Relays on our cars. For me I use one when I relocate the Battery to the trunk so the long positive cable is only hot when starting.
 
See less See more
#2 ·
After installing the extra solenoid, the OE solenoid still has to have the S terminal wired for engaging the starter drive.
Unless I missed it... Over 40 Thing.
Its another route, shorter in wire resistance, in getting full battery current to starter motor.
Clean all terminals thus reducing resistance.
Heat will increase resistance in a wire/terminal connection by both ambient temperature and current drawn through the connection.
 
#4 ·
After installing the extra solenoid, the OE solenoid still has to have the S terminal wired for engaging the starter drive.
Unless I missed it... Over 40 Thing.
Some times a jumper went between the top solenoid post on the starter and the S terminal. Ford products used Delco style starters on many 429 and 460 engines and that is how they were set up. Same normal small solenoid on the fenderwell and the Delco style solenoid mounted on the starter that operated the starter drive.
 
  • Like
Reactions: jimnecci
#3 ·
In the early 70's, I was a parts guy at a large service garage. We got to see every kind of problem you can imagine. Starter problems were seen quite often on low mileage large engined cars that were mostly driven on short trips by little old ladies and little old men. Starters, batteries and battery cables were replaced repeatedly with the best that could be found. Problems persisted. Heat soak was blamed, but these cars didn't have headers or modified exhaust. One of our customers that previously had starting problems need his engine rebuilt due to having a wing nut dropped into the carb and passing through the engine that caused valve and piston problems. The engine was severely carboned up. Carbon in the combustion chambers, carbon on the back side of the valves, and worst of all, carbon in the ring grooves and behind the rings that kept the rings dragging on the cylinder walls. After the rebuild, the customer no longer had any starter problems, even the hottest part of summer. After much discussion, one sales rep suggested putting Blaster in the oil of problem child cars to see if the starter problems could be reduced. We put a can of Blaster in the oil at no charge and let the customers drive as they normally did, then changed their oil the next time and put another can of Blaster in along with the normal oil. At least 90% of the cars that previously had starter drag problems no longer had the problem. We were sure that the mechanic in a can had loosened up the carbon behind the rings that had been causing the ring drag problem. So, instead of the repeated changing of everything when we ran into a hot start problem, we put a can of Blaster in the oil, and just changed whatever part of the starting system was suspect.
 
  • Like
Reactions: George Leonard
#7 ·
I think a better question is unless you are doing a numbers restoration, why use the original style starter at all.

Gear reduction mini starters are readily available and I think standard on everything now. It's kind of like using a mechanical cooling fan, sure it works and so did the wagon wheel.

If your wiring is good just ditch the giant old starter all together.

With all due respect.
 
#9 ·
When i was running my '68 at the track with open headers and 90+ degree days, I never had a problem using the OE wiring and a GM hi-torque starter - identified by the copper extension between the solenoid and starter motor terminal.
Worked every time when asked.
 
#14 ·
I'm another one who says (and recently posted) heat soak is a myth so I agree w/ the OP...
I don't see ministarters as being an improvement. I tend to think the mfgrs wanted to save weight and money so they introduced them. One thing they don't seem to like is prolonged cranking.
The biggest point to all this is to figure out the actual problem, not just start throwing parts at it, and not to simply cry heat soak. Read the recent thread on this subject and try to find a voltage measurement or anyone but me saying do some troubleshooting. There are none as of yesterday.
 
#17 ·
on a somewhat related note, i'm still using a stock starter for the simple fact that could not find a staggered bolt pattern mini-starter from any of the catalogue guys when i was putting my motor together. my block is a '74 400 SBC and the starter bolt holes are staggered as opposed to the two holes side by side. does anyone have a good reference to a quality mini starter with a staggered bolt pattern?
 
#18 ·
oh, and BTW, i'm running long tube headers, 11.5:1 compression and never have had a problem with my stock starter. works everytime. i'd just like the weight reduction and cleaner look if i could find a good mini to work
 
#19 ·
Myth, maybe I don't know. I don't claim to be a smart man. My tow truck has a big block like I'm sure many other trucks have. It builds a crazy amount of heat under the hood. It came factory with 1/2 in fuel lines, and a huge pump mounted on the passenger side of the engine. The wrecker builder put the pump on, but GM put the fuel lines on. GM also put a hood on it that has 4 Rowe's if functional louvers. To help control the heat. Yes this was a GM thing. The same hood came on very heavy service trucks , even some ambulances. From day one it has had starter issues. In 1985 the dealership put the Ford style system on. This truck was one year old at the time. They said something about a service sheet on the problem. I never saw or asked to see the sheet, just wanted the truck to function. It fixed the Myth in my truck. I also don't step on cracks in the sidewalk with hopes that my mother's back will be ok, and to some point do believe in ghost. I don't know if the sidewalk crack thing is a myth or not, but my mother is very old , and has no back problems. Myth? maybe, but they both seem to be working. Rip my post, ignore my post, whatever. And that's all I have to say about that.
 
  • Like
Reactions: 69Z28
#22 ·
I think we agree "heat" is the core cause of what is often referred to as "heat soak starter". That heat fatigue wears wiring and electrical components in a starter. Cars with headers often see the source of heat (exhaust) is closer to the starter and the result of that closer and hotter heat will eventually compromise the wiring in, to and from the starter.

So of course fixing the fatigued wiring is needed, and in the case of battery cables thicker gauge cables help. But if you still have the heat "source" that was the core cause of starter and wiring fatigue than the problem will reoccur. Defense like remote solenoid takes that out of the heat source point blank range. Ceramic coating the headers greatly helps. Offset gear reduction starters help, especially with more performance built motors with 11:xx compression.

IMHO on motors with stock exhaust manifolds and wiring to starter and starter are in good condition the starter should not have what is often referred to as "heat soak". Its modified cars that have higher compression and exhaust close to starter that you need to have solid wiring and often some form of heat defense like a blanket, remote solenoid and or gear reduction starter

Just my $.02
 
#23 ·
Just to add a bit to the rebuilding content and growler testing. I worked for an electric
motor rewinding/rebuild shop many years ago. We tested a lot of armatures using a growler.
They were tested at room temp and also warmed in an oven to simulate operating temp and
then retested. You would be surprised how many failed when warmed.
 
#25 ·
"You would be surprised how many failed when warmed"

I get so many people telling me that testing ignition coils is done with an ohm meter, cold, but, most coils fail when heated to ops temps. Then, I get told I am an idiot, liar, moron for stating to test the coils at ops temps, but, there is where they fail, extremely few fail cold.

So, I agree with the above about growler testing of starter windings, HOT, tells the real tale (at least, that's the way it has worked for this idiot, for over 45 years).

Me, I'll stick with no Ford solenoid, and ducting cool air onto my starters, that has worked for me all those 45 years, so far.
This is what I've been stating for years, although I've never used ducting as a cooling aid.. A rebuilder who is dedicated to quality can properly rebuild a starter. None of my correctly rebuilt starters have failed, even in big blocks with headers. My friend with over 50 cars uses only stock starters and all his cars start fine, even those with high HP and headers. Other older gearheads I know never had issues either.

Many rebuilt components out there suck. Find someone who still takes pride in their job and reputation.
 
#24 ·
"You would be surprised how many failed when warmed"

I get so many people telling me that testing ignition coils is done with an ohm meter, cold, but, most coils fail when heated to ops temps. Then, I get told I am an idiot, liar, moron for stating to test the coils at ops temps, but, there is where they fail, extremely few fail cold.

So, I agree with the above about growler testing of starter windings, HOT, tells the real tale (at least, that's the way it has worked for this idiot, for over 45 years).

Me, I'll stick with no Ford solenoid, and ducting cool air onto my starters, that has worked for me all those 45 years, so far.
 
#26 ·
So what y'all are saying is that a Ford style solenoid fix and ducting air to the starter fix, are both a crutch for a starter or wiring problem. All of the old starter rebuilding shops around here have shut down. Thanks for the info guys.
 
#30 ·
One might argue that when you change to the external solenoid you are most likely changing out the wiring as well. It could be the real "fix" was the wiring upgrade and the solenoid move was an inert result of the process.

Living in the Mojave Desert summer heat I have never had a heat-soak-starter problem.

Count me among those saying, simply having a good starter and good wiring is the trick. :wink2:
 
#27 ·
I must say, in defense of the Ford starter kit for "heat soak", that it has worked for me. I got really good at parking on inclines so I could pop the clutch to get it started. After tiring of the sometimes starting I installed the kit. May have bought it from Midwest or possibly Summit. It does have the jumper piece between the terminals on the starter mentioned previously. So I installed it about 1993 and it still functions today. There has never been a "heat soak" since then.
 
#29 ·
I too defended the remote silonoid as I have it on my truck. Has been there since 1985 and worked. I have been told it is a myth. So be it. I park my truck beside a unicorn that eats nothing but Skittles. They are both real.🤔
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top