[68chevelle8111112222]

hey guys I have 1968 chevelle which I am having a hard time with when it gets hot. What happenes is when the car is driven for a while and it gets hot it wont start back up!! The starter won't even click or do anything!! and when you try to start it you can kinda see the interior lite dim as if there was a load on the battery. Ok now you guys are saying the starter is gone well its not the starter because ever since this problem started I have put 3 batterys 2 starters and 2 altenators and the problem will not go away!! If you let the car sit for a about 1 to 2 hours all the sudden it comes to life and the car cranks fine the battery shows no sing of being dead or low!! I even listen to the stereo while I wait sometimes and I have a big system in it so there can't be nothing wrong with the battery!!! Now this is what kills me is if I have someone boost me the car will start right away I don't have to wait for anything!! Or if im at home and it wont start and I hook up my tiny little trickle charger to the battery and the dame car will crank and start no problem!!! and the funny thing is I can crank for as long as i want!!! now if the battery was low or bad then how would the car start and crank with just a trickle charger and how could i listen to my big stereo system while I wait for it to cool down and the battery still beable to start the car so this problem has got me way messed up!! Well let me know what you guys think and hopefully we can figure this out thanks guys

 

[cjlandry]

Your problem is called "Heat Soak".

It's very common when you have headers.

The starter windings are heated by the exhaust, and the resistance goes sky high. This means that your battery must provide a sky high amount of current in order to deliver 12-volts to the starter.

The solution is to use the heaviest gauge cable possible from the battery to the starter. Same on the negative to the block. This allows the battery to supply all it's available current to the starter.

Some of us, myself included, use Ford solenoids mounted on the fender as extra insurance.

Follow this link http://www.chevelles.com/techref/ftecref4.html to get all the answers you need.

I've used Ford solenoids on Chevy cars since I first started driving. It works.

 

[MalibuJerry350]

Where do you have the negative cable connected? Through the last 34 years of driving the Chevelle, I have found that the WORSE place is the alternator bracket. If ALL of the connecting bolts holding the water pump, alternator bracket, thermostat housing, etc, have been recently removed, cleaned and reinstalled, everything will work normally...for a while. As corrosion sets in and electrical resistance increases, the voltage to the starter via all of these avenues will decrease causing "hot start" problems. I have just had this re-occur with my Chevelle after a couple of years of perfect starts. The simple act of moving the negative cable to the front bolt of the exhaust manifold cured the "no hot start" problem. When connected to the alternator bracket, the electrical ground has to run through bolts which are subject to moisture/corrosion problems. Add the long length of the positive path (along the radiator support, along the left fender, into and then back out of the passenger compartment with #10 wire) and you have a recipe for hot start trouble. If you have hot start trouble, first, connect the negative battery cable to a GOOD CLEAN spot on the engine block. The bolt in front of the fuel pump is good. Use a "star" type lock washer under the bolt head. Make sure your cables are in GOOD condition! The simple act of connecting the negative cable to the engine block will help.

Now, how did I find this? I always carry a VOM in my tool box. I had previously "shaved" off a tiny bit of insulation from the purple wire which runs along the firewall and connects to the "S"
terminal on the solenoid. I had made a short jumper with some #10 wire with an alligator clip on each end. Whenever the problem occured, I would leave the ignition in the "on" position and clip one end of my jumper to the purple wire (where it begins it's vertical journey to the solenoid). I would then connect the other end for a moment to the positive battery terminal. The solenoid would pull in, the starter would turn, and I'd be on my way. One day, I decided to check the voltage at a couple of points to see where the problem was. I connected the positive lead of the VOM to the purple wire and the negative lead to the negative battery terminal. Even though the solenoid wwas not pulling in, the VOM read 12.5 volts. Mmmmmmm. Ok. I then moved the negative VOM lead over to the engine block and read 9.5 volts in the "start" position!! The voltage drop was on the negative side, not the positive side. I disconnected the negative battery cable from the alternator bracket, removed an exhaust manifold bolt and connected the cable under that bolt instead. The problem was cured. I first discovered this around 1976. Through the years, if I replaced the water pump and/or the thermostat, I would clean the bolt threads and the bolt holes. I would put the negative cable back (for originality) and everything would be find...for a while! The moral is DON'T OVERLOOK THE NEGATIVE BATTERY CABLE CONNECTION! If all of your wiring is up to snuff, you won't need an external solenoid.

 

[John_Muha]

Heat soak is a magazine myth. If the car starts by jumping it, the solenoid isn't frozen.

 

[HOTRODSRJ]

John, I have to respectfully disagree that "heatsoak" is a myth. Heat adds resistance to starter and solenoid wire to the detriment of current......which as you know means loss of wattage or work. Heat also effects the output of the source battery as well.

Also, when you jump a battery that has been run down or even at near full charge, the charging battery (and vehicle's alternator) can have up to 15VDC to apply to the culprit battery. I have used this trick to prod solenoids to move on occasion...works great.

 

[BrentsChevelle]

Originally posted by John_Muha:
Heat soak is a magazine myth. If the car starts by jumping it, the solenoid isn't frozen.

So, John, if my Chevelle is suffering from this problem, would you suggest relocating the negative battery cable (it's on the alternator bracket right now), instead of purchasing a starter heat shield?
If so, when would one actually ever need a starter heat sheild?

Thanks

 

[John_Muha]

Ah, yes the heat soak argument again. I love it. Been way too quiet and stirs things up. Still don’t believe it exists. Adding headers and running the car for an hour doesn’t even compare to running a car all day across the desert floor during the summer. It both cases its dang hot under there. When “heat soak” occurs and jumping it with another car appears to correct it, has one tried what Jerry suggested. Or maybe shorted solenoid terminal “S” to solenoid terminal “B+”? Actually it’s way to hot under there to get in with a screwdriver to actually do it.
1, Believe that some of the “heat soak” fixes are compensating for a low voltage to the solenoid “S” terminal. The Ford solenoid “fixes” this by adding new wires and a new contact switch to provide a decent voltage to the solenoid.
2, Believe that some of the “heat soak” fixes are caused by old or poorly manufactured (cheap) components.
3, Do agree with Steve Jack, that there’s a point where the stock solenoid/starter is no longer capable of turning over a large, built, high compression engine.

 

[Peter F.]

I'm with John. "Heatsoak" isn't the real reason why the engine won't start. The reason can be traced back to GM being too cheap to put a heavy enough wire into the car. The 10 guage wiring has too much voltage drop when trying to energize the solenoid, which then means it won't energize. The only reason the problem occurs when it is hot is because it is harder to energize when hot. So, the heat is a contributing factor but it isn't the true cause of the problem.

In all cases, providing a better 12V connection to the S terminal will fix the problem. If you stick a Bosch relay with the contact between the battery and the S terminal and power the coil from the purple wire that was on the S terminal that will fix the problem. Usually, if you go through the wiring and check all the terminals and connections you can get it to work fine. The added bonus of doing this is that you can make the headlights brighter if you eliminate voltage drops in the power to the dash wiring. Using a true GM solenoid can help too.

If your car won't start hot then it is actually very close to not starting when cold either. Leave the lights on for 15 or 20 minutes and it wouldn't start cold either.

Peter

 

[cjlandry]

And I agree with all of the above, but I still love the convenience of my Ford solenoid for turning the engine over during valve adjustments or whatever. It's very nice to hook the clips on my remote starter button right there within easy reach.

I used Ford solenoids in my earlier days because of the "heat soak" issue. This was before I learned that bigger wiring and clean, tight connections solve the problem nicely. It was an easy fix, and it worked every time. I still recommend it to people for just those reasons.

I can tell you from experience that heat soak always showed up for me right after installing the headers. I put headers on all my V8 cars, and had "heat soak" on all of them right away even though i could drive 'em all day before with no such trouble. So I still refer to it as "heat soak" even though the heat is only one of a few contributing factors. It's always been "the straw that broke the camel's back" for me.

 

[cjlandry]

68chevelle8111112222, have you returned to read the responses to your question?

 

[John_Muha]

And Chad, if you do make it out to California's oil fields, brews on me.

 

[HOTRODSRJ]

There are some bandaid fixes to the "heatsoak" problem and I don't know how you guys define heatsoak, but I define it as excessive heat induced electrical problems. So, regardless of what heat causes this, it's "heatsoak"? I don't think its a myth either. Read on...

FWIW, I have driven across the dessert and the under the hood temps get pretty hot. But the proximity of headers to the starter is much hotter (can be near 700 degrees)due to lack of airflow thru the compartment.

I do agree that wiring size can be a culprit and has to be sized to the application, but literally thousands of feet of copper wire in both the solenoid and starter are at risk. Sometimes remote solenoids really help. But, if the starter gets real hot and the battery is at losses due to heat, well that can still be a problem.

Here is a great link to discovering heat impedance issues with motors http://www.amptec.com/adobe/heatrise.pdf . Now this site is dedicated to running motors, but resistance is resistance and heat is heat. So, it applies to this situation alone. I know for a fact that the starters can be 350 degrees F. I have measured this myself. That't alot. So based on this criteria, a 10degree C rise produces about a 4% increase in resistance for a general assumption. Some of this is based on design I realise..but follow me here. Now, at 270-350 degrees typical, this would be about 40-50*C ish. So, this represents about a 16-20% increase in resistance. Add to that the battery reduced capacity and this is a big gap to fill in watts to get everything to move. So, the myth is really something called "Heat induced resistance in copper" and is a very real physical property.

As a remedy, I just don't use turn-of-the-century (1900s) electrical motors anymore. I prefer permanent magnet minis myself. More torque, less current meaning smaller wires, easier on the battery, smaller, lighter, easier to fit/remove, and sounds cool as can be.

Another phenom that goes on is cheap connections. These connections become mechanically compromised and also add to the fray when hot.

 

[MalibuJerry350]

Originally posted by HOTRODSRJ:
There are some bandaid fixes to the "heatsoak" problem and I don't know how you guys define heatsoak, but I define it as excessive heat induced electrical problems. So, regardless of what heat causes this, it's "heatsoak"? I don't think its a myth either. Read on...

FWIW, I have driven across the dessert and the under the hood temps get pretty hot. But the proximity of headers to the starter is much hotter (can be near 700 degrees)due to lack of airflow thru the compartment.

I do agree that wiring size can be a culprit and has to be sized to the application, but literally thousands of feet of copper wire in both the solenoid and starter are at risk. Sometimes remote solenoids really help. But, if the starter gets real hot and the battery is at losses due to heat, well that can still be a problem.

Here is a great link to discovering heat impedance issues with motors http://www.amptec.com/adobe/heatrise.pdf . Now this site is dedicated to running motors, but resistance is resistance and heat is heat. So, it applies to this situation alone. I know for a fact that the starters can be 350 degrees F. I have measured this myself. That't alot. So based on this criteria, a 10degree C rise produces about a 4% increase in resistance for a general assumption. Some of this is based on design I realise..but follow me here. Now, at 270-350 degrees typical, this would be about 40-50*C ish. So, this represents about a 16-20% increase in resistance. Add to that the battery reduced capacity and this is a big gap to fill in watts to get everything to move. So, the myth is really something called "Heat induced resistance in copper" and is a very real physical property.

As a remedy, I just don't use turn-of-the-century (1900s) electrical motors anymore. I prefer permanent magnet minis myself. More torque, less current meaning smaller wires, easier on the battery, smaller, lighter, easier to fit/remove, and sounds cool as can be.

Another phenom that goes on is cheap connections. These connections become mechanically compromised and also add to the fray when hot.

That is all well and fine, HOWEVER, when you measure the voltage AT the solenoid "S" terminal and find 9 volts, it is NOT because the windings of the solenoid INCREASED resistance. The problem is external...normally a problem with the + feed OR the ground connection from the battery CAUSING this voltage drop. The solenoid is still drawing current, BUT not pulling in due to the voltage drop. As far as permanent magnet DC motors being the "new technology"...nothing new there either. They've finally been able to manufacture permanent magnets with the desired stronger magnetic field. Permanent magnet DC motors have been around since the inception of electricity. However, for my daily driver Chevelle which gets about 36,000 miles a year on it, I prefer original "off the shelf" components that I can purchase anywhere in case of a failure. Again, as John stated, this isn't to say that a high compression, built-up engine wouldn't present a problem to a stock starter....but, if the solenoid doesn't pull in due to a voltage drop, better look for another cause.

 

[cjlandry]

Originally posted by John_Muha:
And Chad, if you do make it out to California's oil fields, brews on me.

I'll look you up when I get there.

 

[Peter F.]

Originally posted by MalibuJerry350:
That is all well and fine, HOWEVER, when you measure the voltage AT the solenoid "S" terminal and find 9 volts, it is NOT because the windings of the solenoid INCREASED resistance. The problem is external...normally a problem with the + feed OR the ground connection from the battery CAUSING this voltage drop. The solenoid is still drawing current, BUT not pulling in due to the voltage drop.

Exactly. It's that voltage drop in the wiring that keeps the starter from engergizing and this is the exact problem the original poster is having. For this problem, installing a permanent magnet starter is just as much of a "bandaid fix" as installing a Ford solenoid.

It's like Chad posted. The Ford solenoid works and it does have the advantage of removing the constant live power wire going to the starter and providing a place to connect a remote starter. As I posted, you can achieve the same fix with a small Bosch style relay (or a Ford solenoid if you want) on the S terminal of the starter without changing the main power feed to the starter. If you look on E-bay there is someone selling mini-starters for something like $80 and they're supposed to work just fine. Any of these ways are fairly simple and cheap fixes that will make it work, even though they all are a band-aid to the real problem.

Peter

 

[HOTRODSRJ]

MalibuJerry......yep you are right about the "start" wiring having enough voltage on it and therefore current thru it. Ya gotta have signal current. But, I don't know where 9volts came from at the terminal you spoke of? Certainly if there is restricted voltage/current to the solenoid this is an issue. This is why I didn't comment on it. But why would "heat" affect the "start" wire per se? This is a single wire and usually short in nature and just doesn't or shouldn't get affected by heat. It's the miles of wire in the solenoid and/or starter that is the culprit in my opinion....and probably the lack of proper size wiring?

In all my trouble shooting on "heatsoaks", I can only remember one incident that involved the start wire where it was mechanically worn (therefore not making a consistent connection).....the rest were typically pure solenoid or starter wiring (insufficient size) or other issues current delivery issues. The obvious test is simply to jump from the bat term on the starter to the S term on the solenoid. This would provide an answer. And moreover, the way the original poster listed his symptoms and claimed the dimming of lights, this indicates to me that the solenoid is probably being somewhat energized and could even involve the starter field windings as well. Usually with this exact symptom, it's a poor battery connection or just poor battery. If I only had 9volts at the S wire, I would be looking for ignition switch issues or full battery voltages etc. I just don't associate heat with this purported problem.

FWIW, the permanent mag starters are "newer technology" (I use that terminology) than the boat anchors of yesteryear. I think the reduced current requirements and increase in torque of these units alone speaks for themselves. And, you can easily find GM minis at all their dealers just in case as well as most aftermarket parts stores such as NAPAs. I usually don't worry about repair per se, whereas I want it correct from the first time. If I had to worry about parts availability for everything, I would have to pull a parts store behind me? Besides, in this case minis are 20 times more reliable based on MTBF calculations (just the current and wire reduction)anyhow. So, I really don't see the problem.

Also, I don't look at the mini resolution as a "bandaid" fix at all. The minis REDUCE the amount of current required and usually befit the currect capacity of the control circuit.

I guess we will see what gives sometime?

 

[MalibuJerry350]

Okay, lets go over this again. IF the resistance of the solenoid winding INCREASED due to a so called "heat soak", the CURRENT draw would DECREASE and the supply voltage at the "S" terminal would be source, or 12 volts. Ohms law enters the picture here. Now, IF the wiring and /or connections (positive OR negative) TO the solenoid increase in resistance, the voltage available to the solenoid decreases, hence the solenoid cannot pull in. Now, if you recall, I said that I measured 9 volts at the "S" terminal using the engine block as reference ground. If I used the battery negative terminal as reference ground, I found 12 volts. Very simple..the solenoid is drawing current, BUT, the negative side of the circuit in introducing enough resistance to cause a severe voltage drop. It is NOT the solenoid causing the problem. In my case, it was the NEGATIVE side of the circuit, the ground connection to the block through the alternator bracket and associated mounting bolts. The heat from the engine causes the resistance to increase due to corrosion/oxidation problems around the threads of these bolts. Basic electrical troubleshooting found the problem. Very easily proven. I can almost bet the farm that if given the chance (and a VOM) I can prove that most so called "heat soak" problems are not the fault of the solenoid. Most problems are caused by inadequate wiring or bad connections. If the wiring is up to snuff and ALL connections are clean and tight, the solenoid should pull in. NOWW, IF the solenoid pulls in AND the starter doesn't spin, THAT'S a different problem.

 

[Dean]

Can I add my 2 cents worth?

First of all I have never ran headers cause their a BIG PITA so maybe not really qualified but the many times I've had a problem with an overheated GM solenoid they did nothing at all, no sound, nothing.

I personally beleive that maybe not all but many many so called "heat soak" problems that are being fixed by adding another solenoid or a mini starter are really fixing the symptom instead of actually finding out where the low voltage problem is.
Many times the problem is voltage drop through switches and connections or just a weak battery.

 

[Ark68SS]

Another thing to try that's cheap, is a new solenoid spring GM #1958679. It's supposed to be a little weaker, so it doesn't take as much current to draw in the solenoid.

BL

 

[MalibuJerry350]

Originally posted by Dean:
Can I add my 2 cents worth?

First of all I have never ran headers cause their a BIG PITA so maybe not really qualified but the many times I've had a problem with an overheated GM solenoid they did nothing at all, no sound, nothing.

I personally beleive that maybe not all but many many so called "heat soak" problems that are being fixed by adding another solenoid or a mini starter are really fixing the symptom instead of actually finding out where the low voltage problem is.
Many times the problem is voltage drop through switches and connections or just a weak battery.

Exactly!