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289 won't turn over when hot

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Outlawboss

Member
It's been a few years, but I started digging back into the mustang these last few weeks and I have run into a problem that I hope to get some help with. I THOUGHT I would be ready for Knott's, but doesn't look like it.

Engine is a 289 in a 66 coupe. It's warmed up a little with an Edelbrock intake, carb and cam. I also have long-tube headers on it.

It was fine when being started cold. Once it was warmed up and shut off for a few minutes it would turn over, but very slowly. Just enough to get it started. The problem was getting worse over time. I did a little research online and determined the old starter must be going bad. It was at least 15 years old. Battery was ok, it could turn the engine as long as I needed it to.

I replaced the starter with a mini hi-torque type from NPD. I also got a new starter solenoid and mounted it next to be battery in stock location.


After installation, the starter sounded/worked great. I had to crank it for less than 20 seconds to get fuel back into the carb and the car started. I warmed up the car, shut it off...and same problem as before only worse. This morning, even when cool, the engine would barely turn over. A few rotations and then it would just click. I couldn't tell if it was the solenoid or skipping gears. Sounds like the solenoid. I tested it with a different battery known to be working and same problem.


Took the coil off the distributor to make sure it's not a timing issue, and confirmed it is not timing.


So it's not the battery
Solenoid is brand new
Starter is brand new


What else? Could it be possible that the mini starter was damaged by the initial startup and/or heat from the headers? If anything, the mini starter should be enduring less heat than the old stock one.


I'm at a loss. Anyone else had this, or able to help narrow it down?
 
had the same trouble with a sbc in my old 40 ford. it was HEI & heat was breaking down something electrical. would do the same thing when hot, but you could raise the hood for a couple mins & let the hot air out & it would start fine. ended up replacing the coil & adjusting the timing.
 
Good to know! I got a flamethrower coil about 13 years ago for it. Maybe that's failing now?

"SELLERSRODSHOP" said:
had the same trouble with a sbc in my old 40 ford. it was HEI & heat was breaking down something electrical. would do the same thing when hot, but you could raise the hood for a couple mins & let the hot air out & it would start fine. ended up replacing the coil & adjusting the timing.
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The engine barely turning over is an indication of a bad battery, starter or wiring between the two. The coil and distributor would not affect how fast the starter turns over the motor, they would affect how it runs however. Back in the day I had a 390 in my truck that would eat a rebuilt starter ever 6 months. It would exhibit the same symptoms of slow to turn over. It was a result of engine heat soaking the starter, especially after running hard and being shut off.

If the "new" starter is a rebuilt unit and you are certain the battery is good, may be time to try a different starter.
 
Thanks kb3. I thought the same thing. The old starter worked fine for years with my headers, and so I assumed that this new one (it was new, not rebuilt), being smaller, would soak up less heat. It turned over fine on the first startup. Then the car got warm and it wouldn't start.

This morning after cooling overnight, it still turns hard. I'm worried that I killed the starter on the first run. Maybe I should try a new battery before going for a replacement starter. There is a little corrosion on the posts of the old one and it's a few years old.

Appreciate the thoughts guys, keep em coming!
 
"Outlawboss" said:
Thanks kb3. I thought the same thing. The old starter worked fine for years with my headers, and so I assumed that this new one (it was new, not rebuilt), being smaller, would soak up less heat. It turned over fine on the first startup. Then the car got warm and it wouldn't start.

This morning after cooling overnight, it still turns hard. I'm worried that I killed the starter on the first run. Maybe I should try a new battery before going for a replacement starter. There is a little corrosion on the posts of the old one and it's a few years old.

Appreciate the thoughts guys, keep em coming!
Click to expand...

I doubt you killed the starter with just one run. I would look closer at the battery and the cables. Make sure the terminals are in good shape as well. It takes a lot of current to turn the starter.
 
"kb3" said:
I doubt you killed the starter with just one run. I would look closer at the battery and the cables. Make sure the terminals are in good shape as well. It takes a lot of current to turn the starter.
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+1
 
I believe it is the starter wire from the starter solenoid to the starter, until you said that it was hard to turn over in the morning. Could you have run the battery down the previous night?
 
Mine has the very same problem, I've just lived with it. It will eventually start when hot. I was told it was a timing issue--too retarded or advanced, I don't remember which. I suppose it could be a wiring issue, though.

See you Sunday!
 
another thought: does the new mini starter have the solenoid on the starter or are you using the stock fenderwell mount solenoid? if its on the starter, you will need a heat shield with headers.
 
"SELLERSRODSHOP" said:
another thought: does the new mini starter have the solenoid on the starter or are you using the stock fenderwell mount solenoid? if its on the starter, you will need a heat shield with headers.
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Not if you have ceramic coated Tri-Y's!
 
Dude, sorry I am so late responding....

You have a bad ground. Replace the ground cable between the engine and the firewall, then replace the cable between the started and solinoid on the fender and lastly replace the cables to the battery.

If the problem persists replace the battery.

Second thought check the cables and change the ones at the battery and the battery.

I had the battery in my 65 which had an 8 yr warranty in there for 13 years, when it died it died real hard. It just stopped working, period.

There is only three things that would cause the engine to not turn when hot.

1- timing
2- overheating
3- electrical

I know your engine and doubt it is overheating, and you said you checked the timing, so that leaves electrical. You changed started and solinoid so the only things left are listed above.

Mel
 
Thanks, I'll check the ground.

I did notice that I can jiggle the cable connection at the starter when I reach down in there, meaning I didn't tighten that nut down. It IS connected, but not tight. That could be it.
 
"Sluggo" said:
You have a solenoid on the apron and a mini starter?

You do have it wired properly I hope.
Click to expand...

I've had a solenoid on the apron AND a mini starter AND the battery in the trunk for 10 years without the first problem.
 
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