We've got a 1950 F1 with a 351W/AOD with a large electric fan & 645 Cold cranking amps battery - will start when
cold but is really slow to turn over if you go out for a drive & stop for any reason. Been totally unable to start it
after the first stop lately ... frustrating. Will start later once it rests. The Battery tests out fine but not charged enough
with AAA & Autozone... Hmmmm......Perplexing.

My operating theory is that we have wired our huge Tbird 18 inch 4,000 cfm fan wrong. Once the truck is warmed
up & you stop - the battery is trying to run the fan & start the engine - can't handle it... Our fan does continue to run
when the truck is stopped for a while..

Will double check the alternator again tomorrow but it's been fine when I checked before. I've seen this explanation
on here but I have no idea what this means.. What is a "blocking diode"? - Could this be the answer? Electricity is not my strong suit..

"Electric fans can also backfeed your ignition. This doesn't sound like what's going on - especially if you're wired directly
to the battery via the thermal switch. If you run off the "run" bus out of the fuse block though, you will need a blocking
diode inline with the fan. Otherwise, if the fan is running when you turn the ignition off, the motor turns into a generator
and will produce enough juice to keep the ignition going for a short time as it winds down. Most of the fans are permanent
magnet motors, so will act as generators when turned (or while spinning down). "

I'll take any suggestions at this point.

Ben in Austin
1950 F1

 

............

 

Without additional testing and going off what you have provided, my money is on a bad starter. You say in turns slow when warm (if at all) and acts fine when cold . This screams heat soak to me. You can try a heat shield for the starter, but that will only hide the underlying problem of a bad stsrter. I would replace it and shield it to prevent it from heat soaking the new one.
A diode is nothing more than a one way switch in a circuit. Diodes are used for example in welders and alternators to convert AC to DC by allowing voltage to flow one direction. You don't need it on your fan but if placed in line with the hot feed it would only allow the voltage to flow from the battery to the fan and would keep the fan generated voltage from back feeding into the truck system.

Hope this helps you. Any questions you can pm for phone #, easier to explain and troubleshoot verbally than typing on a phone.

 

Hey Dave,
"Heat soaking the starter". Can you tell me more about this?

I haven't heard any weird grinding noises from the starter. It's one of those mini starters - I needed to
keep the size down to get the power steering pump & exhaust in.

I appreciate the feedback. I've been concentrating on the dead battery path or significant
drain on the electrical system but all tests show the battery is good. I'll take a run at the starter & report back.

Ben in Austin
1950 F1 (351W/AOD)

 

Mine was doing the same thing, new battery fixed it.
no problem starting first thing when cold, but was very slow to turn over after being run.
I am sure all of your battery cables are relatively new so voltage drop should not be an issue, but It is always a good idea to check all battery and ground connections.

 

Try boosting when it's hot if more amperage doesn't help the its mechanical , poor starter , poor ground ( the starter grounds to the trans and need to be bare where it bolts ) , check timing ( too much advance will make it hard to start hot ), Good luck

 

Have you double checked your connections going to your starter? Poor connections will require a massive draw from the battery. Just at least make sure that they are all tight.

 

I would SWAG your fan draws 30a which should be minimal compared to what the starter requires.
Edit: Try disabling the fan next time the problem happens.

The Battery tests out fine but not charged enough
with AAA & Autozone... Hmmmm......Perplexing.

Is the alternator belt tight?

Not sure what you're saying here. What does your battery read static and with the engine running off idle? Is your AC compressor also on while trying to start?

 

Could be a couple of things. First I would test your battery when it's cold and then again when it's hot? Also try jump starting her when she's hot? I would test the starter too. Ground wire getting hot, due to not having a good ground? What shape are the power feeds to the starter / battery / ground? Doesn't sound like an alt problem to me! Good Luck! I've had the same problem and I had to change the starter and a ground wire

 

Thanks Guys
I appreciate all the help. I'll check all the ground wires on the starter
& I'll check the alternator belt tension as well. My son has the truck up in Waco making it harder to just get it done. I was up there yesterday
& took him by Autozone thinking it was simply a battery problem but they say it's not.

I generally start by replacing the battery & work up from there..

His belts do squeal more than I think is normal.. I'll check that out Ray.

I'll report back as we delve into the puzzle a bit deeper.

Ben in Austin
1950 F1 (351W/AOD)

 

A squealing belt is a slipping belt. A slipping belt is not doing the job.

 

If you have that tight of clearances that you needed a mini starter to install two separate systems it could definitely cause problems. The heat soak I spoke of is when a component is close enough and conditions exist that allow it absorb heat that in normal conditions would be dissipated. In the case of your starter it absorbs heat which causes all the metal to expand which cause undue clearance issues inside the starter. These clearance issues in addition of the fact that heat is not good for electrical components can cause your starter to bind up and put a very heavy load on the rest of your electrical system. If all your connections and battery are good I still think you will find it is a starter issue.

 

Thanks Dave,
I'll get a pic of the starter from my son tomorrow & post it.
If you'd let me know what you think as far as heat shields etc.

Thanks a lot. It's going to get in the 20's overnight tomorrow - coldest day in a couple of years.
You'd think the world was ending... Everyone running around getting groceries, firewood, faucet
covers, etc. You'd find it funny.

Ben in Austin
1950 F1

 

If it just clicks when you push the starter button, the issue may be with the ignition switch that the key goes into. I went through pulling and testing my battery and starter both checked good. Put a new solenoid in and still had the issue. Happened to jiggle the key while pushing the button and varroom. Swapped the ignition switch and life has been good since then.

 

LOL... "My truck won't crank!" I can hear it now.

The faucet covers might not be a bad plan. The problem is, homes built in warmer climes down south aren't always insulated very well compared to their northern bretheren. So an unseasonable global cooling snap can result in busted pipes. Not fun. One thing that helps for the plumbing, pipes along an outside wall tend to freeze first, or uninsulated crawl space. Crack a cold water faucet in the kitchen juuust a trickle, about the diameter of a pencil lead, and let it run. This will keep things moving and help prevent a freeze-up.