Heat Soak?

[wheels87k5]

Here's the issue:

I start the engine and let it run for a few minutes. Shut it down. 5 minutes later I go to start it up and it barely will crank over. Like it has a dead battery. But the battery reads 11.3 volts. It will start, after 30 minutes, like nothing was wrong.

New battery.

The starter tested good but I replaced it anyway.

It does this with/without the remote solenoid.

 

[Wes Harden]

11.3 volts is a low battery, 12.6 volt is full charged. So check for high resistance, corrosion, ends and in the cables, loose connections, cables that are to small to carry the current needed when hot.
Headers? may be a heat shield for starter. I have a factory style on mine no headers.

 

[wheels87k5]

All cables are fairly new. I can try a bigger cable to the starter and see if that helps.

Ceramic coated headers and not really too hot at the starter. I can add a heat shield to cross that off the list.

The longer it sits without trying to start it the volts will climb.

I also put the voltmeter on the battery while it was running and it only reads 11.30 volts....at the back of the alternator was 11.20 volts.

 

[Wes Harden]

So next question is why is the engine so hot after a few minutes? Also is the charging system doing a good job? I know you've been doing a lot work to the truck lately, and may have been using a lot of battery. I try to charge mine over night, when in similar situation.

 

[Bent77]

Hmm. You tested the alternator already? So maybe there’s a voltage loss in the wiring someplace. I think @Justin V went through this years back and had a bunch of ground issues

 

[Fastereddie]

All cables are fairly new. I can try a bigger cable to the starter and see if that helps.

Ceramic coated headers and not really too hot at the starter. I can add a heat shield to cross that off the list.

The longer it sits without trying to start it the volts will climb.

I also put the voltmeter on the battery while it was running and it only reads 11.30 volts....at the back of the alternator was 11.20 volts.

You are not charging. Should read 13-14 volts while running

 

[rampage]

If you’re starting with a cold engine and run it for 5 mins I highly doubt that’s enough time to cause a heat soak issue. Think you have another problem.

 

[wheels87k5]

You are not charging. Should read 13-14 volts while running

I thought it was odd to not see at least 12.5v or more.

If you’re starting with a cold engine and run it for 5 mins I highly doubt that’s enough time to cause a heat soak issue. Think you have another problem.

I'm going to replace the alternator.

All engine components came from a non running C3500. There is no telling how old these components are so I'm replacing with new as needed.

So next question is why is the engine so hot after a few minutes? Also is the charging system doing a good job? I know you've been doing a lot work to the truck lately, and may have been using a lot of battery. I try to charge mine over night, when in similar situation.

The engine isn't getting hot, so to speak. It was at 188 degrees. But it would do this when the temp was 100 degrees so it's probably safe to say it isn't a heat soak issue.

Hmm. You tested the alternator already? So maybe there’s a voltage loss in the wiring someplace. I think @Justin V went through this years back and had a bunch of ground issues

If you mean tested by me putting the voltmeter on the battery post of the alternator, that's it. I haven't taken it in and actually had it tested.

 

[Bent77]

I thought it was odd to not see at least 12.5v or more.



I'm going to replace the alternator.

All engine components came from a non running C3500. There is no telling how old these components are so I'm replacing with new as needed.



The engine isn't getting hot, so to speak. It was at 188 degrees. But it would do this when the temp was 100 degrees so it's probably safe to say it isn't a heat soak issue.



If you mean tested by me putting the voltmeter on the battery post of the alternator, that's it. I haven't taken it in and actually had it tested.

Just know that going point to point fro the alt al the way to the battery can yield some interesting results

Let us know how it tests at the store though

 

[Fastereddie]

I thought it was odd to not see at least 12.5v or more.



I'm going to replace the alternator.

All engine components came from a non running C3500. There is no telling how old these components are so I'm replacing with new as needed.



The engine isn't getting hot, so to speak. It was at 188 degrees. But it would do this when the temp was 100 degrees so it's probably safe to say it isn't a heat soak issue.



If you mean tested by me putting the voltmeter on the battery post of the alternator, that's it. I haven't taken it in and actually had it tested.

You say c3500... so like a 90’s truck? Do you have any wires connected to the plug on the alt. or just the battery cable on the stud?

 

[wheels87k5]

You say c3500... so like a 90’s truck? Do you have any wires connected to the plug on the alt. or just the battery cable on the stud?

It is a one wire plug and is connected to the alternator. The plug is in the original harness that was reworked by Team208motorsports.

UPDATE: The alternator passed. It is a CS140 alternator. I put in a 4 gauge line from battery to alternator and it didn't change anything. So I jump started the truck and took a reading with the voltmeter. It was loosing the charge. It started at about 11.6 volts and was going down fairly quick.

Do I have a cable hooked up incorrectly?

I have a cable from the + post of battery going directly to the "Battery" post on the alternator.

 

[rampage]

It is a one wire plug and is connected to the alternator. The plug is in the original harness that was reworked by Team208motorsports.

UPDATE: The alternator passed. It is a CS140 alternator. I put in a 4 gauge line from battery to alternator and it didn't change anything. So I jump started the truck and took a reading with the voltmeter. It was loosing the charge. It started at about 11.6 volts and was going down fairly quick.

Do I have a cable hooked up incorrectly?

I have a cable from the + post of battery going directly to the "Battery" post on the alternator.

Have you checked all your ground connections, both visually and with an ohmmeter? You can also check for a voltage drop from the negative terminal of the battery to the case of the alternator.

 

[diesel4me]

Timing too far advanced maybe ?...I've had small blocks that ran fine (better!) with it advanced beyond stock specs,with no pinging,but they didn't like to crank over a few minutes after shutting it off...Ruh...Ruh...Ruh...Ruh..too slow to fire up..-let it cool off 10+ minutes , and it'd spin right over fine..I thought it was the starter for quite some time,but another good one I put on did the same thing..a good battery didn't change anything either..

One 400 SB I had I rigged a toggle switch to the coil so I could get it whipping over good before turning the spark on,and that "fixed" it...I think the timing chain was sloppy and advancing the timing helped compensate for that..

 

[Fastereddie]

Maybe this will help out. Sounds like your alternator isn’t getting triggered to charge. Maybe the harness is wrong or not connected to the right spot.

 

[wheels87k5]

Update:

After talking with Magikal it seems that I forgot to hook up the "tan" wire on the other end of the harness to a light on the dash. I hooked the tan wire to one side and a keyed 12V to the other to trigger the alternator to charge. Now all is good. Battery is being charged and it will now start like is should after shutting it off. Just one more thing to check off the list.

Thanks for everyone's input.

 

[Justin V]

Ok I didn't read back at all but there is a an exciting connection on most alternators and you'll need to pull from battery voltage to connect to that hook up. This can be accomplished many many ways but as long as you have direct connection from alternator charging to battery than use a short wire from the charge post to the excite post on the alternator. Then you'll end up triggering the inner SJW in the alternator and it'll charge.