Starting issue, thoughts?

[unity]

So when I drive my Mark and its gets hot I have an issue with it wanting to turn over. If I am on the highway and exit to fuel up it usually starts right up. But if I am driving around town where ambient engine temps get higher it may take a few times to start.

Its just as if the battery is dead. Turn the key and it turns a little and the dome lights dim to all but out. But then when it does eventually start, it starts right up. Might take 3 or four attempts. If I let it cool for 20 minutes or so, also starts fine. The car can sit for days and still start so I dont think its the battery.

I had this problem with my 73 and it was the starter solenoid being baked by the exhaust. So, I replaced it on the VIII. It did not fix the problem at all. Battery is in the trunk with 2 main grounds and a 4 gauge positive lead to the front. Gold connections. I cleaned all the other connections, at the starter and at the relay box, with a dremel so they are REALLY cleaned up.

Dont think its the battery. Its a newer issue, so I am thinking its not the cable which should be the right size.

The only thing I can think of is the starter itself? It was rebuilt by a friend and I, but we are not experts....

 

[Icarus]

4 gauge wire running from the rear to the front isn't enough to carry the load of the starter (normal draw is 130-220A!)
It sounds like a mix of the heat and the to small wire imho...
If you have access to an induction amp meter, you could test the draw of the starter to see if it's drawing too much as well, but I'd start with a much bigger wire first...

 

[Icarus]

Some more info for your amusement/reading:

Maximum starting circuit voltage drop (battery positive terminal to starter terminal) at normal engine temperature is 0.5 volt.

Voltage Drop Tests

If the starter cranks slowly, and the battery is satisfactory, there may be a malfunction of the starter or in the cranking circuit wiring. To determine if the problem is in the wiring, a voltage drop test must be performed.

These tests are performed to determine if there is excessive resistance in the starter motor circuit. Always make the volt-ohmmeter connections at the component terminal rather than at the wiring end connector. Making a connection at the wiring end connector could result in false readings because the meter will not pick up a high resistance between the wiring connector and the component.


Starter Motor Feed Circuit

1. Prevent the engine from starting by disconnecting the ignition coil (12029).

2. Connect a remote starter switch between the starter solenoid S-terminal and the battery positive (+) terminal.

3. Connect Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent positive lead to the battery positive (+) post. Connect Rotunda Digital Volt-Ohmmeter 007-00001 or equivalent negative lead to the solenoid M-terminal.

4. Engage the remote starter switch. Read and record the voltage. The voltage reading should be 0.5 volt or less.

5. If the voltage reading is higher than this, indicating excessive resistance, move the volt-ohmmeter negative lead to the starter solenoid B-terminal and repeat the test. If the voltage reading at the B-terminal is lower than 0.5 volt, the concern is either in the connections at the solenoid, or in the solenoid contacts.

6. Remove the cables from solenoid B-, S-, and M-terminals. Clean the cables and connections and reinstall the cables to the proper terminals. Repeat Steps 1 through 5 above. If the voltage drop reading is still higher than 0.5 when checked at the M-terminal or lower when checked at the B-terminal, the concern is in the solenoid contacts. Remove and replace the starter motor or starter solenoid, if available.

7. If the voltage reading taken at the solenoid B-terminal is still higher than 0.5 volt after cleaning the cables and connections at the solenoid, the concern is either in the positive (+) battery cable connection, or in the positive battery cable itself.

8. By moving the volt-ohmmeter negative lead toward the battery and checking each mechanical connection point, the excessive voltage drop can be located. When the high reading disappears, the last mechanical point that was checked is the concern.

 

[kustomizingkid]

I would upgrade the main power feed to 0 or 2 guage. Also, what kid of grounds to you have going from the motor to the chassis?

 

[unity]

I would upgrade the main power feed to 0 or 2 guage. Also, what kid of grounds to you have going from the motor to the chassis?

There are two 4 gauge grounds from block (not heads) to fenders and one connection from block to the normal battery grounds.

 

[kustomizingkid]

Damn, sounds like you are covered when it comes to grounding. Maybe you could use some exhaust wrap or a heat sheild to try and keep the starter cooler.