Restarting problem

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Danno

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1972 Fastback, Sportsroof
72 302, new battery, fuel pump and coil all changed last year due to dying problem after about 20 minutes of idling or driving.

The car now starts and runs fine, but if I go for a short, 30-45 minute drive, shut it off for about and hour or so, and come back  to restart it, it acts it like it has a battery problem, very slow cranking. It will finally start, but "grudgingly".

It can sit for days, and it'll start right up when I turn the key, but after driving a while and going back, it really sounds like a bad battery/starter. Possibly a problem with the starter being close to  the exhaust manifold and overheating? I has a '66 that I installed a battery shield on for that reason. It has always restarted up to now, even tho it sounded like it wouldn't.

Any ideas?

 

mjlan

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1971 J Code Mach 1
1972 H Code Mach 1
So when hot the starter can't spin the engine very fast?

If so, it could be the battery cables degrading and having too much resistance or the starter getting hot and requiring too much current. This assumes that your battery is ok...

 

Danno

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So when hot the starter can't spin the engine very fast?

If so, it could be the battery cables degrading and having too much resistance or the starter getting hot and requiring too much current. This assumes that your battery is ok...
Shoulda included that all the cables are new too. Just went out and tried a restart after about an hour or so of being shut down, and it cranks strong.

 

Tnfastbk

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So when hot the starter can't spin the engine very fast?

If so, it could be the battery cables degrading and having too much resistance or the starter getting hot and requiring too much current. This assumes that your battery is ok...
Shoulda included that all the cables are new too. Just went out and tried a restart after about an hour or so of being shut down, and it cranks strong.

I would guess heat soak on the starter or Timing issues.

 
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I would also suspect the starter. When the bearings wear the armature gets too close to the field and will drag sometimes. 

You can take it off and take apart and see if signs of dragging but if apart easy to install new bearings and clean up armature. DO NOT SAND the armature pick up. The grit gets into the copper and eats the brushes up. You can also get new brushes and install. The trick to the brushes is to attach wires that hold the brushes retracted so you an insert the armature. Then you release the wires. If armature bad you would need to take and get turned on a lathe but no sand paper. 

I have a Ford van with tube headers on it and it was bad for starter to get too hot especially in slow traffic. Have had to let sit for hours to cool off so starter would work. It was bearings in it.

 

Tucaz520

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the ole hot start issue lol

for me i dreaded stopping for gas unless it was a splash and go. people would comment nice car etc.... then i would get in and cross my fingers it would start.

man i think everyone has suffered from it and has somehow figured it out but its different for each car.

for me i started with a spacer under the carb , made sure the hard fuel line was as far away from the engine as possible which isnt very far.

when that failed to correct the issue i started replacing ignition parts because nothing had been touched since the 90s on this car. points, condenser and a coil did nothing either. i was just about ready to try a high torque mini starter when my radiator sprung a leak. for some odd reason replacing the radiator made the issue 90% better.

 

Don C

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Your old radiator tubes were likely partially plugged. Even though the engine is shut off coolant should continue to circulate, as long as the thermostat is open. As the water in the block collects heat from the engine it gets hotter, expands, gets lighter and rises. The opposite occurs in the radiator, the coolant cools, gets denser and heavier and moves down.

The new radiator may have helped this circulation, as well as cooling efficiency, and helped remove the heat soak from the engine, especially the heads.

 
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