Hard/Slow Crank When Hot

Thanks for the replies.

Today I replaced the negative battery cable. I also confirmed that the ground was a clean, unpainted contact. I also recharged the battery.

I let the car idle for a while just like I did the other day to let it get warm. It started ok...repeatedly. The true test will come when I get back to driving it regularly.

https://www.youtube.com/watch?v=zTVzTdfCj6Q

 

Sounds like it is still dragging a little.

 

Maybe you should upgrade to the Ford style starter solenoid. mount it on the firewall or somewhere out of the exhaust heat.. This makes a big difference....
Good Luck, Gary G

 

It will make NO DIFFERENCE AT ALL on a starter that cranks the engine slowly.

It can be a miracle-worker on a starter that does not crank at all when warm.




When starters crank OK when cold, but crank slowly when the engine is warm, and the issue isn't overly-advanced timing, the problem usually turns out to be one of two things:
1. Failed battery (undercharged, sulfated, or simply too-low CCA rating.)

2. Failed starter (heat causes excess resistance in the internal windings, the resistance reduces the starter power.)

Of course, there are other causes, but those are by far the most common. I gotta say, melted front cam bearing is new to me.

 

Yep, both used a high volume oil pump and pushed bearing material around the journal area. When cold it turned over,but when hot the material grabbed the journal. Have you ever had to pound out the cam from the back to remove it?
gary

 

Yeah at first crank it is a tad bit slow. I'll continue to monitor this, with the expected plan of replacing the battery in the near future.

 

Make sure to check your starter current draw. If it is over about 150 Amps, it should be replaced. A worn starter is just going to take the new battery down faster. I've seen worn starters that drew 700+ Amps.

 

The big Delco starters can be OK at up to about 225 amps, especially on a big-block. 200 is more common as a maximum figure.

Thousands of years ago, I worked for a "mass merchandiser" that also had an auto service center. We tested customer cars for starter amperage draw as part of the charging/starting "power team test". There was a spec-book listing a bazillion cars and the allowable starter amperage draw--but I can't remember who published the thing. Perhaps Sun Electric, the manufacturer of our amperage/voltage gauge. At any rate, GM vehicles had the highest starter amperage draw, and while it was often listed at ~170 for small-block cars, the big blocks occasionally went as high as 225.

 

yep go to your local parts/shop and have them do a starter draw test .....in the old days we simply put our headlight on and watched if they went extra dim during cranking

we use to use those old Sun vat 40 boxes to test ....dont know what they use today

 

I'm working on an old memory- I went to work as an engineer in '84, and quit mechanic work for a living then. I just hated to sell a battery to a customer unless I checked everything out. It is embarrassing to have them come back a week later with a dead battery, when it turned out that (for instance) the alternator belt was too loose, but not enough to squeal. It's good to get updated! :grin: