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Starter slow when engine is hot

6K views 49 replies 16 participants last post by  emdoller 
#1 ·
I’ve read most threads I could find on this as I start to debug. I have a new battery and the car starts fine when cold. If I drive the car for 10min (it’s 97° here) and shut it down it sounds like it’s not going to start but always does. Just cranks real slow.

From what I’ve read it could be a bad starter / solenoid, bad wiring, bad lockout switch, or bad ground. The positive cable is brand new as well and high quality.

Where‘s the best place to start?

Ed
 
#3 ·
No headers. Stock exhaust. Car has AC so it gets warm under the hood. I was going to buy a remote starter switch do I could jump the purple wire to “S” to the 12v cable coming from the battery. I thought that would be an easy place to start.

Ed
 
#7 ·
I was inspecting the wires and noticed the wire connected to the R terminal that runs back to the coil looks a bit worn. It‘s my understanding that this wire switches 12v to the coil to aid in the car starting and shuts off once the key is released. I’m not really sure if it even was frayed whether or not it would cause the starter to crank slower. Hard for me to imagine that happening but looking for feedback.

Ed
 
#9 ·
What is your initial timing? If >10 degrees, try moving it back to 8-10 and see if it cranks better.
Keep in mind there are two battery cables and clamps. I had one ground cable that the lead clamp looked fine and everything was clean and tight, but it still wouldn't make good contact to the battery post. Try putting a jumper cable from the battery to ground.
If all else fails, remove the starter and take it to a shop and have it tested.
 
#13 ·
First place I would look is the entire ignition wire circuit and check that all connections are clean and tight. Inspect the wires for any damage/kinks.

In addition to the initial timing question asked by R66... What kind of distributor are you using?... and do you know if the distributor is using the lightest tension advance weight springs?
If you have a timing light, look at the initial timing when the engine is cooler (but can idle at normal rpm / no fast idle) and then check initial timing when the engine is hot. If initial timing increases when the engine is hot, the heat from the engine may be causing the advance weight springs to lose some of their tension... and cause additional advanced timing at start-up.

If you are using a "coil in cap" HEI, remove the cap and check that the the distributor's advance centerplate is installed correctly and the advance springs are holding the advance weights against the centerplate with no play between the two.
 
#15 ·
I came out to work on the car this morning and the battery was dead. Reason: my wife, who was cranking the car so I could measure the voltage drop, left the key on. So instead of introducing another variable, I’ve hooked it up to a charger and will get back at it tomorrow afternoon.

I appreciate the help.
Ed
 
#16 ·
I thought the readings that you took yesterday at battery and starter were when the car had not run. That is why I suggested to drive the car then check it. I thought we could compare readings at those two locations in a cold condition and it a hot condition. Sorry for the confusion
 
#19 ·
All the current to and from the starter motor runs through the big cables and there's no need to worry about the small wires on the solenoid. If the starter is slow, timing could be too advanced, the starter going bad, the solenoid contacts burned, not enough current due to a discharged/bad battery, or resistive connections/cables. I may have missed one or two...
Where is the big ground cable grounded? It's best to run it to to the block.
Measure the battery voltage after it sits, with the engine running, and while cranking.
Measure the voltage while cranking from one end of each battery cable to the other, as well as from the starter case to where the big ground cable connects.
You can check for hot spots at the big cable ends after cranking to feel for resistive connections acting like heaters.
 
#20 ·
Here’s a picture of the engine compartment. The battery is grounded to intake and also to the quarter panel. The battery is everstart maxx from Walmart (yea I know not the best) but I’ve never had an issue using them.

I’m charging it with a trickle charger and I believe it will be ok by tomorrow morning. Both the ground and positive cables are new. Bought them from Lectric limited (good quality).

I really want to know what the timing is.

Ed
265002


265003
 
#23 ·
Today I decided to start by setting the timing. Because this car has AC and PS getting a good view of the timing tab is a PITA. First a loosened the distributor and while doing that I of course moved it so not exactly sure where it was. However, I set it to 4° BTDC as that’s where it’s supposed to be. After doing this I took it out for a ride and i can’t believe how much better it runs. Like a different car. So that tells me it wasn’t right. After driving it a few miles and having the car running 15min or so while I was setting the idle and timing, it fired right up after shutting it off. Now granted, it’s 70° right now not 97°. I plan on running it around this afternoon to get it good and hot to see if it still has the issue. I’ll report back.

Ed
 
#24 ·
Just took the car out for a ride. I knew something was different as soon as I cranked it over cold as it immediately fired right up. After driving it in 95° for a while, I shut it off and it fired right back up.

I seriously didn’t think it was a timing issue. Can someone explain why this was happening??

Thanks so much for the help!!!!!

Ed
 
#25 ·
Timing can do that. Depends o your motor. 4* btdc is not much but I don't recall what you have. I am at 14* and as long as the battery is charged no problem. Stock timing specs were not necessarily for performance.
 
#28 ·
You may gain performance and milage by advancing the timing to 8 to 10 degrees, but without finding true TDC and using a degree wheel, I would recommend no more than 12 degrees. With ethanol, you could experience hot start problems with the new timing and also detonation.
The problem is GM used many advance curves in the stock distributors. I have found stock mechanical advance setups with 40 degrees that required a 2 degree ADC initial timing and also mechanical advance setups with only 17 degrees and 6 degrees BTC in the 70s smog cars. Some guys that set their total mechanical advance to 36 or 38 degrees with a 18 degree distributor are running 18 degrees initial advance and have your hot start problems.
If you are going to stray too far from the factory specs, I would recommend you do some research to determine what you have and what you can do. There are a couple of gurus on here that can help.

Ron
 
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