Hard Starting when Hot

[Gary H.]

Re: Hard Starting when Hot

Could be your battery. Not enough CCA to get the job done with a hot engine. Try to jump the car the next time you have an issue.
Gary

[Edward J.]

Re: Hard Starting when Hot

Terry, Wow a lot of ideas here on a hot restart- slow crank, I think Ken is on the right track- sometimes timing is a big reason for slow cranks when hot, stuck advance weights are pretty common on a old dist. the grease drys up and will stick the weights wide open, or just overly advanced base timing.

Have you had the battery load tested to make sure your not dealing with a sick battery. generally a healthy battery standing voltage is 12.66, But this sometimes does not mean the battery holds up well under a load, such as a starter load, which is why to have the battery load tested. sometimes the discount Auto parts stores do this test free of charge.

To check the starter health, If you have a meter that has a amp. clamp, Put it around the positive terminal and see the amps. the starter draws when cranking the engine over, You have fully warmed the engine and you sould see about 200 amps. when cranking engine.

[Paul O.]

Re: Hard Starting when Hot

One other quick check item that I have posted before is to check both battery cables even when the engine is cold if ether get excessively hot when starting the engine. There is a high resistance in that or both cables and the hotter the engine compartment gets the worse the problems gets. It is an easy check done with your hand as the engine is cranking on the insulation material of the cable. Much easier done on a mid year then a shark.

[Joe L.]

Re: Hard Starting when Hot

The issue that you describe is common. It happens to old cars with old wiring that have high resistance, just as you describe.

That's not what causes slow cranking when hot though.

Old crusty wiring, or other high resistance items along the entire system can/will cause the starter to do absolutely nothing when hot. Not even a click of the solenoid. If the solenoid plunger and washer isn't pulled into the battery terminal and motor terminal, nothing at all happens. No connection to the motor.

The problem that Terry is having is completely different. The solenoid is functioning correctly and passing current from the battery terminal to the motor terminal but if there is an issue with the coil or field winding's, the motor won't be near as powerful.

When the solenoid washer contacts both the battery and motor terminals in the solenoid cover, the rest of the entire vehicle electrical system is out of the picture and has nothing to do with slow cranking. Current flows directly through the washer to the field terminal of the motor.

Slow crank is not uncommon in rebuilt starters if the field winding is not up to original specs.

I have a small block starter in my 66 425 HP 427 car (for the last 30 years) and I have never had any issues with cranking, even when well over normal engine temp.

Michael------


In my case, I always got an "anemic" cranking response, not nothing at all. I had this problem for many years with the car.

Among the many things I tried was the installation of a brand new GM starter (including solenoid). The same problem persisted with the new starter. After I installed the slave solenoid I never experienced the problem again, not even in Death Valley in July.

[Dan D.]

Re: Hard Starting when Hot

As Paul said, clean the battery terminals. This is a common cause of hot cranking problems. This can also be a battery problem. Sometimes the plates will warp and short out one cell when hot and you loose the voltage that cell develops (2Volts).

A simple test to perform is to measure the battery voltage when cold and operating normally, both no load and while cranking. Place the meter leads directly on the battery posts. Then do the same test when hot and you have labored cranking. Compare the voltages from both conditions. A simple $4 VOM from HF will do this. -Dan-

[Domenic T.]

Re: Hard Starting when Hot

RESISTANCE!!
In my earlier post I refered to cooling the starter in the most primitive way, water. I only used water in a desperate situation.

My problem was with a fully restored car that had new bat, cables, distributor rebuilt & advance curves set, etc.

I doubted the cables and used 6 volt cables (larger).
I doubted the bat and tried another.
I switched starters making sure it was the GM high torque.
Then I cursed a bunch.
One thing that's hard to forget is that they didn't do it off the showroom floor as said earlier.
Lots of good advice and I didn't try Joe L method but the only thing that worked for me was a cool starter. we switched one on the rack while the engine was hot and the engine started as if it were cold.
It's a curse GM puts on starters so we buy new cars.

DOM

[William C.]

Re: Hard Starting when Hot

use a voltmeter across the battery connections AT THE STARTER to see what the delivered voltage is under cranking load. Measurement at the battery can give you a very false sense of security...

[Dan D.]

Re: Hard Starting when Hot

Measuring voltage at the battery will give you an accurate indication of the battery's health. Measuring at the starter and the battery, and comparing the readings will test the cable and terminal condition. -Dan-

[Enrico R.]

Re: Hard Starting when Hot

Mike------


The hard starting when hot syndrome was once-upon-a-time explained to me as being caused by high electrical resistance induced by high heat conditions in the "S" (purple) wire to the on-starter solenoid. The fact that a remote (slave) solenoid completely and permanently solved my problem completely supports the aforementioned cause. The fact is that if the problem were rooted in anything else, the remote solenoid would have done absolutely nothing to correct it.

The remote solenoid simply is a device to ensure that full voltage is applied to the "S" terminal under all starting conditions. Kits are available which include the solenoid, wiring, and instructions. Installation is relatively simple.

Is the "Purple wire" at the heart of this problem, then?
But the "purple wire" was there when my car was new ('68 327/350) and I never had the problem for the first 20 years I had the car.
Oh, I just remembered, A few years ago, I replaced my original engine harness (which includes the "purple wire") with a one I bought from Lectric Limited. Could it be that the Lectric Limited (or any after market engine wiring) "purple wire" is constructed in a way that makes it susceptible to high heat resistance? More susceptible than the original wiring?
Could it be that, if you've changed your engine harness, then you may be more likely to encounter the hot start problem?

[William C.]

Re: Hard Starting when Hot

Is the "Purple wire" at the heart of this problem, then?
But the "purple wire" was there when my car was new ('68 327/350) and I never had the problem for the first 20 years I had the car.
Oh, I just remembered, A few years ago, I replaced my original engine harness (which includes the "purple wire") with a one I bought from Lectric Limited. Could it be that the Lectric Limited (or any after market engine wiring) "purple wire" is constructed in a way that makes it susceptible to high heat resistance? More susceptible than the original wiring?
Could it be that, if you've changed your engine harness, then you may be more likely to encounter the hot start problem?

MUCH more likely that there is a problem with the connection between the engine wiring and the IP wiring at the "front of Dash" passthru. The metal connections are ore of a design named "twinlock which was a first attempt at miniaturization. They were not designed with a 50+ year life cycle in mind, nor to they take kindley to rough handling during service. With proper care in installation a new engine harness should reduce rather than worsen the problem...

[Ken A.]

Re: Hard Starting when Hot

You are correct re: aftermarket harnesses. They use less wire & more casing to achieve proper size but 16G is really 18G.

[William C.]

Re: Hard Starting when Hot

Ken, is that all the current reproduction manufacturers? I know when I worked at the old Packard Electric, we had a group that actually provided the original prints to vendors who were purchasing their components from us?