The Stovebolt Site Forums The Shop Area Engine Shop hard start when hot

I have been driving my truck lately and took it on its longest ride in some time, about 12 miles each way.

I drove there and hung out for about an hour then drove back no problems either way. After getting home I shut the truck off and tried to start again 5 minutes later and it turned over really slow then a little faster but would not catch. it was a nice leasurely drive nothing over 40MHP. (Not like my test drives)

I ran the battery down a little so I jumped it and she started right up.

I may have a battery problem but can't rectify the slow crank to the fast crank. Is this an over heated starter or a vapor lock problem?

This has happened before. Temp gauge never goes over 180 degrees.

6v system?

If so, are you sure you have 6v battery cables? They should at least be 2 gauge and even thicker cables are better (1, 0 or 00 gauge).

The starter is less efficient when it gets hotter. This is more noticeable, the older the starter. It might need to be rebuilt or replaced.

Were it me I would do, in the following order (testing after each step to see if the problem is fixed):
1: Verify battery cable size as Tim mentioned. Replace if necessary.
2: Clean the battery cable ends (pay special attention to the ground cable).
3: Load test the battery. Replace if bad (the more CCA the better).
4: Test starter. Rebuild or replace if bad.

If you don't have it fixed by then you have larger problems.

I would also make sure I had the thermoplastic insulator under the carburetor and verify that the float is proper and that fuel isn't dripping into the manifold after a hot shut down.

Stuart

Guys

I believe the cable is 00 but will confirm.

The starter is old and the only work I did on it was to clean it up. Seems to work fine 95% of the time. I have a local place that can check it.

I will also check the grounds but they too are all new (like all the wires and cables)but it doesn't hurt to check

I do have an insulator under the carb. I have had sevral carb issues but it seems fine now.

The battery is suspect. I have tested it with a hydrometer and it seems ok. But that is not a definitive test. How do you load test a battery? I have never done that.

Thanks for the help
RB53

Take it to a local supplier auto zone , napa, pepboys etc they can load test to verify battery integrity. Most have a computer analsis and will do it free as they know you will buy a battery if it fails.
Brad

Rich, have the starter rebuilder, rebuild it, it should only run $75-$80 then you won't have to worry about it till they plant you. Clean, Clean, Clean. That's the biggest problem with our 6v systems. ALL the connections and switches have to be CLEAN and a good battery and generator and it will operate just as good as a 12v system. The main reason they went to the 12v system was to save material, the wiring is a lot smaller than it is on the 6v systems. You can imagine how heavy the complex wiring harnesses of today would be with all the electronics if they had stayed with a 6v system.
Denny Graham
Sandwich, IL

Something also to think about is percolation- I find on my 1/2 and 3/4 ton that when the engine gets warm after a drive, then I park, then after a short period- less than 1 hour or so, I need to put the pedal to the floor to start the truck- It starts right up then- It does not explain the slow cranking, but might be worth the try- But a service on the starter is not a bad idea- a clean electrical system is a happy electrical system.
BTW I have Carter W-1's on all my trucks
Sam

Sam, as you may have read, I've been doing some experimenting with the W-1 that's on my 216. First it goes without saying that the heat valve has to be completely free. Most of the time the thermostatic spring is shot, they rust out where they slide into the shaft. If you have a new one installed then it probably needs calibration. I was having the percolation problem with mine and did a lot of temperature measurements on the manifold and the carburetor. The problem completely goes away if I wrapped the base of the carb with a wet rag right after shutting down. This told me that the heat was rising up from the manifold after shutdown and heating up the fuel in the foatbowl. The level was set correctly and I even tried lowering it a little but that made no difference. If you ever get a chance to look at a Hudson Hornet you will see heat shields under the dual carb float bowls. Apparently they had percolation problems right from the factory. http://www.pbase.com/dennygraham/image/116683197

When I installed the new spring (not Genuine GM) it was to tight so I started winding it tighter to relieve the bias on the valve and I now have it where when at cold idle it holds the valve closed but as soon as it starts getting hot the valve will stay open at idle. This seems to have relieved a lot of the hot start problem. Apparently the balance between the counterweight and the bias spring is quite critical.

And yes, a sluggish engine rotation has nothing to do with the fuel mixture, indication of bad connections or weak battery, timing advanced to far, a bad starter, or a tight spot in the engine, in that order.
Denny Graham
Sandwich, IL