The Stovebolt Site Forums The Shop Area Engine Shop What causes hard/no starts when engine hot?

My 235 starts good when cold and many times when hot but sometimes when hot it cranks like weak almost dead battery and no fire. The battery is good, I've cleaned battery terminals, starter terminal and main ground lead to frame. This is 6V system. Thanks for any input.

IF your battery load tested OK and all of the connections are clean the slow cranking is likely a failing starter. Ignition timing advanced a tad too far could contribute. Other than slow cranking, hard starting when hot is common with these engines. The reason is heat. With the exhaust manifold in intimate contact with the intake, when you shut off a hot engine a lot of heat soaks into the intake system. It can vaporize fuel in the float bowl which can then flood the intake runners. Picture starting a hot engine with the choke on. Another possible contributor is the heat riser. If it's stuck in the heat on position there is far too much heat being directed to the bottom of the carb which will exacerbate the issue. Good luck with it. FWIW you'll likely always have it problem to some degree. It's just common due to the poor intake/exhaust design.

Edit: Tim makes a very good point. I had a senior moment and never considered the size of the cables.

BruceO,

What are the gauges of your battery cables and ground straps?

They should be 2 gauge or thicker/larger.
1, 0 (1/0), or 00 (2/00) gauge are better.

Try running a ground strap to a starter-to-clutch-housing attachment bolt.

Other possibilities:
- The battery is weak.
- The starter needs maintenance.
- You need a tune-up (timing/carburetor, points/plugs especially)

Disconnect all cable/straps, and clean them again, make sure they are shiny, and then coat contact surfaces with copper impregnated anti-oxidant anti-sieze "grease".

Something in the system is "marginal". This is not an uncommon situation.

Good luck.

I helped with the same problem on a '54 Pontiac straight eight. I replaced the cables with 0000 cable from work we had laying around. The old straight eight would crank much better and start every time, no matter how long it would crank after setting for weeks.

Joe

Thank you guys!!!!

I'm not too knowledgeable on the stovebolts. I'm coming over from working mainly on bikes and primarily dirt bikes. On dirt bikes, it is often a sign of running rich. Some bikes even have a "hot start" lever that works the opposite of the choke and allows extra air in for hot starts. Hence the name.

How hot? And where? Vapor lock at the fuel pump?

How would running rich and/or vapor lock cause ". . sometimes when hot it cranks like weak almost dead battery and no fire . . " ?

It wouldn't, as far as I know. I perceived you intended to make a statement of fact rather than ask a question, but that is a moot point. I hadn't paid attention to that in the original post and that does sound mostly like an electrical issue. If the starting is craking fine but it doesn't start, then I might suspect something more like what I normally see on dirtbikes regarding hot starting issues.