Thread: 400 won't start after warming up

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I have a 1972 SBC 400 I put in my boat. When I first start it, it runs and starts fine, but after I go run it for a while it turns over very slow and acts like the battery is low. I checked the alternator and battery and they are both fine. If the boat sits for awhile it starts up no problem until I shut it off again. This is the second starter I put on it, trying to correct the problem. Please give any suggestions.

could be its heating up the starter sylenoid? sounds like what my dads tow truck did run it till noon shut it off try to fire it back up turns over slow soemtimes jsut clicks acted like battery was dead come to find out the starter and sylenoid were getting cooking hot and after it cooled off for a few minutes it would fire right back up. so maybe wrap the starter try to find a way to keep it cool maybe?.........scooter

Thank you. I will try a coffee can and insulation, unless you have any other ideas.

You can certainly tell it is summer time. This is the 3rd request for help in the past couple of weeks regarding the small block Chevys!

I would guess that heat is your enemy. Either the heat is keeping the solenoid from working correctly, assisting the timing in keeping you from starting, or giving your wiring difficulty carrying the necessary amps to get the job done.

You might want to take a look at these links to other posts...the idea of a remote soleniod will probably eliminate your troubles. But before you go to the trouble, you might want to make sure the timing is set correctly. The timing could cause this symptom as well. If the timing is on, then make sure your battery cables are not loose and the right gauge. Again, heat is your enemy. So if the cables which carry the load are under-sized then the heat will halt the amps from being transferred to the job at hand. If the timing and wiring are good to go, then moving the duties of the soleniod to a remote location (away from the engine or exhaust heat) then you shouldnt have any problems taking care of the starting whenever you request.

Here are the links...

http://www.clubhotrod.com/forums/sho...&threadid=1582

http://www.clubhotrod.com/forums/sho...&threadid=8035

Hope this helps!

Either a starter or solinoid problem. It's a cheap fix to replace the starter and try to insulate it from the exhaust manifold/header.

I would agree with the heat problem, I had the same problem with my mustang. I purchased a powermaster starter and solved all my problems. Look into titon or powermaster and get one of thier starters it should solve your problems.

You've got to load test your battery. A bad battery can build a surface charge that is enough to start an engine once, but not be able to crank quickly enough afterwards. After the battery sits for a while, it can build up that surface charge again.

Heat on a boat? Does it not have water cooled exhaust?

While your at it check the main cable running from the starter motor to the battery if it's to long and is only 50 amp and is over 2 meters you have a resistance probllem and it is heating up the cable therefor lowering the voltage and giving a hard start situation. Solution go up to 70 or 100 amp cable that should fix it. Do remember to do the same for your main earth wire as well.