My 39 Caddy starts fine when it is cold, the starter cranks the engine fast and it starts quickly. I drive the car 25 or 30 miles then shut it off. If I try to start it again while it is warm the starter will just crank the engine slowly. The 346 has been over hauled and has 500 plus miles on it. The distributor has new points & condenser. The starter was rebuilt with high output field coil. I have cleaned all battery cable connections (they are 1/0 cables). I also replaced the ground strap going from the engine to the frame. The car has a new battery. We have checked the starter & battery cables for resistance, in the process found a bad master disconnect switch that has been replaced. When we did the tune up on the engine a friend used his distributor machine to adjust points. Any suggestions what to do next? I am hoping to drive the car to Columbus next week.
Bob Nixon
#16285
I recently had a similar condition with my '49. After driving on the highway for 30 miles, I turned it off upon reaching my destination. I had to re-start the car to move it to another spot and it cranked very slowly as if the battery was very weak. After sitting a while, it cranked fine.
I checked my generator belt and found it a bit loose. After tightening the belt, it has been performing fine. In summation, check the tension on the generator belt. Perhaps it's not putting a proper charge back into your battery.
Ray Schuman
Sounds like you have checked most of the obvious stuff with the electrical system. A good battery and charging system are essential. You should make sure the ground path to the starter is good, I run the ground strap from the battery to one of the starter lugs to make sure. Remove any paint between the starter face and the bell housing, you need a really clean connection here.
I suggest you get a lot more miles on this car. 500 miles is not very much since a rebuild. Your engine is probably still pretty stiff. Slow cranking when hot is common in these engines, they all seem to do it to some degree. My '40 still cranks slower than I would like, but it always fires up anyway.
Bill.
You mention a master disconnect switch.
Is it hooked up with a battery cable going to it and then a 2nd cable continuing on to the starter? If so, are the cables going to and from it significantly longer than the single battery cable they replaced? If so, this might be a source of added resistance which in a 6 volt system can be just enough to cause the problem you have. A friend once had this very problem with a '49 and could only cure it by discarding the master switch and replacing the 2 cables to and from it with the original single cable.
Electrical conductivity is reduced as the metal gets hot. This could be the resut of a lose connection at the strarter, or a missing heat shield. Since the engine was rebuilt and came out of the car, re-installation of any heat shield may have been overlooked. This is common in 1960's and 1970's cars of which I am much more familiar with. Electrical properties don't change no matter the year. I would look for a weak connection or heat related issue.
Good luck,
Scot
I went through a similar problem with my 50. As Jay and others stated, at 500 miles the rings are still tight and as the metal expands from the heat, there is more drag on the pistons making the starter work harder. 2, I would rather see 00 cable on any 6 volt system. Cadillacs pull a huge amount of current to turn the starter and the tight engine only adds to the strain. 3. What is the current rating of that kill switch? The "little green wheels" are not appropriate for the Caddy 6 volt units, they are a current bottleneck. The knife style is a hair better, but in my opinion, lose the kill switch and put the starter cable directly to the battery. At least give it a try. Properly tight, the cable can be easily removed with a slight twist. Ron
A friend of mine has a 41 and his did that same thing. Rebuilding the starter again helped.... Notice I say again.. Most of the trouble was in the big switch on the top of the starter that activates the starter. theres points in there that weren't makeing good connection.
Chris
Go with 1 gauge battery cables...
I would start by checking voltage drop when cranking.
great suggestions by everyone
for the cables, maybe a 1 ott cable would be better choice, quite a bit more current carrying ability than 1 gauge cable
also ,on the disconnect, that may be part of your problem
even a perfect connection will have a little but of voltage drop across it
plus the disconnect switch may be less then perfect, the drop may not be significant to a 12 v car but is for a 6 volter
if you want to keep your disconnest switch, install it after the starter connection
run 1 piece cable to starter, them from starter to disconnect they the other side of disconnect to car
bit more cableing ,but then you have full uninterrupted power to starter