Reproduction Parts for 1916-1964 Chevrolet Passenger Cars & 1918-1987 Chevrolet & GMC Trucks
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I took my 36 to a local car show yesterday and I missed Best Pre-War Stock by 2 spectator votes. I think my classic car club had something to do with that! This was the first time I've had it out since I resolved most of the issues it had. But that 10 mile trip brought up a couple more. It's got a new battery, rebuilt generator and new cut off. When running the amp meter sits just on discharge edge of the zero mark. Figured that is just where it sits, but when I turned the headlights on, it went to full discharge. Although I wired the cutoff like it was marked, do I have the wires crossed, or can I cross them? Or?
Second, when I stopped, it dumped white foamed up coolant out of the overflow tube. I've mentioned this before and it was suggested that the water pump was cavitating. During my recent work I wondered if it was getting hot, since at the time the temp gauge wasn't working. I flushed the cooling system, added about 40% coolant, (here in CA I don't need any more than that) and added some water wetter just for luck. Now that I have a working (and calibrated) temp gauge, I see that it runs at about 150-160, so it's not hot. The 36 Manual doesn't mention a thermostat except it might be needed in cold climate. The 37 manual says 142 or 162 degree thermostat. Cavitating would indicate that the water pump is just spinning and not pushing any coolant, or maybe there is an air gap? But the engine temp seems normal, so coolant must be moving through the system. In 50s-70s V8s, no thermostat causes the engine to over heat because the coolant isn't in the radiator long enough to cool down, but those are pressurized systems. I assume the same would be true on my 36. I can see coolant in the bottom of the fill neck. Ideas?
Thanks
Ken
Ken, First lets debunk the thought that coolant can flow too fast through the radiator to cool. It is and has been spread for a few generations but that does not make it true. In your case the fact that the coolant temperature or 150-160 deg. F is being measured at one of the hottest locations in the cooling system supports it being untrue.
The white (or other colored) foam being dumped when the engine is air mixed into the coolant. The most often cause is air being drawn past the shaft into the water pump. It may or may not result in cavitation. It is a similar to making whipped cream. Air mixed into an liquid. If cavitation then flow through the cooling system is reduced and overheating would be expected. If the coolant level is too high some coolant will be dumped when the engine speed is reduced or stopped.
I suspect that the generator has not been polarized. All it takes is instantly shorting across the output wire. It orients the magnets to begin to generate power.
How sweet the roar of a Chevy four
Participant on Chatter since 11/22/2001
19758 posts on the former Chatter site
I'm no expert with electricity. If I understand correctly, I run a wire from the terminal that goes to the battery to the block or ground? For the water pump, do I just tighten the bolt on the water pump shaft?
Thanks for the information Chip.
Ken
Regarding polarizing the generator...
NO!
Don't jump a wire from the battery terminal to the block!
If your car has the original style cutout, the simplest way is to use a jumper wire from the battery terminal on the cutout to the generator terminal on the cutout.
In other words, just from one side of the cutout to the other.
Just a light brush of the wire and a spark will do.
Ole S Olson
Saskatoon, Sask, Canada
1946 DR 3/4 ton stake
1139 old site posts
Tightening the packing nut will help if there is still enough to compress a bit around the shaft. A partial turn on the grease cup will also help seal out air. If the shaft is corroded it might need to be replaced, additional packing may be needed or the pump rebuilt if it continues to suck air.
How sweet the roar of a Chevy four
Participant on Chatter since 11/22/2001
19758 posts on the former Chatter site
Thank you to both of you.
Ken
Stovblt, I did that, and nothing changed. Still discharges.
Ken
Are you sure the generator is even trying to charge?
Check for voltage at the armature (output) terminal on the generator when it's running.
Ole S Olson
Saskatoon, Sask, Canada
1946 DR 3/4 ton stake
1139 old site posts
I thought I sent this, but my computer says something went wrong, so you may get this twice
I disconnected the wire from the cutoff to the battery and did more testing. I do not get any voltage at the cutoff wire coming from the generator. I just had this generator rebuilt and they put on a new cutoff, so I assumed that part was good. I guess not. Monday I'll take it back to them and listen to their excuse and then tell them to re-do it.
Well, I found the problem. I didn't know until I took the generator in to be rebuilt that it wasn't the correct one for my 36, but what the heck, it fit and should work after it got rebuilt, so I went ahead and had them rebuild it. Got it back, looked great, but I didn't have much of a chance to drive the car as I was working on other problems. So, when I did and discovered it wasn't charging, then I went to you fellas, and even that didn't work. Turns out, this generator is not grounded inside the case and the ground stud is insulated from the case. So the guy told me to just run a jumper from the ground stud to someplace on the generator case and it would work. And, it does! I'd never heard of such a generator, but since I spent $200+ having it rebuilt, I don't see a problem with using it as it does what it's supposed to do. One irritating issue taken care of! Thanks for all the help, even though it didn't solve the problem.
Ken
Ken, What is the Delco tag number on the generator?
Dave
Dave, sorry I didn't respond sooner, but I was under the weather for the last few days. Anyway, here is the number on the Delco tag, 935V 145068.
Ken
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