Thanks to a lot of advice from this forum, my 1927 Chevy Jitterbug drove for the first time since the 1990s yesterday. The videos are too large to load, but she runs very clean and very smooth. I was able to stop all the various small water leaks by tightening the applicable bolts. There is one leak that is concerning. As you will see in the picture, there is a small round spot in the engine block, it weeps a very small amount of water. I am guessing this is a hole in the block that was fixed long ago, but I don't know. Any thoughts?
The engine is running very well, starts easily, and the timing sounds perfect. However, it seems that she is running very hot. Since I have no prior experience, I am not really sure what "normal" looks like. It was 35 degrees fahrenheit outside yesterday. She took almost two gallons of distilled water to fill. After running for about 15 minutes, as soon as she sat still for a couple minutes, the radiator cap came off and she was steaming pretty hard. Keep in mind, the threads are gone for the radiator cap so my cap is just an upside down can, so there nothing keeping it on except gravity. The fan and water pump shaft were both spinning rapidly throughout.
I think I need to confirm that the pump is working properly. But I do not know how to test this. Any other comments, thoughts, or remedies?
The block has been cleaned well, and I ran a lot of water through the radiator prior to remounting it. A lot of sediment and rust came of of the radiator when I flushed it. However, there is probably still rust and sediment in it.
I just rebuilt the water pump and it leaked some water around the packing nut when I first filled it. But after tightening it some, the leak stopped, so I would say its safe to assume it is sufficiently tight.
After doing some more reading and research, it seems like feeding her thermo-cure and attempting to carefully straighten some of the bent fins are the first remedies to attempt.
I concur the casting plug is likely rusting out from the inside. They are relatively straightforward to replace if it becomes a larger leak. In my experience, a plugged radiator is the most common cause of overheating on these 4-cylinders and it can be deceptive. You can flush them out both directions, have good flow, and they still overheat. A large number of tubes in the core can get blocked and you will still see good flow but the heat transfer will suffer. Try running the motor up to operating temperature and put your hand on the center of the core and feel outward to either side. You will probably find the core is hot in the center and much cooler on either side. On a good core, the temperature should be relatively even. Good luck!
I concur that most likely the core of the radiator does not transfer heat like it is supposed to.
Do you have a two blade fan or a four blade fan? If you only have a two blade fan, putting a four blade fan will move twice as much air.
Lurch's old honeycomb radiator didn't cool worth a damn, so last year I broke down and got a new core soldered onto the old tanks. Luckily, I found a local old-school radiator shop that did the work. The cost was $780. That was for a normal type, three tube copper radiator core. If I had gone the honeycomb core route, it would've cost over $3000 just for the core!!!
My neck threads were worn too, so I got a couple of old '27 radiators from another VCCA guy (Herb Sullivan) and had the radiator shop swap the neck on the top tank with one that had better threads from Herb's stuff.
Now, Lurch runs cooler and I can drive faster (35 mph) and not overheat. ;-) Since the radiator neck has good threads, I have a cap with a Motometer in it so I can see how hot the engine is running.
In 2017 when I rebuilt Lurch's engine, the block that I used had a LOT of rusty crud caked in the water jacket around the rear two cylinders. With a screwdriver and a clothes hanger wire, I was able to loosen that crap up and vacuum it out. I did this while the head was off so I had access to the water holes that carried the coolant from the block to the head.
Soooo, if you want to pop the head off, you'll be able to see if you have similar blockages at the back of the block.
BTW, the machine shop that bored out my cylinders removed all the freeze plugs and put new ones in. The plugs were for a Model T and the shop used JB Weld to ensure a good seal around each plug.
Hope this is helpful. Dean
Dean 'Rustoholic' Meltz old and ugly is beautiful!
Thanks for all the advice! I will definitely be purchasing an infrared gun to help isolate where the heat is coming from.
Fortunately, I made a rookie mistake and put the four blade fan on backwards! I suspect this will make a big difference in how well she cools. All things considered, she stayed pretty cool considering the fan was on backwards. It will probably be a few weeks before I have time to run her again, but then I'll know how much of an impact the fan has.
