Ok I guess it’s time to bring it to the pros. I’ve been on here for the last 3 days and nights reading every thread I can find about this. Tried a few things I found on here, but no remedy yet. This is a first fire up minus run on a motor stand after rebuild about 9 years ago. Start with: 1957 392 rebuilt basically stock with a very mild cam. Stock valves, not bored over... blah blah Hot heads BBC pump, cross over, intake. Blocked off at rear heads. 180 thermostat with two 1/8” holes drilled Bypass run from water pump to back of cross over (see photo) 16 radiator cap Speedway aluminum’32 radiator HH stainless freeze plugs cause first fire up and one stock one shot out... First problem was I left radiator cap off to burp it and temp got to 140 and radiator shot coolant like a geyser. I put cap back on and it seemed ok, sat at 195 for 10-15 minutes and I shut it off. It did push a lot out of the overflow tube though. This last time it gets to about 185 degrees and then bam shoots up to 220 and climbing and radiator pukes everywhere. thermostat checked in boiling water, opens as it should. Took gauge sender out and checked that in boil water with a thermometer, it’s good. I initially suspected temp sender because it’s very slow to read temp, then it falls extremely quick. Also my electric fan sender does not seem consistent. Like it’s not reading water temp, but maybe steam sometimes and water sometimes? Both senders are in HH manifold ports at the front of the motor. radiator is higher than block and I had the front wheels up on stands. Is it possible to have this much air in the system? where should I go with this next?? thanks!
Sounds like it has a big air pocket trapped in it. Try filling it with the temp sender out to allow air to escape while filling.
No water in oil, no water dripping anywhere. I’ve broke in several chevy motors, but It’s my first mopar and I’m trying to learn...
What is the brass fitting in the intake manifold for ? I believe the stock location for the temp sender is in the rear of the water crossover manifold ( yours has a hose connected there ). I would make sure that hose is not full of air ( connected to the top of the pump ). Mine connects to the front of the water crossover , it's a really small 90 degree hose ( very similar to stock from memory ).
Brass fitting on water pump, brass fitting on backside of crossover. Hose connects them for my pump bypass. brass fitting on intake manifold is temp sender. Passenger side has the same fitting for my electric fan sender. Both are front of the HH manifold
Only 3 pic?,more would help,,The water pump pulley an crank pulley look missmatched size wise in pic=water pump running too slow for rpm. Pic angles not real good though to really tell; Can be lot of other stuff or combo of.
Gee, I wish I had an answer for you, but it's all that I can do to get my Hemi to 180. Most early Hemis are kinda cold blooded due to the amount of coolant they hold. I hope you solve your problem, they're great engines! KK
I'm not seeing a mechanical fan so I'm guessing the electric fan is on while you are getting this figured out ? I am not sure of the function of that location on the intake manifold on later heads ( 55-58 ). It is a leaving water passage on 1954 and earlier car and all truck heads ( 331 all -354 truck ) I believe .
There are reverse rotation BBC pumps. Presumably if you got it all from Hotheads it would be correct but it couldn't hurt to ask.
I am aware that OTHERS make a reverse rotation pump. What I do know is that the reverse rotation era pumps on both big and small block Chevrolet engines are long style water pumps. What I also know is that the pump that is utilized on the adapters from Hot Heads is a SHORT style pump (and what is shown in his picture is a short BBC pump). How I know. There is one on the front of my Hemi. Weiand makes two Action-Plus water pumps for the Big Block Chevrolet: short and long. Your choice: as-cast, or polished. All are standard rotation.
How high are you filling the radiator? Modern cars push coolant out to a bottle when hot, and suck it back in when they start to cool down. That is a recent-history thing. Old-school rides just have an overflow tube. My suggestion is to not fill the radiator to about 2-inches under the lip that the lower seal on the cap sits on, so long as that covers all of the tubes. This gives room for the expansion of the coolant when it gets hot. Without room for expansion, it will come cranking out. Systems like this should theoretically self-balance, meaning that once they puke once, the level should then be correct. I would rather see a 13lb cap on there, rather than a 16lb cab, though.
I can switch to a 13 cap... I filled it a little high the first time, but after it puked out into the bucket, I left it with some room. That was when I had the temp shoot up from 185 to 230 almost instantly. Is that my air bubble converting to steam and causing some kind of expansion and more heat?? I got one of those fancy radiator burp funnels. I was thinking of pulling the thermostat and running it without one to see what I can get out of it... maybe the combo of air/steam and a 180 t-stat not opening fast enough to bleed the system before coolant get too hot is causing problems?
It sometimes takes a couple of heat cycles to get the air all out. I would run it through a few. I would leave the thermostat in, bur make sure that the the hole for venting steam is at the top. Thermostats don't like to open properly unless there is liquid contact.
OK, you aren't probably going to believe me but in my 73 years, probably 99.99999% of all overheating problems are due to bad air flow, not water side problems. I see an anemic thin electric fan, suspect problems with ducting into tthe radiator and out of the engine compartment.
I think that bypass hose is causing a flow problem. try just plugging the two with plugs and run it that way I run mine that way since I don't have a heater. The temp swings could be air pocket by temp sender. Burping system a couple times should help getting the air out. Rad fill level when cold about 1 inch below top of radiator for expansion.
GM offered an overflow kit as an option starting around 1946 to about 1955 or later…..It’s now available as a repop
I initially didn’t have the bypass hose and that’s when the problem started... added the hose in attempt to fix it. I can plug and try it again though.
GM did not make a Chrysler Hemi, or a '32 Ford radiator. Overflow is not the same thing as coolant recovery.
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