I'm racking my brain and run out of solutions... I have a 331 hemi in a 52 dodge pickup. I have a big 4 core aluminum radiator, electric pusher fan rated to move about 3000 cfm. 7lb radiator cap, no heater (I have a heater hose connecting the inlet and outlet for the heater), timing appears to be spot on. I finished the build not too long ago and finally took her out for a longer drive and she overheated(temp gauge basically max on hot). This was on a back country road, mild temp day, no stop and go traffic with what I would think was great air circulation. I have removed the thermostat, burped the system, and change the electric fan to start when I start the truck (use to not kick on until about 160 degrees) And she still runs hot. A friend mentioned about running rich, but I don't think it is, and the throttle response is great. Oh and it has a 700r4 so when I'm doing 55+ I'm pulling about 2000 rpms Thoughts on where to look next? Joe
Shitty California gas, everything seems to be running hotter than they did on leaded or unleaded with no ethanol. I had to speed up my water pump by putting on a smaller pulley. Is your trans on a separate cooler or in the radiator bottom. I personally don't like a pusher fan but I doubt that's all your problem. Your Dodge truck radiator area should be able to handle the 331. I had a 53 Dodge pick up with a 361 Chrysler and Torqueflight and didn't have a heat problem with the stock 6 rad. I didn't change the rear gears which were 4.10's as I remember so the engine ran a higher rpm and never had a load on it. That could be part of your problem. Drive it without using the OD and see if there's a difference. Good Luck.
Thanks Jimmy, I'll try driving it without using OD and see what happens. The trans has a separate cooler. I was concerned with room in the engine bay, oh and the stock fan is off, just the electric fan doing the work, again because of the room situation. I'll have to search for a smaller pulley to see if that will work.
Thanks Mike, The engine was rebuilt, with that said I did flush it when I had to drain it to take out the thermostat.
Did you check your timing? I chased an overheating problem in my '55 with a 327 for almost a year. Would start great, and run cool at highway speeds, but overheat quickly in normal traffic. It turned out that I had the wrong damper on it, and was timing it by the marks. My friend, Baron, timed it by hand, and figured out the problem. It now runs like, well, a Chevy!
I had a friend chase an overheating problem a few years ago. The temperature gauge was reading that the engine was running 240 degrees! He spent hundreds of $s, no luck. I said does it boil over? He said no, well then it's not over heating! He brought the car over, it was reading 230 degrees when he arrived. After it "cooled" down, I removed the cap and had him start the car and let it run till the gauge read 230 degrees. I put a digital thermometer in the top of the radiator and it read 182 degrees (180 thermostat). After all the expense and time, it was a bad gauge. Check that your gauge is accurate! KK
Also where are you getting the reading from, get a lazer thermometer and check @ different spots, like when the water goes into the rad and where it comes out, will tell you how much it cooling.
post a couple of pics of motor & radiator - there are very thin efficient electric fans that would be better used as a puller / with shroud if possible - if the radiator is in good condition should be running about a 16lb radiator cap - need some type of restrictor for water flow, try a 160 "big mouth" thermostat - what rate of coolant running? - where is trans cooler located? - do not run a 700 trans without having TV Cable connected and adjusted correctly - sometimes a radiator has too much restriction because has too many rows - have a coolant recovery tank? is it functioning properly?
Plenty of research to be done. Recall that water must stay in the radiator long enough to give off heat to the cooler metal so more flow may, or may not, be the answer. As said, check the gauge; are you in a 'boil-over' condition or just a hot reading? Do you have a shroud? .
X3 on confirming your actual radiator temps. You didn't mention it boiled over, just maxed the gauge, so first, confirm the gauge and sender accuracy. FWIW, don't believe the Chicom remote point and shoot devices either. I saw one of those reading way wrong; a mechanic friend calls them "random number generators." A probe in the radiator reading on a industrial gauge is going to be most accurate.
Do the early hemis have any coolant drain ports down low on the side of the block? Maybe some threaded plugs down near the pan rail? If so, try removing them and check that the passages are not restricted. Get some lengths of coat hanger or similar wire and poke and prod and root around in the coolant passages in the block and see if it dislodges any real rust or scale. If it's plugged up badly you might need to remove the expansion plugs on the side of the block to really get things cleaned out.
(as above) What is "running hot"? Is it boiling over? I'd run a 12 lb cap, instead of 7. Boiling point is hotter as the pressure goes up. What thermostat? I run either a 180 or 195 in mine.
A friend built a 409---2-4 barrel T bucket that after a half hour of street time became overheated.He changed water pumps radiators ,thermostats,fans,pulley sizes,etc and finally fixed the problem by running more coolant thru a sealed up frame that held more water and was also pressurized(the frame) so that the cooling system was enlarged by 3-4 gallons.
Wow, as always great help from this board. I will have a chance to run it tomorrow on the same path as last time, I'll bring my temp gun to check the temp compared to the upper hose and check for variance between upper and lower radiator hoses. I don't have anything more industrial. I'll order a 12lb cap to see if that will help. To answer other questions, I do have an over flow canister which gets full and then overflows itself below the truck, this is what happened after my last run. I have no thermostat, and run a mix that is more heavy in antifreeze then water. the Trans cooler is below the radiator and not in from of it. I don't have a shroud, the original truck never had one and the aftermarket radiator mat require modification so I'll look at that. Attached is a pic I had on my phone, I'll have to take a better one tomorrow.
Assuming the gauge is correct, the water pump is working, and thermostat isn't frozen, my experience is cooling problems are 99.9999% air flow problems. Pusher fan is a red flag; pushers cut an airflow pattern the shape of the fan thru the core. They do not use the entire radiator. Absolute best setup is a puller fan with a shroud which by definition uses the entire radiator core. All that being said, I use a totally wrong setup; a tall 30s radiator (with a new 3" core), and a pusher fan on my Willys with a '52 331 hemi bored 1/8" over to 354. No room for anything else. Home made Chrysler electronic ignition, stock compression, 60s Honest Charlie '3/4' cam whatever that means. It runs in the 220F range on 110F Bakersfield summer days. I would look really hard on the air flow side of the equation. And just read that you are running an anti-freeze rich mixture. That is a mistake. Nothing has a higher heat capacity than water - liquid, solid, or gaseous. Running too much ethylene glycol cuts way down on the cooling ability of the coolant.
Are you sure your pusher fan is pushing swapping the neg.-pos. wires will make it run backwards. This may sound basic but I have run across this.
Thanks, keep the suggests coming. I'll have to create shroud and I don't think I can fit a fan on the engine side of the radiator. I did check to ensure the fan is blowing in the right direction, I was thinking the same thing that is could be blowing the other way, but it is good. I'll look at putting the thermostat back in to see if that makes a difference. I drove it today for a 12 mile trip and she did great, It was a hard pull at times since I was going for about 100ft elevation to 1500 feet. One section is a 500 foot difference, at this point in the trip the temp gauge started to rise and I could smell antifreeze. once leveled off the smell went away. When I got to my destination, the laser temp gun showed 180 at the top of the radiator. There was a difference of about 30+ degrees from the top hose to lower hose and from points at the top of the radiator to the bottom. Outside air temp was around 63. Slight radiator fluid smell. I haven't swapped the 7lb radiator cap yet and was radiator fluid was missing this morning I replaced with water.
Ok so something new happened when I drove the truck back home from the place I mentioned above. The volt gauge kept going down while driving and as it got close to 8 volts the truck started to backfire through the carb, run like crap, and my brakes became very stiff. I got her home and the volts at the battery was 7.5 I'm running a 12 volt generator that was checked out and makes plenty of power, so I know it's not the generator. I need to test the voltage regulator (anyone have suggestion on the best way of doing this?) and I need to check my wiring from the voltage regulator back to the battery through the starter solenoid. I think this might be the cause with the truck running hot, as the battery goes down the engine misfires and raises the temp? I know some will say scrap the generator for an alternator etc, but I do like having it correct for the age of the truck. I may look at the alternator that looks like a generator, if I can swallow the price tag. But in the end the generator isn't the issue. I went into the garage the next day after the battery charged and she started right up and ran fine, the multi meter show a consistent voltage 12.33 on the battery as it was running, but no fluctuation when revving the engine. When I would use the turn signal or brake there would be a dip in volts but then would go back up afterwards, although not back to where it was prior to using the signal and brakes. I also have a master kill switch that I turn off when I turn of the truck, so there is nothing draining the battery when the truck is off.
Generator not generating and cooling pump not pumping, & fan not turning. Sounds like belt is slipping really bad?
They both need regulators, otherwise you could fry your battery even at moderate speed. Chrysler alternators (and Ford too?) have an external solid state regulator much smaller than the mechanical one on generators and GM has a solid state one built into the guts of the alternator so folks get to thinking there isn't one.
Thank for the idea on the belts, I did tighten them up but unsure if it is the issue. I do have to take it back out for a run, but while in the garage the battery volts (via multimeter) before starting was 12.58, then when started and at idle it dropped to 12.17. I rev it and no change in volts. When I turned on the turn signals the battery volts dipped. I hooked the multimeter up to the BAT terminal of the voltage regulator while running and had a reading of 12.11 when running with no fluctuation when revving the engine.
So I wanted again to thank everyone. It turns out it was the generator. It's been awhile, but I saved a bit and went with the Alternator that looks like a generator and now she's running great !!!!
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