We have a 1957 Buick Roadmaster Conv that has been heating for years. We have tried everything we could think of including: - rebuilt water pump - larger diameter and more agressive fan - fan shroud - new 4 core aluminum rad - various diameter water pump pulleys - flushing the rad and block (repeatedly) - thermostat (currently running without) - checking block and heads for cracks Since we have done all of this, it now seems to only run hot on the highway. We will add the thermostat back into it, but I really would like to know what the original water pump diameter was. I want to ensure this is not a contributing factor. The car does not have AC, if that changes anything. Any suggestions or comments would be sincerely appreciated! Thanks!
Running hot at speed ,make sure air flow is going through the radiator and not around it ,over it ,etc.
The fan is a 19" diameter 429/460 ford with 7 blades. The fan shroud is custom built, basically a shallow box that encompasses all the cooling surface and a hole just large enough for the fan is sit in. Thanks guys!
The fan actually had a clutch but has been made solid by using two small welded tabs between the hub and the fan. I don't trust those things when it comes to heating problems, that is why it was made solid.
I would ditch it all together go for a stock type fan. Also get it as close to the radiator as you can.
This is poor advice. The large fan and shroud will move a much greater volume of air than a small fan with no shroud. I agree that you need to check to see if all the air entering the grille goes through the radiator. On cars of that vintage there was often a piece that mounts to the underside of the hood, sealing off the area above the radiator. Make sure it and the accompanying rubber seal are intact. Make sure all large holes in the core support are sealed. Also check to see that you have ample area for the air to exit to the sides and rear of the engine. ~Alden
Where is the fan located in proportion to the shroud? Half of the fan should be out of the back of the shroud, if the entire fan is inside the shroud it will not work correctly. My knowlage on early engines is a little fuzzy, but for 401-425 engines there is two different part numbers for the water pumps. A/C and non A/C an A/C pump has two more vanes on the impeller, otherwise they are identical. When chasing an overheating problem don't forget to check timing and carb jetting. Lean or retarded will cook an engine quite quickly. Good luck.
I just went through all of this in a Merc witha a 401 nailhead. Had major problems with it not cooling at idle. I tried bob diameters on the w/p pulley. The best for me was the small one. The small one is 4.5" and the large one is 6.5". Come to find out with my cooling issue was the cam over lap was too much. The water pump I modified the impellers to fit as tight as possible to the timing cover so there is no cavitation. A 180* thermostat. Which created too much cylinder pressure, that causes heat. Now the cam has a different profile, a Lincoln mk VIII 2 speed fan a custom shroud and performs perfect. One your fan set up you should keep it as stock as possible.
I've got a 1957 Century and have been fighting these issues lately too. Here are a couple things that I ran across: 1. The right side exhaust manifold has a valve to redirect the exhaust through the intake manifold and pre-heat the carb when the engine is cold. From what I've read, these are more trouble than they are worth, especially with modern fuels. The little thermostatic coil spring on mine was long gone, and it wouldn't move freely. I don't know that it's 100% to blame, but it's hard to re-start my Buick once it's heated up and sits for a few minutes. At a minimum, make sure your valve isn't stuck in the closed position. Best case, remove the valve and plug the holes where the shaft penetrates the manifold. 2. You might want to think about the transmission cooler, especially since your Buick overheats more at freeway speeds. The Dynaflows put out a lot of heat, and the transmission cooler on these cars is in the lower part of the radiator. It's possible that the trans cooler is warming up the radiator and preventing efficient cooling of the engine. You might want to get a laser thermometer and check the temperature of the top of the radiator vs the lower part where the trans cooler lives. 3. It's basic stuff, but check your gauge. My original guage doesn't have any numbers, just a vague (C - N - H) marking. I was seeing temps on the high side of "N", which scared me quite a bit. After installing an aftermarket temp gauge I found that I was only running 180-190 most of the time and seeing peaks of 210-215 on hot days. Many folks will say that's really not too hot for these engines, though I'm always happier staying under 200. I've also read that with modern fuels higher temperatures may be better for complete combustion, though my brain doesn't love the "pucker factor" of that situation. Is the coolant boiling or spewing out of the radiator, or are there other symptoms of overheating beside the gauge? You may be better off than you think. Good luck!
Have you checked to make sure the suction side of the radiator hose isn't collapsing? They usually have a spring in there to keep it from happening. The hose can collapse from the suction of the water pump at speed and block things up, but you'll never see it because it usually doesn't happen at idle.
Solved! Thought you guys might be curious, and I always hate it when the answer never gets posted... The magic ticket was to run a 170°C thermostat and to set the timing using a quality timing light. The car runs cool on a 100 degree day It never moved past the low side of Normal (175°F on the aftermarket gauge). I was convinced it was either the water pump or the wrong pulley diameter. THANKS FOR YOUR HELP! Happy cruising. - Preikster
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