Tried the search, but could not find the right answer. I have a 302 Ford motor with a 65 Mustang radiator in my project. The radiator is not aluminum it's br***/copper. I'm running a 13 lbs radiator cap. The car does not overheat (it stays at 180-190) but it dumps coolant after engine shut down. I just installed a dump tank, but I still believe a 13lbs cab is too low. Should I get a 16lbs cap?????? Thanks for your input.
I have the SAME problem...my truck runs right at 190*, SBC, and a '65 Mustang rad......will spit coolant out overflow tube when shut down... Running a 16lb. cap.(I think) I'm going to add a recovery tank....once I find something cool...no beer cans.
Try going way lighter first. The more pressure the more heat the coolant is allowed to hold all in all.
The top tank also acts as an expansion tank. If you fill it completely it will puke expanding coolant. A lot of times this will happen after shutdown because of heat soak. Adding a coolant recovery tank will allow you to keep the rad full and avoid coolant on the ground.
I wouldn't go to a higher pressure cap, as you might start to spew water out of different areas instead of the overflow. I would definitely go with an overflow tank, as the cooling system works on a sealed system and is designed for an overflow. When the water heats up and expands, it'll expand out the overflow. When it cools down, it is designed to '****' the water back into the cooling system, thereby negating any air pockets. Just think about whenever you're bringing a motor up to temp to make sure the thermostat it working. You fill the radiator, and wait... as it warms up, the water starts to expand and leak over the top of the filler neck. It keeps doing this until the thermostat opens and allows the water to flow and the level drops. Keep in mind too that when you've got a good water pump, it'll cause some 'flow suction' (for lack of better wording) each time you throttle up the motor. When you let off the throttle, you'll recieve a backwash from the release in that pressure and spill more out the top. Bottom line - add the overflow tank. You can probably make one out of muffler tubing or smaller diameter pipe and some stainless brake line. Weld a cap over both ends, but drill 2 holes in one end - 1 for a vent, and 1 for the stainless tubing to go into. I'd cut the tubing so it rests about 1" or so from the bottom of the tank to keep trash on the bottom of the overflow tank, but still allow water to be ****ed back up into it. The tank size doesn't have to be large diametered to hold plenty of water. A 24" long piece of 2 1/2" tubing is roughly equal to 1/2 Gallon capacity. Or - if you've got room and are running under a closed hood - find a overflow tank off of a car or truck that'll suit your needs. At the last swap meet I went to, there were several overflow tanks in billet, but if you were to blast it a bit and then paint it, it would disappear under your hood.
Hey Greg, thanks for all the info. I've already installed a tank as stated in my original post. I guess I'm good to go.
What's bad is that I didn't even see that part. I'd fill the radiator completely full and the overflow tank as well, and then just run it - but keep an eye on both the radiator and overflow tank levels. If everything is working right, it should 'level itself out' in a day or 2.
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