Operating temperature
- Thread starter daoust
- Start date
Pete Fl/Wi
Senior Member
Sorry to hijack your thread but I for the first time had overheating with my 40 with an 8ba. It was during our local summer fest parade which I have done before with this truck in same weather conditions and no problems. Had to be pushed off parade route. Not fun. I lost a gallon and half. I noticed this year when I started it up for the first time in the spring I had backfire in the exhaust and today I had same backfire. Only on startup does it backfire. I am thinking it's timing but before I dig into it I am looking for advice. PS have electric fuel pump, Skips pumps, stock fan and electric pusher fan. Temp was well beond 210.
Thanks, Pete
Thanks, Pete
You didn't say what year your car is. You can put a modified fan on the generator mounted ones but the crank shaft type has a pretty good fan but is mounted to low in my opinion. Attached is a picture of my 39 P/U with an industrial 6 bladed fan and a shroud. This blade is as quiet as the 4 blade and has a different air flow pattern. The stock fan throws the air toward the fenders and this blade moves the air back over the engine which I think is better. The end results with a 4 lb pressure cap, Skips pumps, no thermostats, 6 blade fan and shroud plus 2 bottles of Purple Ice are, runs at a fast idle for over 2 hours at 100 degrees outside temperature for over 2 hours and never gets to 180. Race the engine a little and the temperature comes down a few degrees, This was done at a National V/8 show in I believe 2006 with many readers of the forum that saw it. Don't ask me who made the fan, It came from the attic of Schramm Company. I cut the blades down and made the aluminum adaptor. It takes more water in the radiator (filled into the neck) more water flow (Skips pumps) and more air flow through the radiator (6 bladed fan). Any one of these items improve cooling some but all of the above get the perfect result. When going down the highway the air is forced through the radiator and cooling is good but when in traffic or long idles on a hot day is when the over heating occurs. With a clogged up radiator non of these improvements will help very much. One other thing is modern thermostats restrict the flow through radiator, any restriction of water flow causes a hotter engine. G.M.
Picture didn't upload. trying again. This fan has been installed for 8 years and over 12,000 miles and still works good. You have to make sure it's balanced and use grade 8 bolts. I check it frequently as I do with any modified fan and never found any problems. G.M.
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Pete parades are a problem with these cars in hot weather. If you lost a gallon and a half of coolant that will make it run hot. Why the coolant lose? You need a good 4 lb pressure cap, good means the rubber bottom end of the cap has to seat down on the brass washer like seat down in the bottom of the filler neck. ALMOST all of these caps are not seating down on that seat letting water escape out of the over flow tube instead of being forced through the radiator. Less water is going through the radiator plus there is a lose of water in the system. The attached photo shows a rubber washer used to make the pressure cap seat. Fill the radiator up into the neck. With a good pressure cap and a decent radiator the water will stay filled for months or even years. G.M.
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Pete Fl/Wi
Senior Member
Thanks George, I will check my cap. I did not think of that.
Pete
Pete
Old Henry
Well-known member
It looks like G.M. has stuck a rubber washer down in the bottom of the filler neck. Such will have the effect of raising the effective pressure of the cap much higher as the spring will be compressed tighter than designed to release at 4 lbs. pressure. Without knowing what that increased effective pressure is it would not be prudent to insert a washer as it could result in blowing something from excessive pressure.
Because there is no recovery tank on these old systems if they're filled to the top they can not help but lose a little water by the expansion of the water as it heats. It is totally normal to have a couple of inches of space in the top of the radiator to allow for expansion of the coolant without loss of it. Loss of coolant in a completely full system until the volume of the expanded fluid is the same as the cooling system volume is totally normal and should not cause any concern. It would be extremely rare to have a radiator cap that did not seal to keep the coolant in after "letting out" the excessive volume of coolant. If there is any resistance to twisting the cap shut that means the bottom of the cap is sealing at the bottom of the filler neck and compressing the spring appropriately. To try to increase the effective pressure of the cap by adding the washer at the bottom of the filler neck is asking for a big surprise somewhere IMHO.
Because there is no recovery tank on these old systems if they're filled to the top they can not help but lose a little water by the expansion of the water as it heats. It is totally normal to have a couple of inches of space in the top of the radiator to allow for expansion of the coolant without loss of it. Loss of coolant in a completely full system until the volume of the expanded fluid is the same as the cooling system volume is totally normal and should not cause any concern. It would be extremely rare to have a radiator cap that did not seal to keep the coolant in after "letting out" the excessive volume of coolant. If there is any resistance to twisting the cap shut that means the bottom of the cap is sealing at the bottom of the filler neck and compressing the spring appropriately. To try to increase the effective pressure of the cap by adding the washer at the bottom of the filler neck is asking for a big surprise somewhere IMHO.
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90 % of the pressure caps don't touch the bottom seat of the radiator neck. I haven't figured if it's the cap or the depth of the bottom seat. A thin washer won't raise the pressure enough to be a problem since the end of the cap isn't touching the seat plus it's a 4 lb cap so if it go's to 5 lbs it won't hurt anything. They went to a 7 lb cap later.
A 4 blade fan with a shroud will help some but a 6 blade is much better for slow speed or in traffic. The best way to test cooling is with a large house type fan AGAINST the grill with the engine at a speed of about 15 to 20 MPH. This gives you the SAME conditions ALL the time. I have done this test at least a 100 times developing and testing cooling improvements. The test results are the same as the driving results after doing the tests. Drive testing is hard to repeat the same conditions every time. Even the wind direction effects the cooling. G.M.
A 4 blade fan with a shroud will help some but a 6 blade is much better for slow speed or in traffic. The best way to test cooling is with a large house type fan AGAINST the grill with the engine at a speed of about 15 to 20 MPH. This gives you the SAME conditions ALL the time. I have done this test at least a 100 times developing and testing cooling improvements. The test results are the same as the driving results after doing the tests. Drive testing is hard to repeat the same conditions every time. Even the wind direction effects the cooling. G.M.