Hello, I hope somebody out there can help me with my problem because I am ready to lose my mind. I have a 1954 Chevy Bel-Air 2 door hardtop with the stock 235 inline 6 with powerglide. I have addied factory power steering, dual carbs with edelbrock intake and a split manifold. As far as the engine goes eveything else is stock we replaced the timing gear, and rear main seal and thats it. The problem I am having is when I drive on the freeway for about 5-15 miles it will start heating up the gauge will steady climb from the normal 180 to as hot as I will let it get. Now here is the wierd part I can drive around town at 35mph in traffic and it will never get above 180 and if I get off the freeway when it gets we'll say around 210-220 it will not get any hotter it is something about driving on the freeway. I have had the waterpump rebuilt twice, the radiator has been recored, the heater core has been byp***ed, two new themostats, I have flushed the coolant and block 4 times, I don't know what else to do or check so if anybody has some tips or something for me to try I would greatly appreciate it. Thanks, Greg
Does it have exhaust plumbed to the intake for heating it up? I had a Chrysler that did the same thing. The heater riser flapper was stuck. Is the trans cooler part of the radiator?
have problem before doing changes? where is trans cooler mounted? replaced radiator hoses with type that has wire inside? gauge working properly? timing/distributor working properly? checked for cracked head? why byp*** heater? did you just block off heater inlet/outlet or loop hose to each? sure have correct water pump? did a search here for other threads on this problem?
generally overheating at high speeds is a fluid circulation problem, could be as simple as your belt slipping ad not powering the pump fast enough also. could also be a collapsing hose under those conditions that only exist at speed. does you lower hose have a spring in it to prevent it crom getting ****ed closed?? Have you actually checked the temp of the coolant in the radiator when this happens. perhaps it might also be a bad gauge or sending unit.
Could be the carbs are leaning off at high cruise. That'll make it slowly heat up.Try pulling the choke a little bit at cruise, see if it runs easier or cooler.
The exhaust and intake are bolted together but we took the flap out the cooler is seperate from the radiator
Checked the belt it is good and tight. I do not believe the lower hose has a spring in it is very short so I had to use that black universal stuff so maybe thats the problem, I changed the stock gauge and put a universal sunpro in and have a Mr Gasket cap wit gauge so gauges are good. Thanks
I am using a va***e advance but will double check timing and weights but seems to run very well. Thanks
Did not really drive it to much before we did everything to it. Trans cooler is mounted in stock location which is right behind radiator mounted to the block. The lower raditor hose does not have a spring in it it is only about 4" long. as far as I know distributer is working properly and does advance. There is no water in the coolant so I would think the head is fine. The only reason I byp***ed the heater core is because the car sat for a long time and I did not want it to leak. I just have a long hose on the waterpump where the heater hoses would go. The waterpump is the original but has been rebuilt twice.
Can't tell from that...does the car cool down after you get off the highway in a reasonable amount of driving? If it cools down good, then I almost wonder if the water is going through the radiator too fast when you are revving so high with that old driveline ratio. I read about using a large washer inside the rad hose to slow it down. The washer is held with a hose clamp centered over the washer. If it stays pretty much over 200 for many miles after getting off the highway , it would make me think the rad size is a bit small for those driving conditions.
Have the block checked for exhaust gases in the cooling system. Most radiator shops should have a "BLOCK TESTER" that will tell you if head gasket is ok. Radiator shop can also tell you if the radiator is plugged too.
How much coolant are you running and how full is the rad.Coolant should cover core only. No more than 30 % coolant
I had the same problem with a '49 Ford with a SBF. Boiled out the radiator and now it runs cool all the time.
New doesn't necessarily mean that the temp gauge is good but I don't think that is the issue. Mechanical or electrical gauge though? I have seen top brand electrical temp gauges be 80 degrees off. On my buddie's A roadster the temp gauge read 260 but he could pull the cap off the radiator and the thing didn't spew any coolant. A test with a thermometer proved that the gauge was off that far. Late timing will also cause the engine to run hot at speed just as running lean will. Or blocked exhust. Any major grill or sheet metal changes on the nose of the car from stock? Missing panels around the radiator or something on that line? Where sitting still or going slow the fan pulls air through the radiator fine but when you get out on the road the air is going around the radiator rather than through it. Bomb's suggestion of wrong impeller strikes a note because the thing is acting exactly the same way that a sbc with V belts and a water pump made for a serpentine belt acts. I don't know if they ever put those engines in boats where the offside engine would run reverse rotation and need a reverse rotation water pump but stranger things have happened. Also some of the rebuilders over the years have used rather suspect impellers that don't push the water that well.
could also be too small of a water pump pully, had that happen with a 52 chevy coupe running a 235 dual 2's and split exhaust. would run hot on the freeway, changed to a bigger pully (i belive it was off a 283) fixed the problem
pull the plugs, are they white-ish in color? if they are showing white its running lean and you should fatten up the jets any spots on the plugs? brown spots indicate pinging, if no spots try advancing the timing a bit then take it back out and see what happens. if it ran cool before the changes it should be running near the same temps now
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