I have a 350 crate engine that is overheating at idle. I bought this car and did not build it. I have been sorting it out for about 6 weeks and I thought I had this problem fixed but I didn't. I replaced the thermostat with a new 180 degree unit last weekend and replaced the coolant. Today it was in the upper 80s and it's still overheating at idle. It has a large radiator, not aluminum, but it should be ample. There was no rust when I drained the system. It has one of those chrome Edelbrock water pumps on it and it has that convoluted flexible SS hose with about 1 1/2" i.d. on both the top and bottom. It also has a polished aluminum thermostat housing but I doubt that matters. The hose goes by the name Flexi Kool, etc. It has rubber couplings and a chrome sleeve that slip over the rubber couplings. The only two things I can think of that may not be up to snuff are the suction side hose may be too small or the water pump may be bad. I've never seen a non-leaking water pump go bad. So, I'm looking for experienced suggestions here. The engine runs at about 190 degrees when cruising (higher than the 180 degree thermostat) but will climb to 240 or higher when idling and start to boil. Not good. Thanks for your help.
You didn't mention a thing about a fan or shroud. Thats one of the most important parts while idling.
You didn't mention a fan shroud, i added one to my truck and no more overheating at idle or low speeds. I've driven in 100+ degree weather in traffic, at stoplights and climbing uphill and have yet to see my temp go past 195.
Oops. Has a flexi fan and a shroud. Good airflow. A sheet of paper will stick anywhere on the condenser.
try a back flush on the rad. while I was building mine, a rodent made a nest in the rad while it was off. can't hurt
in order to cool you need just a few things. flow of coolant heat transfer into and out of coolant big enough radiator. air flow most of that is easy to check. the apparent problem is the heat transfer in the radiator. sometimes they get a buildup on the inside and that actually acts as insulation. check that out. Edit: Maybe some genius powder coated the outside of the radiator
Get rid of that flex fan and get a quality steel fan and shroud it, but sounds like a timing issue also.
Man your problems are timely for me Rock. So much to learn. Profited from the take-home message in the MII thread . . . guessing that one of the take-home messages here will be . . . Electric puller. Going to school on this '54
FNG here, just something cheap to check make sure that the suction hose out of the bottom of the radiator isn't collapsing, especially while the system is hot. This will restrict the water flow in the system. Also there should be a coil spring in the suction hose it to keep it from collapsing. Check timing, make sure the T-stat works, fan shroud is a plus, good quality fan, back flush the radiator. If non of the above corrects the issue replace the radiator with a fancy expensive new aluminum one.
Where is your vacuum advance line plugged in? You want manifold vacuum, not ported. This causes many SBC to idle hot, mine included, switched to manifold vac and problem dissapeared.
I have the same problem. Its the radiator. I am not sure what you have, but mine is a recored stock in my 40 chevy. It works fine by itself, block a little air with the condensor, and she is right on the line. Anything above 80, she will over heat when at a light, and never quite cools down once rolling again, the radiators capacity is maxed... You can take a house hold square fan, and put it in front of the grill on high, and it should be enough to keep it controlled, if it does, and like you said paper sticks to the front, then its the same problem.... If it does not, then your pulleys might be turning the pump to slow.... Or some blockage somewhare
Now this is the kind of stuff I'm looking for. I do smell raw gas at idle. My stainless steel hose isn't collapsing. I've got good airflow. It's a fairly new radiator. New thermostat. Etc. etc. I'm going to check the timing.
Pictures please,base timing and vacuum advance,what are they,what size pulleys are onit,fan needs to be half way out of shroud
Just checked and the vacuum advance is hooked to the ported connection. Jesus. I don't think much on this car is right. There is another vacuum line connected to the manifold vacuum port. It is connected to to vacuum switches under the dash. Is that for the torque converter lockup? What else could it be? I'm going to know this car before I'm done, even if I didn't build it.
2nd on getting rid of the flex fan if its aftermarket,I had one years ago that would heat up at idle and as soon as I put a stock fan back on troubles were gone. I try to use factory flex fans from a/c equipped cars on my projects.
just because radiator is "big enough" and no rust when flushed does not mean it is not clogged. take it to radiator shop and have it checked for pressure test and overall condition. raw gas smell could be carb float problem or too big jets.
Am I probably correct on the "other" vacuum switches! If they are for the lock up, does it matter if they are on ported vacuum or manifold vacuum? Since timing is easy. I will start with that on my attempt to cure my problem.
There may be an unused manifold vac bib on the carb. If the bib is below the throttle blades it should be manifold vac. I have had to put a tee in a tapped and plugged hole in the manifold to get manifold vacuum. I had this problem on a car and was at a car show when a guy pointed out the the vac lines was on ported vacuum. I made the switch and it instantly cured the overheating at idle problem i had with that car for a long time.
I'm a '51 Merc but SBC and this is my car. My temps don't climb super fast but once it's up there, nothing short of driving 60 mph will help the temps drop. One of my culprits is my big cam + tight converter. But I'm going to swap in a new aluminum radiator for $300 too since my radiator might be from the 80's. And a shroud.
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