The Stovebolt Site Forums The Shop Area Engine Shop overheating...I'm stumped.

I had my 1958 235 rebuilt by a custom rebuilder (now dead). It ran well before rebuild. It runs well now with 2or3 hours on it EXCEPT after driving it will overheat if left to idle. I measured the coolant at 207. The block is clean inside (rebuild). On startuo the copper headgasket failed mixing water and oil. I had the head checked
(Flat/cracks/magnaflux/clean) new fiber/metal gasket---another new 180 thermostat-tested both and they opened right at 180. replaced water pump with short shaft from Patricks. New Desert cooler. HELP! Any Ideas.

Short Shaft pump could be the problem. Most of the short shaft pumpr set a little to low and don't pull air through the rad at the right place. Also a fresh engine will sometime tend to run a little on the warm side till broke in.

What kind of shape is the rad in did you get it cleaned or boiled if it's the old one and never been cleaned could be blocked so it's not flowing properly.the pump pulls from the bottom of the rad and pushes it in from the top when you start on a cold engine as the engine warms up you should be able to put your hand on the rad and feel the rad get warm from the top down across the whole rad and slowly move down evenly across if it's cold in a section it might be cloged.


Pete

make sure your fan is within 1/2" of the rad and fairly centered on the rad, otherwise you should have a shroud

Bill

Sounds like a fan problem, but what about pressure. A good system can handle a 7 lb. pressure cap.

Double check ignition timing.

When I replaced the water pump on my '60 Chevy it did the same thing. I would let it cool down, empty some water out of the rad, fill some more water in the top of the rad, and after a few times it stopped overheating. I don't know if it was air in the rad or not, but it worked.

Oh, while doing this process, I turned on the heater full blast to make sure coolent was circulating thru the heater core and push out any air. And I would start the engine and rev it up a little to push the water.

Is it overheating so much it pushes water out? or just getting hot according to the gauge? Have you double checked the gauge accuracy? Just how hot is it getting? Use a hand held infra-red gun if you can find one local, check the block, head, and thermostat housing, comparing the readings to the radiator tanks and core.

Most new engines, if built right, will run hot till they get some miles on it. Was it broke in correctly? does it have some highway miles on to seat the rings? is the timing and vacuum lines correct? is the vacuum advance working?

What about the fan clearance to the radiator, as stated above 1/2" or less with stock fans and stock idle rpm. A modern big blade fan can stand to be a little ways back from the core.

Desert Cooler radiators, are they copper 4 cores? or aluminum? Aluminum will be much more efficient and should have no problem cooling anything behind it. Some of the four core radiators have so many fins that they require a lot more air flow just to get through the core. Is yours a tight fin unit or can you see through?

Add a overflow tank or bottle so any coolant pushed out will be drawn back in once it cools down, this assuming you have a overflow tube and correct cap. If there is air trapped in the engine, the overflow should take care of it after a few cycles.

What about your cap? A new radiator will handle 14psi caps just fine, old stock units should stay under 5 or 7 depending on condition. My new aluminum radiator came with a 14 psi cap!

If you are not sure if you have all the air out, pull the thermostat out and push it open and stick a aspirin in it to hold it open. The pill will dissolve after you start filling the coolant back up, but not until all the air is out.

Typical coolant problems are cause by air flow at idle speeds and poor condition radiators at driving speeds, assuming the engine tune is correct.

Joe

thanx It is very new ( 2hrs and 30 miles around block ) It seems to overhaet if I drive it and then let it idle. The gauge goes up to 210 or so. I checked the coolent temp and got 207 with good thermometer. I got the pump with the 7" pully and large 4 blade fan and a 4core triple flow (US Rad) Desert Cooler from Patricks. I lowered the radiator 1 1/8" and the fan clearance is about 1/2". I pulled the new thermostat and replaced it after checking both on stove ( they were both spot on at 180. maybe your right and I need to break it in some more. Any advice on breakin? When it gets hot the oil press drops to 15-20 lbs at idle. I'm worried about that. It has 30W with zinc add. in it right now. Tom

Thanx It is the triple flo Desert Cooler copper/brass and it very tight compared wit the stock Radiator. I figured that would give it more surface area but now that you mention it air flow might be more of a problem. Anyway im stuck with it now and it took 3 times to get them to make one correctly so I don't want to do that again. It has the recommended 7 lb cap. I'm going to recheck the timing. I used a vacume guage and turned max vac 20 and backed to 17, new vac adv. rebuilt carb. New everything!!! RUNS GREAT!!! How do I check to see if it is running to lean at idle? How muck fuel press is required for the rochester (new AC vac assist fuel pump)
thanx Ton

Thanx I'll try that. I used my vacume guage, disconnected the new vac adv from the new distributor and plugged the line, then turned the dist to max vac (approx 20) and backed off to 17mmhg. valves are adjusted and engine runs good. manifold heat valve is free and I'll have to visually check to see if spring works properly. When the truck sits for a few days it it acts like the carb is empty of fuel (grinds a long time to start) after that it starts instantly. Might the carb empty into the manifold or fuel leak back into tank thru fuel pump? Thanks for your advise and any ideas are appreciated as they may lead to the solution, I've already had it looked at twice by professionals with no luck and great expence. I live in Seattle and haven't found anyone who is competent with stovebolts. Thanx TOM

Thanx The heater is shut off with the inlet and the outlet valves so it doesn't exist as far as the cooling system is concerned. I "burped" the system when charging it by removing the temp sending unit until all the air was purged. Anything else you can think of? THANX TOM

I had the same problem and I tried it all. New fan, waterpump, radiator, belts, radiator caps 0,4 7 degree pressure) and it still happened to over heat. This went on for two years.

Finally I put on the water pump adapter that fits the 261/235 engine. I moves the fan up a few inches in the center of the radiator. I never have the over heating problem anymore.

IMO: I have tried it all and nothing works better than that adapter. And I installed in while the motor was still in the truck.

I would drill the thermostat and make sure there's no air pockets in the block. I usually park mine on a very steep incline and drill the thermostat during initial warm-up to prevent the airlock problem,
Scott

... all of the above very good answers. I've certainly had my share of problems over the yeas and over time each of the things mentioned above has been found to be the problem.
I do think that if its only running hot while its idling then there is not enough air moving through the radiator. While your moving it is getting plenty "forced" through.

If the engine is "sitting low" in the frame you may want to consider running an electric fan along with the regular fan. I did this on my 37 which only ran warm in a parade. Put on an electric fan with a switch inside and no more problems. You may want to consider running a BIG electric fan and doing away with the original. One that covers the whole radiator.

Just my pennies worth to the ideas above.

May as well add my 2c worth!
A common problem with re-built or engines that have laid idle for a while, can be loose scale in the water jackets.
If the new engine block was not caustic washed, or has sat for a while out of the vehicle, all the rust scale breaks away when the engine is first run and becomes lodged in the cores of your brand new radiator.
This effectively cuts your cooling capacity to a degree that the engine will overheat on the freeway and at idle speeds.
I always put steel screens (eg. flyscreen) over the radiator hose ends when I first run motors that I rebuild.I just drop the hoses each day and clean all the scale out of the screens. It can take up to a week of driving before all the scale finally stops appearing in the screens.
A lot cheaper than having to have a new radiator pulled apart and have the cores rodded out!

.........good luck