235 straight 6 running hot....DRIVING ME NUTS!!

Ok heres the deal, I have a 235 straight 6 out of a 58' impala in my little A Model pickup. Runs great when idling or stop and go traffic but at steady highway speed(45-65) the tempature steady goes up. Heres what ive done to try to fix it. First, it has no thermostat so i thought maybe the water is moving too fast so we put a restrictor in the neck,didnt change a thing. Next we thought maybe we just dont have enough radiator. So we found a bigger one and put it in(holds about 2 1/2 gallons of water. That still didnt change anything. Thought maybe the belt on the water pump was slipping since it was a little old, so we replaced that also......no change. It has the max size electric fan that i can get on this radiator and the water pump seems to be working at full pace. Keep in mind it runs great while sitting at idle. It doesnt run hot until you hit a long stretch without bringing the rpms down. Any ideas because im stumped? its creeps up to about 220 or 230 on long runs(about 5 or 10 miles non stop)

 

Retard your ignition a little and get an oil cooler if need be.

 

Vacuum advance might not be working. Keep in mind, that you should be able to watch the distributor rotate a few degrees as soon as the engine cranks. If it doesn't, you have a bad vacuum advance or the vacuum advance assembly is misaligned with the distributor or jambed up with filth and not allowing the distributor to rotate.

Also, I had over tightened the valve lash on my 235 years ago to the point that they almost no clacking sound at all. I had the valve clearance to tight. Mine would run fine at idle, but as soon as I drove at speed, the engine would boil over.
Of course the other possibility is a cracked head allowing hot gasses into the water jacket.

 

use a thermostat

 

The one in your avatar ?

Take off the sheet metal grill and don't run the fan on the highway. See what happens.

You have enough airflow at slow speed, but not enough at higher speeds when you shouldn't even need a fan. The ram air ought to keep it cool.

retarded spsrk makes it run hot, as does way too advanced. Get the timing right and make sure the vac advance is working and the mechanical advance in the dist.

 

ill look at this stuff. I have no way to put a thermostat in it because the way the water neck is made

 

I have run it with the grill shell off and it still ran hot but i have not check the timing. Im going to do that this evening

 

All of the above plus have a radiator shop test your coolant for exhaust gas.

 

the fluid is moving to fast and does not stop / slow down in the rad..
to get its turn at cooling off....

 

Which way is your electric fan (what is max size) mounted, in front or behind (blow or suck), how are you controlling the fan (what kind of thermo switch in fin or in radiator or block),,,,,is it coming on...... radiators usually don't work too good without some sort of shroud.
Are you low on fluid all the time.....white smoke, leaks, contaminated oil??

boooooob

 

Is this something new, or have you driven it for awhile and this started? What type of water neck are you running that you can't put a thermostat in?
I had this problem and went as far as tearing engine down and replacing gaskets after boiling mine at least a dozen times only to discover it was a bad thermostat, which was bad out of the box. You can run a 6 in the winter without a thermostat but it's almost a necessity in summer months.

 

Sure would help to know more about the vehicle. Can you post pics of the fan and radiator setup? how's the rearend gearing? what is the total ignition timing, and does it have vacuum advance? if so is the vacuum working?

 

Sorry guys ive been out in my garage tinkering on it ill post some pics in just a few i did mess with the timing and i got it running a little better but did not fix the running hot issue

 

To answer some of the questions i have my fan on a toggle switch it is working properly its mounting on the back side of the radiator so it pulls the air through

 

Vacum advance is working. Rear gear is not a issue its got a pretty tall gear with a 5 speed behind it

 

heres 1 pick more coming.............

 

Water is cavatating (air bubbles) in the lower rad hose ? It's an old drag race trick (flex hose) as the air pumps easier than water, not so good on the street some times. The faster you go the worse it gets.

 

Get it checked for a combustion gas leakage into the cooling system. Old Chevy 6s are almost as bad as flathead Fords for cracks.Chevys do heads for the cracking. 5/8s -3/4 restricker size if you must instead of a stat.

 

run that picture a little to the left so we can see the chevys
block housing where the thermostat usually goes

 

Have you checked accuracy of temperature gauge?

 

inquiring minds need to see more

 

x2... or no bigger than a 5/8" hole in restrictor plate

 

This was told to me by an other hamber:
So a pirate goes to a bar with a boat steering wheel? Stuffed in the crotch area in his pants,so the bartenders asks:
"why do you have a steering wheel stuffed in your pants?
Pirate:--its driving me nuts!

 

Is your system pressurised?? If you are running a 13lb cap, ( 3 degrees boiling point raised for every 1 lb pressure) Meaning it can get up to 150 degrees before it boils, so your 120 - 130 degrees is ok ..

 

what he said

 

The fan probably isn't blocking airflow too much at speed, there's plenty of room aruound it.

I'll echo the question about if it's pressurizing the cooling system like a leaking head gasket.

 

I have a gauge on the water pump and in dash there both reading the same so i suppose they are correct. It is not puking any water i think my next test is to check for air pockets that flex hose may be an issue.

 

Heres a pick of the water neck....no way to get a thermostat in there.............

 

i have a restrictor with a 3/4" hole

 

have you tried a 1" hole?

also...did this problem just start or has it always been like this?