Technical running hot 210 degrees mild weather

Ok so I have a 64 chevy truck. 3 core brass and copper rad. 7 blade mech fan with shroud. 160 degree t. stat. short aluminum water pump. 350 v8 th350 auto and 3.73 gears with 28 inch tall rear tires.
I spin 3200 rpm at 70. Truck runs 210 degrees even at 60 degree day.
It warms up quick to 180 degrees. When I go down the interstate it will hit 210 pretty fast. Within 5 miles.
Most of the old stuff I drove run 195 even with 4.10 gears.
I have flushed the system.
It has a 16lb cap. 50/50 mix.
I have not checked timing yet. I did change plugs and wires. Plugs looked clean. Light brown. r44 plugs.
Open to thoughts.

 

Check the timing?

 

What kind of fan?

 

Check temp with gun. I see 2o degree difference between gun reading and gauge readings on some cars.

 

You could bring that thermostat to boil in a pot of water to see how much it’s opening. It sounds like Moriarity is on the right track though.

 

I’m not sure how visible the front of the radiator is on these trucks, but is it possible some debris has gotten stuck to the front side of the radiator and is stopping the air flow?

 

Try a 185 ,
Check timing, 12-18 deg of initial
Verify that your temperature gauge is reading correctly compared to another do not trust just one gauge

 

7 blade steel fan. new 160 t stat. I do think there was a spring in lower hose. Front is wide open and clean.
I had rad. out to fix a leaking petcock on the drain Looking inside seems to be clean.
It has cast heads.
It will spit out water when I stop. It just has a hose for pressure relief.
Water pump is new .
Upper hose feels solid when I stop.

 

A little back ground. Bought the truck a month ago. I put 1800 miles on it. Drove it about 175 miles on a 70 degree day. Stopped for gas and it spit out a 1/2 gallon of antifreeze. Filled it left the cap loose drove another 125 miles . Truck runs fine. No smoke.
It's a 78 truck motor.
I checked compression. All 8 cylinders were between 135 and 140.
I have since put another 300 miles on it.
I drive it 70 to 75 mph. 3200 to 3400 rpm.
I added a new gauge to the old sender in head. Electric gauge.
If it matters it gets 10 mpg. Not very good. It should get 14 or 15.
Maybe bad t.stat?
Would a 185 stat help? I'm thinking if t stat is open temp range wouldn't matter. It should read about 10 degrees hotter than stat temp.
I have a hard time thinking rad is the problem. It's huge.

 

I will rebuild dist and check timing. Maybe vacuum advance is sticking. Weights hanging up.
It's hei.
Truck feels sluggish. I thought maybe because it's stock. Low horsepower. 175hp.
Truck weighs 3600 lbs.

 

Does the gauge match the sending unit??

A more accurate temp reading, in my experience would be at the front center of the intake manifold.

210 degrees isn't really all that hot, unless it climbs as ambient temp rises.

 

I assume gauge and sender would match. The truck does run hot.
My thoughts on sender placement is it will show cooler at the front manifold. That doesn't mean it is not running hot.
I'm only concerned about this summer when it's 95 degrees out. It will overheat then.
I would like it to stay below 200 degrees.

 

That 64 should have a top flow radiator originally,
You could have air pocket , is the heater hooked up?
If so try / see if needs burped . By pass hose if no heater used ?
I have several gauges and I have also experiment to make sure all read within a few degrees of each other, wants you find a gauge Know to be accurate ,
If you install in SBC between 2&4 6&8
1&3 5&7 or on intake @ or near thermostat you will get different readings at all different locations 5 -20 deg differences, sometimes it's best not to know these things!!!
As long as coolant does not boil over , its not really getting Hot,,
Few other test /things to do,, take antifreeze out run straight water,add a water weeper for long term use ( straight water)
,water dissipate heat better than antifreeze .
Is the water pump a OEM style with bypass hole in pump to match block ? Bypass hole is under passenger side of water pump below bottom water pump bolt ,
Is the crank & water pump pulley 1to1 same size outer diameter,?
It you fill radiator up with coolant and pull the bottom radiator hose does it completely drain within about 10'-15 seconds?
Does plugs seem rich , lean ?

 

I have to agree it sounds like the lower hose is getting sucked shut. Seeing how it is boiling over. A 1/8” hole drilled in the flat of the thermostat will go a long way to making sure no air is trapped in the cooling system. Most new radiator hoses don’t come with the springs in them anymore to keep them from collapsing. However you used to be able to get them from NAPA or Amazon.

 

Betting that radiator is plugged. Check the front of the radiator with a heat gun, left to right, top to bottom. Or spray the front of the radiator with water when it is hot. The area that DOES NOT dry right away is plugged.

Ben

 

I like it. Also, how old is the radiator? At times I have removed the t-stat to help solve problems like that. It could also be a bad one. Definitely install a 180, it is the cheapest thing you can do.

 

Get a high flow thermostat. Made a big difference on my T-Bird.

 

Water pump bypass is plugged off. I did put a hole in t stat before I installed it.

 

I agree with the rad idea. Said you had it out to fix it but didn't have it flushed or checked for flow--take it to a good rad shop and sometimes they'll do that for small bucks.

 

Checked rad it is 110 in front at bottom and 160 along the top. Pretty sure is is clogged.

 

Ok so I'm confused. Looking at the readings it would seem to be right. hotter at the top .
I thought the lower hose pumped into rad. Top hose sends it back to motor.
I have read that is backwards. So it would be hotter at the top just like my readings.
I still think I will pull rad and get it cleaned.
50 degree drop top to bottom should mean rad is good.

On a side note could the sender not match the gauge? Sender is stock and gauge is aftermarket.

 

Yes top from engine ( return )
Bottom Feeds engine ,,
If that a pretty much 40 plus yr old radiator the tanks will need to be pulled & rodded out , If core is still good

 

Another thought would be if mpg is much lower than anticipated, an over rich mixture will cause excessive heat in the engine, rather than out the exhaust.
Over rich can have two components. A rich carb, or not enough ignition advance (static, mechanical and vacuum), especially at cruise speed, but also at the stop light.

 

But you are pushing coolant out the overflow?

Did you try the spraying water on the radiator bit?

Ben

 

Is 210 hot?
190-210 sounds perfect for 70s up engines

 

I see the temp is high running down the interstate, how is it sitting and idling, or running around town? If its OK at slower speeds but heats up fast at higher speeds, its very likely your fan is blocking the air flow through the radiator at speed. At speed the airflow through the radiator is faster then the spinning fan will allow to pass. If that fan sits completely inside a tight fitting fan shroud, the faster moving air gets stopped by the fan, and the radiator heats up.

If you are reading a 50 degree temp difference between the bottom of the radiator and the top of the radiator, it is very likely not plugged. Are those temps consistent across the radiator? Is it cooler at the center then it is at both sides? If the temp is different at either across the top of the radiator, or across the bottom of the radiator, that could tell you if a part of the radiator is plugged or not, a hot spot shows no fresh coolant flow = a plugged section of the core.

At 3200 - 3400 rpm @ 70 mph, I wouldn't expect much better then 10 mpg in a less then aerodynamic truck. Taller tires or less gear would be helpful. If your timing is too slow, that will also cause higher temps at higher speeds, and will reduce gas mileage.

Dumping coolant after shutting a hot motor off is the reason coolant recovery systems were developed. Adding a least a quart sized recovery tank with the coolant entry from the radiator at the bottom of the tank will likely solve the coolant dump.

 

I will add a tank.
Temps are same all the way across.
I will pull rad and get it cleaned.
I need to check timing.
I know 210 isn't terrible. I'm just use to 195 or lower.
I've had other cars running 4.10 gears that didn't run that hot or get that bad of gas mileage.
Thanks for the help will know more after this weekend.