69 F100 overheating
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69 F100 overheating
I have a 1969 F100 with a recently rebuilt 302 engine in it. I have brand new points and condenser brand new spark plugs and plug wires and a brand new coil. I used a vacuum gauge to set my fuel-air ratio and to set my ignition timing. The timing chain is brand new and the truck runs perfectly but continues to run at around 210 degrees. I have a 195 thermostat in it but cannot get the truck to run at 195. Any help would be greatly appreciated.
Senior User
Joined: Nov 2005
Posts: 422
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From: FL
You might Start at the Radiator? Is it NEW or Reconditioned? Hopefully you didn't connect a newly rebuilt engine to an old radiator 
Is the Radiator TOO small for the New engine?
BLOCKAGES in the HOSE? New HoSES? Some hoses do not come with internal springs and can suck shut at higher speeds, which will overheat the engine.
Is the Radiator TOO small for the New engine?
BLOCKAGES in the HOSE? New HoSES? Some hoses do not come with internal springs and can suck shut at higher speeds, which will overheat the engine.
Cargo Master
Joined: Oct 2011
Posts: 2,242
Likes: 299
From: Kenner,La.
195-210
Get a infrared heat sensor and check if there are any “hot” spots in the radiator. I have seen the inside of a radiator hose collapse and block water flow while the outside still looked normal. Another possible problem could be the sludge from the casting mud blocking the rear of the engine block, the same stuff that blocks up radiators. Is the temperature sender getting the reading from the intake manifold or the top of the thermostat housing?
Lead Driver
Joined: Jul 2011
Posts: 8,679
Likes: 191
From: On the Edge of the Desert
If you want the truck to run at 195, you need a 180 thermostat.
People don't realize that the temperature rating is the temperature that the thermostat will BEGIN to open. Meaning just partially open. It doesn't fully open until 20 degrees higher than the rating. So running at 210 with a 195 stat is about normal. Especially since a fresh engine is going to run warmer at first until it gets broken in.
Ideal engine temperature is 195-205. That's where oil is formulated to perform best and everything else plays nice together. 210 is a little on the warm side, but it's not "overheating".
Cooler than 180 and wear starts going up drastically.
Like has been mentioned, check your radiator first, and make sure it's up to the task.
People don't realize that the temperature rating is the temperature that the thermostat will BEGIN to open. Meaning just partially open. It doesn't fully open until 20 degrees higher than the rating. So running at 210 with a 195 stat is about normal. Especially since a fresh engine is going to run warmer at first until it gets broken in.
Ideal engine temperature is 195-205. That's where oil is formulated to perform best and everything else plays nice together. 210 is a little on the warm side, but it's not "overheating".
Cooler than 180 and wear starts going up drastically.
Like has been mentioned, check your radiator first, and make sure it's up to the task.
Cargo Master
Joined: Jan 2016
Posts: 2,671
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Temp sounds about right for the t-stat being used. Wouldn't hurt to get it up to temp, slowly remove the radiator cap, and measure the coolant temp to verify the truck gauge is close.
Also, fresh rebuilds sometimes run a little warm for a few hundred miles.
Also, fresh rebuilds sometimes run a little warm for a few hundred miles.
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Senior User
Joined: Nov 2005
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From: FL
@351Cleveland C4
QUOTE "If you want the truck to run at 195, you need a 180 thermostat. "
Well why didn't I think of that first?? That's right, that 195 starts opening at 195 AND starts closing when the Temp falls below 195 which means It should run 195ish with a 195 stat but the temp of the engine will most likely fluctuate around that temp. Remember that a Thermostat is basically made to keep the engine WARM not COOL ! That is, it's to keep the heat in the engine from escaping when temperatures are COLD. Most engines without a Thermostat and good radiators will run below optimum temperatures but that is not good for the engine. Like 351 said 195 to 205 is good for the oil to provide minimal wear.
QUOTE "If you want the truck to run at 195, you need a 180 thermostat. "
Well why didn't I think of that first?? That's right, that 195 starts opening at 195 AND starts closing when the Temp falls below 195 which means It should run 195ish with a 195 stat but the temp of the engine will most likely fluctuate around that temp. Remember that a Thermostat is basically made to keep the engine WARM not COOL ! That is, it's to keep the heat in the engine from escaping when temperatures are COLD. Most engines without a Thermostat and good radiators will run below optimum temperatures but that is not good for the engine. Like 351 said 195 to 205 is good for the oil to provide minimal wear.
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Senior User
Joined: Nov 2005
Posts: 422
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From: FL
I used to own a 1959 Ford with a 6 cylinder, I ended up putting a radiator in it which wasn't even close to an exact fit. I kept having the engine run hot. One day I was searching for the problem and just by accident was looking at the bottom radiator hose when someone sped the engine up. I couldn't believe that radiator hose sucked in like a straw with a plug. Makes me mad to think about this because much later I also had a 400 which was overheating when it ran down the hwy, BUT I NEVER EVEN thought of checking the springs in the Radiator hoses. I took the engine out and it is sitting in the storage.... It might be a great engine after all ???? Live and Learn.
FTE Legend
Joined: Nov 2015
Posts: 30,906
Likes: 4,122
From: Angier, NC
Now that was funny !!
I used to own a 1959 Ford with a 6 cylinder, I ended up putting a radiator in it which wasn't even close to an exact fit. I kept having the engine run hot. One day I was searching for the problem and just by accident was looking at the bottom radiator hose when someone sped the engine up. I couldn't believe that radiator hose sucked in like a straw with a plug. Makes me mad to think about this because much later I also had a 400 which was overheating when it ran down the hwy, BUT I NEVER EVEN thought of checking the springs in the Radiator hoses. I took the engine out and it is sitting in the storage.... It might be a great engine after all ???? Live and Learn.
I used to own a 1959 Ford with a 6 cylinder, I ended up putting a radiator in it which wasn't even close to an exact fit. I kept having the engine run hot. One day I was searching for the problem and just by accident was looking at the bottom radiator hose when someone sped the engine up. I couldn't believe that radiator hose sucked in like a straw with a plug. Makes me mad to think about this because much later I also had a 400 which was overheating when it ran down the hwy, BUT I NEVER EVEN thought of checking the springs in the Radiator hoses. I took the engine out and it is sitting in the storage.... It might be a great engine after all ???? Live and Learn.
BTW new hoses DO NOT come with the spring so you need to swap the spring to the new hose.
It is also hard to come by a spring nif the lower hose does not have a spring in it. I had to buy a ribbed hose made to fit any motor that had a spring in it. I pulled the spring and had a he11 of a time installing it in the new lower hose.
Dave ----
Logistics Pro
Joined: Aug 2015
Posts: 4,093
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From: Lind, WA- Eastern WA
The lower hose on my 54 Whilly's would suck closed. So I made a lower "hose" out of PVC pipe and fittings. I left about 2 or 3 inches of rubber hose at the ends, so it could all flex. I will use copper pipe on the 69 F250, so it will look a bit better.
Fleet Mechanic
Joined: May 2001
Posts: 1,396
Likes: 4
From: Cupertino
I have had my 302 overheat after a rebuild. The problem was crud that came out of the block- residual from he dip tank- that was depositing along the top row of the radiator tubes. The solution was was to pull and boil the radiator and then put an inline filter on the top hose.
Senior User
Joined: Nov 2005
Posts: 422
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From: FL
That is a pretty ingenius idea, never thought of using pipe, but why not!
Senior User
Joined: Nov 2005
Posts: 422
Likes: 0
From: FL
I have had my 302 overheat after a rebuild. The problem was crud that came out of the block- residual from he dip tank- that was depositing along the top row of the radiator tubes. The solution was was to pull and boil the radiator and then put an inline filter on the top hose.