Is my Bronco running too cold?

[pclancy]

All,

Thank you for your help with this question.

Ever since the weather turned a bit cooler (I live in Washington DC, and this will be my first winter with this truck) I have noticed that I can't seem to get my engine to run hotter than about 150 degrees. My driving is mostly in the city, and this is what she reads (with an aftermarket temperature gauge that I believe is accurate) after 30 minutes of running in 40-50 degree weather.

I have a bone stock 302 in a 1969 Bronco. Stock radiator.

In the summer, with the temperature in the 80s and 90s, she runs at between 180-190 degrees.

The heater works just fine.

I have yet to see what the story is with my thermostat--plan to do that today. Have never checked.

But my Bronco Doctor/mechanic said not to worry. Should I? What degree thermostat should I have in it? Is it OK if it runs this cool? What temp should the engine warm up to in winter?

I am not a mechanic, so your advice is welcome!

 

[patterdale]

Sounds like the thermostat is stuck open. Shouldn't hurt anything you just won't get much heat the colder it gets.

 

[jw0747]

x2 Your thermostat is stuck wide open. Does it take a long time for your heater to get hot? Does your engine run okay at 150 degrees? No stuttering or hiccuping when it hits 150? If running okay and your heater gets hot pretty quickly then don't worry about it. If you decide to change your thermostat probably good to reinstall one rated at the same temp as the one your remove.

 

[pclancy]

Thanks.

It does not take long for the heater to run warm, and the engine purrs (once it warms up). Plus it seems that it's a hassle to check the thermostat, the way it is positioned, so I guess no big deal?

 

[DirtDonk]

Not huge, but it's still nicer overall to have the temps in the summer range you get. That 180 to 190 is perfect.
I think a stock t-stat rating for your year would have been something like a 180, but I like even 195's when suitable.
Engines can be a little more efficient at the higher temps, but depending on the tune may not like it. Which is why a lot of the old racers used to either get rid of the t-stat or use a colder one in the 160 range.

I'm kind of surprised the heater works well at only 150, but that might simply indicate your heater is working better than some. When mine was running a 160 t-stat for instance, my heater could hardly keep up with winter temps. And that's around here, which never sees average winter temps as low as you do I bet.

But like the others, I say it's not a huge deal. Just something to keep in mind and an eye on as it gets colder.
If it stays cool enough, the carburetor choke might not pull off fully.

Paul

 

[carmi]

I would be nervous about temps that cold. Like others have stated your engine will not be as efficient at getting complete combustion and will probably run a little rich. If it's too rich, you can cause problems with the excess fuel scrubbing the cylinder walls clean and excelerating wear. In addition, a motor that is not properly warmed up will also cause excessive wear because as the motor warms up the cylinder walls expand and create the proper tolerances for the piston and rings.

 

[clarrance]

This is interesting to me, I also have a bone stock 69 with a 302. It never runs much warmer than 150-160, it doesn't matter summer or winter. I have replaced the entire cooling system, and I am running a 190 tstat. I have double checked my gauge, and used a laser thermometer gun on the engine to verify the temps, and still in the 150-160 range. Mine also puts out good warm heat. Very strange.

 

[pclancy]

We are checking the engine temp tomorrow with a laser thermometer. I will probably pull the thermostat to see what's going on. Will keep you up to speed.

 

[jckkys]

Ford specifies a 195 degree thermostat for most all small blocks including all the EB V8s. A search of ideal engine operating temperature will recommend 200 degrees. Engine wear increases with lower temps. The production of sludge is another side effect of low temps. There's no up side to lower temp thermostats.

 

[sykanr0ng]

Do yourself a big favor and get a good quality thermostat, like a Robert Shaw.
Critical engine parts is no place to cheap out.

 

[Whoaa]

I live in cold climate, as I type this the current temp is -9F. We occasionally get some really warm/hot temps in the Summer, but 50's and 60's are the norm.

Because the damage to the engine running them below full operating temp and lack of performance, many daily driver cars here have some type of canvas in front of the radiator to keep air from moving through. And slipping a piece of cardboard down the inside of the radiator does about the same thing.

Obviously something is wrong, prolly a stuck thermostat.

 

[edmedlin]

Whoaa!! That's even cold for Wasilla in Nov... We used to do the same in Wi in the winter to keep the engines warm. I would definitely put a good thermostat in that Bronco. They like to run at 180-195 degs. Mine, with AC running in the hot summer will sometimes see 200 in city traffic doesn't complain much. It cools down quickly. Can't wait to get it out of the paint shop. Finally bit the bullet.