Is my bronco overheating?

[Broncobowsher]

Found a spec for a thermostat. Opening at 180 is where it lifts off the seat at, but not fully open until 203. And won't fully close until 171. It's not exactly our application, but is representative of a normal engine thermostat.

 

[chuck]

UPDATE
Got the small water pump pulley on and switched to a 16lb radiator cap.
Now runs 180 down the road and NEVER hit 200 at the stop lights ;D- even got caught by a train crossing and sat (nervously) waiting for it to pass.

Sat for 15 min in the driveway after getting back home-still didn't hit 200.
Opened the hood after that with it still running and temp dropped another 6-8 degrees. HMMM - time to vent the inner fenders???

I guess the bottom line is it really doesn't matter why it works as much as the fact that it does. Glade your problem is fixed.

 

[Justafordguy]

Opened the hood after that with it still running and temp dropped another 6-8 degrees. HMMM - time to vent the inner fenders???

I installed a hood scoop and cut out the sides of the inner fenders and got a 10 degree drop while sitting at idle.

 

[NCBeachBronco]

Yea kinda what I've heard. Gotta give that hot air an escape route.

 

[Slowleak]

I checked mine with a Anemometer against the grill to measure air speed. At idle air was moving at an average of 472 ft/min. I need to do some tests with the hood open vs. closed to see how much difference there is.... I'm sure vents would help, especially on the road when more air needs to move.

https://www.amazon.com/HOLDPEAK-Ane...coding=UTF8&psc=1&refRID=QH1ZVS91N9QD54X60NFX

 

[chuck]

I may be wrong about this but it is my thought that the stock setup will force the air that passes through the radiator will be forced across the engine and down past the exhaust and out the bottom of the EB and help remove more heat. The air has to go someplace.
The holes in the back of a hood would cause pressure while driving inside the engine bay from the air that hits the windshield but would allow some air out when stopped.
That is guessing but this is what I know, I mounted a wench under the front of my EB by bolting a plate from the cross member forward to the frame near the bumper. Basically a plate from the bumper back to the cross member and from frame rail to frame rail and just touching the bottom of the radiator. I noticed that the engine temp went down 10 degrees. But the wench got hit by every other rock so the wench thing didn't work out. When I removed the plate my temp went back up 10 degrees. My thought on this was that the air was being pushed more back and cooling the exhaust better. Air flow is not my strong suit so maybe some of our more knowledgeable members could explain why it works?

 

[chuck]

I checked mine with a Anemometer against the grill to measure air speed. At idle air was moving at an average of 472 ft/min. I need to do some tests with the hood open vs. closed to see how much difference there is.... I'm sure vents would help, especially on the road when more air needs to move.

https://www.amazon.com/HOLDPEAK-Ane...coding=UTF8&psc=1&refRID=QH1ZVS91N9QD54X60NFX

I just ordered this meter, thank you for the site.

 

[sykanr0ng]

I may be wrong about this but it is my thought that the stock setup will force the air that passes through the radiator will be forced across the engine and down past the exhaust and out the bottom of the EB and help remove more heat. The air has to go someplace.
The holes in the back of a hood would cause pressure while driving inside the engine bay from the air that hits the windshield but would allow some air out when stopped.
That is guessing but this is what I know, I mounted a wench under the front of my EB by bolting a plate from the cross member forward to the frame near the bumper. Basically a plate from the bumper back to the cross member and from frame rail to frame rail and just touching the bottom of the radiator. I noticed that the engine temp went down 10 degrees. But the wench got hit by every other rock so the wench thing didn't work out. When I removed the plate my temp went back up 10 degrees. My thought on this was that the air was being pushed more back and cooling the exhaust better. Air flow is not my strong suit so maybe some of our more knowledgeable members could explain why it works?

/\/\ I have seen air dams there mentioned before, I think it was Steve83.
Using some kind of rubber, plastic or vinyl sheet.

Forcing the air to be pulled through the radiator instead of around it was believed to be the effect there, like the air dams at the top of the grill a vendor sells.

 

[chuck]

I haven't seen one under the engine before. My intention was a wench mount not a cooling devise. I have occasionally thought about making a cooling aid product but never gotten around to it. If anyone wants to try it a L shaped piece of sheet metal about 22" wide can be clamped into place for testing.

 

[DirtDonk]

I think it's basically smoothing out that turbulent area and forcing more air through the radiator and out the "back" more behind the crossmember where it's naturally better flowing and less effected by high pressures at higher speeds.
That front area is a real hotbed of turbulence.
I've got an old Con-Fer skid plate that covers that area to a point, but I tried closing it off more and kind of re-designing the wheel at one point. It really wasn't designed to close it off. But it does channel air flow more to the bottom of the differential.
Not sure, but I'd say that your flat horizontal plate in that area would be more effective at ducting heated air through and away.

As you said, easy enough to experiment with. Would be a more effective test when done by someone with a little bit of a heat issue I would think.
My '68 doesn't even get up to full thermostat temps all the time. At least according to my gauge. I have not verified it's accuracy in any way though.

Good topic for further discussion. With all the people around here fiddling with sheet metal and playing around under their Broncos these days, I would think we could get someone to try different things.
For the street Broncos too, you could give it an air-dam extension of varying lengths and check it's effect on fuel economy.

Paul

 

[73azbronco]

One word: Fan shroud. OK two.

Air is air. Reading years of posts on this site leads me to firmly state fan shrouds with a fan that fits are probably the single biggest improvement to prevent overheating.

There is no way vents on top of the rear part of the hood would keep airflow from getting through the radiator as long as the radiator has a shroud around the fan blades.

There is no way lack of an air dam at the front of the engine bay prevents air from going through the radiator if the fan is shrouded.

Yes, the thing is as aerodynamic as a brick and does in fact build up higher pressure on top of the hood area, and may result in a dead end for air entering the front of the radiator, but people generally ignore that most air exits down and aft under the body (thats why the cab is so hot), so long as air is being forced through the radiator with a fan using a shroud.

 

[sykanr0ng]

A fan shroud is important that is true.
But getting the hot air that has gone through the radiator and absorbed the heat from the engine and the outside of the exhaust out of the engine compartment is as important.

 

[Slowleak]

Underbody panels are different from front air dams. Underbody panels are used to eliminate high pressure and turbulence. Air flowing under a Bronco hits the crossmember and engine components, enters the engine bay and creates high pressure. Air flowing thru the radiator, and shroud, needs low pressure air behind it in order to flow out. All that pressure and turbulence is probably the main cause of underdash and firewall heat. No air flows smoothly under or over a Bronco.

I would think that a simple panel under the frame and radiator, and back to the crossmember would help eliminate high pressure in the engine bay. It would also prevent hot air from recirculating back to the front of the radiator at idle.

Look under any new car and you will see panels covering the entire front area.

 

[nvrstuk]

Agreed with all the posts about turbulence and pressure...which has more capacity for determining which way air will move...a fan having to pull air thru a radiator or air being forced at 45-70mph up under the engine compartment and creating a high pressure area that the fan has to overcome in order to "pull" air thru the radiator...?

We need a WIND TUNNEL to test these theories!!

 

[bronconut73]

I think Aaron Kaufmann called it "Air stacking" on his Pikes Peak Falcon.

 

[Slowleak]

I did some testing on mine this week. I measured max airflow at idle, with the meter up against my condenser, using various fans and a smaller pulley. Here's what I got.

Six blade 17 in. stock fan, stock pulley - 492 ft/min
Six blade 17 in. nylon flex fan from Summit, stock pulley - 708 ft/min
Seven blade 18 in. stock flex fan, 5.4in pulley - 846 ft/min

So, I got a 72% increase at idle. I'll see what that does for my A/C head pressure and engine temps.

 

[DirtDonk]

Nice results! Glad you're going to all the trouble. Too bad you didn't get a direct comparison of that 18" fan on a stock pulley. But it looks like you're on an upward swing for sure.

Paul

 

[Slowleak]

Nice results! Glad you're going to all the trouble. Too bad you didn't get a direct comparison of that 18" fan on a stock pulley. But it looks like you're on an upward swing for sure.

Paul

I know. I did not expect to have enough clearance for the bigger fan. I swapped the pulley and after I found the fan fit, I didn't want to take it back off. It's a real pain getting the spacing right when swapping different depth blades.....

 

[nvrstuk]

Great info...amazing difference between those fans and pulleys...

Now you need to mount it on the grill with your cell phone on a selfie stick also in front so you can record the readings while a different speeds going down the road...be interesting to see what happens with air dam effect, etc... just kidding, but that's the type of stuff I enjoy doing...better quit typing and get back out to my project...

 

[Slowleak]

Now you need to mount it on the grill with your cell phone on a selfie stick also in front so you can record the readings while a different speeds going down the road....

Hmm... now you got me thinking My meter will hold a max reading. I may use some cable ties to strap it to the grill and try a few experiments.

I had to edit my earlier post. With the big fan and small pulley, I actually got over a 70% increase at idle.