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Is my bronco overheating?

chuck

Bronco Guru
Joined
Aug 14, 2001
Messages
6,474
Loc.
Ingram, Texas
As usual Chuck brings the eb education to the table.

In Blu's defense he always forgets how modified a lot of our eb's are. He has kept his remarkably stock.
He did the 5 speed for the overdrive but probably liked the 3 on the tree. He had to do the twin stick with the 5 speed, but he definitely preferred the J-Shifter. I think like a lot of us he had to do a/c; I swear its hotter now than when I was a kid in the 70's, lol. I believe Blu has a slight lift too but prolly only to get better quality/riding springs.

He strongly believes in the original engineering of our eb's and only strays away when he can't go back to stock.
I was responding to Blu saying he didn't understand the need to change pulley size. I was not trying to offend him or anyone else. Also many don't need to change the size. I think maybe because the engine is older and a little looser so does not make as much heat. Often the heating problem come when there is a change like a rebuild.
 

NCBeachBronco

Jr. Member
Joined
Sep 29, 2002
Messages
64
My pulleys are the same size. I bought a small water pump pulley but neglected to change it when I had everything apart - second guessed the need for it and got lazy not wanting to go the auto parts store for new belts. %) ...on to REV 5 ;)
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,916
I was responding to Blu saying he didn't understand the need to change pulley size. I was not trying to offend him or anyone else. Also many don't need to change the size. I think maybe because the engine is older and a little looser so does not make as much heat. Often the heating problem come when there is a change like a rebuild.

Chuck you do not offend us, you educate us.
Lol
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
I was responding to Blu saying he didn't understand the need to change pulley size. I was not trying to offend him or anyone else. Also many don't need to change the size. I think maybe because the engine is older and a little looser so does not make as much heat. Often the heating problem come when there is a change like a rebuild.

I understand what you're saying. I spent my career working on centrifugal pumps and understand the principal. Sure I think there situations where speeding up the pump would be a good idea. Slow off-road driving would be one of them. But the coolant flow, on even an idling engine, is restricted by the thermostat, even when it's all the way open.

It's just that I've seen most overheating issues are caused by real problems. The owner will try all sorts of band-aids, that couldn't possibly fix the problem. The culprits are usually plugged radiators, thermostats in wrong, or coolant passages blocked by incorrect gasket installation.

Under normal circumstances, the OEM parts are all that are needed. But I will make one exception to that. On a Bronco, it's very important to block the area between the grill and shroud to keep the hot air from recirculating back through the radiator. That was definitely a bad design.
 

NCBeachBronco

Jr. Member
Joined
Sep 29, 2002
Messages
64
(On a Bronco, it's very important to block the area between the grill and shroud to keep the hot air from recirculating back through the radiator)

Are you referring to using an air dam at the top of the core support to grille or something else?

I have the air dam - gotta put it on...
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
(On a Bronco, it's very important to block the area between the grill and shroud to keep the hot air from recirculating back through the radiator)

Are you referring to using an air dam at the top of the core support to grille or something else?

I have the air dam - gotta put it on...

Here's an example of what I'm talking about. I've seen them made from everything from metal to vinyl flooring.
I had access to a sheet metal brake and made a set from aluminum.
I think by now, most of our regular vendors have them.
It also makes a nice tool tray when you're working under the hood.;)

http://www.wildhorses4x4.com/product/SS_Radiator_Air_Dam/Bronco_Radiators
 

NCBeachBronco

Jr. Member
Joined
Sep 29, 2002
Messages
64
Yes, that's what I have. Made them a while back from 20ga stainless, just gotta put them on
 

jim3326

Bronco Guru
Joined
Jul 12, 2010
Messages
1,781
Loc.
Appleturkey
I am wondering if the lack of exits from under the hood could be part of the problem. I have never had an over heating issue since I finished mine. I don't have the riser to the hood from the vent and the passenger side air box has a hole cut in it where I plan on making a cold air intake. All this lets the radiator breathe a little better I think.

I have the BCB a/c and pulley system, 17" Flex-A-Lite fan, cross flow rad. unpainted, homemade shroud and I consistently run 185-193.
 

chuck

Bronco Guru
Joined
Aug 14, 2001
Messages
6,474
Loc.
Ingram, Texas
My first EB was a 70 with a 351w and 3 on the floor. No air, P/S or power brakes. I was driving 70 miles each way to work and thought I could save some money by changing to a 302. So I built a 302 and installed it and it ran hot. The 351 ran 180 in LA traffic but the 302 would go up to 230 before I would pull over and shut it down. Over the next 9 mos. I checked timing A/F mixture, vacuum leaks, changed fans and water pumps 3 times, diff mixes of coolant, water wetter, no t-stat, 180, 160 and 190, had a 5 core radiator made, no shroud and full shroud, a couple of diff. recovery systems and it still would go over 230 in traffic. Finally I went back to my 351w and noticed that the water pump pulley was smaller but it didn't cross my mind that that would fix the problem but I added P/S and the 302 water pump pulley would not align with the 3 grove pulley that I used for the P/S so I used the smaller 351 pulley and the temp after that went down to 180 in traffic and 160 on the road. After a while I thought maybe that little pulley was the fix so changed back to the bigger pulley for a test and the temp went back up. So it fixed my problem. Soon after the 302 got a flat cam so I built a 69 351w and it still does not get hot. More power and same mileage.
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,615
I think what the difference is with the smaller pulley is the pressure that is created when the pump is rotating faster and it is trying to push more water thru the system even IF the t-stat could be creating restrictions it is NOT the flow of water but it is the PRESSURE of the water in the block. Hence the theory behind what FloKooler water pumps seems to be promoting now in their literature.

I called all over the US a couple years back (couple dozen conversations) tracing a slight overheating issue and ran into the weirdest test ever that I was challenged to do on a couple different engines to test and prove the theory...it worked.

When your engine is running you have 2 different pressure areas in your block. One is in the block behind the t-stat and the other is the "outlet" side of the t-stat/radiator/lower hose even with the t-stat open! Obviously the pressure cap regulates the pressure in the radiator and lower hose- all prior to the water pump.

When the engine is running and the t-stat is not open yet place a pressure gauge in the intake manifold (before the t-stat of course). You should have well over 20# of pressure in your block literally FORCING the water against the block helping to eliminate steam pockets but with more pressure you get better heat transfer as we all know is true. This is all BEFORE the pressure cap is starting to build pressure in your radiator.

NASCAR guys I was told run upwards of 50#'s of water pressure in their engine blocks which keeps them cool. My 351W was running about 12#'s of pressure and my friends engine (actually the one I built back in '86) was running 28#'s of pressure. His cooled, mine didn't.

There's more to it than this but without trying to write a book from what these different radiator company owners explained to me this is the just of it. Try it, you will notice a huge difference. Ron Davis explained to me that this is a test they do on many vehicles...

I was laughed off a well known Mustang list for proposing this theory (not my theory-I just forwarded it) and the test, then one of the "respected" guys tried it and verified it was accurate.

So many guys have so many other issues going on but this works many times when all, and I mean all other typical problems are reviewed and eliminated.
 

toddz69

Sponsor/Vendor
Bronco Guru
Joined
Nov 28, 2001
Messages
10,080
I think what the difference with the smaller pulley is the pressure that is created when the pump totating faster and it is trying to push more water thru the system even IF when/if the t-stat could be creating restrictions it is NOT the flow of water but it is the PRESSURE of the water in the block. Hence the theory behind what Flocooler water pumps seems to be promoting.

I called all over the US a couple years back tracing a slight overheating issue and ran the wierdest test ever that I was challenged to do on a couple different engines to test and prove the theory...it worked.

When your engine is running you have 2 different pressure areas in your block. One is in the block behind the t-stat and the other is the "outlet" side of the t-stat/radiator/lower hose.

When the engine is running and the t-stat is not open yet place a pressure gauge in the intake manifold (before the t-stat of course). You should have well over 20# of pressure in your block literally FORCING the water against the block helping to eliminate steam pockets but with more pressure you get better heat transfer as we all know is true.

NASCAR guys I was told run upwards of 50#'s of water pressure in their engine blocks which keeps them cool. My 351W was running about 12#'s of pressure and my friends engine (actually the one I built back in '86) was running 28#'s of pressure. His cooled, mine didn't.

There's more to it than this but without trying to write a book from what these different radiator company owners explained to me this is the just of it. Try it, you will notice a huge difference.

Brian - could you provide a link to that thread again? I remember following along and I learned a lot as well. Would like to re-read it again. Thanks.

Todd Z.
 

NCBeachBronco

Jr. Member
Joined
Sep 29, 2002
Messages
64
Going down this path myself - gotta find a local carb guy - think mine is off

Been chasing the running hot issue for over a year. Made several changes & none of them made significant changes, but there there has always been two constants - Timing and Carb setting and I have no idea what either of them are...

Initial set up - Skinny Flex Fan w/ full steel shroud, triple pass rad from WH, stock water pump with same size pulley as crank, 180 deg Tstat, 50/50 mix in rad and Vintage Air A/C condenser in front of rad
Ran 180 deg down the road, but quickly crept to 230+ while sitting
REV 1 - added two 12" pusher fans up front
Ran 195 deg down the road, crept to 215 while sitting-but not as fast as before
REV 2 - removed A/C condenser (considered remote mounting it if this worked)
Ran 180 down the road, crept to 210 while sitting
REV 3 - (Current Set up-finished Sunday) Swapped flex fan for rigid fan from WH, removed pusher fans, put A/C condenser back in, added Royal Purple Ice to 70/30 rad mix. I reluctantly had to modify core support for this - seems rad is mounted almost straight up and down and engine has a slight tilt backwards so had clearance issues at the bottom. I removed lower rad supports and cut off "lip" of lower part of the core support in front of the rad then re-attached rad supports to now flat area on lower part of core support and reinforced it with 1 1/4"x 1/8" Flat Bar. This almost matched the rad tilt to engine tilt and now the fan fits and the condenser still fits between rad and core support.
Now runs 175 deg down the road, slowly creeps to 200 while sitting - the best so far, but don't like it and won't wheel it like this

Engine is a mild build 331 and the builder failed to put a timing pointer on it-the mech who installed it didn't catch it until he tried to time it so timed it by ear.
While doing the work above I added a Scott Drake timing pointer to the drivers side of engine (couldn't see the stock one on pass side even if it was there because of water hose) and found TDC & put a MSD timing tape on the balancer. Now have to get a light and time it.

Hoping for improvement when timing and carb are right cuz I'm getting close to the last straw!

Well, checked timing this weekend...
It was at 2 deg ret.
At that setting it ran at 175-180 down the road but crept to 200 or a little over at lights. I stumbled and popped and would not take the gas when you got in the pedal - so ran poorly.
I re-set timing to 12 deg adv - engine RPM increased dramatically as I rotated dizzy, then lowered idle screw after locking it down.
Took it for a drive - WOW, I have a lively 331 now...
Temps...meh, different story- drove it 35-40 min. 95 deg high humidity outside
Ran 185-190 down the road and crept to 200 at several lights and to almost 210 at a long light, but dropped right back down to 185-190 once I got moving again. Still not happy with this- don't feel comfy going wheeling like that.
Got a small Water Pump pulley waiting in the wings... TBC %)
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,615
Sounds like low air flow SINCE it seems to cool fine when air flows thru at speed but DOES NOT seem to flow enough air at idle...could be wtrpump tho
 

Slowleak

Bronco Guru
Joined
Sep 12, 2013
Messages
3,732
Loc.
Georgia
Sure sounds like airflow. You might try checking the radiator inlet and outlet temps with an IR thermometer when it is idling and hot. There should be a pretty significant difference in the two temps. If there is not, then water is flowing thru the radiator without being cooled which indicates an airflow issue. If there is a significant difference in temps, and you are running hot, then you have a water flow issue. I would expect the lower radiator outlet hose to be 165-175 degrees if the upper inlet hose is 200 but that's just a guess.
 
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