Is my bronco overheating?

[NCBeachBronco]

Never thought of that - I like that test.
Too bad it's all torn apart again - lol. Gonna try a smaller water pump pulley.
Also, I have a full shroud, but only a 17" fan. An 18" will hit the A/C compressor pulley.
I saw a post on YT from Tom's on moving the compressor back out of the way to clear the fan. Might do that too.

 

[Slowleak]

Never thought of that - I like that test.
Too bad it's all torn apart again - lol. Gonna try a smaller water pump pulley.
Also, I have a full shroud, but only a 17" fan. An 18" will hit the A/C compressor pulley.
I saw a post on YT from Tom's on moving the compressor back out of the way to clear the fan. Might do that too.

I have the same problem. If I move my compressor back any further, my pulleys will be out of line. I could move it towards the fender with a little work.

I'm currently running a stock 6 blade 17 inch fan. Might try this one. It's a thin, high pitch flex fan.
https://www.summitracing.com/parts/der-19118/overview/

I've waiting to see how the new pulley works for you....

 

[bmc69]

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 %)

I might have missed it in a previous post...but what degree thermostat are you running?

 

[NCBeachBronco]

I have the same problem. If I move my compressor back any further, my pulleys will be out of line. I could move it towards the fender with a little work.

I'm currently running a stock 6 blade 17 inch fan. Might try this one. It's a thin, high pitch flex fan.
https://www.summitracing.com/parts/der-19118/overview/

I've waiting to see how the new pulley works for you....

That's the fan I started with - it didn't work for me AT ALL - temps would creep to 230 fairly quickly at stop lights.

Yea, I have high hopes with this pulley swap - but I had high hopes on every other change too


Running a 180 t-stat bmc69-

 

[chuck]

Never thought of that - I like that test.
Too bad it's all torn apart again - lol. Gonna try a smaller water pump pulley.
Also, I have a full shroud, but only a 17" fan. An 18" will hit the A/C compressor pulley.
I saw a post on YT from Tom's on moving the compressor back out of the way to clear the fan. Might do that too.

The 17" fan works fine and will not be your heating problem. We use it because the 18" gets too close to the shroud.

 

[NCBeachBronco]

Thanks chuck
Will keep you posted on the pulley swap - I know you are a fan of it.
May make my one piece shroud a two piece in the process - Man it's a PITA working around it...

 

[bmc69]

Running a 180 t-stat bmc69-

I had much (MUCH) better luck getting the cooling woes with my 408 cleared up once I went to a 195 stat. After that, and a SPAL pusher with 7-blade clutch fan, I saw 190-195 rolling, 200-205 at long lights and never more than 210-215 on even the most sever of trails. All happy numbers. The SPAL only came on at 205, so very seldom except crawling hard trails in hot weather.

I couldn't keep the highest temps down reliably with a 180 stat.

 

[jim3326]

This is the fan I'm using with my home-built shroud. The back of the fan would just barely touch the clutch so my solution was to slightly bend the base of the blade to get a 1/4" clearance. Been working fine, run between 185-195.

 

[NCBeachBronco]

I had much (MUCH) better luck getting the cooling woes with my 408 cleared up once I went to a 195 stat. After that, and a SPAL pusher with 7-blade clutch fan, I saw 190-195 rolling, 200-205 at long lights and never more than 210-215 on even the most sever of trails. All happy numbers. The SPAL only came on at 205, so very seldom except crawling hard trails in hot weather.

I couldn't keep the highest temps down reliably with a 180 stat.

I don't understand what difference the open temp of a tstat really makes when trying to regulate engine temps above the setting of the tstat.
When a tstat opens - it's open and out of the equation unless temp drops below its set point - right?

That is how a temp switch works on a fan... fan (cooling system) comes on when set point is reached and stays on until temp drops below that set point.

So if I'm seeing temps of 195-210 why does a set point of 180 really matter?
Almost seams that I would want the tstat to open at a lower temp so the cooling system can be working to prevent a 195 deg reading...

Not doubting the science - just don't understand it.

 

[Broncobowsher]

Also need to remember that the thermostat is NOT digital. I really wish more thermostats would publish the opening curves. At what temp it starts to open and when it fully opens. I know that would confuse a lot of people, but it would really help out some of us.

So you may have a thermostat that starts opening at 180, but isn't fully open until 200. At that point the thermostat will be throttling the waterflow in the 190 range.

Many years ago in the winter I was driving a 4.0 V6 Ranger (that I later dropped a stroked 5.0 into but that is another story). On the highway you could watch the thermostat fighting for control. It would close, get warm, open too quickly and flush cold water through the engine. The temp gauge would drop and the thermostat would close again. This cycle kept going for the whole drive. took maybe 30 seconds per cycle. This is a case where the thermostat didn't have a big enough window, it was trying to hold too tight of a temperture window. It needed a wider hysterisis. A sloppier thermostat that wasn't as good at holding a specific temperture would have been better.

Good luck finding the thermostat opening curves. I've never found good documentation on it.

 

[Slowleak]

In hot weather a 180 thermostat may stay open too long, or all the time, once the engine is hot. That can allow water to flow thru the radiator faster than the radiator can cool it. A 195 will cycle open and closed allowing water to stay in the radiator longer and release more heat. That doesn't mean it's right in all situations. It depends on airflow, water flow, radiator cooling capacity, etc....

 

[NCBeachBronco]

In hot weather a 180 thermostat may stay open too long, or all the time, once the engine is hot. That can allow water to flow thru the radiator faster than the radiator can cool it. A 195 will cycle open and closed allowing water to stay in the radiator longer and release more heat. That doesn't mean it's right in all situations. It depends on airflow, water flow, radiator cooling capacity, etc....

That makes some sense...

So what I am doing now (going to a smaller water pump pulley) may actually do more harm than good as it will flow water faster and not allowing for heat transfer in the radiator... geez

but if the water is in the radiator longer and releasing more heat, isn't the water that is trapped in the engine getting more heat put into it - creating even more work for the cooling system to do once that gets there...

This is maddening lol

 

[Slowleak]

That makes some sense...



So what I am doing now (going to a smaller water pump pulley) may actually do more harm than good as it will flow water faster and not allowing for heat transfer in the radiator... geez



but if the water is in the radiator longer and releasing more heat, isn't the water that is trapped in the engine getting more heat put into it - creating even more work for the cooling system to do once that gets there...



This is maddening lol

I know. It is confusing for sure. Look at it this way. The smaller pulley is going to increase fan speed and airflow. That allows the radiator to release more heat.

The faster water pump will increase water flow but the thermostat will still control it. A 195 thermostat could allow the water to absorb more heat.

Then you have more heat being absorbed from the engine and more heat released by the radiator. Absorbing more + releasing more = a cooler engine. That's where you want to be.

 

[gr8scott]

as it will flow water faster and not allowing for heat transfer in the radiator... geez

Pure myth, read this article:
http://www.pirate4x4.com/tech/billavista/Cooling/

 

[Slowleak]

That's a lot of reading..... All I know is that if I put two beers in my fridge and leave the first one for 5 minutes and the second one for a hour, the second beer will be a lot colder.

 

[chuck]

Pure myth, read this article:
http://www.pirate4x4.com/tech/billavista/Cooling/

A lot of hi quality info, thank you.

 

[NCBeachBronco]

WOW - ALOT of reading.
Seams this guy is a fan of aluminum radiators with electric fans for sure.
Reading his article maybe my Triple Pass radiator is not the answer...

Chuck - he supports your smaller water pump pulley!!!
Hopefully by the weekend I will too!

 

[Slowleak]

I understand the logic behind the "more the better" theory but there must be a point where the additional engine heat generated, by pushing water faster, is more than the radiator can disperse with all other things remaining constant. That said, I don't think that smaller pulley alone will put you anywhere near that point.

If the smaller pulley will solves the problem we still won't know for sure if it was airflow problem or a water flow problem. If it wasn't torn down, I would say, let it idle until hot, measure the in and out radiator temps, stick a big portable fan in front of the radiator, and see if it cools down sufficiently.

I'm going to bet that the problem here is simply airflow as is the case for most Broncos with A/C. When you put a condenser in front of a radiator and swap to a smaller fan which doesn't fit the shroud, it drastically reduces airflow. I'm going to do some more testing on mine while I await your results!

I'm also going to conduct my cold beer test several more times for verification.

 

[NCBeachBronco]

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. It 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 %)

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???

 

[DirtDonk]

Excellent news! Not only for your peace of mind when driving your rig, but for another data point showing a fairly consistent improvement for the faster driven water pump.
Thanks for the update.

Paul