• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

My overheating journey never ends

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,604
To follow up on Pauls comment about block pressure i learned a lot when researching radiators, block pressures, etc. Talked to dozens of radiator, etrpump manufactureres and several big time racers about block pressure...read my Torture test post on this forum...very intereting info on a block pressure test without the rad cap (because its a totally different system)...more block pressure=better cooling (to a point of course).
.

Good luck!!!
 
OP
OP
M

mduenas

Sr. Member
Joined
Dec 29, 2015
Messages
511
Loc.
Los Angeles
mduenas, is yours an automatic tranny?
The idle speed on those is critical.

it is an automatic. 700r4. My idle sits around 720. I went to change it in the fitech controller to turn it up, and it won't change, even sending to ECU, turning the truck off, then turning back on. What should my idle be? How do I actually turn it up? I know how to with a carb, but fitech is new to me.
 
OP
OP
M

mduenas

Sr. Member
Joined
Dec 29, 2015
Messages
511
Loc.
Los Angeles
Paul,

Thank you so much for in depth response. When I advanced a 1/4" turn I didnt notice a difference in driving, and temp seemed to be around the same. When I went 1/4" more I was certain I was hearing knocking, I could very well be crazy. Throttle response felt better, but I also felt like I smelt an oil smell out of my exhaust, although I could be looking into it to much.

I also did a chemical test to see if I had a blown head gasket and I passed that.

I just drove for about an hour today, in some traffic and some smooth flowing sections of street. It is 80 degrees out today and I kept the ac on. I hovered around 205 the entire time, and heavy traffic it got to 207 then dropped back to 205 or so. So such a slight fluctuation. When I put the truck in park, for 2-3 min the temp started rising before I shut it off. I do have a much higher idle in park, it sits about 1100, but in gear it sits around 720, I am not sure how to change the in gear idle though, as I know if my fan moves faster, the truck will stay cooler in traffic, or so I assume.

I am going to try and play with the timing again and drive longer
 
Last edited:

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,604
IF you can't cool at 720 rpm, your cooling system still needs help..

Re-read the post.. didnt see any answer..

are your clearances between the shroud and fan spot on? Is the fan 1/2 to 2/3 of the way into the edge of the shroud? These are a must...

If you try to stir a bucket of paint with a yardstick and its only sticking into the bucket one inch...not much is going to happen. Stick the yardstick in to the bottom, spin it the same amount and you are now mixing..
Same concept...
 
OP
OP
M

mduenas

Sr. Member
Joined
Dec 29, 2015
Messages
511
Loc.
Los Angeles
IF you can't cool at 720 rpm, your cooling system still needs help..

Re-read the post.. didnt see any answer..

are your clearances between the shroud and fan spot on? Is the fan 1/2 to 2/3 of the way into the edge of the shroud? These are a must...

If you try to stir a bucket of paint with a yardstick and its only sticking into the bucket one inch...not much is going to happen. Stick the yardstick in to the bottom, spin it the same amount and you are now mixing..
Same concept...

It is definitely inside the shroud. And about 3/4” to my radiator. I complete understand that. The fan creates enough suction to hold a shop rag to the grill and small hand towel. But I know my condenser is definitely blocking some flow.

I’ll play with putting my fan more into the shroud. I can’t push the fan closer to the radiator, but I am thinking I can put rubber under the shroud to push it around the fan more? I have attached a photo of the depth. I have aluminum tape around it to seal it fully against the radiator. This shroud was hacked to death to fit with my 1” body lift. So I put aluminum tape to reshape or round and close to the fan blades.

I tried brand new shrouds and couldn’t get them to fit, they either hit my pulleys and or I couldn’t get them to hang low enough for the body lift. I tried steel ones and a full circular one. I’m down to try and make anything work.

I can’t afford the explorer serpentine swap for a bit. So I’d love to do what I can.
 

Attachments

  • C17E8128-1A2C-4077-84FE-9107161D749F.jpg
    C17E8128-1A2C-4077-84FE-9107161D749F.jpg
    71.6 KB · Views: 122
  • CFB74362-9D92-47CF-87B3-B4ADA127480C.jpg
    CFB74362-9D92-47CF-87B3-B4ADA127480C.jpg
    87.9 KB · Views: 115
  • 8C51D616-1ADF-456E-9853-5A741E3972B6.jpg
    8C51D616-1ADF-456E-9853-5A741E3972B6.jpg
    85.6 KB · Views: 114
  • 76D05BB4-EF19-48FF-9D70-2D28C06A2B04.jpg
    76D05BB4-EF19-48FF-9D70-2D28C06A2B04.jpg
    85 KB · Views: 105
Last edited:

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
Your radiator hose is routed higher than the top of the radiator. That almost always creates an air bubble in the upper hose. The early V8s had a surge tank and the pressure cap was up there to make sure to get the air bubble out.

I would recommend trying a remote upper radiator hose fill. Several versions, this was top of the Summit racing search https://www.summitracing.com/parts/hre-3423/overview/. Put a lower pressure cap on that and a higher pressure on the radiator. This will mean the hose fill will open first, venting air out of the upper hose. The cap on the radiator should never open. Run both hoses into the same overflow so if either sucks anything back in it will be water and not air.

I find it odd that you can drive around with the A/C on and it runs a perfect 205. But idle, with the 1100 RPM in neutral idle, it gets warm. If anything that should be the sweet spot where it cools the best. No load, a little extra RPM for the fan. The pictures look like it should cool. Everything looks right. The fan depth looks good (I can't see the diameter for sure but it looks fine), shroud, even the extra sealing. The only thing that looks wrong is the upper radiator hose has a high spot that is too high above the cap.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
Do you know what the transmission fluid temperature is? Do you have a temperature gun to get temperature readings.
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,604
I read the 4 other links you had. I co firmed the flex fan...ditch the flex fan... similar posts like yours here---flex fans--- replaced and all had improvement
 
OP
OP
M

mduenas

Sr. Member
Joined
Dec 29, 2015
Messages
511
Loc.
Los Angeles
Your radiator hose is routed higher than the top of the radiator. That almost always creates an air bubble in the upper hose. The early V8s had a surge tank and the pressure cap was up there to make sure to get the air bubble out.

I would recommend trying a remote upper radiator hose fill. Several versions, this was top of the Summit racing search https://www.summitracing.com/parts/hre-3423/overview/. Put a lower pressure cap on that and a higher pressure on the radiator. This will mean the hose fill will open first, venting air out of the upper hose. The cap on the radiator should never open. Run both hoses into the same overflow so if either sucks anything back in it will be water and not air.

I find it odd that you can drive around with the A/C on and it runs a perfect 205. But idle, with the 1100 RPM in neutral idle, it gets warm. If anything that should be the sweet spot where it cools the best. No load, a little extra RPM for the fan. The pictures look like it should cool. Everything looks right. The fan depth looks good (I can't see the diameter for sure but it looks fine), shroud, even the extra sealing. The only thing that looks wrong is the upper radiator hose has a high spot that is too high above the cap.

Would I put the radiator hose fill close to the inlet for the upper hose? Can I use my existing hose and just cut it? Also, where do I route the overflow too? My overflow tank only has one inlet.
 
OP
OP
M

mduenas

Sr. Member
Joined
Dec 29, 2015
Messages
511
Loc.
Los Angeles
Do you know what the transmission fluid temperature is? Do you have a temperature gun to get temperature readings.

I don’t know the temp. I don’t have a temperature gun, I’ll see if I can borrow one from a friend. Would the transmission fluid possibly be heating up my coolant, as it runs through the radiator?
 
OP
OP
M

mduenas

Sr. Member
Joined
Dec 29, 2015
Messages
511
Loc.
Los Angeles
I read the 4 other links you had. I co firmed the flex fan...ditch the flex fan... similar posts like yours here---flex fans--- replaced and all had improvement

So are you recommending a rigid 17 or 18inch fan? I’m really thinking of trying to see if I can fit an electric fan. With no shroud. I have 3” from radiator to pulleys. So I need a compact fan, something that pulls around 2700cfm or so? I feel at idle that would be more efficient.
 

bronconut73

Bronco Guru
Joined
Aug 7, 2012
Messages
9,916
The only electric fans that seem to actually keep an eb cool are oem Taurus/Lincoln/Volvo fans.

These require a lot of room.
The Explorer serp system will give you that extra room but then you could use the best mechanical fan for an eb, the Explorer serp fan.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
Would I put the radiator hose fill close to the inlet for the upper hose? Can I use my existing hose and just cut it? Also, where do I route the overflow too? My overflow tank only has one inlet.

Just cut and splice it at the highest possible point. In a conventional cooling system the radiator car is used to degas the cooling system. Splice the overflow lines together.
 

mjschneidy

Full Member
Joined
Nov 21, 2016
Messages
224
I didn't read through all the posts but you mentioned the motor is newly rebuilt? A common mistake is head gaskets in wrong with the block to head water passage at the front instead of the back. This will cause all kinds of cooling issues.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,345
I don't know how much this would effect things, but that idle in neutral is way too high and perhaps it's putting enough load on the transmission at idle in Drive that it's building up more heat than the system can eliminate.
Seems like the neutral idle should be 800 or less, and 600-700 in Drive at the most?

I'm no expert on the subject either, but seems to me that automatics don't like to idle that high (in drive). It's like putting your foot on the brake and then giving it gas to load up the torque converter. Puts stress on the trans and builds more heat.
Doesn't seem like it would be enough to make it overheat at the level yours is, but it might be adding to the dilemma.

I know you said you tried to bring it down some and were unsucsessful, but it seems it should be able to lower your idle all the way to 500 if that's where you want it.
Have you had any time to pop over to the FiTech facebook page, or their online forum where actual users (along with the tech guys) seem to be answering questions better than calling in on the phone.

I agree that 1100 rpm in neutral should keep the engine cool though. Just how high do you rev it when you're running hot, in order to cool it down quickly like you've described? Just a couple hundred more rpm? Or more up into the 2000 and above range?

Paul
 
Last edited:

pcf_mark

Bronco Guru
Joined
Jun 11, 2010
Messages
3,574
I think the funky upper hose position and the solid non-flex fan are really hurting the situation. Mentioned above is the use of an early surge tank in the upper hose. I had one stock in 68 but when I changed the radiator to a later one I just eliminated it. The solid flex fans are just awful. I could have a box full of them if I kept every one of those I took off muscle cars with guys trying to get them to run cool. It would also help if the shroud wrapped around the sides your cooling air is leaking out on the sides but it is covered nice on the top. You could mock that up with some thin aluminum strip and pop rivets.
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
it is an automatic. 700r4. My idle sits around 720. I went to change it in the fitech controller to turn it up, and it won't change, even sending to ECU, turning the truck off, then turning back on. What should my idle be? How do I actually turn it up? I know how to with a carb, but fitech is new to me.
That sounds too fast.
There is an RPM window where the air & coolant flow is good, but the torque converter isn't pulling. That's what you want. Too fast and the torque converter is dragging and making heat like crazy.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
An automatic (the torque convertor) won't be making heat with the transmission in park of neutral. Only makes heat in gear.
 

blubuckaroo

Grease Monkey
Joined
Jun 11, 2007
Messages
11,795
Loc.
Ridgefield WA
An automatic (the torque convertor) won't be making heat with the transmission in park of neutral. Only makes heat in gear.

I always set my idle speed with the auto tranny in gear.
That's too fast for most torque converters with a standard stall speed. It would create lots of heat.
 

nvrstuk

Contributor
Just a Bronco driver for over 50 yrs!
Joined
Jul 31, 2001
Messages
8,604
YES!!

Quoted: "So are you recommending a rigid 17 or 18inch fan? I’m really thinking of trying to see if I can fit an electric fan. With no shroud. I have 3” from radiator to pulleys. So I need a compact fan, something that pulls around 2700cfm or so? I feel at idle that would be more efficient"

Absolutely toss the flex fan and go with a Ford 7 blade fan.
 
Last edited:
Top