My overheating journey never ends

[mduenas]

Also what should my in gear idle be? It is at 720 or so right now, and in Park I’m around 900-1100 (starts high, then slowly drops) trying to get everything.

Paul, I’m going to write you back, just waiting till I sit at a computer!

 

[PaveBronco]

Been reading and empathizing lots of info, agreed on the shroud there is too much of a gap, got to be moved down, thought I saw actual lowering brackets somewhere. looked like strips of metal with two holes. Not sure that's a good permanent fix, but you could make some then test drive. And the AC doesn't help either, it puts a load and heats things up.
Anyway on the FiTech here is a good link, lots of good info for tuning and setup.
https://www.youtube.com/watch?v=A80SLaM1bnw&index=17&list=RDQMeDA_AzRN-7o

 

[mduenas]

I have no idea if this has anything to do with my overheating issue... but this morning I made a sharp turn and a good amount of water poured out of my heater / ac vents. I smelt it and it did not seem like coolant. But my coolant mixture is so low it is hard to tell. I ran the ac all day, condensation maybe? Looked in my vents and I see water droplets, but not full of water. I’m perplexed.

Edit: it is a new heater core

 

[mduenas]

Been reading and empathizing lots of info, agreed on the shroud there is too much of a gap, got to be moved down, thought I saw actual lowering brackets somewhere. looked like strips of metal with two holes. Not sure that's a good permanent fix, but you could make some then test drive. And the AC doesn't help either, it puts a load and heats things up.
Anyway on the FiTech here is a good link, lots of good info for tuning and setup.
https://www.youtube.com/watch?v=A80SLaM1bnw&index=17&list=RDQMeDA_AzRN-7o

I feel like I have scoured for a bracket to lower the shroud wirhot straps. Seems like I could make one with a strip of aluminum

 

[PaveBronco]

Something like this might work.

 

[mduenas]

Something like this might work.

Perfect visual. Thank you!

 

[Socal Tom]

I'm coming in late, but here is what I learned over the years.
Assuming that your cooling system is in proper shape, you can still overheat a bronco in the following conditions.
1) Automatic transmission, Big Tires, stock gear ratio and slow moving, or idling in gear.

If the Torque convertor is making torgue ( under ~1500RPM) then it makes heat. If you have tall tires and a 3.50 or 4.10 gear ratio, then city driving can put you at low RPM. I was amazed how temps dropped in mine when I went to 4.88 gears.
You can check this by making sure to keep the RPMs up, and make sure to move to neutral while idling.
Tom

 

[DirtDonk]

Was that you asking about shroud straps a week or two ago mduenas?
I popped back in to bring that up, but I see a couple of others have already done so. I was just thinking that the "straps" you mentioned were in fact just spacer strips, or in this other case lowering brackets, simply to lower a shroud to accommodate a body lift.

After all, when the fan is sized to the shroud, there is very little leeway in lifting the body before the fan hits the shroud. If you have enough clearance that you can raise the body more than an inch, you may have too much clearance between fan and shroud, as was being talked about.

But it's close sometimes. Every Bronco and every shroud is a bit different in their own right. But pretty sure any "straps" you were wondering about are just going to be for lowering the shroud.
Optimally you want the shroud open to all the cooling fins, but in the case of straps vs the lowering brackets pictured, I'd prefer the brackets because they leave more fins exposed to air flow.
It's not optimal, because the shroud itself is not covering the fins. But the most common alternative of covering them and literally blocking them by laying a flat strip across the fins, is less desirable to my way of thinking.
Because even in a situation where the fins are exposed to air outside of the shroud's coverage, air is still going to be pulled through the fins from the action of the air flowing through the main core and shroud. Whereas the strip is blocking that flow completely, unless it's standing off from the fins.

Most of us that have body lifts, including me, do use strips though. And most of us definitely don't have an issue with overheating. That little tiny percentage of fins that are blocked by the straps should never be enough to cause a problem. If so then the radiator is sorely under-sized to begin with. Something the factories almost never do anymore. Maybe 60 years ago, but they learned their sizing lessons well over the years.

The perfect shroud is one that fits the fan size and location, is located over all fins and tubes, and is sealed pretty well around the edges.
Hard to accomplish this with so many different setups, so it almost has to be a custom unless sold as a "pair pack" cooling system.

Maybe not at work here in your case. Just bringing it up for the sake of discussion.

Paul

 

[mduenas]

Paul,

I messed with the timing and drove a lot today, well about 70 Miles, free flowing and traffic, it is 85 degrees out today. I stuck around 205. Which is great for my truck, but after about 30 min In spots of traffic and then moving and traffic and so on, I got to 215, before I stoped at my destination, it hits a point where it will just keep going up.

With even a quarter inch turn if the distributor it sounds like I have marbles in the engine when I accelerate. Making me believe it is too far advanced, so I feel like can rule out the timing? The difference this time adjusting my timing was that I reset the fitech to learn again. No more knocking. But like I said, sounds like marbles when I accelerate.

Also, if I put the truck in neutral and give it gas, hold the RPM’s at 1500, my temperature starts to drop. The moment I drive, moving not in traffic it will climb. This makes me
Believe it is my Torque converter. But then again what do I know.

I ordered another new shroud and the 18inch rigid fan from wild horses. I am going to add an upper hose fill, and change to a 16psi cap. When I get the time, I will pull my
Headers and wrap them.

And yes that was me asking about the header straps.

What else am I missing?

 

[mduenas]

I'm coming in late, but here is what I learned over the years.
Assuming that your cooling system is in proper shape, you can still overheat a bronco in the following conditions.
1) Automatic transmission, Big Tires, stock gear ratio and slow moving, or idling in gear.

If the Torque convertor is making torgue ( under ~1500RPM) then it makes heat. If you have tall tires and a 3.50 or 4.10 gear ratio, then city driving can put you at low RPM. I was amazed how temps dropped in mine when I went to 4.88 gears.
You can check this by making sure to keep the RPMs up, and make sure to move to neutral while idling.
Tom

I have 33’s that are wide, and stock 3.10 gearing. I’ll look into 4.88 since I have overdrive.

 

[Broncobowsher]

You are correct, too much timing advance. Back it down a little. The pistons and rings don't like the detonation (might as well be throwing marbles in there).

Forgive me if this hasn't been discussed before, but how is the transmission cooler routed? For what you are fighting the best route is generally out of the transmission (front port on a C4) to an oil to air cooler, and from there to the in radiator cooler, back to the rear port on the C4.

The oil to air cooler is fussy about port orientation as well. Both ports on the bottom is generally the worst, for side ports it should flow bottom up to top.

 

[mduenas]

You are correct, too much timing advance. Back it down a little. The pistons and rings don't like the detonation (might as well be throwing marbles in there).

Forgive me if this hasn't been discussed before, but how is the transmission cooler routed? For what you are fighting the best route is generally out of the transmission (front port on a C4) to an oil to air cooler, and from there to the in radiator cooler, back to the rear port on the C4.

The oil to air cooler is fussy about port orientation as well. Both ports on the bottom is generally the worst, for side ports it should flow bottom up to top.

I have a 700r4. It is routed from the transmission along my frame on the passenger side, into the radiator and back to the transmission. I don’t even know where I would have room for an oil cooler?

 

[DirtDonk]

Yep, marbles is too much. Strange that so little is too much, but it is what it is.
Glad that tuning the FiTech got rid of the knock, but that in itself is a little off the normal path too. Wonder what was going on there?
I wonder if the FiTech tuning is creating a condition where that too much advance arrives too early. Perhaps from running lean as an example.

Thanks for ordering more parts. But sure hate to see you chase your tail around in ever-smaller circles! Smaller is good of course, but circles are circles and as they get smaller you just get dizzier quicker!

You're going to have one heck of an entry into the local swap meet I bet!
I think we may be seeing you at our Broncotoberfest Swap-Meet at WH.%)

Paul

 

[mduenas]

Yep, marbles is too much. Strange that so little is too much, but it is what it is.
Glad that tuning the FiTech got rid of the knock, but that in itself is a little off the normal path too. Wonder what was going on there?
I wonder if the FiTech tuning is creating a condition where that too much advance arrives too early. Perhaps from running lean as an example.

Thanks for ordering more parts. But sure hate to see you chase your tail around in ever-smaller circles! Smaller is good of course, but circles are circles and as they get smaller you just get dizzier quicker!

You're going to have one heck of an entry into the local swap meet I bet!
I think we may be seeing you at our Broncotoberfest Swap-Meet at WH.%)

Paul

Definitely have some parts to unload haha.

I just looked at my overflow tank. And it is about 1/4-1/2 lower than it was this am, I topped it off. I did a chemical test to see if I had carbon in my
Coolant and I didn’t. So it’s not my
Head gasket, and none is leaking..... there was water in my heater this morning that came out, maybe a bad heater core causing this? It is new though.

 

[nvrstuk]

I know you cant spend the time doing this BUT...it would be fantastic IF you could replace one item at a time so you absolutely know what fixed the problem! (we hope!!)

Throwing all the parts on at once and you will never know what the cause was...

Most this wouldn't be an issue...for me, I'd have to know...I'd have to replace one at a time!!

 

[blubuckaroo]

Also what should my in gear idle be? It is at 720 or so right now, and in Park I’m around 900-1100 (starts high, then slowly drops) trying to get everything.

Paul, I’m going to write you back, just waiting till I sit at a computer!

The in-gear idle RPM depends on the torque converter stall speed. Your 720 seems a bit fast, but not by much for a stock torque converter.
You should be able to tell. If the tranny is trying to pull the car at idle, then the idle speed is too fast.

 

[mduenas]

The in-gear idle RPM depends on the torque converter stall speed. Your 720 seems a bit fast, but not by much for a stock torque converter.
You should be able to tell. If the tranny is trying to pull the car at idle, then the idle speed is too fast.

It absolutely pulls the truck at idle, a good rate too. I need to figure out how to drop the idle speed in gear. What should it be around?

 

[mduenas]

I know you cant spend the time doing this BUT...it would be fantastic IF you could replace one item at a time so you absolutely know what fixed the problem! (we hope!!)

Throwing all the parts on at once and you will never know what the cause was...

Most this wouldn't be an issue...for me, I'd have to know...I'd have to replace one at a time!!

I wanted to just replace the fan. But the. I have to empty and remove my radiator for my seventh time in a month, then again for the shroud, I’m losing my mind pulling it out so much. But I want to know so bad what is causing it.

 

[gr8scott]

It absolutely pulls the truck at idle, a good rate too. I need to figure out how to drop the idle speed in gear. What should it be around?

In gear most C4's like 550-600 RPM.

 

[DirtDonk]

Agree. I can't imagine a Bronco with an auto and a 1000 rpm idle speed. They clunk going into drive enough as it is even at the normal idle speed!

There is a spec of course, but I don't remember exactly what it is. I've always set them around 700-800 in neutral, and that puts them around 600 in drive.

A modern computer car is different of course. I just verified what I suspected with a Buick Regal today, that it idles at 700 rpm in drive and about 701 in neutral!
In other words, you can tell it's in neutral, but it doesn't really change enough to take notice. The computer just tells things to do what they're supposed to and they do.
Yours is not computer controlled, so is more along the lines of what we're used to with a C4.

But either way, you should not have to really press on the brake to keep it from creeping forward. Sure, there is some push from the engine when you're sitting still, but it's not much. You should be able to let off the brake and have it start to roll forward at a modest pace.

I've never seen an engine that wanted to be idling at over 1000rpm in neutral with an auto. Definitely try to get it down to a normal idle, even if your temperatures seem to prefer the higher speed. Correct everything and other things might follow along.
It's just not proper for any engine I'm familiar with to idle that high.

Could there be any little characteristics of a GM transmission that we're not thinking of?
Did they have big coolers on them in their original applications? What was this one out of originally?

Paul