Let’s talk about egts and water temp

laserjock

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So I have a pretty well documented issue with water temps. While waiting to get my freeze plug issue resolved I’ve been kicking around a few things in my head. One of them is EGTs. Running a 110 from CDD and with my setup I can manage EGTs pretty well I think. In 4th gear climbing grade, I can just about push it flat on the floor and hold it there if I want. I get to 1000-1100 maybe a little more on a really long pull. Problem is if I get over 900F water temp really starts climbing. I guess that makes sense to me. I’ve been told you can run these engines at 1000-1100 F all day long and not hurt them. Well, I can’t because I can’t keep it from overheating. So I guess my question(s) for the masses are these.

1. Do you see similar behavior? Should 1000 F really drive up water temp fast?

2. If you see that behavior are you turbo, turbo + IC, or NA?

I’m starting to wonder if the problem really is the IC dumping heat into the rad when I’m working the truck. I know the charge pipes get really hot. I’ve been wanting to measure how hot that is but hadn’t taken the time to measure it. I really only make about 20-22 psi of boost. I suspect it would be more without the IC. Is the IC just really working well and causing a secondary issue? The big fan and 6.4 clutch have helped but I feel like I’m still not quite where I want to be. Maybe I need to shed some more heat elsewhere?
 

Nero

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You could look into water to air intercooler, I know some modern diesels have them with good results.
 

hacked89

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I saw the pic of your intercooler setup in your build thread. Have you considered any impacts of it on airflow?
 

Clb

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Once egt's spike +1000 deg mine will treat the temp gauge needle like a tach!
I think the cooling systems are at marginal capacity on a good day.
Shedding turbo heat into the rad sure don't help.
Just my .02
 

gandalf

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I have no answer for you, just some questions. Just to be sure, you're talking about the '91 F-250 in your sig block?

What is the condition of the radiator? If it has any flow problems when you're pushing the edge of the envelop...

What gear are you in when this happens? What rpm are you turning?

You have a Facet fuel pump. How is that working for you? Is it supplying enough fuel when you're really pushing it up a hill, or might it be running lean?
 

Big Bart

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Some thoughts -

1) Make sure you have a Motorcraft thermostat. Others can cause overheating.
2) Make sure your timing is on, if off it could be creating some of the heat.
3) Tripple ditto above, if anything is blocking the radiator perhaps you have a airflow issue with the radiator.
4) Make sure you have a good radiator, it could be partially clogged if old.
 

catbird7

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Sounds like what you really need is more data. One piece of info that would be extremely helpful is air temp between intercooler and radiator particularly when the coolant temp spikes. It would be interesting to watch the interaction of boost, egt, coolant temp and air temp between intercooler and radiator, and how each reacts as values change.
 

Cubey

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Basically:
lower rpm = higher EGT / lower water
higher rpm = lower EGT/ higher water

At least when it comes to steep climbs, since the engine winds down so much in higher gears until you downshift.

It's a balancing act. You have to let one go up to let the other go down.

A weak fan clutch can result in at least 10-15 degrees higher water temps. The fan clutch and thermostat on my RV got replaced in 2019 (both Motorcraft parts) and it instantly ran that much cooler.

Since then, on highways, it usually runs 180-195 (water). EGT is usually in the range of 600-900. Depends on wind, hills, temp outside, etc. I often stay at 55ish, though.

Mountains can bring EGT up to 1100 if I'm not careful. But typically I just downshift, or if in 1st already, just let my foot out of it a little.

Water got to 240 last summer on a steep dirt road because I forgot I had AC on during an 80-85F day. I had my eyes glued to the gauge as it was climbing, and I was able to stop and let it cool down when I saw it hit 240. I opened the hood and blasted the heater to give it as much cooling as it could get while letting it idle for the fan and water to cool it off. It only took a matter of 5 minutes to get it down to 220 just sitting there.
 
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Black dawg

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What I have noticed is that anything above 1100 or so degrees, and coolant temp becomes an issue. I can pull all day at 900 degrees (at highway speeds) and around 9psi and temp stays comfortable.

This is with maxed out 7.3 pump and ats non wastegated turbo with 6.0 intercooler. From all of my testing with IR gun on different points of cooling system, I decided that the water pump just doesnt flow enough (for a turned up turbo engine). Bottom of radiator was never as warm as it should have been with t stat open and engine hot. I have seen a factory turbo truck (turned up) that was a typical overheater, get a smaller pulley built for the water pump, and have no heating issues afterwards.....
 

laserjock

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Thanks for the responses.

Yes it’s my truck in the Sig.

Radiator was a new champion when installed.

Typically if I’m pulling hard I’m in 4th turning 2300-2500 rpm.

I have very much considered that it still may be an air flow issue as the fan helped but like I said, didn’t quite get me there.

I’ve considered pulling the IC just to see what it does. I don’t want to keep it that way but I could do it as a test.

It’s certainly worse with the AC on.

I’ve tried bypassing water around the stat. No real change. It is a motorcraft stat though.

Timing is set at 8 BTDC I think. Don’t remember for sure now but I did set it and re-check it.

I’m starting to think it really is coming down to capacity.

Good discussion guys. Keep it up.
 

Clb

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An fwiw anecdote...
So my 93 has low miles but the rad was internally fouled.
The search for a replacement was as you know, f u b a r.
The 4 hunneret dollah s h i t was not an option, the custom shop back east was like 4k or some stupid s t u f f! A hand built local was stupid monies.
So old school it was.
Red devil lye
Aka sodium hydroxide just like the rad shop used to do...
A rinse with detergent for safe keeping and a soda bath to neutralize the acid and gtg!
If you pull the rad, set it on sawhorses ports up you can completely fill it. Use a disposable rad cap.
 

IDIBRONCO

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From all of my testing with IR gun on different points of cooling system, I decided that the water pump just doesnt flow enough (for a turned up turbo engine). Bottom of radiator was never as warm as it should have been with t stat open and engine hot.
This sounds like it would be a good test for a Flow Kooler water pump.
 

laserjock

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Possibly. I also forget that the water cooled turbo is dumping heat in the system too.

I wonder if something like this would be enough to do anything as an aux rad.



I know the right answer is more data. I don’t know why I keep putting it off.
 

IDIBRONCO

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That seems like a pretty good price if it's decent quality. ATV/motorcycle radiators are usually pretty high priced for no bigger than they are. You'll have to do something about the overflow port (I doubt you'll want that) and I'd hook an electric fan to the radiator just to make sure that you'll have enough air flow to cool the coolant.
 
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