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Cooling System Overhaul - Stumped and Frustrated

don't want to take anything away from a cable, way cool tool... just don't want an IR guns value to be diminished...

when I test run boats, it's THE tool I bring with me.. invaluable...

have a good time! :D
 
Actually the best way I've found to purge them is to drive them around corners and stuff. Then add coolant. It's almost impossible that his thermostat is never opening and once it opens and starts to flow, that takes care of any air underneath it. But if there was air in the area of the temp sender it could give erratic readings.
 
Couple of points. If the cooling system is full with no air, then there are several things that can cause it to run hot.

But, wide temp swings are almost always one of two things.

Thermostat or fan clutch.

I have seen some weird ones, like the impeller slipping on the water pump shaft, or a glazed belt, but that is really unusual.

My Ford, came with the supercooling package. Which included a more aggressive fan and heavier fan clutch.
First time I took it out on the highway, I was driving along on the four lane and heard a car about to pass me.
I had not seen him in the mirror, and he never went by.
Just faded away.

About the third time that happened, I realized that it was the fan kicking in. Made fairly loud roaring sound.
Nothing you would notice over the radio, but definitely different.

I also noticed my temperature gauge would move over toward the high side of normal, the fan noise would ramp up, the gauge would move down and the noise would ease back off.

The gauge has numbers, but I don't remember the swing. If I had to guess, I'd say about 20 degrees or so.

Probably 300K later, it still does it. I have replaced the clutch a few times over the 24 years, and a couple of times I got the standard fan clutch by mistake.

Every time, the noise did not happen, the temp swings did not occur, but it ran hotter and the clutch did not last long.

If you have aggressive tires, you probably cannot tell, but if its fairly quiet, try listening carefully when the temp gauge gets to the top of its swing.

If its the fan clutch, you might hear the fan noise increase.

Of course, if you do not have a fan clutch or are using an electric fan, then don't bother reading the first part of this........
 
Yes, don't get me wrong, IR temp is valuable, and would definitely be cool to help understand how well the radiator is working, etc. You can't do that with an ALDL cable.

My only concern, which I suspect isn't an issue on a boat, is that you can't "watch" the problem as it occurs in a vehicle. I'm guessing on a boat you can stand there with the thing at X throttle, and shoot the temp anywhere necessary. On a vehicle you'd have to stop to do that, and with temperature swings, that's impractical.

But to verify the gauge reading, IR is definitely the easier way to do it.

For cooling you aren't getting anything you wouldn't with an IR gun, except that you can graph the coolant temp, understand at what MPH/RPM/load the problem occurs, etc. Really not valuable in this case I suspect, but you can set it up and go, and review the data after a drive without having to watch or do anything else while driving. Honestly our cooling systems aren't that complex, being able to look for trends shouldn't be particularly valuable when trying to figure out a cooling problem.

Laptop is an additional expense to ALDL, I'm not sure what software is out there for things like a tablet and the like. I was lucky and have found multiple laptops on ebay for $50-100, which although horribly antiquated for other uses, are perfectly useful for troubleshooting/diagnostics.
 
yeah, it's one I've been meaning to get around to. I need a good copy of windows... I have an older Toshiba that would be fine, just need an OS in it...
 
Blue85 said:
The reason I don't like the 30/50 mix is that the radiator isn't full.
Click to expand...

:haha: :waytogo:





I tried doing the "30/70" mix of antifreeze/water at the dunes last summer and I didn't notice any difference. Tried some of that water wetter too and saw little notable difference. My 408 stays under 220 beating on it at the dunes with a big aluminum rad with mechanical and electric fans, but I still don't like when the gauge goes over. 210.
 
System pressure tester is here, IR temp gun shipped.

Hoping to tear into it this weekend.
 
Blue85 said:
The reason I don't like the 30/50 mix is that the radiator isn't full. :D
Click to expand...

Why did you change my statement to 30/50? :whistle::haha:

I haven't heard any "reliable" stories of water wetter actually dropping the temp a meaningful amount, however theoretically being able to replenish the additive package of the coolant, without needing to change it, is a pretty big benefit IMO.

But again, the IR gun is probably the best bet, looking at radiator efficiency, gauge accuracy, etc.
 
Deuling said:
:haha: :waytogo:





I tried doing the "30/70" mix of antifreeze/water at the dunes last summer and I didn't notice any difference. Tried some of that water wetter too and saw little notable difference. My 408 stays under 220 beating on it at the dunes with a big aluminum rad with mechanical and electric fans, but I still don't like when the gauge goes over. 210.
Click to expand...

How many cores does that big aluminum radiator have? :dunno:
 
So, as many of you saw, I put a crate motor in this truck.

Before swapping the old one out, i pressure tested the cooling system, and found a small leak at a heater hose. Haven't' fixed this, but will fix it this week.

That being said, i'm still having the same issues. T-stat doesn't open until gauge hits 3/4, then drops back down around half, and floats at 200-220 off and on.

Wtf.

Any further suggestions? Would my LITTLE pressure leak that i know of cause fluctuation like this?
 
So the IR confirms the temp swings? They are definitely occurring as you state?

I guess in a really complicated strange turn of events sort of way a small leak could cause issues (pressure drops, fluid starts to boil, thermostat opens, fluid cools, boiling stops, pressure drops, repeat?) but that just seems unlikely.

I know you can back your radiator cap off one "notch" so it never builds pressure without loosing coolant, but I don't see how that would prove much, unless pressure changes are the issue.

Very long thread, did you do the whole boiling water/t-stat test?
 
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Well at least you eliminated the engine as a cause of the overheating...:D

I could imagine how frustrating that must be when you swap out the motor and still have the same issue. Does you heater work - just confirming that your lines to your heater core are not clogged? Did you replace both your upper and lower radiator hoses? New or old temp sender? The whole thing is odd because the system just is not that complicated.
 
Yes, i boiled the Tstat. And replaced it multiple times. Multiple working thermostats are behaving the same.

Forgot about that IR gun. Will verify temps tonight. I'm much better a throwing parts at things than i am at diagnosing them sometimes.

Will fix that pressure leak, retests the system, and hit it with the IR gun.
 
Started reading thread, have you verified the temp gauge is reading correctly, and the sending unit isn't flakey?

They are normally bulletproof but that's why you bought the IR gun as I recall.

Obviously fix the leak. Known problems first, diagnosis/assumptions/random guessing later. :)

Oh, and my Dad just recently had a problem with his engine "overheating". Turned out the gauge connection to the printed circuit "board" was bad. No comment.
 
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I swear i'm going to look at this this week.

Didn't really have to tow this weekend, so this fell off the priority list last week.

Although, i did tow a couple miles, and it definitely feels stronger with the new motor. Thing actually makes some torque, and doesn't need to be at WOT to get moving anymore. Was even able to peel out up the ramp with a loaded trailer!

Towing a 22' Malibu VLX up from Naci this weekend though, so I need to get this cooling issue sorted out, or i'm going to have some big issues.
 
Well, got the 2 SMALL hose leaks figured out. System holds pressure, no issues there.

Still heats up too much before tstat opens. Tried to hit it with a temp gun, but with a lag as the metals heat up, its hard to tell what is really going on.

What else could be causing me to be so maxed on cooling capacity all the time?

New Rad, cap, tstat, hoses, water pump, MOTOR, fan clutch.

WTF.
 
So, towed with it this weekend.

Damn truck heats up quick. Small grades unloaded gets the gauge moving north, and it heats up pretty fast under load.

As much as this truck is my pride and joy, it only remains that as long as it gets its job done. And it Barely did that this weekend.

New motor runs good, a bit more power than before, but unless i can keep the skinny pedal burried, it struggles.

Didn't have the temp gun to check temps when it was getting hotter, but will next time.

Any suggestions?!

Considering radiator or fan upgrades.
 
you need to verify temps.. i'm not buying this at all anymore with a different motor in there.. YOUR GUAGE IS INACCURATE...

does the truck actually overheat, or is this you seeing high #'s on the gauge?
 
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