7.3 temperature gauge dropping under load

[03wr250f]

put a aftermarket coolant temp gauge and a napa brand (stant reboxed) 13 psi cap on it
see what it does from there.

fan clutch should lock on first cold start of the day and run for about 30 sec to 2 min before getting significantly quieter. Basically should sound like a schoolbus/ airplane taking off next to you on cold start or when working it hard
if you dont hear that, its likely time for a replacement, but i dont think the fan clutch is your issue, not saying it cant be, but based on what you are describing, likely not.

 

[Kizer]

if you dont hear that, its likely time for a replacement

x2

Or search "fan clutch mod", or some such.

I've got a post on it, from way back.

 

[92gold]

Been driving the truck and it hasn’t gotten any better with the new cap. I got one of the pressure release ones with a red tab at orielly. I’ll try one at Napa today just to eliminate a cap issue. Here’s a video of what it’s doing. Temp stays normal until I give it more than half throttle and comes back up when I let off. Radiator hose looses pressure too when this happens

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[92gold]

looked at the fan this morning after it sat all night cold and I’m able to move it by hand, is there any other way to test it besides just hearing it?

 

[tradergem]

Sometimes an old lower radiator hose will collapse under suction from the water pump and block the flow of coolant causing part of the system to lose pressure temporarally. When you slow down the suction from the pump will lesson enough that the collapsed lower hose will expand open and allow the coolant to flow again and everything will look normal. It is really hard to diagnose because you can't see it while driving and it goes away when you slow down. If you squeeze the lower hose and it is really soft you might try replacing it and see if your tempurature readings smooth out.

 

[92gold]

Hose is one of the ones with a spring in it so it doesn’t collapse

 

[Cubey]

Sometimes an old lower radiator hose will collapse under suction from the water pump and block the flow of coolant causing part of the system to lose pressure temporarally.

Hose is one of the ones with a spring in it so it doesn’t collapse

Yep. It pulls out and has to be swapped to the new hose. Hoses don't come with it.

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[92gold]

Returned the O’Reilly cap and got a Napa 13lb cap with the safety lever and it’s still doing it

 

[Cubey]

Returned the O’Reilly cap and got a Napa 13lb cap with the safety lever and it’s still doing it

Get a real gauge, like I said. They're $30 for an Equus mechanical one and takes about 30 minutes to install. You can wire up the backlight later, if you don't want to immediately. It doesn't need any wiring done for the temperature reading. No need to drain any coolant either. Install it in the dummy light port or the stock gauge port. It'll work in either one and they are near each other. You're probably wasting your time trying to make the stock gauge work.

 

[92gold]

Would the mechanical one pickup the temperature change that quick? Since it only does it under heavy throttle then back to normal. Still confused why it’s losing pressure

 

[Cubey]

Would the mechanical one pickup the temperature change that quick? Since it only does it under heavy throttle then back to normal. Still confused why it’s losing pressure

How fast are we talking? I mean, it's 8 gallons of coolant flowing through the engine. It's not actually instantly heating and cooling because that's impossible. The point is that your factory gauge is likely faulty, if it's swinging wildly in a matter of a few seconds. Mechanical gauges will show the change in better real time than electric ones.

Start with a real gauge and see what it's really doing, then worry about pressure. If the temperature is fine and it's not losing coolant, I would leave it alone.

 

[IDIBRONCO]

How fast are we talking? I mean, it's 8 gallons of coolant flowing through the engine. It's not actually instantly heating and cooling because that's impossible. The point is that your factory gauge is likely faulty, if it's swinging wildly in a matter of a few seconds. Mechanical gauges will show the change in better real time than electric ones.

Start with a real gauge and see what it's really doing, then worry about pressure. If the temperature is fine and it's not losing coolant, I would leave it alone.

I agree with everything that Cubey said here.

 

[92gold]

How fast are we talking? I mean, it's 8 gallons of coolant flowing through the engine. It's not actually instantly heating and cooling because that's impossible. The point is that your factory gauge is likely faulty, if it's swinging wildly in a matter of a few seconds. Mechanical gauges will show the change in better real time than electric ones.

Start with a real gauge and see what it's really doing, then worry about pressure. If the temperature is fine and it's not losing coolant, I would leave it alone.

I agree, that makes more sense. I’ll order a gauge tonight. Looking at the gauges looks like there’s a mechanical full sweep gauge that’s 130-270 degree and a short sweep that’s 130-280. Which one would you recommend?

 

[Cubey]

I agree, that makes more sense. I’ll order a gauge tonight. Looking at the gauges looks like there’s a mechanical full sweep gauge that’s 130-270 degree and a short sweep that’s 130-280. Which one would you recommend?

Either of these:

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6242 (black) or 8242 (white)

Both have 240 as a major marker line, which is the absolute highest you want an IDI to get. Both are mechanical. I have the black one.

 

[Cubey]

My ill fitting but still useful universal pillar pod with it.
.

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