Just been out today on a freeway type 60 mile cruise at about 60-70 mph.
It was VERY WINDY and a lot of drag on the truck was evident.
I wasn't towing anything.
Today I noticed that my temp gauge was moving from a needle thickness below half way, which is normal all the time for my 75,000 mile Hemi, to about 3/4 of the way to high, then back to just below 1/2 way again.
It was cycling between the two all the time, taking between about 3-4 minutes, between the lower and higher readings.
I've not noticed this on my Hemi before and whenever I've looked in the past, it was alway rock solid, one pointer thickness below 1/2 way.
Any ideas???

My oil is ok no emulsion etc, no loss in performance and no bubbles in the coolant.
I did have a coolant leak about three months ago and fixed it with a "stop leak" type radiator additive.
It was the typical Hemi radiator problem where the seems on the rad have a slight split.
The reading on the temp gauge was always at just below 1/2 way until today.
This is it's first longish run out since adding the "stop leak" stuff.
My thoughts are,
1) ?? Radiator blocking up.
2) ?? Stop leak is causing somthing.

I think the thermostat is OK, as the temp ranges from low-medium high then back to low. I' m thinking this signals that the thermostat is working.

Any help is appreciated

 

Sorry for the double post but I think that the web site computer gremlins just kicked in????
Al.

 

You might want to check the coolant temp sensor. If it's going **** up it could easily give you erratic readings. I see on the aircraft I work ever so often. I wouldn't totally rule out a thermostat yet. It could be stuck in the patially open position until pressure gets high enough to force it open the rest of the way, and thencloses it again. I tried to embed a page from the overhaul manual that has the location of the temp senderfor the 5.7. It has a couple of the motors from 03 on there. Sorry if it comes out crappy. It was my first time uploading a photo.

[IMG]local://upfiles/57181/DD52281D72744C0E8EC53EFB0753A4FE.jpg[/IMG]

 

Not a problem tafet
The attachment came out just fine.
Thanks for the info.
I'm just ordering up the 180 degree T stat from Moe's and before fitting it I will pull the radiator and have it professionally repaired and flushed.
I'll refit it then do the T stat.
I sure hope that will be the end of the problem???
Plus, I'll have a 180 degree T stat mod as well.
Al.

 

Your problem might be that stop leak crap that you put in there, it may have blocked something up. Could be your stat blocked or just a passage somewere. You should never use this stuffI have seen it cause more problems then it fixes.

 

My guess would be the t-stat, as well. Mine started doing that so before it failed, I went ahead and changed it. Now there are no "drifting" movements in the gauge. With my 180 'stat, it now rides a bit below 1/4 on the highway. In town, it rides at the original "normal" position, just below 1/2. I have my e-fan set to kick on at just over 1/2. Even in traffic, the e-fan pulls it back down to a bit over 1/4 in 3-5 minutes. The 'stat is easy to change -- make sure you don't leave any coolant behind for a critter to find. You'll wind up needing to capture about a gallon of coolant. If you catch it with a clean container, you can just pour it back in. It took me less than thirty minutes to do mine.

 

Hey Al,

Since you're going to have the system drained, and in for a flush and fill, you may want to pull the pump and inspect it too.
Nothing worse than doing all that, to find out the impeller is going to hell on you, and you end up doing it again, especially if you have to order parts--since you live in the land of fog.

 

Ha ha ha LMAO Gone Fishinabout the fog crack.
It's also one rainy place these days as well. Something about global warming???
I might just do that and crack open the water pump.
Is it easy to do??
The T stat I think, can be changed wiithout pulling all the serpentine belt etc, that the manual says you have to do.
Any experience on that?
Anyhow............thanks for the help and the good laughs.
Take care.
Al.

 

The belt is the least of the problems. The biggest problem you might find is the big nut that holds the fan clutch to the pump shaft, In fact, that is what I would approach first, with the belt still on. If I remember right, the nut turns the normal clockwise to tighten facing the fan-so leave the belt on, insert a shop towel between the belt and the fan pulley so as to bind the belt, then with the wrench in place, and a decent size hammer, smack the wrench to break the nut loose. Then pull the belt and remove the clutch. Now you should be close to being able to pull the water pump. FSM says it takes a 36mm wrench. The FSM calls for the shroud to be removed and a few other things, but it doesn't lookdifficult at all. I would guess a couple of hours--done.

 

While ya got it all taken apart, getcha a Flex-a-lite Black Magic Extreme 180 e-fan. That's easier if you pull the shroud, but not necessary. You don't have to pull the belt, the shroud or anything else to change the t-stat. Be careful not to damage the gasket.