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Temperature Problem - Gauge or Actually getting hot?


adamzan
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Hey, so for the past little while I noticed my temp gauge is not working properly. It seems that whenever you use anything that takes a decent amount of current (power windows, headlights, rear defrost, blower fan) that the gauge will spike up slightly and then go down. And when you drive it will go slightly over half almost to 3/4 sometimes and then drop back down while idling. Should not be doing this especially in the middle of winter here. I swapped clusters, did the same thing, swapped temp senders did the same thing.

I am starting to think that I actually have two issues here. Is there a certain ground that may be bad? Also what could be causing it to run hotter, I have a 180 deg thermostat but it has been in there since before last winter and I did not have any issues with it.

I made a video of it, it is idling my garage but you can see what I mean:

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Definitely sounds/looks like a ground problem. Check your grounds from the engine to the body. You know, the ones on the exhaust manifolds that are always coming off or people don't put back on. Make sure the ground at the battery is clean and see if the cable is still attached to the body as well.

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Yea that's a strange one. I would think that there is a bad ground in the chassis but I don't know where you would begin looking for that one.

 

First guess would be body to cluster ground but I'll look through the FSM and see if anything obvious jumps out at me...

 

Sent from my SGH-T999V using Tapatalk

 

 

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He tried a second gauge cluster already and it did the same thing.

 

I took this pic earlier when we were talking to show Adam where my temp sits, I have a 170 degree thermostat, this is about how hot my temp gauge runs all the time:

 

dnzig8.jpg

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Definitely sounds/looks like a ground problem. Check your grounds from the engine to the body. You know, the ones on the exhaust manifolds that are always coming off or people don't put back on. Make sure the ground at the battery is clean and see if the cable is still attached to the body as well.

I will check that out, I have headers now, so could I just re attach those grounds to another place on the motor? Also, where did they go on the other end? Mine are all non-existant. I have one of these style battery terminals on the negative side. I always thought that they gave a ****** connection. I think I will try and buy a new negative cable.

 

dontuse.jpg

 

Round dash truck. This has been covered before Adam :P

 

Take the cluster out and give all the screws on the back about 1/8th to a 1/4 turn to tighten.

 

Report back afterwards.

Yes I tried that, even on the other cluster I swapped in. I cranked that @!*% down tight, got almost 1/2 a turn out of all of them. On both clusters I tried.

 

Noticed that at idle the temp drops down to normal, but when driving it goes up...like past halfway.

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I have one of these style battery terminals on the negative side. I always thought that they gave a ****** connection. I think I will try and buy a new negative cable.

 

dontuse.jpg

 

 

Don't waste the time, energy or $ replacing those as long as they are not deformed or severely corroded. Every vehicle I have owned in the last 30 years had that style connector, and they were always more than sufficient. Are they the best? No. Do they work just fine? Yes...

 

B

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My temps gauge was sitting a little higher today, after I replaced the plug wires, cap and rotor, I started the engine and the temp gauge seemed like it was not moving at all so I pulled the connector off the sender and than pushed it back on to make sure t was making good contact, than it started to move and ended up a little higher than in my picture above.

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Okay so I took a good look this afternoon. The ground that bolts to the body halfway through the neg cable was loose! And it was screwed to the inner fender with a self tapping screw. Wtf? Looks like its been that way for years. I removed it, wire brushed the crap out of it, and bolted it to a threaded hole. Also cleaned the battery terminals, they were pretty clean but couldn't hurt. Gauge "seems" to be working better now. But I took my meter and started measuring things.

 

From the battery to the alternator ground wire on the rad support. I have about 19 ohms. From the Batt to the coolant temp sender body I have about 4. From the batt to the inner fender ground of the cable I have 1 ohm.

 

I come from a computer/electronics background and in my opinion all grounds should be 0 ohms...Can anyone confirm this for me on their pathy?

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Well I took it for a drive, and the gauge seems rock solid now...Still going to replace all the motor to body grounds that have vanished. Can someone take a pic of theirs for me so I know where they go?

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Well You should just put the grounds where ever you can, you know there was one from the exhaust heat shield to the body, I know you have headers but I'm sure yo can find some spots to use.

 

Marked some bolts or threaded holes you could use, the mark on the pass. valve cover there is a bolt that holds the bracket that those plugs attach too you could use:

 

2a5abg7.jpg

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Okay so I took a good look this afternoon. The ground that bolts to the body halfway through the neg cable was loose! And it was screwed to the inner fender with a self tapping screw. Wtf? Looks like its been that way for years. I removed it, wire brushed the crap out of it, and bolted it to a threaded hole. Also cleaned the battery terminals, they were pretty clean but couldn't hurt. Gauge "seems" to be working better now. But I took my meter and started measuring things.

 

From the battery to the alternator ground wire on the rad support. I have about 19 ohms. From the Batt to the coolant temp sender body I have about 4. From the batt to the inner fender ground of the cable I have 1 ohm.

 

I come from a computer/electronics background and in my opinion all grounds should be 0 ohms...Can anyone confirm this for me on their pathy?

It was getting dark so I couldn't see the alt ground, but I measured from Bat Gnd to the AC line bracket on the rad support and got 2 ohms, to sender body was .5 ohms, .7 to the top header tube and 1.6 to an idler arm bolt. It was even 2 ohms to my fairlead...

Another strap or two might be a good idea.

 

Well I took it for a drive, and the gauge seems rock solid now...Still going to replace all the motor to body grounds that have vanished. Can someone take a pic of theirs for me so I know where they go?

Good fix. :aok:

I'll see what I have tomorrow.

 

B

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Not to change the topic but would this also effect the speedometer as well? What i mean is when its cold out (around 30 to 60) and i start up the truck the speedometer revs up with the rpm's. it will be at around 1200 rpms and it will show that im doing 30 mph. i always heat up my truck hot or cold but if i give it a few minuets it will settle back down and not do it again.

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