temp gauge after installing V8

[ges55]

We just put in a 1985 305 V8 in my 67 3/4 ton that had a 250 in it. The temp gauge goes from below the lowest mark to just over the lowest mark at operating temperature. I bought a huge aluminum radiator for it & a friend checked the temp with his no touch temp meter & got only around 164 degrees. How can I get the temp to go in the operating range on the gauge? I don't know what t-stat is in the newer motor.

[bosco200]

what degree of thermostat is in it now?

[ges55]

I don't know which t-stat is in it now.

[Shyguy]

If it were me I would put a 180 degree thermostat in it and then see what the temperature gage reads.

[ges55]

It had a 195 degree t-stat in it. I put in a 180 degree t-stat & it hasn't changed. Somewhere I heard something about the ground on the motor?

[bean]

i had the same problem. replaced the temperature sending unit with a better one i purchased thru Eckler's. Problem solved

[lyrikz]

Originally Posted by ges55

It had a 195 degree t-stat in it. I put in a 180 degree t-stat & it hasn't changed. Somewhere I heard something about the ground on the motor?

I ran into something similar. What you need to do to save you some time is first go get a new guage and install it. Get the engine up to operating temperature and make sure its actually running at the correct temp. If it is you have some options. What i did was just replaced my factory guage with the aftermarket autometer. I just removed the face and used the factory guage face. Works perfect.

My guage was reading normal at freeway speeds then would peg hot at idle. My guage spring in my old ass guage just wasnt working correctly...

As for grounds. You should have a few on the truck.. Frame to engine, frame to cab. Good grounds are a must.

[PHAT TONY]

I've tried many new temp senders and have yet to find one that works correctly with factory gauges, in more than a few trucks. My Blazer reads as yours does now.

[ges55]

The temp gauge worked fine with the 6 cyl motor in it. I did replace the sender & no change.

[bean]

i was told the temperature send units you get thru the local parts places are junk. the one i got thru ecklers was like 25 buck i think. but once installed it works great.

[Jofin66GTO]

I'm having the same problem now. I see one post for gauge and another for sending unit. All that's left is the wiring haha. Please post what you did to fix. Thanks
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[PanelDeland]

Try the sending unit out of the 6.It should go back to reading like it alweays did.

[Jofin66GTO]

Ok. Figured out a good indicator. The temp gauge works off resistance value of sender unit. To see if it's gauge or sender. Just ground the sender unit or wire to it and turn on key. If gauge pegs to hot then your sender is bad.

Now granted I'm still troubleshooting mine, so I'm not leaving out possibility that low coolant or air or another such factor is in effect. My gauge pegged so now to figure out range of sender unit both cold and hot

I'll then read it cold and throughout warm up till run and read ohms on sender unit. I think it goes from 220 ohms cold to 68 ohms at middle of gauge. Hope this helps
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[ges55]

I was going to try the old sender, but it has different size threads.

[lyrikz]

Originally Posted by Jofin66GTO

Ok. Figured out a good indicator. The temp gauge works off resistance value of sender unit. To see if it's gauge or sender. Just ground the sender unit or wire to it and turn on key. If gauge pegs to hot then your sender is bad.

Now granted I'm still troubleshooting mine, so I'm not leaving out possibility that low coolant or air or another such factor is in effect. My gauge pegged so now to figure out range of sender unit both cold and hot

I'll then read it cold and throughout warm up till run and read ohms on sender unit. I think it goes from 220 ohms cold to 68 ohms at middle of gauge. Hope this helps
Posted via Mobile Device

No, thats not right. To test to see if the guage is working, you ground it.. It SHOULD peg.. If it pegs its reading right. The correct way is to find the resistance of the sending unit, and the resistance of your guage in your truck.. The issue is, that guage is old man. So the resistance changes over time.

Mine did. Change the guage out and be done... Quick/ easy/ more accurate.

[lyrikz]

Originally Posted by ges55

The temp gauge worked fine with the 6 cyl motor in it. I did replace the sender & no change.

This is funny cause i went through this EXACT thing. Used different senders, aftermarket and expensive. Nothing worked. My guage had just become to week.. So when it was at the correct ohms for 190 degrees it would go all the way to hot.