temp gauge raises straight to hot

grimley

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Hi all, I have a commando 383 and having an issue with my temp gauge.

One the thermostat opens it shoots straight to hot. The radiator gets hot so I'm assuming the thermostat works fine. I've replaced the temperature sender but still having the same issue.

Is there a possibility there's a short in the cable somewhere? Worth changing the thermostat? Anyone else got any ideas or had similar issue?

Thanks guys
 
You need to answer some questions before you can get meaningful input:
Stock Rad? Recore? Aluminum?
Have you got a fan shroud?
Stock fan? Electric?
Are the heater lines properly hooked to the heater core? Are they looped to bypass the core?
Has the car sat idle for a long time?
When the rad gets hot does it spit coolant? Or just steam? Have you burped the system for air pockets?
Are the rad hoses good? Does the lower have a spring? Are they spongy?
 
Last edited:
Exactly what Mr. C said. Need to know what some of the variables are first before troubleshooting can commence.
 
Stock Rad? Recore? Aluminum? Stock rad

Have you got a fan shroud? just the stock shrod

Stock fan? Electric? Stock


Are the heater lines properly hooked to the heater core? Are they looped to bypass the core? Id have to double check, but i think theyre hooked to heater core


Has the car sat idle for a long time? only about 5 minutes or so for the thermostat to open. as i said, the gauge shoots straight to H, not a gradual increase like you would expect if hot.

When the read gets hot does it spit coolant? Or just steam? Have you burped the system for air pockets? id have to take the cap off, ill inspect this tomorrow and get back to you. as i mentioned, it didnt seem to be excessively hot (the rad/rad cap). seemed to be normal temp

Are the rad hoses good? Does the lower have a spring? Are they spongy? hoses seem reasonable. bottom hose could do with a replacement, but not bad enough to effect anything i would of thought

ill do some more testing tomorrow and ill post up anything i notice.
Thanks again
 
Stock Rad? Recore? Aluminum? Stock rad

Have you got a fan shroud? just the stock shrod

Stock fan? Electric? Stock


Are the heater lines properly hooked to the heater core? Are they looped to bypass the core? Id have to double check, but i think theyre hooked to heater core


Has the car sat idle for a long time? only about 5 minutes or so for the thermostat to open. as i said, the gauge shoots straight to H, not a gradual increase like you would expect if hot.

When the read gets hot does it spit coolant? Or just steam? Have you burped the system for air pockets? id have to take the cap off, ill inspect this tomorrow and get back to you. as i mentioned, it didnt seem to be excessively hot (the rad/rad cap). seemed to be normal temp

Are the rad hoses good? Does the lower have a spring? Are they spongy? hoses seem reasonable. bottom hose could do with a replacement, but not bad enough to effect anything i would of thought

ill do some more testing tomorrow and ill post up anything i notice.
Thanks again

just a quick update, theres no spring in the lower hose. as soon as the car is started, the gauge raises all the way to Hot (sorry i paid a bit more attention this time!). only steam, not spitting. looks like maybe the heater lines are bypassed as im pretty sure the connections are on the right of the attached picture, yet the hoses are connected to something that looks self fitted on the left.

Is it possible a faulty voltage regulator? the fuel gauge doesnt work either (only put the tank back yesterday) although it could be a faulty tank sender as the tank was in pretty poor condition (wish i tested the sender while i had the tank out :/)

20141017_134523.jpg
 
So with the engine cold, once you turn the key to "on" the gauge pegs to hot? That's electrical and could be many things (bad sender, bad regulator).
 
So with the engine cold, once you turn the key to "on" the gauge pegs to hot? That's electrical and could be many things (bad sender, bad regulator).

correct, at first i didnt notice but started it up today and watched the gague rise instantly. i have replaced the sender so ill replace the voltage regulator and inspect the wiring.

thanks!
 
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