Temp gauge stability

[gman-1970]

This has been bothering me for awhile now, so thought I'd get some input here.

All things being equal: speed, incline, ambient temp, gear, etc, etc. Just cruising down a "flat" highway for instance. Should the temp gauge indicate a stable / fixed temp; or will it vary "slightly"? Mine moves back and forth between the "O" and "M" in "Normal". Not quickly; perhaps 1-3 cycles per minute - and if you're not paying attention you may not notice, but I'm anal / OCD / whatever and I notice $hit like this and it bothers me!

The only "mod" I have is a 2 core "automatic" Radiator instead of the single core that came on the manual. Pretty sure the gauge was acting this way prior to the rad replacement, but don't recall. I've also replaced the fan clutch, thermostat (several times now).... what else... Heater Core which shouldn't matter...

I THINK I have all the air out of the system, but I wouldn't bet my life on it.

TIA for any input!

Gary

 

[Earl43P]

Change the gage sender yet?

Most temp gages stay pretty steady.

 

[bcammons]

Most should stay stable but if you want a better sense of what the temp fluctuation is than buy a gauge with number on it replacing your temp sensor with a probe. Did this on mine and its great.

 

[gman-1970]

Yeah, good ideas on using a "real" sensor and gauge. If nothing else even for testing / validation.

FWIW: the needle "slowly" climbs up to the "M", then will drop pretty quickly back to the "O"; then starts all over again. Last night on the highway it did this about 3 times / minute. I'm thinking about posting video of it if it will help, or maybe some will just find it entertaining?

Would a T-Stat cause this? It seems unlikely, but I'm wondering if the Tstat is say.. 20% open and kinds sticks there so the temp slowly climbs. Then the temp gets high enough to kick the T-Stat open to 80% or whatever, and the temp drops pretty quickly. Then the cycle starts all over again.

I replaced the T-Stat with... I THINK a Stant "Super"Stat a few years ago. I THINK I tested it in boiling water first. I have lots of bad luck with tstats, so I started testing them before I install them.

$hit - lunch time....

 

[fyre82]

What you see could be your thermostat doing what it is supposed to do but that could also be an indication that your thermostat is getting weak.
Those stock gauges aren't any more than an idiot light without the light and aren't reliable, a manual gauge or taking the temp of the radiator wold help diagnose the gauge behavior.

I can watch the cycles on my manual gauge.

I wrote this up a while back in case you are interested in putting in a manual guage.
http://www.therangerstation.com/forums/showthread.php?p=1103204#post1103204

When I do any work on the cooling system I will run the truck until fully warm in the drive, watching those thermostat pulses. It can take awhile just sitting there but it works for me.

Rich