Temp gauge won't come up to normal

[austinrick]

Not sure where to look next. A week or two ago I noticed the temp gauge in my '93 XLT 3.0L auto wasn't coming up to normal hot level and attributed that to very cold weather, but after a few days it wasn't coming up higher than you see in the photo (which was taken today).

I decided the thermostat (installed ~5 years ago) had stuck open and ordered a new one.

Today I installed the t-stat (Stant) and a new temp sender (Wells) in case it wasn't sending an accurate reading.

Just finished a test drive and nothing on the panel has changed.

Where should I troubleshoot next, short of pulling the instrument panel out? I've never seen instructions or a guide for disassembling this particular panel. Could there be just a poor connection somewhere between the sender and gauge?

Any suggestions? –TIA

 

[SenorNoob]

Bad connection is certainly possible. Pretty sure that gauge just reads resistance to the engine block. You can ground the wire to see where the gauge ends up. It should be pegged on the high side (I think).

Got an alternative way to measure the temp? Those cheap laser thermometers can be pretty accurate.

 

[austinrick]

RESOLUTION! – Looking through some old posts on Ranger Station I saw a comment that literally answered the question of why my gauge hasn't been coming up. Someone advised someone else to be sure and NOT wrap teflon tape around the threads on the new sender. Well, Idiot Me, knowing better, had done exactly that when I installed the Wells unit. I just pulled it back out, cleaned the threads, reinstalled and the gauge is working almost normally now (coming up to around the "N" in normal – we'll see how she does on a warm day). Two points to make here besides I'm stupid:
1- the original problem was the old sender (I put the old thermostat in a pan of water with thermometer and it opened normally at ~200°).
2- for those of you stating you have the same issue with your Ranger, remove your temp sender and look for anything like tape or sealant; that really will interrupt the grounding. (I also ran a remote ground from the red/white wire to the – post on battery, turned the key on and the gauge went full HOT, so this all narrowed it down to the grounding of the sender).
Thanks for everyone's input – I'm sorry I didn't do a more thorough job of troubleshooting to start with.

 

[ekrampitzjr]

RESOLUTION! – Looking through some old posts on Ranger Station I saw a comment that literally answered the question of why my gauge hasn't been coming up. Someone advised someone else to be sure and NOT wrap teflon tape around the threads on the new sender. Well, Idiot Me, knowing better, had done exactly that when I installed the Wells unit. I just pulled it back out, cleaned the threads, reinstalled and the gauge is working almost normally now (coming up to around the "N" in normal – we'll see how she does on a warm day). Two points to make here besides I'm stupid:
1- the original problem was the old sender (I put the old thermostat in a pan of water with thermometer and it opened normally at ~200°).
2- for those of you stating you have the same issue with your Ranger, remove your temp sender and look for anything like tape or sealant; that really will interrupt the grounding. (I also ran a remote ground from the red/white wire to the – post on battery, turned the key on and the gauge went full HOT, so this all narrowed it down to the grounding of the sender).
Thanks for everyone's input – I'm sorry I didn't do a more thorough job of troubleshooting to start with.

Good job. I was going to suggest that the replacement sensor might be bad. New parts can be iffy or bad, as we've discussed here.

 

[ekrampitzjr]

Next time you do the job, see if you can find an actual Motorcraft (Ford) thermostat. The aftermarket replacements have a bad reputation for failing, especially for sticking closed and not opening at all.

 

[austinrick]

The Stant replaces a Motorcraft t-stat that appears to still work fine. I'm keeping it and if the Stant (which is a quality brand) gives me trouble it will go back in.