Should I replace coolant temp sender to fix bad temp readings?

[belfert]

My temperature gauge reads high and Dina didn't put one at the rear.  Should I replace the temperature sender to fix this or try the gauge or both?  Someone did say something about replacing the sender a while back, but I want to verify with you guys.

JD at C&J Bus Repair recommended against replacing the sender because he said the extra resistance of all the wire to the dash might be causing problems.  He recommended a mechanical gauge at the rear, but that doesn't really help when driving.

Will I have to dump a lot of coolant to replace the sender?  I just replaced all my coolant.

Brian Elfert

[gumpy]

I agree with C&J's recommendation. The problem is likely the resistance of the wire.
I'd first add a mechanical gauge in the rear, and calibrate your front gauge against that one.

Yes, you have to drain the coolant down to the level of the senders to replace them. Probably will have to drain down to add the mechanical gauge, too.

[Rich (Prevost)]

Around $60 for both the sender & the Gauge. Easy to replace.

Rich
800-468-5287

[belfert]

Around $60 for both the sender & the Gauge. Easy to replace.

MCI sells the parts for about $40.  I just don't want to dump all my brand new coolant if there is guarantee that a new sender and gauge will fix anything.

Brian Elfert

[Ace]

I would highly recommend changing BOTH as a matched set. Sometimes the gauge is not matched to the sender and you'll get a false reading. Been there personally!

Ace

[Len Silva]

Brian,

There is no reason you can't save and reuse the coolant, probably won't loose more than a cup or two.

As with the others here, I recommend replacing both the gauge and sender AND adding a mechanical gauge at the back.  Might as well put a mechanical oil pressure gauge and maybe a fuel pressure gauge back there while you're at it.

Probably do the whole job for a hundred bucks.

Len

[DrivingMissLazy]

I recommend you invest in an infrared temperature gun first!...Then you will know for sure and you will still have the gun and you will use it over and over and over again and again and again and again. Do you get what I am saying?
Richard

I would highly recommend changing BOTH as a matched set. Sometimes the gauge is not matched to the sender and you'll get a false reading. Been there personally!

Ace

[Ross]

I'm taking a different approach.  I don't trust electric guages with that long of a wire run...especially with those wires being 20 years old.  So...I got some good quality mechanical guages that I will mount in a sealed box (guage faces inside the box), then a low lux video camera goes in the box.  The camera is connected to one of the ports on my bbackup camera monitor.  I basically just push a button on the monitor to switch between guages and backup camera.  I have all the parts...putting it all together is on the ever shrinking list of things to do.

[JackConrad]

If you install a new electric sender, do NOT use teflon tape on the threads.  I repaired a transmission temp gauge that was not working properly. The teflon tape was preventing a good continuous ground.  As already mentioned, we have an electric gauge in the dash and a mechanical gauge in the engine compartment. Same with oil pressure and fuel pressure, electric in dash and mechanical in engine compartment.  Hope this helps, Jack

[Busted Knuckle]

Boy it's hard to argue with any of the answers you got Brian! I persoanlly would put in a new sending unit, and add a mechanical gauge in the engine compartment! Now put the new sending unit in before having the bus hooked up to a computer scanner then compare what scanner temp is showing compared to the gauges! Richard has a good idea also on the temp gun I use the heck out of mine (but I got no idea where it's hiding lately) ! Oh and by the way you can either drain an catch that new coolant or if ya got a helper what I usually do is have a helper pull the old on out while I stick my finger in the hole and have the new one in my other hand and quicky screw it back in (if installing another gauge I screw in a nipple with a "T or Y"  (when available I prefer a Y) and already have the sending units on each end of the "T or Y", with a large catch tray under the bottom you'll probably lose a 1/2 gallon which can be saved from the catch tray and reused! Just my 2 cents worth save the change! LOL!  BK