Faulty Temp Gauge? Coolant temp sensor?

So I replaced my water pump over the weekend, as it was leaking. Took the car on a test drive, all seemed fine. Parked it, good to go - or so I thought.

Last night I used it to go pick my mom up from work, and on the way over the temp gauge hovered around 3/4 the whole time. Normally it would stay parked at 1/4 and never move. I didn't think too much of it, since it wasn't "hot" and the car didn't smell of coolant or anything like that. So when I get to her job I check it out. Coolant isn't leaking from anywhere, it isn't boiling or anything either. All fine and good, I suppose?

On the way back home, still keeping my eye on the temp gauge, I notice it inches closer and closer to the red zone up top. As I pull up to a stop light, it decides to swing all the way up to the H, then all the way back down to C. It stayed around 1/2 the rest of the trip.

Temp sensor? The gauge going bad? Thermostat maybe? Any suggestions appreciated.

It goes high with les and less resistance. It the wrong wire gro9unced it would go high.

I'd start by checking that wire harness for were it may have rubbed through.

I suppose it could be the thermostat hanging up. If you had to replace the pump due to old age, it's not hard to consider replacing the thermostat for the same reason as well. They are cheap enough. Start there. I'm running a 160 degree unit instead of stock helps to keep the temps in line better

you had an air bubble in there,. it,s mebbe passed it thru,.check the level again when it,s cooled off.

keep driving.
remember 1843.... oh thats right its runnning now,.


Nick

Hahaha, I don't think you're ever going to let me live that down.

I would not use a 160 T-stat. If may effect closed loop option on a TBI car. Stick with the original temp. The White Elephant has has wierd temp gauge problems. I have changed the sensor on the head, with little difference. Mine does not go into the red, but shows 220 occasionally. It could be your fan clutch, because that is what I am going to change next. Low water or a bubble may be the cause, but mine acts the same no matter what. I have not noticed the engine compartment temp varying much, and when it was acting up in a prior episode I pulled the thermostat, and I could put my finger in the coolant comfortably when the gauge read 230 degrees. I even swapped out the radiator when it did boil over from low water level. The only thing I did not change was the fan clutch.

So, I would try a used fan clutch. Change one thing at a time so that you know what actually fixes the problem.

I actually just changed the fan clutch when I did the water pump, I noticed it was exceptionally difficult to turn so I figured it was cheap insurance.

Make sure it is turning the fan correctly. If the new one is too loose it may be aggravating the problem.

What do you mean correctly? It only fit one way.

Correctly means that it is providing enough revolutions per minute to pull enough air through the radiator.

oh boy,.
car is running,.
guy removes intake to fix oil leak,.
oil leak fixed,.
car not running,.
experts say try lots of things including changing fuel pump,.
change wiring harness, re-wire complete car,. add led tail lights all will be fine,.
guy figures out his mistake car running fine again. wiring harness now good,. fuel pump working again,.
car not overheating but waterpump leaking,.
guy changes waterpump, and fan just for good measure,.
fan is supposed to be hard to turn when cold when cold ,.that indicates a working clutch fan
but guy changes fan anyway.for fan that is much easier to turn when cold,.
car now overheats,.
experts now say wire harness needs to be changed again,.


will the experts say the fuel pump needs changing,.??

or maybe the v belt waterpump wasn't the right one for a serpentine belt motor,.or the v-belt fan clutch is pushing air thru the rad on a serpentine system,.and maybe the gauge is actually working and showing the air bubble going thru the system,.or actually recording the fact the engine is getting hot!! as we all know air doesn't actuate the gauge very well,.
gauge was working, but mysteriously now gauge isn't working after changing waterpump,.
so change the wiring harness,. change the tail light bulbs,. because now the resistance from the tail lights is screwing up the ground for the gauge,.
not mention the distributor is clocked wrong which is messing with the flux capacitor,.
so distributor must be in wrong,.

maybe guy might change fuel pump for good measure.and wiring harness too,.

Then car probably won't start,. but the overheating problem will be fixed,.



I gotta say, if you change the wiper blades,. you better pray it doesn't rain,..


nick

No nick - lol The fan took way too much effort to turn - even dad said the clutch was no good, so I changed it.

perhaps you might investigate how a viscous fluid clutch fan works,. they really roar when cold for a few seconds,.the roaring sound is because they are hard to turn,. ..*sigh*

go and put your old fan back on the car,.

then give dad a hug,.but don't tell him you changed the fan,.

i think all will be good,.

you learning anything yet about fixing something enough till it's finally broke??

If you change your headlights,. don't drive at night ok?

nick

Ps,. you think your fuel pump has enough pressure???,. i mean,. it,s kinda old right?

I'm not sure why I even bother posting.

Forget it.

The fans almost never have too much effort to turn. They always fail by not having enough effort to turn (as in, do not turn fast enough when running). I would rather have one that is tight than one that is loose. Put the old clutch back on, and see if it cures your problem. Only fix those thing that are broken, and only fix one thing at a time (unless it is obvious damage). You never know what you did right, if you fix more than one part in a system at a time. The confusion leads to all of the heckling you are getting from a certain individual, whose first initial is nick.

I agree with Fred. When troubleshooting a problem it's important to make one change/fix, then observe. Otherwise you're not sure what really fixed the problem... or made it worse.

I just finished doing this with the cooling system on my Cruiser.

I replaced the fan clutch because it wasn't turning like it used to once the fan was put back onto the motor. I guess I worded that wrong - there wasn't enough effort to turn the fan, because it was turning noticeably slower than before.