High temp gauge!!!?? Trouble!? Help!!

[Hugh Januss]

Hi everyone I recently [last week] did an oil/filter change as well as a coolant flush, and while i was doing the coolant flush i installed a new thermostat, we took out the old one because it was giving us a HIGH TEMP READING and so we assumed it was sticking and not opening anymore, so we took it out and simply left it out for a couple months and the truck drove fine, and the other day i decided to install the new one and now driving it my TEMP GAUGE is WAY above the halfway mark and between 3/4 to full, so its reading as REALLY HOT and almost max's out the gauge [although it seems to drive just fine] and Im not getting any check engine lights? I made sure to install it correctly and made sure all my coolant is full as well used about 1 gal and 1/2 of antifreeze (not 50/50) then added water.... so whats going on!???? is it a sensor?? I'm scared my engine might blow a gasket or somethin? but since it was a problem before and still a problem now what could it be?

we did swap the cluster a while back, the Odo stopped turning, and so we got one from a junkyard cant remember what year it was.... could it be a bad cluster? bad gauge????

1996 v6 4.0 liter 2wd ranger w/ 187k

 

[RonD]

If you are not getting coolant spilling out into the overflow tank then "sender" or gauge could be at fault.

Running without a T-stat should have kept the gauge down below 1/4, depending on outside temp.
With 192degF t-stat gauge should run just below 1/2.

So what did the gauge show with no t-stat?

There is no Check Engine Light related to engine overheating.

You can do a simple test on the gauge.
Just above the T-stat on the intake there is a 1 wire sender, this is for the temp gauge, only 1 wire connected(the ECT sensor for the computer has TWO wires, looks similar but not related to gauge).

Disconnect this 1 wire connector, turn on key, temp gauge needle should go down below C.
With key still on, Ground that 1 wire, gauge needle should go above H
If it doesn't go below C or doesn't go above H then gauge is bad, or wire to gauge.

If gauge does go below C and then above H, replace sender.

Never use "tape" on any 1 wire sender, the bottom few threads need to be grounded to engine or the sender can not work properly.

 

[Hugh Januss]

Running without the T-STAT kept it at around 1/2 its been fairly cold here in San Diego and just started warming up recently, I dont do a whole lot of driving so its not like im putting the engine under a lot of stress... and the overflow tank doesn't seem to getting any extra fluid either.... and about the sender [noob question] by grounding the wire like touching it the engine? and will it be ok if i still keep driving?? cuz i have to get home today!???? what should i do?

 

[RonD]

I would say the sender or gauge is the issue if it was showing 1/2 with no T-stat, 1/2 on Ford gauge is about 225degF

You don't need to drive with sender wire grounded, unhook the wire, turn key on, check gauge, and then ground the wire, check gauge, it is a quick test of the movement of the gauge needle.
Then hook wire back up to sender.

 

[Hugh Januss]

hey y'all hows it going, i've recently (moments ago) finished installing a new Water Pump and Fan Clutch which was a big PIA... but i finally finished, and still my temp's reading rlly high, i bought and installed the sender unit and i also bought the boot connector for it however i dont have an electric solder gun and i dont exactly know how to do it either so im still left with a truck/temp gauge that is reading very near to H on the temp gauge...

i have a blue wire connector the square one like this one:


as well as a circular one like this one:


i know you said no tape but given the circumstance's and being without a Solder Gun, would these be unsuitable to for connecting the new boot connector? and how far back should i trace the electrical line to replace it with the new boot?

 

[RonD]

No tape on the threads, where it screws into the intake manifold.

second connector would be best

Did you test the gauge?
by grounding

 

[snake]

borrow one of those infrared laser thermometers and shoot it at the upper hose. Should be 195 or slightly less. If it is, something isn't reading right but it isn't running hot. Do you have heat in the cab? No heat no circulation so make sure you don't have an air pocket in the cooling system.

 

[fyre82]

+2 on the senders and funky gauges.
Another thing that will cause a 'high' temp reading is a plugged
radiator. Plugged from the outside by bugs, sand etc. Hose it out gently but thoroughly.

Good luck
Rich

 

[Hugh Januss]

Alright well i just replaced the send unit connector, was around mid range at idle after about 5 or so minutes and took it out for a spin around the block and almost immediately the gauge spiked... [check below for temp readings]

i did run water through the radiator with a hose and it seemed to flow fine. I ran water through the neck, and both the top and bottom in/out lets but maybe not enough water is flowing through? so i might get a new radiator from summit and see what happens....

also i've heard that i should see the antifreeze "flowing" not sure if in a circular motion? but im not seeing much movement, other then the bubble's at first, they stopped after i topped off, i've double and triple checked the level of anti freeze..... but there isn't much movement other then it dropping down when the T-STAT open's and rising when it close's back up....

update: i took the infrared scanner and let the car idle until the temp gauge spiked and these were the hottest readings i got [I took temp from the rad neck, the top rad hose, and right next to the temp send unit]



rad neck


upper rad hose


and send unit


so it seem's that for whatever reason maybe the gauge spiking means its simply running at normal op temp???? i guess???
what y'all think??? whats the normal op temp of a ranger supposed to be?

Since the T-stat is supposed to open somewhere around 198'F I guess it should be alright to drive????? However it's still scary as hell, I feel like my engine is gona blow up and shoot straight up into the sky

 

[fyre82]

I suggest starting back basic with the mechanical parts.
Let's see if I have this right . . .
You have replaced the sender, good ground and send wire contact?.
You have installed a thermostat, is it installed correctly, is it operational?
Back flush the outside of your radiator, in other words, spray water from the fan side out to push out bugs, sand and all. I say this because I struggled with a similar problem on my '88 that was the result of the cooling fins being clogged with beach sand.
Ensure that the cooling system is full, please recycle and recover water that you use, we are in a drought

You also talk about swapping clusters, did the truck 'overheat' before the cluster change, or only since the thermostat installation? Is that timeline correct? Cluster then thermostat?

If none of that helps, troubleshoot the electrical.
Inspect the wire where you can.
Check your work, you can swap the gauge back and see what that does.

This is all stuff that's free to do before you throw parts (and money) at it.
Take Saturday, put out a jar of sun tea and start to work back through what you have done. If it starts to stress you out, have a glass of said sun tea and come back in a little bit, break during cool downs.

Use that scanner, 198 is about average for a fully warm ford engine.
If that's what you see with the scanner, all the mechanical is good, the gauge is 3/4, and the gauge has been changed . . . draw your conclusion.

Float me r/t from Reno and I'll help you . . .

Good luck
Rich

 

[RonD]

As said before, remove sender wire
Turn on key
Where is the temp gauge needle at?
Should be below C

Ground the sender wire
Where is the temp gauge needle at?
Should be above H

I would rack your memory for the year of the gauge cluster, and get a sender for that year not your model year.

Gasoline engines operate with best economy(MPG) and lubrication between 200-230degF
All engine oil viscosity is measured at 212degF

 

[70roadrunner]

as long as the temp guage needle is between the lines, its normal. most rangers have a switch type sender. only has cold, normal, and hot. it doesn't show actual temp

 

[RonD]

as long as the temp guage needle is between the lines, its normal. most rangers have a switch type sender. only has cold, normal, and hot. it doesn't show actual temp

Never heard that one before??

Oil pressure is a switch, on or off, but never heard of a Ford temp sender with 3 positions

 

[SenorNoob]

Me either. It's actually cheaper/simpler to build a (mostly) linear relationship for temperature readings. All you need is a resistor that is sensitive to temperature changes.

 

[hondaxr650]

as long as the temp guage needle is between the lines, its normal. most rangers have a switch type sender. only has cold, normal, and hot. it doesn't show actual temp

Incorrect. The temp gauge sender is variable, the oil pressure switch is on/off.