bikedave99

Quick question for the gurus. I have an '88 Xtracab with a '94 22re swapped in. The coolant temperature gauge works, but it will only ever climb to maybe an 1/8" above the bottom mark. That is even when crawling around on trails really slow when it should be getting hot. It does move, just hardly at all. Did the sender change somehow between these years that my reading seems to be so low?

Thanks

mt_goat

That would be my guess. Do you still have the sensor from your 88 engine? If so, swap it in and see.

bikedave99

Unfortunately I don't... I didn't figure there would have been a change but I guess it is possible.

92 TOY

do you have a thermostat in?

when i ran for a short time without one, my gauge would hardly move.

bikedave99

I'm certain that I do, but that is an excellent suggestion. I need to flush the system anyway so I will test the thermo at the same time.

boxer.fan

When you do get the thermostat make sure it for the right temperature. I believe OEM is 195 degrees. If you get one that is colder you will be running rich condition and your gauge will never rise very much. Also check your fan clutch, it may be bad keeping your engine too cold.

mt_goat

From the 93 Truck FSM ( http://personal.utulsa.edu/~nathan-b...51thermost.pdf ) the 22re engine t-stat is:
I run with a wide band air/fuel ratio gauge and a 20* cooler t-stat and can say running a cooler t-stat doesn't make you run rich.

Blue_petersen77

Where is the needle suppose to sit on the temp guage at full operating temperature in a 94 3vze runner?

mt_goat

Mine stayed in the middle.

bikedave99

Just flushed my coolant system forcefully with the hose attachment system from Prestone. I pulled my thermostat and it is a 180 degree thermostat, which is a few degrees cool but not enough I wouldn't think... it looked new but I put in a pot of water and raised it to boiling and it indeed activated appropriately. The fan clutch idea is interesting considering my fan starts immediately even when the engine is cold. I have wondered if that was right or not. However, I would think that after a long drive the needle would go up regardless.

Yeah, I'm not that far off on the T-stat. What I curious about now is whether the sending unit from 88 to 94 changed spec's. Mine was in spec for my 88 engine, but maybe it is different. I'll download and check the 94 manual.

bikedave99

Hmmm... don't think its the fan clutch anymore. Did some more perusing and found the fan always spins when engaged or not, just not as fast as the engine when not engaged. And it definitely cycles on when I first start it and roars for 20 seconds before disengaging and quieting down. So, I don't think it is the fan clutch.

yayfortrees

Sounds like a case of not broken, doesn't need fixing. I would say that is the normal position for your gauge, with the setup that you have.

If you really wanted to check everything out, you could check the temp. sensor's resistance at various temps, from cold to normal operating temp. If you want to make sure the gauge will tell you that you're overheating before problems would occur, you could remove your sensor, but leave it hooked up. Run longer wires if you have to. Then, place the sensor in a container of really hot water, maybe close to boiling. Turn your key on, and see what the gauge does. If it doesn't read any higher than normal, you have reason to fret. If it does read higher than normal, you know that you don't want to see it there, but everything is working ok.

bikedave99

Good call on the test, I may try and pull that sensor if I can do it without dumping all my new coolant and test it.

drew303

You're using a crappy factory analog gauge that is notorious for failing. You want to to know the accurate temp of your motor you need to run an aftermarket temp gauge with a number readout.

The guages in my SR5 cluster, my brothers and ive even had a standard cluster gauge fail. It's common.

a 180F T-stat is to low. In my own experience with T-stat experimenting, once to much fluid begins circulating in the block the motor never heats up to operating temp. This is caused by 3 reasons, first one is obvious, no t-stat, second one is a t-stat thats rated to cool (180F) ...

btw the FSM says the T-stat should open between 187 and 194F,

http://personal.utulsa.edu/~nathan-b...51thermost.pdf

This page in the 93 FSM is a mistype, "187-184" ... 86C-90C is 187F to 194F. This is the range at which time the valve begins to open, it should be completely open by reaching 100C (212F)

The third reason a motor won't run up to operating temperature is an oversized gas release nipple (or hole). Any hole larger than 1/16" is gonna be to large on a 22r. This is a hole that is drilled through the T-stat flange to allow gas (air) to move through the stat and still restrict fluid movement. To big of a passage and to much fluid moves through the t-stat which makes the motor take longer to heat up or it never will (depending on how large you've drilled your hole) .. I've never seen a t-stat that came with this nipple cause this, only seen this by drilling a hole to large into a t-stat that doesnt have this factory hole.

The hole is critical as well. Without the hole air gets trapped below the -stat as the motor cools and the t-stat closes. When the motor begins heating up, the t-stat doesnt reach it's opening temperature so it doesnt open, which causes the motor to overheat.

The usual sympton of this is seeing the needle rise at a normal rate, but never level off at in the "middle" It'll continue rising then suddenly drop down rapidly (as the t-stat finally opens as the wax melts) or in my own experiences, may not drop at all, but a good rev of the motor creates more pressure in the cooling system and allows coolant to finally reach the t-stat so it opens.

This is extremely bad for the motor, you're asking for a headgasket failure or the head to crack. (I've had both happen as a result from overheating)

I have a aftermarket temp gauge obviously and I run at 195-198F all day long, the E-fan I run is set to about 208F and does an excellent job of not allowing the motor to run over 210F .. I also sport a 3-row Radiator.

Goodluck mate! cheers

GenXr

My money is on either the sensor reads at a different resistance than the earlier sensor or the gauge is failing....with the likely culprit being more towards the gauge failing. I have the SR5 cluster in my 95 truck and my voltmeter is pegged at 18 volts. I thought my new alternator was failing so I took it in for warranty work only to find out it tested fine but that the gauge is bad.

I'll eventually put an aftermarket gauge in but after i get bigger tires and some new paint!

highway

Also if you run too cold of a t-stat, it will put the computer in closed loop mode thinking the engine is warming up and make the engine run rich.

highway

mt_goat

Good catch on the misprint, I didn't notice that before.

mt_goat

You have it backwards, closed loop is where the ECU is using all the sensors for A/F ratio feedback and adjustment. Open loop is where it runs rich (like at startup or wide open throttle). BTW I'm usually out of open loop before I can get out of the driveway, way before the t-stat opens or before it gets close to OP temps. Running a cooler t-stat will not in my experience cause you to run rich and I monitor my A/F ratio constantly.