Junkers88

Noticed this morning that my temp gauge will go from reading ice cold to operating temp in just under a minute after start up, then it goes back down to cold after another 30 seconds or so and back up again a few seconds later. It never gets above normal operating temp and I'm just wondering if the gauge is faulty or is this a sign that something bad is going to happen to my motor?

Oh and one other question. Where does your alternator gauge read? Mine sits near the top of the normal spectrum and only moves if something like the blinker is turned on. Then it just bounces a little.

Thanks in advance for your replies.

DCYota

Have you replaced the t-stat with the dual stage thermostat? It sounds like the common temp gauge overshoot problem that many of these trucks have. Go to 4Crawler's site and read about it. He has the part number listed on there for the Toyota t-stat as well.



As for the volt reading, that's normal.

4mydogs

That site references the 22RE. Does it apply to the 3.0, too?

mt_goat

No, the 3.0 is different, no need for a dual t-stat with it.

drew303

this only happens on the sr5 guage cluster as far as i know. ever since i did my cluster swap iv had no idea what temp my engine is running at. it just hops to operating temp soon as the engine is turned over. i havent had time to dig and see i can remedy it.

pita to say the least.

anyone know if its possible to adapt the guage guts from a standard cluster to the sr5? just the temperature guage.

mt_goat

You probably need to switch to an SR5 sender to match your gauge.

drew303

i wasnt aware the senders were different i thought only the oil sender varied?

mt_goat

I may be wrong, it wouldn't be the first time.

rdlsz24

Fluctuating temp gauge is a symptom of low coolant.

Rob

tj884Rdlx

mine does this too. warm to cold to warm again. doing this since i swapped in an sr5 gauge cluster. i've had the t-stat replaced 3x and same effect. i don't know what to do here. i looked at swapping the temp gauge from the original cluster but it won't just swap in, it would require microsurgery which i'm not qualified.

interested in more opinions from those in the know.
*subscribed*

drew303

*bump*

if the senders are different this would help remedy things but theres no reference in any of the service manuals i have access to to suggest a difference between sr5 and deluxe.

There is definetly something NOT working right, whats at fault, who knows?

the temp guage in my brothers 85 ...whom i did a sr5 gauge swap for works fine. Same engine as my 87... exactly. 22r carbed... i cant imagine the sender being different? both trucks were dlx versions with identical engines. The 22r didnt change for our washington model trucks in that year... atleast i have no idea what could have changed.

If i understood how the gaujge worked that would probaby help me understand... well all of us understand why the gauges malfunction.

Temp guage is probably the most important guage to =/

mt_goat

That's the way I feel too, I installed a real temp gauge for that reason. The factory gauge is little more that a fancy idiot light, but of course you want to get it working. Try ordering a new sender and see if there is a different part # for different years or something. Maybe your donor gluster is from a different year than you think it is. Toyota has been known to change electronics and ECUs from year to year and sometimes even mid-year. Just throwing out ideas. Good luck.

Yotaboy

Mine has done the same thing since I have put the SR5 guages in. It will go to operating temp as soon as I start up and will go down to cold about 2-3 minutes after running. I know it will show it over heating after it goes up though. Ive over heated it on the beach thats why I know that the gauge works.

scope103

At least in 1994 (which is all I checked) the Sender (not the Sensor, that's a two-terminal device for the computer; the Sender is one-terminal) is not only a different part number between the 6-cyl SR-5 and the 4-cyl DLX, it appears to have a different connector. So unless you did connector surgery when replacing a panel, it seems unlikely you've got a sender mixup.

The Service Manual gives a procedure to test the gauge which is quite simple; 3.8watt test light to batt, and gauge should read hot. This suggests that the sender is just a thermistor. But, oddly, they don't give a procedure to check the sender (just: if the gauge OK, get new sender). This wouldn't make me suspicious, except that they do give a procedure to test the oil pressure sender, which states that it should FLASH an led test light when there is pressure, and that the flashing should vary with engine speed. That could be a pressure-varying resistor (flashing with the pulses of the oil pump), but maybe not.

So it's a mystery, but I don't think that's your problem. My guess is that you are uncovering the sender; I would check coolant level before anything else.

kcrunner

My truck does the exact same as OP described. Before my radiator replacement and top-end rebuild, it used to actually read hot when it got hot, now it does what OP described. I'm guessing it's reading right once engine warms up. But who knows.

just a 22re

its your gauge it self i think it could be just really dirty or something try to clean it out or something

DudeBud

try tapping on the gauge itself.. mine will do that but if i tap on nit it will fall back down

ozziesironmanoffroad

well mine does the same thing, but my coolant is topped off, so that idea is busted. i just let it warm up for 8 minutes, then drive it. you can usually tell if your engine is warm or cold. when mines cold, its sluggish and stuff, when its warm its real peppy. what i want to know is why the sr5 temp gauge is affected by RPM. if i keep it at high RPMs, to pass someone, it shows overheating. when i let off the gas, and the rpms drop back down, the gauge suddenly reads normal. im thinking i may just install an aftermarket temp gauge, along with the oil pressure. it shows i have little to no oil pressure. i put the new sending unit in, but have the wire on the center, not the side connector. significance? we'll see once i tear into my electrical system this weekend. im sick of my feet kicking wires and stuff. plus main reason is the electrical system keeps blowing fuses. well, back to the temp gauge. let us all know if you figure out what it is!

drew303

I'm thinking its an issue with the actual gauge. I've never heard of this happening on the standard clusters. My old cluster worked perfectly and was very sensitive to temp changes.

Tapping does effect the sr5 gauge but only sometimes if u hit it hard enough itll tap back down but mine then just jumps back to op temp.

Coolant isnt the issue. The system is full and this problem was from day one when i installed the sr5 cluster.


i think when i get back into town in a few months ill tear it apart, see what i can figure out... probably just install an aftermarket gauge.