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I have been fighting the coolant temps on my 22RE on my '91 Pickup since I got it. You can read about my escapades here.
TLDR of that link if you don't want to read through it - I got scammed and bought a fake eBay temp sender which kept showing that my truck was overheating, so I ended up changing the head gasket, water pump, thermostat, etc until I finally found out it was the temp sender. After replacing that the truck was running fine, but it still seems to sometimes show that it's too hot.
Recently I changed the radiator to a CSF 2314 3 row, found out my Aisin fan clutch wasn't kicking on at all and replaced it with another Aisin fan clutch, and changed the heater and coolant hoses. However, I still get hot temp readings on the gauge:
That was from today. It was about 105 out today, but the ambient temperature doesn't seem to matter. It will get that hot whether it's a cool 60 degree night or a boiling 100 degree day. Also worth noting is it gets hotter on the highway and then goes back down in town. I also heard my fan clutch kick on around town so I know that's working as well.
I decided to (carefully) open the radiator cap while the truck was running and the thermometer showed the water was at 185 degrees. This leads me to think it's the gauge. Since the temp sender is new, is there any way I can get the gauge to read correctly? I'm going to take the cluster out tomorrow and check the contacts and plugs, but is there anything else I could check or do? I'm going to take the truck on a 1200 mile drive in a few weeks and want to be able to trust the temp gauge. I do have an SR5 cluster I haven't put in yet - would it help to swap that in?
BTW, the truck doesn't look like it uses any coolant, and the coolant and oil haven't mixed in either the engine or radiator.
Between the white bar on the left and the black gap on the right is the operating range, your guage doesn't indicate it's too hot.
Do you have an IR temp gun to check this against?
Why do you say the guage is inaccurate?
How well did you clean the lower intake threads this thermo sender threads into? (This is a one wire sensor, it relies on the ground provided by its threaded interface and the primary EFI ground having clean metal and a tight connection)
Between the white bar on the left and the black gap on the right is the operating range, your guage doesn't indicate it's too hot.
Do you have an IR temp gun to check this against?
Why do you say the guage is inaccurate?
How well did you clean the lower intake threads this thermo sender threads into? (This is a one wire sensor, it relies on the ground provided by its threaded interface and the primary EFI ground having clean metal and a tight connection)
If I am cruising on the highway at 65 mph on flat ground I wouldn't want the temp gauge to show that hot as if I was climbing up a steep mountain grade with a heavy load in the back it would probably show that it's overheating. I am saying the gauge is inaccurate because the thermometer shows the coolant is 185 degrees at the radiator neck, which makes sense as I have a 190 degree thermostat. My IR thermostat shows 170 degrees at the thermostat housing (I guess that would make sense as the aluminum housing would dissipate some heat).
I believe that the intake is clean but I can remove and try again. I will try cleaning the plug on the sender first since that's easy to get to and then try to clean up the back of the cluster to see if that helps before removing the sender (since I don't want coolant spilling out everywhere).
...I will try cleaning the plug on the sender first since that's easy to get to and then try to clean up the back of the cluster to see if that helps before removing the sender (since I don't
Yes, Assuming all your replacement parts are good electrical connection between sender and gage would be the suspect.
Pretty much stays here with or without A/C on, driving on highway, or idling in traffic. Checked with a temp gun and thermostat housing is about 185 and so is the valve cover. 🤔 Can't trust this gauge unfortunately. ....I also tried cleaning the connection on the sending unit.
Disconnect the wire from the sender. Gauge should be bottomed out. Run the wire to ground (manual says through a 3.4w test light). Gauge should move up. If it doesn't do those things( especially bottom out), I'd suspect your gauge. Have you tested continuity through the sender?
Install an aftermarket temperature gauge in top radiator hose inlet. if you don't have the ability to do so, order yourself a KOSO gauge and go that route.
I ended up unplugging the sender and putting some dielectric grease on it, and then pulled the cluster out and tightened all the screws on the back and also greased the connectors and took it for a drive in 105 degree weather and it looks much better:
It looks like where J94's second picture shows?
The KOSO gauge looks really nice, I might go that route if the gauge keeps acting up. Is there any way to T off the wiring for the KOSO gauge so the dash gauge still works?
My pickup's gauge reads just below 1/2, driving 70 on the highway in the summer, 90° outside. A little higher going uphill, a little lower downhill.
My 4Runner reads about 1/4 with the heater off, 3/8 with it on. wherever or however I drive it. It may get as high as 1/2 when it's warming up with the heater on. I DO know the gauge will go up to the redline if the truck overheats. Thrown the water pump belt twice in the 25 years I've owned. Bad belt from the store both times. Just my luck, is all. Considering all the belts I've installed in my two over the years I'm lucky, I guess.
I could be confusing my knowledge with Nissan info but wasn’t there a mod to make the water temp more accurate? I remember reading a write up how they have resistors built in so the needle dosent fluctuate as quickly and keeps the needle from moving to much as long as the temp is within spec. Vaguely remember reading you could add resistors or short something out to make the gauge read more accurately but to me is a moot point because gauge is too small to have accurate numbers and as long as it’s not in the red zone I wouldn’t worry to much about it.
I could be confusing my knowledge with Nissan info but wasn’t there a mod to make the water temp more accurate? I remember reading a write up how they have resistors built in so the needle dosent fluctuate as quickly and keeps the needle from moving to much as long as the temp is within spec. Vaguely remember reading you could add resistors or short something out to make the gauge read more accurately but to me is a moot point because gauge is too small to have accurate numbers and as long as it’s not in the red zone I wouldn’t worry to much about it.
I'm fairly new to these trucks but it doesn't sound unlikely. A capacitor is used to smooth out gauge readings (think of it as an energy reservoir.) The resistor(s) would be used to "tune" the gauge. The gauge uses the resistance through the coolant temp sender to figure out what the temperature is. If you add or remove resistance from that path, your gauge will move up or down respectively. So, with your temp sender unhooked, the gauge will read cold. That means if you add resistors to the wire in series, you would get an overall lower gauge reading for the same temperature. If you want it to read warmer, you would need to add a resistor to ground in parallel with the sender. The better way to do this is to add a potentiometer to the circuit so you can tune it with a screwdriver. This is how the mechanical meters in a DC power supply I have work. There's a potentiometer added to the circuit to tune the gauge. They ARE calibrated gauges.
But as you said, this isn't a very specific gauge. I don't think I would go through that trouble personally. If it's not in the red, don't fret. If it is running higher than it used to, look for a reason why.
... If it's not in the red, don't fret. If it is running higher than it used to, look for a reason why.
This ^^^ sums up how we should treat the cooling system. When mine crept up to upper white line I had it towed, becoz I have free AAA towing, so I can troubleshoot it MYSELF at home.
Sep 6, 2020 | 09:36 PM
