Temp Sending Unit

[levi.watson]

Ok, so I have a 89 2.4 4Runner, just put a rebuilt engine in, but the temp gage isn't really doing anything... I just replaced the temp sending unit today, but that really only moved it up a tiny bit, just barely above where the needle starts. Any suggestions?

Also, it seems like it's running real hot. After a while of running, the hood is uncomfortable to hold my hand on it, and it smells pretty hot. Read about a bad fan clutch, sounds like I have one, but would that contribute enough to make it be that hot? Thoughts there? Thanks so much.

 

[nevada]

Ok, so I have a 89 2.4 4Runner, just put a rebuilt engine in, but the temp gage isn't really doing anything... I just replaced the temp sending unit today, but that really only moved it up a tiny bit, just barely above where the needle starts. Any suggestions?

Also, it seems like it's running real hot. After a while of running, the hood is uncomfortable to hold my hand on it, and it smells pretty hot. Read about a bad fan clutch, sounds like I have one, but would that contribute enough to make it be that hot? Thoughts there? Thanks so much.

a bad fan clutch will let it overheat. its what drives the fan to cool the engine. usually when the clutch goes bad, the fan barely spins, but nowhere near as fast as its needing to, to prevent overheating.

 

[flyinhawaiian01]

Was the gauge working prior to the new replacement engine? It could be a ton of things, like a broken wire, bad gauge, unplugged harness somewhere, etc.

Check to see if the fan is spinning properly. With engine off and cold, turn fan by hand, there should be drag on the fan when you spin it, and you shouldn't be able to spin it much more than a quarter turn without it stopping from friction. If it spins freely (half or more revolution), the clutch is out. Search for replacing viscous clutch fan fluid.

If it doesn't spin at all, its locked up and you'll need to replace or repair clutch.

If it spins properly, then check thermostat. Rockauto will show you what the oem stock temp thermostat should be for your engine and year.

Use a thermometer in the radiator. Place it in the filler neck, wait for engine to come up to temp. When you see water rushing past the neck, note the temp. It should be near what the oem specs should be for your thermostat. If you don't see water rush past and it is overheating, replace thermostat.

If its good and you still overheat, and you don't see water moving past the neck, replace water pump.

If all the above is within range, only thing left is the radiator itself. Either rod the radiator or buy a new one. Personally, I'd rather spend a bit more and just get a new radiator, as rodding a radiator is around a hundred bucks at most shops.

Where in ID are you in?

 

[levi.watson]

a bad fan clutch will let it overheat. its what drives the fan to cool the engine. usually when the clutch goes bad, the fan barely spins, but nowhere near as fast as its needing to, to prevent overheating.

Ok, thanks.

 

[levi.watson]

Not sure about if the gauge was working prior... It's been sitting in the field for a couple years. But it's moving it a little bit which better I guess than not before I replaced the sending unit.

Ok, so it sounds like my fan clutch is out. It's spinning freely, so it sounds like I have to replace some sort of fluid in there? I'll have to look more at that. I'll check how hot it's running, I have a new radiator, new thermostat, and new water pump. So I guess it's the fan... Thanks! Any more thoughts on the Sending unit? And I'm in Nampa.

 

[flyinhawaiian01]

LOL! So am I! Near Victory and McDermott.

Check out the how-to for the fan clutch fluid replacement on Ih8mud:

No need to use expensive toyota fluid, just run some shock fluid for r/c cars! Cheaper and available at one of the local r/c shops in Boise!

 

[levi.watson]

Haha nice! I'm right next to you then. Doesn't look like the clutch fluid replacement tutorial came through... I'll look for it now and see if I can find it though. Thanks so much for you help!

 

[levi.watson]

Ok, I found it, I'll hopefully get to that tomorrow night. Thanks for all your help!

 

[flyinhawaiian01]

Oops! Sent the link with an image tag instead, my bad! In case anyone else needs the link:

Fan Clutch Service | IH8MUD Forum

 

[penbergm]

Which temp sensor did you change. Some have 3, others jsut 2. Some have 1 on the neck for the thermostat. That is used for the AC. There is one that points straight out below the throttle body. That is used by the ecu. Then there is the one on the intake right next to the middle of the valve cover. That is the one that goes to the gauge.