Running hot, trying to narrow it down

Greetings all from a long-time reader, seldom poster ...

My temp gauge has been bouncing around for a while, and the vehicle runs hotter than it has in the past, electric fan kicks in a lot, blah blah blah…

I installed a CSF 3-row about 16k miles ago, and a new water pump, t-stat, radiator cap, hoses, and wp pulley about 20k ago. I’ve never replaced the fan clutch.

127k on the odo.

I’ve done a search on the boards here, and it seems it could be one of several things (or a combination).

I see that the heater control valve is sometimes the culprit, so I may buy one eventually, but I’m trying to do things one part at a time to figure out the issue.

I first bought a “Coolant Temp Sensor" (p/n 3300 4281), and right before installing, I noticed that there are two sensors under the hood that look identical to me: one at the t-stat, and one on the driver’s side on the intake manifold.

1) I believe the one on the manifold is the air temp sensor - correct?

2) my parts manual doesn’t actually show where the coolant temp sensor goes. I assume the one I bought threads in by the t-stat?

3) Also in my research, I noted that there’s another sensor called the “Engine Temp Switch” (p/n 5602 7012 or 5602 6710). I believe it’s located on the head or the block itself? Should I add this part to my list as I go through my process of elimination?

Thanks…

1.yes
2.yes
3.no but I would test it. Plenty of threads on how to do that and what the ohm readings should be at a given temp. If bad yes replace it.

If the temp gauge is fluctuating alot you may have an air pocket in there. Try bleeding the air out. Lisle makes a sweet bleed kit set up. It helps alot with the mess of coolant overflow. When you bleed it make sure that your heater is on. Most people forget to do that.

You may just be low on coolant as well.

And the ones with a heater control valve need to be on heat cycle engine running, or the line open to air when they refill the entire system, or the air will not leave!!!!

3) If you have a dash OEM temp gauge, then is a sensor not a switch. The switch was used for idiot light dashes, on/off, no dial. Located back of the head, driver's side, by the firewall.

Good points.

Thanks, gentlemen, I'll do a little more searching re: bleeding, and I'll check out that heater control valve, etc., etc...

Thanks again...

May be time to replace the fan clutch. At the very least, that would a good place to do some trouble shooting. Get the engine at max temp, shut the engine off, and see how much effort it takes to rotate the stock fan. The fan should be hard to rotate by hand when the engine is at max operating temps. When cold you probably can't tell much difference.