Relatively new issue. '89 4runner 22re / 5 speed has started running at the hot end of the gauge at freeway speeds.

I drive 40 miles each way and in the morning at about mile 30 the temperature gauge will be 3/4 of the way up between the white lines. On the way home, in the warmer air and more traffic, it will be up to the upper white line within 20 miles. It doesn't go past the upper white line into the red, but it definitely gets close.

It used to always run 1/4 - 1/2 way up the gauge no matter what, so the higher readings are scaring me.

I also have coolant residue on top of the radiator under the cap, so I'll swap caps and hopefully that will fix that. However, I'm worried that the the residue is from too much pressure in the radiator.

Thoughts are:
Clogged radiator - Is there a way to backflush?
Cap leaking - Will replace.
Head gasket - No milky residue, no loss of coolant, hopefully not the case.
Fan Clutch - I get a grinding sound from the front of the truck only at 15 mph, could the fan clutch fluid be low or cause this?

Thanks!

 

The Prestone kit will not get your radiator clean. If you dont want to replace it with a new one, pull the radiator and take it to a professional shop and you will be suprised at what will come out of it. It looks worse then muddy water.

I would check thermostat, and fan clutch while at it. I doubt you have a head gasket issue from your post. Fan clutch is a consumable part and should be changed periodiacally.

A new thermostat and radiator cap is cheap insurance. Get a good quality one.

 

Replaced the radiator today. It was hot outside and the gauge held steady between 1/4 and 1/2 like it used to. Pretty sure that's what it was.

 

Could be water pump. May be a small. I had my water pump go out on me. It can be a job since its close to timing belt I'd replace that too

 

What symptoms does a failing water pump give you?

 

Well I was driving one night at 2 am coming from buddies place. Had my friend drive my 93 pickup. Then started her up no heat and it was freezing was looking around here for signs of it failing. Looked at my temp gauge red hot I had a bad bad leak thinking it was the radiator. Flushed all the fluid out was bone dry put some water in it next day not one leak on the radiator. It was coming from water pump. Pouring out.

I had someone replace the water pump thermostat and timing belt since its right there. It was never replaced. This could be your thermostat failing

 

The most noticeable is the small coolant leak you'll get when you look under the vehicle. You'll just see dried coolant that has seeped down (the water pump has a seep hole as a fail safe to prevent excess pressure). It'll get worse and worse until it fails and then the coolant doesn't move in your engine and it gets really hot, really fast.

Mine's on its way out but just started leaking. I'll get it replaced in the next few months.

Anyway, glad you fixed the issue, your old radiator probably had a blockage of some sort.