94 22RE 4x4 pickup

On the way to work today, my truck had high idle, then wandering idle between 100 and 2500 rpm. Also, I had no heat, even after the temp gauge ramped up. Lastly, it overheated after about ten minutes.

The engine (95k-ish on it when purchased) was replaced 5k miles ago with a new waterpump added.

I suspect a bad t-stat. Any ideas?

 

It could be the T-stat however this same hing happened to me last year about two weeks after I bought my truck, and the previous owner had the wrong coolant to water mixter and it all froze tight. So I had to pull it in the garage and crank the heat till it started to melt, then dumped in hot water and ran it.
I had no heat either untill I got the frozen cheunks out, it also started ideling correctly on its own

 

check your coolant level (in the radiator not the reservoir). no heat would mean no coolant in the heater core, since coolant can flow to the heater core even if the t-stat is stuck closed . . . low coolant would be my first thought

 

I've had that problem before. When it happened to me it was because the block heater blew out the side and all the coolant went with it. Check the fluid level first. The engine doesn't get a fead back from the coolant temp. to say where the idle should be - high for cold or low for warm etc. - which is why it wonders.

 

R8624,

What do you mean "the block heater blew out the side"?

I will certainly check the fluid level.

 

I'm guessing he meant a block heater that installs into one of the "freeze plugs" -- used for extreme cold weather areas

 

Update:

I checked my oil again - it was nice and brown with no frothiness or discoloration.

I checked my radiator and found the coolant level just at the top of the tubes; certainly low, but not low enough to cause my problems. What I did notice was a bit of icing at the top of the tubes.

I drained the coolant to a level below the upper hose and pulled the t-stat. I dropped it in boiling water and it opened up just nicely. No issue here.

When I went back outside (yes, I was working in my driveway), I noticed the coolant that I had drained was a little slushy.

Icing in the radiator and slushiness in the coolant: ding-ding-ding! 93toyrunner wins the prize! The radiator or t-stat probably iced up this AM. After all, it was coldest morning that the truck has seen since the engine was replaced. It appears that the bonehead mechanic that replaced the engine (that would be me) didn't put the proper coolant mixture into the engine. So, I drained some more coolant and made it up with a 50/50 mixture.

I drove it around for a while, got heat in the cabin and never saw the temp gauge go above halfway. It never idled poorly. The exhaust never smelled sweet and the coolant never bubbled (no sign of coolant leakage into the combustion chambers or air leakage into the coolant chambers).

I will drive it tomorrow and, if the icing recurs, I will heat the vehicle in the garage and drain and replace all of the coolant.

 

I knew your symptoms sounded familer, I was exactly correct. I went through the same thing but mine was so full and cold it would not drain and I could not dump in boiling water.

 

Block heater is where one of the freeze plugs normally go. Canadian eh!
Took it for a spin last winter and it popped right out.
Happy to hear you solved it. Assumed it was coolant related because mine had similar symptoms but with a different resolution.