I just finished installing my new motor in my 96 SR5 4Runner and went for a ride. My temp gauge/coolant goes up almost to the red zone, but not to it. I have everything new in this truck, new temp sending sensor, radiator, water pump etc.... The truck doesn't seem to be running hot as far as being sluggish so I was wondering what would be the normal operating temp of this truck. I have a crappy pic that I took with my phone but you can kinda get an idea where it is. It's really blurry but it is not in the red zone.....lol, the pic looks like it though.

 

clutch fan maybe...my friend has a 99 taco...when warmed up..the needle sits above the middle of the gauge, but not as far up as yours is sitting.

 

I think that's the only thing that I didn't replace new.....but I checked it out and it seemed fine. Thanks.

 

Possibly air trapped in motor

 

thats deffinately not where my needle sits

 

Gotta burp the system. see This Thread

 

I will try burping the system....Thanks!! I had my friend who has helped me with the build, who also is a toyota tech at a dealer, and he said that was not normal especially on a cold day. I took a better pic and I also realized I have to replace my IAC. Just a few of the things I had no idea what condition they were in when I took on this project.

 

On my '96...the needle sits a little below the halfway "mark".

 

Yeah, that's way hot. I have a 170 thermo and mine sits a few ticks below 1/2, even on a 115 degree day. Burp the system, then look at testing the thermo or checking the fan again.

 

I will burp the system once I replace the rear heater lines that burst when I started the motor for the first time. They looked really rusty and I know I was taking a chance of not replacing them but for now I bypassed them.

 

^^^^ That is normal for a 3.4L

The pic you showed, the motor is running hot so you should take care of that quickly. My bet was that you still may have air bubbles in the system. You need to open the entire system (turn on all the heaters in the truck, front and back, etc) to allow the coolant to circulate. It may also be the thermostat (even if it was new). My suggestion would be to remove the thermostat, top off the coolant and try driving the truck on the highway......then stop, check the coolant level, top off if low and drive again on the highway. If the temp stays high, you have a more complex issue at hand (could be water pump, blocked coolant passage, head gasket issue, etc). If the truck's temp looks low, you probably had either air in the system or the thermostat is bad. Just hang the thermostat in a pot of boiling water to check for operation (don't let it touch the bottom of the pan!)

 

OK, I changed the thermostat and I also changed the IAC.....the IAC was stuck so I had to do that too. Now, I filled the motor through the upper hose and then started it up with both heaters on and on high. The truck's temperature is normal now, it almost gets to halfway but just under it. Now, the weather here in NJ is 10, so maybe the truck is just running cool. The upper hose gets hot and the lower one is still very cool just like the lower radiator. I am used to GM's so the thermostat is on top so I might be a little confused, is this still normal? Or do I still have a problem??

I drove the truck about 10 miles and the temp gauge will not move more than halfway and the heat inside the truck is fine. After my trip I got out and felt the lower hose and it was still cold.....wtf??? The lower hose was pretty solid so I know it's holding pressure and the truck is not over-heating.

 

I was curious about the same thing a while back, but the general concensus was that a hot top hose and cold lower hose is normal for cold winter outside temps. Sounds like your truck is 100% back to normal.

 

If the lower hose is cold I'd say your t-stat is not getting hot enough to open, that or you have a clog somewhere. What temp t-stat is it? Did you test it before putting it in to see what temp it opens and closes? Did you try it without running the heaters yet, because in cold weather the heater could cool the coolant down enough to keep the t-stat closed.

 

I found out that is precisely what happens.....same thing exactly on mine and it only happens in winter. He's up in the northeast so it's plenty cold enough right now for that to be normal. If the thermostat was truely not opening propely or you had a bad radiator blockage, then the coolant temp would start climbing above the halfway point. To me the temp looks fine and the cool/cold lower hose is completely normal.

 

I did some more driving and again, everything seems fine.....Thanks to everyone for your help and knowledge.