So my truck is getting hot. I've had it for 3 years, 1998 sr5 180k on the clock.

I'm never sure how much info to provide because I want to provide enough info to help the community diagnose this, but I do not want to provide too much because some of the info might be irrelevant.

The short story is I drive a 1/2 hr home from work in NJ (80s temps outside lately). The first 3/4 is highway and the last few miles is traffic and lights.
About a month ago I was in traffic (end of trip home) and my coolant started to bubble over, I shut the car off for 10 minutes and drove it home no problem with AC off. Drove 2 weeks (never using Ac and had no problems). Replaced fan clutch and drove it home full blast AC to test it and it just started to get hot when I pulled into a parking spot. If I put the heat on it goes back down to normal. The car has gotten hot once on the way home without the AC on during a really hot day last week. I never let it get in the red, once it starts to climb I stop. (The truck never gets hot on the way to work??)

The coolant does not look like it has oil in it./ The oil looks clear as well. There is no Ominous cloud of white smoke either.

Yesterday, I flushed the coolant , radiator cap, changed thermostat (set to 6 oclock), radiator hoses and drove it home with AC blasting. Literally right as I was parking it started getting hot again (end of trip after 1/2 hr driving).

Since I bought the car, I have replaced the radiator (preventative), plugs NGK dual ground, all new coil packs, wires, air filter as well, valve cover gaskets as well.

The long story, which again may be irrelevant starts about 2 years ago. I was off-roading in the Pines and a rock broke the coolant lines to the rear heater core. I pulled over when I realized the car was getting hot, there was no coolant in it and the needle was pretty far toward the red. I made it to the trail head and bypassed the rear heater core by looping the hoses together (and forgetting about back core heater- it is still bypassed to this day). I filled it up with water ( to be honest, river water was all I had) and drove it home. Flushed when I got back and had no problems. Since then and until the events of last month( 1st time it was overheating in traffic) I have gone off roading on this mountain trail by my house. The truck gets hot at this one steep section every time I get to it. I let her cool and she runs fine for the rest of the day.
After the initial broken coolant line event in the pines, I had the compression tested and it was good….

My questions are now- does this sound like a head gasket?
What’s the best way to test for a Head gasket?
Are there other variables I should consider? (I do know it needs a pinion bearing in the rear, could this effect it?)

I want to get a temp gauge so I can be more accurate than the stock one, what is my best option for getting a true engine temp?
I know most people run in the 190-210 degree range? What temp can I run to before it would be best to pull over? What is dangerous?

Thanks!

 

So... #1... t-stat needs to have jiggle valve at 12 o'clock, # 2.. I been dealing with a similar situation... my rad was plugged up... I used a super flush type chemical in my coolant, and now, I no longer overheat, but I have no heat... seems like the gunk got moved to my heater core...

do yourself a favor.. its easier to change a radiator, than a heater core... swap out the rad....

 

i'm going with a weak tensioner allowing the belt to slip on the waterpump.

 

Thanks for the feedback thus far.
The radiator is only about 1 year old, so I am not sure if a clog would make sense, I also just flushed it.

I know there has been a lot of back and fourth on the jiggle valve positioning.... but it seems the majority of people say 6 is better than 12? In any event it was at 12 before I changed it to 6 and it was still overheating.

Now the suggestion of the water pump belt tension-er, that is interesting... Is this a common problem? Has anyone ever had this happen before? How do I go about checking?
-am

 

Just a quick observation, Toyota Service Manual states the thermostat jiggle valve position should be 6 o'clock position and the system should be properly burped.

 

You can't without taking the front stuff off the engine. It will most likely only show slippage by the timing belt being worn and brittle, and some rubber melted onto the water pump pulley. I would definitely do a compression test and check for gasses in the water first.

 

Yams, I appreciate your help here. I just had a compression check and a block test on Friday. Both hot and cold, several times. It came back negative for exhaust gases and the compression was good in all Cylinders.

Since I posted this originally, I have noticed the car starting to get hot more often. Now that may be because we are having 80-100 degree temps this week.
Again though, never on the highway, only at the end of a trip, in traffic.

If anyone can suggest an expert to look at this in North Jersey, I'm not ready to give up on this yet- and I have a few dollar to throw at this.

 

didnt yota come out with a different thermostat years ago to help with temp swings to the hot side ?

 

Do a leakdown test !

 

i use a lisle anti spill funnel which allows for a good through coolant burp ,great investment ,im a tool whore anyway

 

Check the fan clutch for a clogged spring in front. Only because most other things have been checked.

 

This was playing out back in July in his commute home from work.

Being in NJ not far from NYC can be quite interesting speeds from as fast as your vehicle can go !!!

Bring passed by a turtle walking along the shoulder.

 

Yes defintly sounds like you warped a head or heads and or either cracked a head or ruined the head gasket. Needs to be disassembled to know exactly. And yes the situation you dewcribed about the rear heater core will defintly have damaged something. It just has been slow to show signs. Have a block test done by someone that knows how to do them properly and i bet it will fail. If you added in a bad quality afterkarket t stat that could be causing it to. Another option is that the radiator is plugged. Stress tests are done on the freeway in 3rd gear and medium to high rpm. If temps start to climb then ur radiator is not removing heat efficiently enough. Either way with hiw many times the needle has seen red your heads or gaskets are toast

 

Yep....Fan clutch. On the highway there is 60 mph winds blowing thru the rad.....around town it's up to the fan clutch to pull air thru.

 

 

Hey guys, I need to identify this hose. It was previously capped by the previous owner. But the cap was cracking and broke. Is it supposed to be routed to something else or just capped? Any info or could you identify this? Thanks


This is near my first spark plug right next to my oil dipstick.