Toyota Nation Forum banner

1 - 7 of 7 Posts

·
Registered
1998 Toyota T100 Xtra Cab SR5 4x4 3.4L 4speed automatic
Joined
·
32 Posts
Discussion Starter #1
My T will run fine and slowly warm up like usual and the temp gauge will get to the middle and it will stay there if I leave it in park at idle but once I put it into drive and get moving it will start to get hot but never get to the red part of the gauge to the point of overheating and as I keep driving it the temp gauge will go back down to its normal running position in the middle after some time. If I start the truck and leave right away it will get hot but not to the red and then drop back down as I keep driving. This happens both driving around town and at highway speeds.
I got a OBDII scanner that has live gauges and when the temp gauge is in the middle its at 230 F. When it starts to get hot it will go to about 235 to 240 F. So the temp gauge isn't broken. There isn't a coolant leak anywhere that I can see, the reservoir is at the full line and has stayed there since I filled it back in august. Also I still haven't fixed my heater core issue from august and I did the bypass with the hoses that are already there that Bam suggested.
I know this is a lot of info and any help would be much appreciated.
 

·
Registered
Joined
·
78 Posts
If you had the time and money, I’d start with a coolant system flush, new water pump and new thermostat. I would consider that the baseline for the cooling system before I would start troubleshooting anything else.

I would also want to confirm my transmission fluid temperatures, because the engine coolant is used to warm up and cool down the transmission fluid. (Ie. A hot transmission will warm up your coolant.)

The next thing I would want to confirm is that my fan clutch is operating correctly. Based on your description of the fluctuating temperatures, it sounds like the only cooling you are getting is from air that passes through the radiator because you are driving, as opposed to air being moved past the radiator by the fan.

I’m not sure your level of mechanical experience, so forgive me if this is insulting your intelligence, but it needs to be said. It doesn’t matter what the dash gauge says, it’s the actual temperature of the coolant (& subsequently the engine) that matters. If your coolant temperatures are really getting to 230°F you’re already running too hot. Something is wrong with the system. And by that I don’t mean an electronic error. I mean a physical problem with the system that’s resulting in a physical state (high temperature) that is incompatible with engine longevity.

All that said... if your coolant looks good and is mixed right, my $ is on the thermostat. R&R the thermostat and see what happens. It’s a cheap and easy experiment.
 

·
Registered
1996 Toyota T-100 3.4L V6 extended cab SR5 4x4
Joined
·
165 Posts
Check your fan clutch. When engine is warm see if you can stop the fan. I used a welding glove to diagnose mine. But just be careful when attempting this
 

·
Registered
Joined
·
279 Posts
as you mention ur heater core might be clocked, flushing it would be the first thing i would do., second i would check the thermostat, it might be shot, that would also be an easy fix with a new one + bleeding the cooling system to get rid off air bubble.
 

·
Moderator
1998 T100 SR5 2WD
Joined
·
14,467 Posts
Back from yer first post in "Introductions" you mentioned this:
have the intake and engine drained of water
What was the cause of this? Did that have anything to do with yer current issue? ;)

I would check fer any debris between the radiator and the AC condenser. It's a common area to miss and debris can build up between there and cause issues similar to yer situation. ;)

Do you still have the radiator shroud installed including the bottom piece? Are you running the OEM fan and clutch? How old is yer radiator? Has the thermostat been changed out? Is the jiggle valve at the 6 o'clock position? Is there any build up inside the cooling tubes? Have you been running coolant or just water in the cooling system? If it was just water, chances are that rust sediment may have developed inside the cooling system and clogged the radiator up. Snap some piccies of the internals and post them. ;)
 

·
Registered
1998 Toyota T100 Xtra Cab SR5 4x4 3.4L 4speed automatic
Joined
·
32 Posts
Discussion Starter #6
Back from yer first post in "Introductions" you mentioned this:


What was the cause of this? Did that have anything to do with yer current issue? ;)

I would check fer any debris between the radiator and the AC condenser. It's a common area to miss and debris can build up between there and cause issues similar to yer situation. ;)

Do you still have the radiator shroud installed including the bottom piece? Are you running the OEM fan and clutch? How old is yer radiator? Has the thermostat been changed out? Is the jiggle valve at the 6 o'clock position? Is there any build up inside the cooling tubes? Have you been running coolant or just water in the cooling system? If it was just water, chances are that rust sediment may have developed inside the cooling system and clogged the radiator up. Snap some piccies of the internals and post them. ;)
That cause was from offroading and getting into some muddy water that came higher than I thought. I don't think it has anything to do with my current issue since it was almost 4 years ago.
I have never touched anything with the radiator, fan and clutch, or cooling system in general. I'm running premixed 50/50.
Also I don't know if this has anything to do with it but this problem started when the weather changed and it stopped being 90 +.
I won't be able to take any pictures or mess with it in general for a couple of days till I get home.
 

·
Moderator
1998 T100 SR5 2WD
Joined
·
14,467 Posts
There are many possibilities on what might be the cause. Yer gonna have to be diligent in looking at the simple basic stuff first. Definitely pull the thermostat and make sure it's working correctly. Check the space between the AC condenser and radiator fer any debris. Look fer any signs of leaks (pressure testing is best with a cooling system pressure tester) that might not be obvious. Inspect yer radiator hoses fer any signs of degradation or collapse. Inspect the fan clutch fer any signs that the internal silicone fluid may have leaked out. Hopefully, the previous owner didn't use any head gasket fix in a bottle stuff in the cooling system. A system flush may show any signs that it was used or not. Test the radiator with an ir temp gun and see what yer temps are running in the radiator. It could be that yer radiator may be clogged up on the inside or outside (which should be obvious). ;)
 
1 - 7 of 7 Posts
Top