1998 Tacoma 2wd 2.4.

Rollon3

Rollon3

New Member
Have have a weird problem I need help!!
My truck has 141,000 miles on it. Runs fine.
Last year pass smog no problem. This year it did not. The mechanic I took it to said the lower radiator hose was cool and the upper was hot.

Temp gauge is where it always is. Mechanic says water pump, I said no way. This is list of things I have tested.
Let truck warm up for 30min.
Throttled it up and checked upper/lower radiator hoses to see if they collapsed. (No)
Popped cap off radiator looked for circulation
(Very little)
Removed thermostate and tested in boiling water.
(Worked fine) bought a new one and tested worked fine. Left it in buttoned it up.
Removed old water pump, looked like it was new from factory, radiator- filled and let water flow though it. (Fine)
This truck has been babied, no leaks anywhere.
All fluids are clean. No work has ever been done on this truck, only oil changes transmission and gearbox fluids has been change by me. Not sure what’s going on.
 
I think your mechanic is right, sounds like a bad water pump, since you're getting some circulation, just not enough. Only other thing I can think of is some partial obstruction in lower hose.
 
Ed209 said:
I think your mechanic is right, sounds like a bad water pump, since you're getting some circulation, just not enough. Only other thing I can think of is some partial obstruction in lower hose.
Click to expand...
I capped off the lower hose and filled it to the top with water, remove my hand and in 7 seconds it’s empty. I have the old water pump and the new in hand, old looks great, fins are metal, no leaks. So i am going to put it back together with new water pump+ new thermostat, and belts. Thanks for your input, I will let you know what happens after I put it back together. Thanks.
 
What was the culprit? I'm going through this same thing right now. Hot upper hose, cold lower hose, temp guage right in the middle (like always) motor is getting hot, smells hot and in fact broke the head of my original motor. Now I have a junk yard engine in there, but it seems like it's doing the same thing. I thought it was a stuck thermostat, so I replaced it. I flushed my radiator, flushed my heater core. I guess I'll put a new radiator in, maybe the old radiator has some blockage? I'm running without a thermostat right now and the coolant stays cold, so I have flow through my radiator, but as soon as I hook up the thermostat my system gets backed up. I hope I don't break another motor trying to figure this out.
 
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