detroitdiesel

Did a timing belt/waterpump replacement. Reputable small shop. I've known the guy for years. He has always been straight with me. And other members of my fam. good guy.

Drove the car home 2 weeks ago. NO heat. Went back two days later and he put a bleeder cap on the radiator. Seemed to bring the heat temp back to normal. Worked ok (or acceptable0 for a day or two then cool again.

Then I poked around on this forum and the web in general. found some air bubble info. I put the nose of the truck up a steep hill and revved the engine while flipping the hot/cold dial. (yes the actual valve arm in the engine compartment changes position) This seemed to do the trick, although the outside temp here in Mass/RI that week was milder than the week before so I'm not sure i'm comparing apples to apples. worked fine for a few days.

Last weekend I took a long highway trip and the heat was ice cold. I would occasionally flip the hot/cold dial. This would bring warm air but only for 30-60 seconds. After which it would slowly cool.

I blocked off part of the radiator with cardboard and convinced myself that it made a difference. I'm not sure it did. Temp gauge was still in the middle.


Someone had mentioned on a forum that the waterpump could be in backwards? Seems unlikely. Truck temp guage is at the mid piont as usual.

Any votes for any of the following?:

---Faulty/stuck/inverted Thermostat. It was replaced. Wrong one? (I know radiator caps come in different pressure ratings, so why not thermostats in different opening temps?)

---Backwards water pump

---Air bubble that is a bee-otch to dislodge

---too high a glycol concentration. Not "wet" enough? No overheat so I don't think so


Any thoughts are certainly welcome. Remember, the heat gets hot when I switch from cold to hot but slowly cools off again.

Cheers, DD

HighLux

Id get an oem toyota thermostat to start. Seems as though you got the air out of the system.

Water pump cant go in backwards so scratch that off the list.

I assume heat was good before right?

detroitdiesel

Thanks HighLux, I will try to find out what he put in for a thermostat. If it was OEM. What's weird is that the heat seemed to work ok for a full week. (although it was a bit warmer out that week.)


Thanks again,
DD

detroitdiesel

I asked a few car geeks today about issue and the thermostat is not considered to be high on their list. The truck gets to "normal" on the temp gauge quite quickly and is gauge is dead center (where it has been for the last 140,000). Two hits against the thermostat being bad.

So, my suspicions lie with a bubble in the system. I believe I'm pushing steamy hot air through the heater core. I will admit that my understanding of the coolant path is limited at best, so criticism is welcomed.

Any other folks want to chime in on this?

I plan to take the vehicle back to the guy (he is more than willing to see it through to a solution) but I wish to gain the knowledge of some heavy yota cats first. There might be a well known thing with these trucks. (stand on your head while chanting and singing and THEN put the nose in the air and bleed)

You get the idea..

Cheers and thanks, DD

P.S. HighLux, to answer part two of your previous question, the heat always cranked. It did fizzle out when I replaced the T-belt and w-pump.