ok lately i have noticed my water temperature sttarting to rise under normal driving conditions. The temperature will start to rise and if i dont do anythign it will go into the red but i havent let it get withign a quarter inch of red on the gauge. IF the tmeperature starts to go up and i goose to throttle or downshift hard the temperature will usually drop back down to normal. To me this sounds liek the thermostat sticking?

 

Not sure which engine you have, but if it is a 22RE, have a look at this:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

 

That would totally make sense that if the heater is on then the thermostat wont open all the way. And my heater has been on a tone lately considerign there is a foot fo snow and its like 20 degrees. But I did notice this temperature thign when it was liek 70 but it didnt do it often. Is it possible that lately my thermostat has gotten even worse in shape and runnign the heater only made it worse?

 

One way to find out is to pull the t-stat out, put it in a pot of hot water on the stove and watch how it opens as you heat the water (use a thermometer in the water to check the temperature).

 

yep i was plannign on doing that later today. Another question i have is how to tell if the gauge sender (water temp) is goign bad?

 

Test it as well. Ressitance should vary with temperature, a Factory Service Manual would have the testing procedure.

 

hmm so about the thermostat could the fact that i can make the temperature drop by goosing the trottle by realted to the fact that the heater is causeignthe valve to close partly from cold coolant the nwhen i goose it it pumps more warm coolant therefor openign it again?

 

I think the cause of the 22RE temperature overshoot problem (as noted on the TSB info on the web page I linked above) is related to an instability in the coolant flow. Even a minor change in something can cause it to start or stop. My engine used to be fine then had a rebuilt head installed and all of a sudden had the overshoot problems appear out of nowhere. In my case all related to the heater being on as the engine first warmed up. In my case, the 2-valve t-stat that Toyota designed to fix the temperature overshoot problem has been a 100% cure, have not seen the symptoms reappear in 8 years since installing the t-stat (and yes, it is still the same t-stat I am running, it is still working fine).

You might also have some air trapped in the cooling system, that can cause similar problems, try burping the air out and see if that helps.

 

well just picked up a new thermo and am gettig nready to instal it someone gave me an idea to drill holes or a hole in the lip and your page says that this does the same thing as the second valve in the double thermostat? Anyone have any info on exactly what holes i could drill? how many how big?
Also i understand the basic concept on how my heater works but does it still suck heat out of the coolant even if the fan on the heater is of cause the lever on my heater (the hot cool) one is broke and stuck on hot. Will this cause cool coolant to always be dumping back in or does the fan need to be on?

 

Information on the small hole is on the web page I posted. That is a fix some folks use in lieu of the 2-valve t-stat. I've never tried it but am passing on the information. Does not do the same thing as the 2-valve t-stat, that basically has a smaller and larger t-stat valve that operate at different temps/speeds. The small valve can react much faster to temperature changes (due to it's lower thermal mass) and can regulate the small temperature changes. The larger valve handles the big swings in temperature, so think of them as a fine and coarse temperature control. A 1-valve t-stat only has the single large valve and is more of an on/off type of control, so the coolant temp will rise and fall more.

The added hole is basically just a leak that allows some small amount of coolant through all the time, even if the t-stat is closed. The issue with the heater is that I think it steals some of the return flow and maybe bypasses the t-stat and that change in flow or the slight cooling of the flow messes things up in certain cases. Since it seems to be a stability issue, the slightest little change can cause it to happen or not. The heater core will take some heat out even with no fan blowing, ever feel how warm the dash gets with the heater valve open and no fan going? Also, as you drive, air is forced through from outside through the core and out the vents, usually about the same flow as you get on the lowest fan speed.

 

When you step on it, how fast is the needle reaction, ie drops now, or slowly comes back to normal? Quick reaction is usually from a poor connection on the blade at the sensor. If its slow, radiator flow, fan clutch, etc could be an issue or low on coolant. Temp should be right in the middle of the gauge.

 

it falls back to normal fairly fast not liek a drop but i dont think it could cool that fast. I changed the thermostat but havent had a chance to drive i around. When i was letting it sit and heat up i watched the gauge slowly rise to normal a little under half but previusly i remember thinking it was weird when i saw it jump to where it usually sits right after startign it. I think i am gonna install a aftermarket sender and temp gauge one thta actually reads degrees not average.

 

Ah, save your money. I suspect its the connectro at the end of the sensor. Cut the blade off and crimp on another one. Also make sure you have a good engine and body ground.

 

I have had that happen. It was the thermostat. If you run the heat full when you first start the engine and the heat guage goes way up and you don't get to much heat, then when you push the clutch in and rev it up a few times then the needle goes down, the heat will pour out of the vents. This is a stuck thermostat as the water is not circulating until it opens. Get a Toyota thermostat and make sure you are full of fluid.

 

well if replaced the thermostat today and havent had a chance to test it with the new one yet but i tested the old one on the stove and it worked just fine opened up just as it should at 190.

 

Yep i was just abotu to go out and check to connector at the end of the sender. I notice i looks liek some cheapo plastic type blade connector i might try replacing.

 

Hmm my books i have tell me nothign about the resitance of the sender or anythign. can someone look these up for me?