Like many others, I put in a new motor and have a temp overshooting condition. I put in the updated dual stage t-stat and am still hving the same problem. Is there anyone else out there that had this problem not solved with the updated t stat? What next?

 

I use a regular 190 degree thermostat with a 1/16th in hole drilled into it. Works perrrrfect.

 

With the duel stage thermostat you shouldn't be having that problem. Unless your fan clutch is going out.

How high is the gage getting? Past the "high line" or just a little above normal?

Did you get all the air out of the system?

It could be you have a bad tempature sender. These trucks have two different senders. One for the ECU and one for the gage in the dash. The one for the gage on the dash sits bewteen cylendars 2 & 3 on the intake manifold.

 

Even with the dual stage thermostat, mine still goes up to about half on a cold start then settles back down to about 1/4-1/5 on the temp gauge. It's been doing this for well over a year and about 30K miles so I'm not too concerned about it.

 

The guage goes maybe 1/8" past normal, or half way. Goes about 2/3 up for a minute or so, then works back down to normal.

I know one of the senders was changed when the motor was swapped. Where is the location for the one for the ECU? My guage sometime does wierd things. It will sometimes rapidly switch between cold and warm a couple of times only as it is warming up. Once it hits normal range it stays there and seems to function fine, unless it is doing the overshooting. It doesn't always gradually and steadily increase to warm the way it should. Sometimes it will also switch right to normal when I first turn the key on, then switch to cold, and back and forth until it hits a spot where it gradually increases to normal. I know that is not right and I would say that a faulty gauge is my problem, but it did this before with the old motor, yet never ever overshooting above normal.

If drilling a small hole in a standard tstat fixes the problem, wouldn't also the dual stage tstat?

 

If you still have the original sensor from the old motor might try putting it in and see if there is a difference.

 

Just checked and it was the sender for the gauge that was changed. If the one for the ECU is faulty, could it still cause gauge problems?

 

I would leave the duel stage thermostate alone. It sounds like you have a bad sender, especially if it did this before the new motor.

The sender for the ecu is on the front of the manifold right below the throttle body. It is a green plug. There should be a brown plug next to it, that is your cold start injector time switch. That is the sender they probably switched out. As mentioned eariler, the sender for the gage on the dash is bewteen cylendars 2 & 3 on the intake manifold. There is a spade connector on it. I would replace that sender and see what happens.

 

Well...I am at a loss then. It's a simple system and I think you've checked all your bases.

What ever it turns out to be, make sure you get back with us for future reference.

 

Unfortunately that would make too much sense. See post above yours. The gauge sender is new. I'm also having a hard start condition, not when hot and not when cold (starts fine then), but in between. I have to give it gas to get it started. Then I'm also getting a CEL with a code 71. Could all this be related?

Not ruling out fan clutch yet, although that seemed to be OK.

 

Is this a 22re?

 

Yes it is. 88 22re.

 

I was just having this problem with my truck a couple of weeks ago with a code 71. Seemed like the check engine light would go off and on and whenever it would be on it would have a hard time starting and run like crap. Go down to your local junkyard and pick up a new egr temp sensor to fix the code 71.

Now in regard to your overheating issues sometimes it may be as simple as making sure you do not have any air in the system. Just trying to make sure you have crossed your t's and dotted your i's.

 

I do not have a wrecking yard near me so I'd have to order a new EGR temp sensor from the dealer or online. Do you know the part number?

 

No sorry. I would see about maybe getting it shiopped from a junkyard. I know my local Toyota junkyard does it. You might want to give them a try.

http://jimsgotparts.com/

You can also pick one up from a local auto parts store.

 

Well I figured I'd post an update since I think I finally fixed my temp gauge overshooting issue. The dual stage thermostat (OEM Toyota) I had installed was worthless. I simply drilled two small 3/32" holes in the single stage one I had originally and put it back in. Problem solved, so far.

Out of curiousity I dropped the dual stage one in a pot of water and set it to boil. From what I could tell, the small port opened at the same time as the big one, and even when it did open, it was only open just barely. For those of you that have this problem, don't waste your money on the dual stage. Drill a little hole or two and be done with it. I see no ill effect to performance at all.

 

The advantage of the smaller valve is that it responds faster to temperature changes than the larger valve. Simple thermodynamics, the ratio of the surface area to volume of the sensing element increases as the size decreases (e.g. half size is 1/4 the area but 1/8 the volume, so the ratio increases by a factor of 2. Heat is transferred to the sensing element via the surface area and the mass of the sensing element (that needs to be heated) is determined by it's volume.

I know the dual valve t-stat worked for my overshoot issue and has been working perfect since installing it back in '98 or so, yes, same t-stat for 13 years. May not fix every overshoot problem, but it is a good t-stat:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

 

It's entirely possible that I got a bad one out of the box.

 

good to know you got it fixed, i drilled 1 3/32nd hole in mine and its flawless

 

The duel stage thermostat fixed my overshoot problem...