Truck: 1994 p/u 22re 200k

About a month ago i had the head gasket replaced at the local Toyota dealer. At this time they also replaced the thermostat. When I got it back and started driving it the temp would vary up and down form 1/3 to 2/3 and back. They told me I had a bad radiator and needed a coolant flush. So i did this and still had the same problem. So i replaced the thermostat again to make sure they had installed the correct one. Now when I start the engine the temperature goes until it almost red-lines then drops back to just below 1/2. After the initial spike it will maintain a steady temp.

If have done some research about overheating but have found no satisfactory results, everyone seems to have different symptoms and results. I have looked into all of the common things I have read about causing issues like this.

I believe the fan clutch is good, because it does not matter if i am at idle or on the highway, plus the temp here is in the mid 20's. The belt is also tight.

Would a bad water pump cause this? It is the only part I have not replaced. I don't want to unless I know for sure it is the problem.

If i did not install the thermostat correctly would it cause this? I know i put it in right side up, but i could have oriented it wrong.

As far as air bubbles go I am fairly certain i have gotten them all out.

Any ideas/suggestion you can give me about what could cause this would be very helpful

Thanks,
Ray

 

so did the dealer replace the radiator and do the flush also?

 

It sounds like the thermostat is not opening quickly enough. I can't deduce why that would occur and then run at normal temp afterward. What temp is the thermostat?

 

I had this happen until I put in the "dual" thermostat. It was worse when I had the heat on in the cab but it happened either way. Spike on startup then back down and solid.

 

Ditto on the dual Tstat.......... Part # 90916-03079

 

X3 on the t-stat:
- http://www.4crawler.com/4x4/CheapTri...tml#Thermostat

 

t-stat or drill small hole in base. funny 4crawler didn't mention that.

 

The small hole is mentioned on the web page

 

+1 on the thermostat. if the water pump was bad or getting stuck the temp wouldn't be going back down to normal after startup.

 

I did the coolant flush, radiator swap and second thermostat change.

I believe the thermostat the dealer put in was the dual temp one. It looked like the one on the left in the picture. the one i have in now is the one on the right from napa.

OEM on the left, Napa on the right

I was totally confused when i pulled it out and they looked different.

What is the function of the dual temp/How does it work?

When I had the OEM one from toyota in I got the oscillating effect. Is that normal or did I get a defective thermostat? I seemed like it opened and closed on to wide of a range.

Hopefully this answers some questions and clears things up.

 

Again check out 4Crawlers explanation of the duel thermostat http://www.4crawler.com/4x4/CheapTri...tml#Thermostat.

 

I only use OEM Toyota thermostat--no issues. What did you use?

 

which two hoses are you talking about? I just have one large one on the bottom and another on top. Could you send me a picture?

 

Ray, I have had what sounds like the same problem for about 10 years. However, this temperature spike (almost to the red then back to normal) only happens when I'm running the heater. When I'm not running the heater, the engine heats up normally.

That said, I have searched for an explanation for quite a while but not found one. While it's annoying, I would not lose too much sleep worrying about it, especially if it causes you to neglect other maintenance.

I will keep an eye on this thread.

 

this has been talked about many times and has also been posted in this thread by 4crawler, solution is simple.

 

I just tested the thermostat Toyota installed in my truck that caused the temperature of my engine to vary in a regular pattern from 1/4-3/4 on the temp gauge. It only opened about a 1/4". Is that normal or should it open further?

 

From the FSM:

THERMOSTAT INSPECTION

HINT: Thermostat is numbered according to the valve
opening temperature.

(a) Immerse the thermostat in water and heat the water
gradually.

(b) Check the valve opening temperature and valve lift.
Valve opening temperature: 80 – 84 C (176 – 183 F)

Valve lift: 8 mm (0.31 in.) or more at 95 C (203 F)

If the valve opening temperature and valve lift are not within specifications, replace the thermostat.

(c) Check that the valve spring is tight when the thermostat is fully closed.

If not tight, replace the thermostat.

 

here's my bump for the two-stage T-stat. This spring, after plopping in a brand-new engine (OER), I had the spike and slow-drop to normal temperatures. Actually, the temp would rise after startup (from cold) to almost redline, drop to normal, rise again, drop and rise again, repeating itself until a normal operating temp was consistently displayed. I can only imagine this gradually diminishing, bouncing/cycling of up and down temps would indicating the T-stat was opening and closing. Strange.

I bought the two-stage T-stat and put it in. I actually still get an excessive temp rise initially, but it really only happens once. I haven't noticed any problems because of this, so I'm not worried about it, but I am curious about a couple things (not necessarily just my problems, but rather with this issue in general)...

1.) I never noticed this problem before, and I'm sure not everyone with the 22-RE has this issue. Why such a discrepancy with who has this issue and what engines have this issue when a 22re is a 22re is a 22re? Wouldn't everyone have this temp spike rear its' head at some point?

2.) I thought I had another question... guess not.


-C

 

Are you sure your water pump is working fine?

 

LOL~