Just for fun, I may flip mine to 12:00 and see what happens on the ScanGauge.

 

I run a 170 degree stat for my sc and it stay 176-178 depending how i'm driving. Thats with the 12 o'clock position.

 

Very interesting thread. I had the local dealer do my timing belt (etc) at 171,000 miles. I'm now at 246,000+ and see a consistent 202-204 degrees on my Scan Gauge II. I installed the gauge late last year, and never gave the temp reading a second thought - until reading this thread...

I am quite mechanically minded - can I pull the thermo housing without too much trouble? I'd love to see where those characters positioned it.


Andreas

 

Drain the radiator, remove the nuts from the thermostat housing, pull the housing, and then check out the jiggle. I believe the lower radiator hose would be flexible enough that you wouldn't have to remove it.

 

Now that's easy! Thanks.


Andreas

 

Update: I picked up two gallons of Toyota red coolant, two gallons of distilled water, the Toyota thermostat (90916-03075), and the gasket (16325-62010). This afternoon I drained the coolant, undid the lower radiator hose at the radiator, and undid the three 12mm nuts for the thermostat housing. This released another deluge of coolant and allowed me to inspect the position of said 'jiggle valve'. Sure enough, it was sitting at exactly high noon. Bastards.

I let everything drain completely, cleaned the thermostat housing, and installed the new thermostat & rubber gasket with the thermostat clocked to 6:00. Snugged up the three nuts, re-attached the lower hose and made a fresh 50/50 mix of coolant before filling the radiator. Once the radiator was full, I started the truck and let it idle for a bit. Then I re-installed the skid plate and went for a good 30+ minute drive. The results?

My Scan GaugeII stayed rock-steady at 186° (instead of the consistent 204° - 207° I've noticed since installing the Scan Gauge last year). While sitting at long traffic lights, it would occasionally show 190°. But not a tick more.

I am quite pleased that I took the time to do this, but annoyed that something this simple is merely ignored by dealership techs, as a matter of routine. It's not as if I paid a grocery store shelf stocker to do my timing belt job two years ago.


Andreas

 

Nice! It would have been nice if you were using the same t-stat to eliminate the new t-stat variable.

The more instances of this behavior makes me think that the internal construction of the t-stat has something to so with the temp depending on the jiggle valve position. My 0.02 worth.

 

Agree, but I'm not making that mess again.

The Toyota thermostat I removed was only two years old - I'm sure it's fine. It still looks new. But I went ahead and armed myself with a new one since I was making this effort.

If anyone wants the thermostat (with rubber ring) that I pulled, just cover postage and it's yours.


Andreas

 

BTW, here is a pic of where I permanently mounted my Scan Gauge. It's cleanly epoxied to the bottom of the ashtray, but still allows the ashtray to open. Very easy to read from the driver's seat.





Andreas

 

Interesting thread. I changed my timing belt/thermostat/waterpump last fall around the time I installed an electric fan. I assumed the increase from 190 to 200 regardless of fan speed was the variance in the thermostat.

According the directions I followed http://www.nwtoys.com/forum/tech-article-submissions/1261-5vz-fe-timing-belt-2.html and the fact that the temps are up I'm sure mine is installed at the 12'oclock position. Guess I'll be flipping it this weekend.

 

tacojeff, post up your results after you flip it to 6 o'clock. Thanks.

 

I rotated the thermostat 180 degrees tonight.

It is confirmed, my temps dropped to 190-193 on the scanguage with the cooling fan completely turned off. I'm not sure how the jiggle valve could have a 10 degree impact on things but it worked like a charm.

 

Excellent! Glad you are back to your normal temp.

 

I changed my t-stat during a timing belt/water pump job a while back. I don't have scangauge, but noticed that the gauge in the truck reads just a little warmer since then. Pretty sure I installed the jiggle valve at 12. I also installed a fairly big tranny cooler in front of the radiator at the same time, and just figured that it was running slightly warmer because of reduced airflow or just a little difference between the new and old t-stat. You guys have got me wondering now. Might have to crack her open and check the jiggle valve position.

 

Wow, I'd never paid any attention to where the jiggle valve was oriented. This might explain the fever my runner has had lately- 229 by the scanguage for a few seconds when I pulled in my garage today, then lingering about 222/3. Factory gauge was right in the middle (they're designed to be numb around "normal" operating temp, although this can be overcome by soldering in a couple resistors). A few days ago it was around 218 but today was about 7 degrees hotter outside.

Out of curiosity, when the fan clutch on these rigs engages, will it sound like an airplane's under the hood like it does on my T100?

 

Yeah, it sure does. You should hear it--briefly--on a cold start-up.

 

It may be a good idea to start you own thread with your issue.

But quickly:
Per the FSM, normal coolant operating range is 176-203 degrees F. A bit of quick heat soak can occur in the garage especially if the fan clutch is bad. If your temps are high around town, start looking at the fan clutch, radiator, water pump, etc.

 

Rehashing an old thread here but I just replaced the timing belt on my 98 tacoma 3.4L with all OEM parts.

My old tstat kept me at 195-204, now I'm running at 198 to 212.

So I asked two different techs at toyota, one's been there 17 years and the other 10.

They said they have always installed the jiggle at 12. Thats the way they come from the factory so that air can permeate from the coolant. They also said that they found the warmer engines are more efficient. That the dash needle doesn't even start to move until you get close to the danger zone of 250.

They also said the GM not too long ago changed thier tstats across the board to operate the coolant to 212. There may be a possibility that Toyota did the same. They weren't really sure since they are happy with the 195-212 range.

And they also said the temp runs cooler with the jiggle at 6 because the jiggle keeps coolant flowing.

Just for added insight, I also asked a buddy of mine that's a master tech at Infiniti. He said all Nissan's run the jiggle at 12. That's the industry norm.

And despite this, I still can't decide if I want to flip the darn thing. I should leave well enough alone.

Thoughts?

Any added insight from the last 3 years?


.

 

FSM for the 3.4l 5vz-fe clearly shows jiggle valve in the 6 o'clock down position, not the 12 o'clock position.

I would not be surprised to see a coolant temp drop if you flip it....others have seen the drop in temp as read by a ScanGauge, etc. The factory OEM t-stat is 180 deg.....well, within rounding.

 

Be sure you get all the air bubbles out if the cooling system too.