Thermostat replacement question

Hi all. I am new to this forum. I have a 99 Tacoma SR5 V6. Today I took it to the shop because the temperature gauge went to the red right after I started the truck. The shop says I need a new thermostat. I am wondering if a novice mechanic can do this repair or should I leave it to the pros? Thanks in advance for your help!

 

If you're a competent mechanic then you should be able to do it fairly easily.

Requires a few tools and some careful attention to detail when removing the old gasket material but outside of that fairly easy.

My buddy who only knows how to change his own oil did it with just verbal guidance when he changed his out on his ranger.

PM me and I can send you the pages on removal/installation from the service manual if you don't already have it.

 

Well I am almost afraid to admit it, but I've never changed the oil myself... I've left most maintenance to the pros over the years but I have more time now and would like to save money where I can. The shop said I need a new air filter, too, and an alignment. I'm going to let them do the thermostat but I will get an air filter (after a bit more research here). I'll have an alignment done soon, too.
I'll try doing the next oil change myself, as well as some other maintenance work after studying up this forum, and then work my way up to more advanced jobs. I never thought about doing these kinds of things before I bought my motorcycle 3 years ago; I spend waaay too much time reading that forum! My old Toy needs some TLC, too.
Thank you for your help. I did get the service manual.

 

the thermostat on these trucks are fairly easy, here is a guide for the 02




REMOVAL
DRAIN ENGINE COOLANT
DISCONNECT LOWER RADIATOR HOSE



REMOVE THERMOSTAT
Remove the 3 nuts, water inlet and thermostat with gasket from the water pump.
Remove the gasket from the thermostat.
INSPECTION
INSPECT THERMOSTAT

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




Immerse the thermostat in water and gradually heat the water.
Check the valve opening temperature. Valve opening temperature: 80 - 84°C (176 - 183°F)
If the valve opening temperature is not as specified, replace the thermostat.




Check the valve lift. Valve lift: 8.5 mm (0.335 inch) or more at 95°C (203°F)
If the valve lift is not as specified, replace the thermostat.
Check that the valve is fully closed when the thermostat is at low temperatures (below 40°C (104°F) ). If not closed, replace the thermostat.
INSTALLATION




INSTALL THERMOSTAT
Place a new gasket to the thermostat.
Install the thermostat with the jiggle valve downward.
Install the water inlet with the 3 nuts. Torque: 20 Nm (200 kgf-cm, 14 ft. lbs.)
CONNECT LOWER RADIATOR HOSE
FILL WITH ENGINE COOLANT
START ENGINE AND CHECK FOR LEAKS

 

I think you'll find this thread extremely helpful for many of the routine maintenance tasks and for more serious repairs and mods, once you're ready for those:
http://www.tacomaworld.com/forum/1s...y-how-thread-compiled-list-helpful-links.html

 

Just curious as to where you got your info...

My Haynes manual states:
"The jiggle valve must be within 15 degrees of the 12 o'clock position when installed."

Photos and illustrations all show it on top.

 

Just to clarify when you say 'right after'. Are you talking seconds or minutes here? Did the engine start out cold?

 

Yes --first things first- FLUID?

 

alldata

because of discrepancy install it the way it came out lol

 

The correct position for installing the thermostat is with the "air-relief valve" AKA jiggle-valve, as high as possible to allow any air bubbles to more easily travel through the thermostat. Thus it should be installed at the 12 o'clock position.

 

I noticed the temp gauge in the red probably within two - three minutes of a cold start, FWIW. I had the thermostat replaced and coolant flushed. Ordered an aFe Pro-Dry S Air Filter.
Thanks to everyone who responded to my post; looks like a great forum here. I appreciate the help and tips.

 

Many folks will swear the "jiggle" valve should be in the "up" or 12 o'clock position. "It helps to purge air bubbles" they say. Google "jiggle valve", most returns including Wikki say "up".

The Toyota FSM specifically says down for the V6 and up for the 4 cyl. The FSM seems to defy conventional wisdom or is just flat wrong (it frequently is) but apparently this time it is correct.

There is some pretty substantial evidence with the V6, putting the jiggle valve "up" consistently causes around a 10* increase in coolant temp. Haven't seen anything with regards to the 4 cyl. You may or may not see it on the dash gauge. They are not real sensitive.

This thread is one of the better ones on the subject http://www.yotatech.com/f2/5vz-fe-ru...easure-249481/
Of the dozen or so original V6 t-stats I have pulled, all were installed at the factory with the valve down.

 

I would like to see ANY evidence that supports the V6 having a 10* temp increase. That "jiggle valve" has nothing at all to do with the thermostat opening or closing. Please post the evidence showing otherwise. While the FMS may say it should be down, I have seen no evidence supporting a reasoning for this. Thermostat purge valves have been installed in the up position when located vertically since I can remember. Horizontally installed thermostats tend to not indicate a direction, since the thermostat is flat anyway, and the air bubbles, as well as a calculated small amount of coolant can flow past it. I have in stalled plenty of Toyota thermostats in V6 as well as I4, and have never seen any signs of a 10* temp change at all.

 

I am not offering any logic. In fact I said the 6 o'clock position seems to defy logic. The whole thing beats the hell out of me, but the evidence is there. Then there is the factory recommendation.

Did you read the link and the links to other threads? Countless folks have verified and re-verified the V6 temp increase with scan gauge coolant temp readings.

 

I would have to do an experiment 1st hand, and simply take an existing thermostat and install it the two different ways. If they REPLACED the thermostat and noticed a temp increase, that could simply be due to differences between the thermostats themselves. I find no logic at all that supports an operating temp difference based on the clocking of the thermostat. Actually now that I think about it, I have a timing belt job coming up and I will test the temp before and after, taking into account the current orientation of the thermostat.

 

I don't know the cause, but I too have seen people posting 10° gains in normal running temperatures after a thermostat swap.

I think I still have the original stat and I run darn close to 200°F almost all the time. Guys running +10 are reporting around 210°F.

I agree; the only way to tell for sure is with a controlled experiment and unfortunately a sample of one is rather small.

 

BTW if you haven't read that Yotatech thread yet (I just read the whole thing), you should. It's pretty convincing.

 

I admit to not having read the specific threads. That is not a site that I frequent. I am basing my thoughts and beliefs on personal experience, and logic. The jiggle valve has no control over thermostat opening temperature, or flow. As the thermostat opens, coolant passes through the center area of the opening, allowing it to flow into the radiator. IF the coolant temperature ever drops below the opening temp of say 180*, then the thermostat will close. The jiggle valve has nothing to do with that operation. My thoughts would be that most people that remove their thermostat do it to replace it. A new thermostat will operate "crisper" than the old one, which may have begun to open sooner due to age and the like. So perhaps the older one was actually opening at 170* resulting in perhaps an engine operating temp of say 190*, but a new thermostat opening at a proper 180* may have an operating temp of 200*. An increase in operating temp, but not having anything to do with the jiggle valve positioning.

 

I agree 100%. It makes no sense, the rational experienced man will say "BS", I did, BUT if you read the whole link and the links within, folks did just the test you suggest, install "up" noticed temp increase, changed it to "down" temp decrease, with the same stat.

 

Hmmm. I find that hard to swallow, but I won't argue their findings, since I was not there. I have a tendency to accept what physics says personally. Never had a complaint in how I installed a thermostat in a Tacoma, or any other vehicle in my 20+ years of doing this. I'll stick with the way I have done it. I will admit it is a curious condition, and would like to find out how this could happen, and if there was anything different in the conditions of the situation. Engine OPERATING temp is different that thermostat opening temp, and is affected by a myriad of conditions from coolant itself, fan clutch operation, AC operation, etc. Ah well.