T/stat change on 3.4, Is it simple to do?

[piecesparts]

I am thinking that the T/stat could be updated on the 97 4 Runner that I just purchased. I see where the T/stat is on the engine (3.4). Is there anything special one should do to make sure the engine is filled properly again? Are there bleeder vents on the engine or does it all vent through the radiator?

 

[LittleCaesar]

Here is a DIY for a timing belt job but this should show you where the T-stat is located.

Just try and not make the mounting studs move. Tighten to 14ft/lbs I believe.

No bleeder screws.

http://www.nwtoys.com/forum/tech-article-submissions/1261-5vz-fe-timing-belt.html

 

[4x4runner2002]

just make sure the jiggle valve on the t-stat is at like 5-6 o'clock. it makes a big difference on the temp of the water.

i had mine installed at 12 o'clock and it was running about 25 degrees warmer than at 5-6 o'clock. other than that its pretty simple.

 

[Zottyzot]

Short answer, yes.

 

[piecesparts]

A couple more questions, If I may.

1. The attached DIY shows them putting the T/stat in with the jiggle valve at 12 O Clock and the input from 4 X 4 Runner says to do it at 6 O clock, what say the rest of you? This may be the reason my heater is running a little cooler than I figure it should be.

2. I take it that the T/stat can be changed without removing all of the goodies around it, is that right? It appears to be that way when I look at it.

3. Does Toyota use a special type of antifreeze or will the standard Prestone green type work?

 

[thor999]

3) Only use Toyota Long Life coolant or the "red" foreign vehicle coolant concentrate, mixed appropriately w/ distilled water, or premixed (pink). Do not use green as it will cause issues down the road. Unless, for some reason, someone has already replaced with green and that is what is currently the coolant in the rad. Then well hopefully someone else can chime in! Can't help w/ the other 2 it has been a long time since I did TB and cannot remember.

 

[UTEP]

Haynes manual says 15 degrees left or right of 12 o'clock. I really can't figure out how this matters.....I guess the valve is to relive a little pressure in the system and allow a little bit to flow so 12 or 6 o'clock who knows. I followed Haynes

Use Toyota Red coolant cut 50/50 with distiller water. Best price I've found usually at Car Quest. I just picked up a gallon for $25 as they had some sale but I think Toyota quoted me closer to $35 a gallon. You'll need two gallons of un cut Red....

Merry Christmas All!

 

[UTEP]

Haynes manual says 15 degrees left or right of 12 o'clock. I really can't figure out how this matters.....
Merry Christmas All!

Well I'll be danged… Haynes disagrees with the FSM! See attachment.

FSM simple says "Install the thermostat with the jiggle valve downward".

I pretty sure I put mine in the 12 o'clock position and run around 200°-205° in most situations I have monitored it. I always thought that was a slightly on the high side as I'd heard lower T's reported here.

Hmmm… Opinions….?

Edit: A little investigation reveals this is a common debate; 12 or 6 o'clock. That said the purpose Jiggle valve is it vents the air trapped inside the cooling system when filling or topping up the system with coolant and hence ensures the 'full coolant no air trap' condition in radiator and water jackets. This would make me think 12 o'clock better as air rises… The couple of threads I found most folks place it at 12 o'clock…YMMV

Merry Christmas!

 

[19963.4lsr5]

I can see a jigger valve being effective when the t-stat is located in the top hose. It's truly at the top of the system and able to vent the air out.

Installed in the return hose (bottom)its sole purpose may be only to allow water to go into the block as air or hot coolant rises up or out of the block into the rad.

I can't see any air being in the lower hose unless its common on the 3.4 to get air trapped in the T-Stat housing

 

[TheDurk]

I have followed the FSM 6 o'clock and my temps are fine.

 

[pluton]

I have followed the FSM 6 o'clock and my temps are fine.

Same here...six months later no problem.