Does anyone know what the proper operating temp for the 3.4L is?

I've got a 3.4L retro fitted into my '93 4Runner. Recently I put in an aftermarket gauge (one that gives an actual reading and not just moves a needle) and I put on Ford Taurus 2-speed fan. I've had it together for about a week now and with the exception of some wiring issues (those fans draw a lot of amps), I think I have it all working correctly.

My only issue is it seems to run hot....like around 200 - 210. But, I really can't say for sure, because all I had before was the factory idiot gauge....which doesn't tell the actual temp. Infact the factory gauge would just move up to one spot on the dial and sit there....no matter what.

I'm looking for actual factory specs for operating temp....and anything anyone else knows about what the temps should be or do.

Thanks

My Scanguage II on my 2001 Taco says my water temperature hovers around 188-194. That said, the stock thermostat is a 180 degree item. I have a 160 degree TRD thermostat in my Taco that came with my TRD S/C kit.

Based on this, your readings of 200-210 are probably about right for a stock 180 degree thermostat (remember that the thermostat on the 3.4 is in the water inlet to the block, instead of the water outlet -- meaning the temp at the outlet is going to be somewhat higher than the thermostat setting by the time the coolant circulates and carries some of the heat away from the engine).

Thanks Whizkidder....

I also called the dealership today and talked to their service manager. He said that 200 - 210 isn't out of line, on a hot day....and yesterdays 90+ temps would qualify for that. I just keep wanting to see it around 190 - 195, I guess. It still seems to me that the taurus fan is struggling to keep up though.

So...just for kicks....and becuase I'm a geek. I took a spare factory temp gauge and sensor from my '93 ShagRunner and wired it up on the bench. Then I applied heat and compared the gauge readings to an infa-red temp sensor I have.....just to see what it all would do....

The method was pretty crude and, I'm pretty sure when I was taking the temp readings I was actually measuring the temp of the surface the sensor was laying on and not the temperature of the sensor itself. Tomorrow, I'm gonna re-do this experiment with the sensor in water and using a thermometer for more exact readings.....but...

The gauge moved smoothly and evenly from 100 to 140 degrees, up to the mid point on the gauge face. From 140 to 210 degrees the gauge sat at the same spot. This is the place this gauge would go to normally. No matter how hard I was beating on the truck, or how hot (or cold) it was outside, the gauge always sat at this spot. Then, from 210 on the dial moved up and quickly....I think it was pegged at 230 degrees.

I also had an ohm meter wired into this setup. Even while the gauge sat still at the mid point, the resistance was changing steadily with the temps.

Based on this, it would appear that the temp factory temp gauge is infact a true idiot gauge. Tuned only for a certain range. As long as it's within that (very wide) range, it always reads the same.

Like I said, This first try was a pretty crude experiment. And, I'm going to redo this experiment tomorrow and try an get some better temp readings. I suspect the temps I was reading with the infa-red sensor were actually low (as in the sensor was much hotter).

Having had the truck for 10 years now and watching that gauge, I kind of figured this was how the gauge would work...I'm just surprised at how wide the range was.

....I'm answering my own post here....

In the past 3 days, I have harrassed every toyota service teck and service manager, AND every toyota "guy" who'll answer the phone....here's what I came up with.

The ideal temps are 185 - 195-degree....But....the stock toyota 3.4L (and probably the 2.2 and 3.0L, as well) will run around 205-210 under normal driving conditions, on a hot day. Which, everyone said isn't great, but as long as you aren't beating on it, and you change the oil regularly isn't too terrible for the motor.

Ofcourse, this is a problem if you wheel your truck....slow speeds....no air being pushed through the radiator...and ofcourse the high loads and RPMS that come with wheeling....all means those temps are going north of 210. Almost all these guys said to go with a 160-degree thermostat if your doing anything more than "normal" driving. One of the service techs did say he's never seen the normal high temps be a big problem. with a yota motor...but that was only 1 out of about 7 guys.

I just installed the 160-degree TRD thermostat in my ShagRunner this evening (little bugger costs $80)....Drove it about 30 miles, doing lots of start/stop around town driving. The highest my temp got was 195 and and it mostly hovered around 185. The 195 was after I warmed it up to 185, then shut it off for 10 minutes. After I started it back up, the temp was 195...but, it dropped to 185 pretty quickly....So, I think I've got my cooling issues solved.

...now I just need a bigger alternator to deal with the draw of that Taurus fan....

I'm curious because I was thinking about throwin in an extra taurus fan i had laying around in my tacoma 3.4L. Does the fan really draw that many amps?

Read his other post concerning this:

Controller frying fuses

Yeah, it does. I was melting (not blowing...actually melting) 30 amp fuses. After asking around, the consensus was that the low speed draws up to 25 amps while running and the high speed draws up to 35 while running.....and if starting up on the high speed wire (which can happen if you re-start the engine after it's warmed up), it can draw around 80 amps momentarily.

After getting it all in and working out the bugs...I love the thing....it's perfect. With the SPAL fan controller and can adjust the thing for the weather. In the heat of the summer I start the low speed at 160 and the high speed at 195. That keeps my temps at 195 when the outside temps are near 100. When the weather cools, I'll re-adjust it so that the low speed comes on at 170.....maybe 175.....and it's easy to re-adjust....just unplug the fan and let the motor warm up....when it hits the temps you want the fan to come on low, you press a button....when it gets to the temp yuou want the high speed fan to come on, you press a different button.

The one thing I really love fan mod is the throttle responce....definetly noticable....no hesitation when accelerating, even at highway speeds (but that is with a 3.4L)

It took a while to work out the bugs on the whole thing though....the one that really drove me nuts was that a stock 3.4L runs at about 210 degrees on a hot day. I couldn't live with that, so I went with a 160 degree thermostat.....which solved the problem nicely.

The other bug (that I just got fixed tonight) was the draw on my old alternator. Granted mine had about 175K miles on it....but at night with the high beams on and the high speed fan running, my volt meter read just 12.0 volts (and that was with the motor at 2500 rpm). I just instaleld a 100amp at idle and 140amp max alternator and now my volt meter reads 14.0 max and 13.0 with ALL accessories turned on.

If you do this mod, I highly recomend the SPAL fan controler. It's pricey (about $110) but well worth it. The Haden controller is a lot cheaper...$34...but I've read too many post about them failing regularly to even consider it. And regardless of whihc controller you go with, make sure you wire it up with 40-amp relays to handle the high speed wire and use MAXI fuses (they look like giant atc fuses and go up to 100 amps....although a 40amp fuses is all that's needed).

Dang, I didn't realize how much current those things draw. Thanks for the heads up.