Trans Temps with Bypassing and Using External Cooler

[jgue467]

Bypassed alone is adequate WITH OD override in Texas heat.

Only because our beloved 3.4s are somewhat anemic on hills and while towing uphills that Require the use of the OD override makes having only the trans bypassed adequate.

In my summer driving pulling a trailer (3000lbs) uphills in 105 degree weather I could hit 237 BUT because we Know OD override is pretty much required to give the engine enough rpms to achieve enough hps to climb and not loose speed (maybe even gain some!) my trans temps Never go above 198, often the OD override brings it down to 180 even in that heat.

Its a decent setup compared to the blunder of a plan toyo had originally. :cowboy:

 

[mtbtim]

Only because our beloved 3.4s are somewhat anemic on hills and while towing uphills that Require the use of the OD override makes having only the trans bypassed adequate.

In my summer driving pulling a trailer (3000lbs) uphills in 105 degree weather I could hit 237 BUT because we Know OD override is pretty much required to give the engine enough rpms to achieve enough hps to climb and not loose speed (maybe even gain some!) my trans temps Never go above 198, often the OD override brings it down to 180 even in that heat.

Its a decent setup compared to the blunder of a plan toyo had originally. :cowboy:

What speeds are you driving while pulling the trailer? I was loaded down with gear and pulling a motorcycle trailer on a recent trip and didn't see the temps spike with the stock set-up until I hit a consistently steep grade for many miles on a mountain road that I was only able to drive around 20-30mph on. I had the OD off. I think as long as you have adequate air flow on the cooler with the bypassed set-up, you're probably going to be ok. It's when you're driving slower, putting strain on the trans that's causing the temperature spikes into the mid or higher 200's like some on this thread have reported with the bypassed set-up.

And, if it were just a situation of high temps, going bypassed with accessory electric fans might be the ticket, but there is the consideration of being in lower temps and not having the benefit of the stock cooler in the radiator bringing the trans fluid temps up to a optimal operating temperature quicker.

I still have a hard time agreeing the stock cooler set-up in the radiator is an engineering mistake. Why would so many car manufacturers use this set-up if it was such an awful design? Wouldn't they have spent the extra $75 on the vehicles price if a stand-alone external cooler was the superior design. I know corporations can be cheap, but if they could improve a design for such a low cost, I think they would be running the external cooler set-up if it was indeed the best choice for all driving conditions.

Thanks for joining in on the conversation.

 

[mtbtim]

I did the same install on Friday. .. B&M 70264 in series with Denson radiator. I also installed a 7" electric fan. I will test my setup later next month in Moab.

Could you share pictures of how you mounted the fan and also let us know what fan you bought and how you wired it? This might be something I would like to do also to bring the temps down a little lower when pushing the truck hard in slow speed conditions.

 

[St Runner]

Its really about the transmission. The 340auto is a poor transmission for low speed heavy duty work because of the amount of heat it puts out. And that is because its a higher geared 3 speed transmission with a slow lockup. Running synthetic fluid with a transcooler in series is the cheapest way to deal with it. You are doing what I call 2% driving. Toyota did not make decisions or design for the 2%, it makes them for 98% who drive on highways and go to the store. I think we are fooled sometimes by how capable these vehicles are off road that toyota must have designed them for that purpose. Putting a R150 transmission in my runner was the best thing I have done for that 2% driving. Its geared better and I don't have to deal with the heat issue.

 

[jgue467]

What speeds are you driving while pulling the trailer?
I still have a hard time agreeing the stock cooler set-up in the radiator is an engineering mistake.

Oh I don't baby it, we're talking 70-80. So at that speed it'll soar to 238 at 105 ambient, with OD override it'll drop to under 200 sometimes even 180. Around town at that ambient temp it'll do about 205-208 until I start using the OD override then back down to 180-190. So for me its just an issue of using the OD which i haven too anyway just to climb hills and mountain passes more easily without loosing speed.

I agree, it is an ok design used by many other manufacturers, i was just exaggerating with the blunder word....and wish it held together better over time. Luck to all! :cowboy:

 

[mtbtim]

Ok Dudes, here's the video I made of me installing the B&M 70264 Cooler and replacing the radiator and thermostat at the same time. It is pretty darn long because I didn't use [MENTION=102606]infamousRNR[/MENTION] great video editing skills and maybe I have a little bit of diarrhea of the mouth, but I think you will find it very informative if you're looking to do this job yourself.

Here it is. Enjoy the show!

<iframe width="560" height="315" src="https://www.youtube.com/embed/2nVbwe2t2T8" frameborder="0" allowfullscreen></iframe>

 

[Jayjayb96]

Hmm makes me think i still have air in my system. Last year my rig overheated i ended up replacing the radiator with a denso unit, thermostat with stant 170, new oem cap, aisin fan clutch and I installed the b&m 70264. Bypassed the radiator. I averaged 185-200 depending on driving conditions.

 

[mtbtim]

I just did another trip to the mountains loaded down with gear and the B&M 70264 cooler did it's job well. On the last trip to my cabin, I hit 232 degrees at the top of a long steep incline. This time around, I hit 205 on the same incline but I wasn't pulling the motorcycle trailer. However, the ambient temps were around 15 degrees hotter than the last time.

I've also used a 7 mile hill in my area as a test hill and my trans temps are consistently 20 degrees cooler with the external cooler. When I first drove the hill without the cooler, my trans temp hit around 220 degrees at the top of the incline. On two subsequent trips up the same hill, with the cooler, I hit around 200 degrees at the top.

Note: I had Overdrive off on all these hills.

 

[BigKitty]

I think after reading everything that's posted I've decided to run the cooler in series and get a new oem radiator and not worry about it.

 

[Kotrin]

Between the badgering I got from one guy and all my reading and research, I've come to the conclusion that it is a plus to get the cooler or a mandatory new radiator. I have played with the OD (on and off) as I drive and noticed OD off is a HUGE improvement on anything that isn't a highway or straight long roads. Anything that is turns, hills 5-10% of the trip, its easily 150-170 versus 200+. I may not like the sounds of it at 55 mph, but I value my transmission!

 

[4racer]

I would like to also know the mounting of the Trans cooler in relation to temp as I have seen many different types of mounting. Especially how close you are to the condenser.

 

[mtbtim]

I would like to also know the mounting of the Trans cooler in relation to temp as I have seen many different types of mounting. Especially how close you are to the condenser.

First of all, there's different mounting locations for the cooler which will get you different cooling results. The most popular is in front of the AC condenser for maximum cooling. From what I've learned from people on this forum and other forums in regards to the mounting position is you want it as close to the condenser as possible so the engine fan will efficiently pull air over the fins of the trans cooler. Because of this, I chose the zip tie route of mounting the cooler to the AC condenser with only foam rubber pads separating the two. So, it sits very close to the AC condenser, less than a 1/4" away. There are other ways to mount it using the brackets and other hardware that comes with the kit, but it's a more involved process to fabricate the brackets perfectly so the cooler is sitting close to the condenser but not rubbing against it.

In my opinion, the zip tie route is the way to go to simplify the install. I pushed the zip ties through the AC condenser and radiator so the weight of the cooler was spread out and not all on the condenser. Like others, you might want to think about changing your radiator at this time and the thermostat but it's all personal preference. I wanted to renew my radiator as preventative maintenance to limit the chances of a failure when I'm on a trip and also reduce the chances that I'll have a trans cooler failure and get the pink milkshake tragedy. And, I chose to renew the thermostat too since I already had the radiator out and the coolant drained.

If you're thinking of bypassing your radiator trans cooler, make sure you do sufficient research to figure out if it's the best way to go based off how you use your rig. I chose to run my external cooler in-series with the stock radiator trans cooler. Check out the video I shared on this thread if you want to see how I did my install.

Good luck!

 

[fourfive]

For those that have bypassed the radiator cooler and also are using a Scan Gauge or other monitoring system, what temperatures are you registering?

I installed my B&M 70268 using the bypass method about a year ago & assumed everything was fine. About a month ago I finally got around to installing my scan gauge ii & have been monitoring my trans temps & was pretty surprised by the temps I was seeing.

Trans>magnefine filter>external cooler (enters cooler on top port & exits bottom port in side mount position):
With O/D on & my typical 150-200lbs cargo weight driving to/from work mostly highway:
-In Georgia's 90-95F hot humid heat, I was fluctuating between 180-200F on the highway going 70-80mph without any inclines. Soon as I hit any type of incline, I would immediately hit 200-220F & would stay there until the road leveled off & would return back to around 190F.

-The above temperatures were similar when I was driving to work in the mornings in 75F humid weather.

-In town driving in 90-95F weather, my trans temp would average 200F & quickly climb to 220F with any inclines.

With O/D off:
-Loaded down with 300lbs+ gear and 4 adults driving through the mountains, my trans temp would avg 200F & would hit 230F+ with steep inclines.





This weekend I rerouted my lines to run my external cooler in series...

Trans>radiator>magnefine filter>external cooler (enters cooler on bottom port & exits cooler on top port in side mount position)>trans
With O/D on:
-90-95F heat, my trans temps were 160-180F on the highway 70-80mph & would hit 190F on inclines

-In town driving, my trans temps were 180-190F & would briefly hit 200F on steep inclines


The ~20 degree drop in trans temps with the external cooler in series mentioned by others seems pretty accurate.

 

[mtbtim]

I installed my B&M 70268 using the bypass method about a year ago & assumed everything was fine. About a month ago I finally got around to installing my scan gauge ii & have been monitoring my trans temps & was pretty surprised by the temps I was seeing.

Trans>magnefine filter>external cooler (enters cooler on top port & exits bottom port in side mount position):
With O/D on & my typical 150-200lbs cargo weight driving to/from work mostly highway:
-In Georgia's 90-95F hot humid heat, I was fluctuating between 180-200F on the highway going 70-80mph without any inclines. Soon as I hit any type of incline, I would immediately hit 200-220F & would stay there until the road leveled off & would return back to around 190F.

-The above temperatures were similar when I was driving to work in the mornings in 75F humid weather.

-In town driving in 90-95F weather, my trans temp would average 200F & quickly climb to 220F with any inclines.

With O/D off:
-Loaded down with 300lbs+ gear and 4 adults driving through the mountains, my trans temp would avg 200F & would hit 230F+ with steep inclines.





This weekend I rerouted my lines to run my external cooler in series...

Trans>radiator>magnefine filter>external cooler (enters cooler on bottom port & exits cooler on top port in side mount position)>trans
With O/D on:
-90-95F heat, my trans temps were 160-180F on the highway 70-80mph & would hit 190F on inclines

-In town driving, my trans temps were 180-190F & would briefly hit 200F on steep inclines


The ~20 degree drop in trans temps with the external cooler in series mentioned by others seems pretty accurate.

Another in-series trans cooler believer! 230 degrees isn't too bad but it doesn't take too much more to start really cooking your fluid and lowering it's life expectancy. I'm glad I learned how to monitor my trans temp and learned how to address it. Turning off the overdrive makes a huge difference and the adding the external cooler was a nice addition.

I had a Honda Accord that I would use to travel to mountain bike races all over the state. I would put 4 guys, 4 bikes, and all our gear and drive up to races in ski towns like Mammoth Mountain and Big Bear. I would push that 4 banger for all it had up the mountains not knowing I was cooking the transmission fluid. On my last trip to Big Bear in that Accord, the transmission started to slip. I kept the car for a while longer buy would never take it on long drives anymore because the transmission would slip when it would get too hot. I gave it to charity at 240,000 miles because of the transmission problem. If I would have known what I know now, I probably could have gotten 400,000+ miles out of that car because the engine didn't even burn a drop of oil. In retrospect, I probably should have just put another transmission in it and kept it.

 

[fourfive]

Another in-series trans cooler believer! 230 degrees isn't too bad but it doesn't take too much more to start really cooking your fluid and lowering it's life expectancy. I'm glad I learned how to monitor my trans temp and learned how to address it. Turning off the overdrive makes a huge difference and the adding the external cooler was a nice addition.

My concern was what would happen in more extreme conditions because I was regularly seeing temps around the low 200's with my daily driving & easily hitting 220-230F in moderate driving conditions. O/D off definitely helps drop the temps by a good 10 degrees but not sure how I felt about seeing the jump in RPMs at highway speeds.

I was never opposed to running the external cooler in series, I was just under the impression that the average size external cooler bypassed such as the BM 70268 or 70264 would be equally effective if not better than the stock cooler with the added safety bonus in the rare event the radiator cooler failed. There will always be pros/cons of any mod but in the end, I felt better about having my trans fluid in the 160-180 range instead of seeing temps regularly in the low 200s bypassed.

*Great job on all your vids man. Keep up the good work and keep them coming. It's hard enough trying to just take pictures of DIY work so I can only imagine how much effort goes into filming and doing technical work in tight spaces.

 

[fourfive]

Side note, after flushing my radiator with distilled water and refilling with toyota red, my avg coolant temp went from 198F to 190F via scan gauge ii.

 

[4racer]

From my testing. The minimum cooler size I would go with if Bypassed is the Tru-Cool 4589

 

[97Run-Man]

Side note, after flushing my radiator with distilled water and refilling with toyota red, my avg coolant temp went from 198F to 190F via scan gauge ii.

I used a OEM thermostat and prestone cut with distilled water. I'm seeing 188F-191F even at 90F+ and highway speed. With an AutoZone thermostat I would see 193F at the absolute lowest. I get to 186F and hold between there and 188F. I wonder if it would drop down at highway speed with OEM coolant. To bad it's so pricy.


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[StreetCreeper]

I used a OEM thermostat and prestone cut with distilled water. I'm seeing 188F-191F even at 90F+ and highway speed. With an AutoZone thermostat I would see 193F at the absolute lowest. I get to 186F and hold between there and 188F. I wonder if it would drop down at highway speed with OEM coolant. To bad it's so pricy.


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Uncut coolant would probably raise the temp by a degree or three. Water is the better of the two at cooling. Coolant is not really there to cool so much as it is to inhibit corrosion and lower the freeze point.

If you wanted maximum cooling, just distilled water would be your best choice. You lose all the protections anti-freeze provides though so that's why nobody but racers and weirdos do it.

 

[mtbtim]

Side note, after flushing my radiator with distilled water and refilling with toyota red, my avg coolant temp went from 198F to 190F via scan gauge ii.

Not to discount your results but I'm having a hard time believing the simple switching of coolants made an 8 degree difference. Like [MENTION=115590]StreetCreeper[/MENTION] already mentioned, the coolant is there for it's anti-corrosion properties, it's "anti-freezing" properties and it also raises the boiling temperature of the water. The usual mix is 50% water and 50% antifreeze. I'm wondering if the coolant you replaced happened to have a heavier ratio of antifreeze and thus lost some of it's cooling potential due to less water. Or, maybe your cooling system wasn't properly "burped" before and now it is.

If Toyota Red Coolant could indeed do this, I'd switch over in a heartbeat. I do however lean towards there's something missing in this equation that caused the reduction in temperature you saw. I average 190 with Prestone Green and I doubt I'd be running at 182 with Toyota Red.

But hell, I could be totally wrong. I never would have thought the position of that little jiggle valve on a thermostat could cause a such a difference in coolant temps but supposedly it can for some people like [MENTION=136650]DK327[/MENTION].

It's good you got your coolant temperatures down though because now you're running where you should be.