Nkschndr

Hi all,

Fairly new to 4runners but pretty technical (15yr volvo technician) with a question/observation I'm sort of embarrassed to share because I probably should know more about this. Okay, just got a 4runner (3.4L Auto 4wd) and installed a tru-cool 4454 bypassing the radiator for fear of a milkshake bringing my 4runner to the (junk)yard. It's installed very happily right in front of the AC condensor with good air flow and I installed a new Aisin fan clutch. However, I live in Tucson AZ so it's HOT. I got the engine link app for my ipod and a wifi connector for my obd2 and now I'm monitoring trans temps. Around town stop and go I'm getting 185F or so at 100F ambient which is okay from my perspective so I was feeling pretty good. Then I decided to torture test the vehicle in preparation for a run across the desert to San Diego in a couple of weeks. I drove the 4runner up a really large mountain outside of town (10,000ft elevation change in about 20 or so miles). Trans temps climbed way out of the range I felt comfortable with (250F) for a few minutes. Yikes. I checked out some other temps with an infrared temp gauge and was looking at 200F pan temps and prob 230F or more at the line out to the cooler, the line back in looked a little better (as it should) at closer to 200F or a bit less. So some observations and questions:

1) The temp sensor was reading correctly (infrared and scan readings matched). What explains the difference in temp between the sensor and the output line to the cooler? Wouldn't you think the temps would be closer?
2) After the initial temp spike and a bit of rest/check time, I took the vehicle out of OD and drove the rest of the way up registering cooler temps (220F or so) still hot but okay. Why would this be? I definitely wasn't driving fast enough to have come close to getting into 4th gear territory. Are there other gearing changes made in this vehicle when you click out of OD or would the lower ambient temps of the higher elevations account for it?

Anyway I ordered a larger capacity cooler B&M 70264 and will install the 4454 as an auxiliary on my wife's 2007 highlander so no wasted cash. Any thoughts on these issues would be great. I realize that at temps like this, having the factory cooler still hooked up would definitely have lowered temps but I'm loathe to do that because of the milkshake. However, one final question, the car has an aftermarket (newish) radiator on it? Anyone ever had a milkshake with an aftermarket radiator or is it a factory radiator only screwup? i.e. was it a design flaw in the radiator which may affect aftermarket copies or was it a quality control issue with the OE radiators? Sorry for going on so long but....

DRCOFFEE

Good grief. Why not just pony up the $130 for a new KOYO radiator and use the new cooler in series? Obviously your old radiator survived 10+ years. A new one will last equally as long and you will probably sell or junk the truck by then. This fear is so irrational IMO and easily solved by buying a new one. BTW, the B&M is the better cooler.

Dont let the facts get in the way of an irrational fear. I will be running to the closet to find my flame suit at a dead run.

J2F42C

I'd make sure you had fresh ATF in it. If your 4runner has an aftermarket radiator, I'd run ATF through it before the cooler and see what the temps are.

I know some members have used a Spal 6.5 fan on front of their tranny cooler with some success.

Yotard

So I have a different generation of 4Runner than you, I have a 3.0 but I believe the transmissions are still similar. I have experienced the same things with temperature. When I drive in TC lockup on the highway I run between 150F and 180F. I put an autometer gauge on the output to the cooler. When I climb hills into the Sierras Donner Pass on hwy 80 the temp stays around 210 and climbs as high as 230. The TC heats the fluid a lot when it is not in lock up so adding in a bigger cooler is really the only way to get rid of the heat and the radiator cooler was not nearly sufficient to begin with...I found this out by driving it up to the Sierras an having the Trans Temp dummy light come on, then I installed a gauge and Hayden 777 cooler. I have found that the TC will lock up in 3rd gear if you leave it in OD but only when I put it in ETC mode. That helps keep the heat down climbing the hills. The difference that I have seen though from your temps is that when I turn OD off it never locks the TC and it gets hot fast.

rworegon

OP, do you have before temp readings? Maybe the temp rose the same way when it was going through the radiator. I run the 4454 on my Tacoma and see 210-230 for short periods of time when climbing in the mountains, but it quickly drops back to 180 or so once the TC locks back up.

Nkschndr

Hi,

Thanks for the replies. I'll try to address some of the points. To the Doctor (MD or PHD?), two things:

Firstly, I didn't make the decision to take the radiator cooler out of the circuit lightly. I'm an ASE certified Master Technician with L1 certification and an Expert Level (the highest possible) Volvo technician. I had extensive conversations with my former apprentice (who now holds the position of Master Level Toyota technician) on the subject. Neither one of us is typically a "modify first, ask questions later" type of person. My preference (and his) usually is for factory parts and systems. However, his experience with Pink Milkshake on a variety of Toyotas is extensive and my experience with glycol contamination in Volvos is equally vast (unfortunately). A person's experiences (and level of familiarity with the subject) color their perceptions to be sure, but my experience with the XC90 Volvo radiator trans cooler and multiple premature transmission failures has led me to be leery of the in-radiator trans cooler setup in general. In particular (and this is definitely true on Volvos), the way that repeated cooling and heating cycles affect plastic tank radiators with metal coolers built in to them makes the design inherently prone to higher failure levels than we experienced when our radiators were all metal. The failure of the coolers inside these radiators is very far from a slight possibility. It appears to be quite common. Often the question is only, does the radiator start leaking first from the outside (at the seams) or from the inside (into the trans fluid)? If that particular radiator design/build appears to tend to be an outside leaker, the trans is usually safe. If not, not. As for the idea that we "know" that they last 10 years or so; I'm not at all certain that we do, and I'm not at all certain that we know how failure-prone the aftermarket radiators are.

That having been said, if I lived in a softer climate (like IL) I might well have made a different decision. The in-radiator cooler plays two roles as we know, to warm the fluid and to cool it. Here in Tucson, all vehicles are running on the very ragged edge of their engineered tolerances due to the extreme heat. However, we very very rarely have temperatures in which transmission fluid warming would be needed or desired. The consensus of opinion among people familiar with heavy duty applications of any kind here in Tucson (heavy truck mechanics, people who tow trailers in this climate and hardcore wheelers) is that a separated system is preferable because the last thing our overtaxed cooling systems need is the additional input of MORE heat from the transmission fluid. A properly sized (and yes I ˟˟˟˟ed that up and put one that was too small in it initially) air-to-oil cooling system will keep temperatures in the transmission at good low levels and not push additional heat into the engine's cooling system.

As for the question of whether or not the same sort of thing (250F+ temps in the tranny) were taking place with the factory radiator cooler, I couldn't unfortunately address that (I've only owned the vehicle for two weeks) but my experience with Jeep Cherokees (which use the same transmission incidentally) tells me that indeed those sort of temperatures could very easily be seen using the factory system. After all, the coolant-to-oil temperature transfer is only so efficient if the coolant temp at the bottom of the radiator is 185F (not at all uncommon in Southern Arizona in the summer). The A340 (in a Jeep the AW4, in a Volvo 960 the AW70-71--all essentially the same transmission) is known to be a very reliable transmission but one that makes "a lot of heat" particularly under stress (I suppose that is true of us all!). The more we can cool these trannies the better.

Thanks to the 2nd gen owner for the info about his experiences with his transmission and the OD lockout and ECT mode. I have looked for more info about how and when these particular controls work on these vehicles and what that would mean for trans temps and have gotten conflicting reports. I will pick the brain of my former apprentice on the subject.

Thanks again. I'm always impressed by how willing people here are to give advice and share their experiences.

Robb235

I know this thread is old, but did you ever find out anything?

reaj

iTrader: (6)

I have bad experiences here in colorado on 70+Degree days with the tranny getting too hot climbing Mountian roads getting to the trail. I was thinking of adding a second tranny cooler this year to help fix that idk? Most likely due for tranny flush but I have 250,000+ miles on it maybe it's just old?