Anyone Had a B&M 70264 Trans Cooler Fail?

Robb235

Robb235

Senior Member
I've had my external B&M 70264 transmission cooler for probably 12 years now, got it when they were all the rage back in the day. Over the past year or so I've been noticing small drips of ATF on ground. Replaced my radiator a few months ago and replaced all the hoses and clamps for the transmission cooler lines, thinking maybe a hose had split or cracked somewhere. Last night while idling my truck for a while in the driveway, it dumped a pretty good puddle of ATF. Definitely coming from the cooler, but I think on the back side of the cooler that's pressed up against the a/c condenser. Doesn't appear to be coming from the hose connections from what I could tell.

Anyone else had one of these fail? Probably going to replace it with something bigger, maybe a Hayden 699 since I do a fair amount of towing my boat.

Transmission Leak.jpg
 

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I’ve never had mine fail (knock on wood) but the one on my rig is a 70268. I do have a 70264 sitting in my closet at the moment pending install on my other vehicle though. That’s very strange to hear though. I’d be interested in seeing some pictures of it from where it failed though
 
JoeT4R said:
I’ve never had mine fail (knock on wood) but the one on my rig is a 70268. I do have a 70264 sitting in my closet at the moment pending install on my other vehicle though. That’s very strange to hear though. I’d be interested in seeing some pictures of it from where it failed though
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My guess is maybe one of the tubes developed a crack that's slowly getting larger. It's definitely coming from the cooler somewhere. Ordered a Hayden 699 as a replacement. Hopefully I'll have time to swap it out next week, I'll post pictures of anything I find.
 
Robb235 said:
I... noticing small drips of ATF on ground. ...Definitely coming from the cooler, but I think on the back side of the cooler that's pressed up against the a/c condenser....

... maybe a Hayden 699...
Click to expand...


My 699 came with rubber mounts that cushion when placed directly onto the AC condenser. The 699 is superb - highest it gets is 194 in repeated SG situations otherwise it will cruise around town and at 75mph at 170 or less in 100+ texas weather.
 
jgue467 said:
My 699 came with rubber mounts that cushion when placed directly onto the AC condenser. The 699 is superb - highest it gets is 194 in repeated SG situations otherwise it will cruise around town and at 75mph at 170 or less in 100+ texas weather.
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Did you bypass the transmission cooler, or running in series? Towing my boat home I have to climb a 6% grade for 3 miles going about 30mph or so. Bypassed with just the B&M 70264 the transmission temps got too hot, like 230 degrees or so. Now I'm running in series with my new Denso radiator, and the temps get up to 200-210. Hoping the 699 can keep them under 200 during this climb.
 
Yes in series. Forgot to mention i added a fan. The temps I stated above are withOut the fan on.

If you add a fan (typical 10" 2200CFM) it will bring temps down another 30 degrees - so I don't run it unless I do a rarish tow of atvs or sidexside (about 3000lbs) during repeated stop go in town - that for me is the scenario that raises temps most in short periods without much recovery time - so the fan helps with that recovery significantly when traveling at low or no speeds.

You're gonna like this. Now if you want More cooling capacity Hayden does make others. This list has HxWxD and cooling capacity so you can make the best choice of different types of coolers I'd attach a spec file but its a pdf that is too big but just google:

https://www.haydenauto.com/media/5475/oil-cooler-brochure_individual-pages.pdf
 
Not on my 4runner, had the Hayden 699 for about 4-5 years no issue. Though mine was mounted on brackets and with a fan and thermoswitch. Not pressed against the ac condenser.

I did have a b&m bar and plate cooler (it was massive) on the chevy 3500 diesel that had a plate separation, man that made a mess.
 
I'd think on staying 1.5" v .75"
Had 70264 on 96Red 1.5" for towing 10+ yrs. died in crash.
Jan 24 699 3/4" on 01 no idea I'd be towing 2900# boat in July, not sure I'm keeping it.
1st only tow 76*F 99.999%H trans temps fine, take away rain add triple digit temps.
What it gona be. :)
 
I've had mine for a few years with no issues. I'm looking at getting a bigger cooler though because I can still see temps around 210 in stop and go traffic in 95-100 degree temps. I'm also looking at the Hayden 699. If you do end up getting that one i'd be curious to see how your temps compare to the 70264.
 
Robb235 said:
My guess is maybe one of the tubes developed a crack that's slowly getting larger. It's definitely coming from the cooler somewhere. Ordered a Hayden 699 as a replacement. Hopefully I'll have time to swap it out next week, I'll post pictures of anything I find.
Click to expand...

I’ve only had to replace the hoses on mine once before and even that was sort of preventative maintenance for the most part. Wasn’t leaving drips of ATF on the ground but I noticed dirty buildup around the fittings where the hoses connect to the cooler.
 
Replaced my old B&M with a Hayden 699. And magically the leaking ATF problem went away. Old cooler had a ton of gunk on the side facing the condenser, presumably all the crap the fluid attracted and built up over time.
 
Robb235 said:
Did you bypass the transmission cooler, or running in series? Towing my boat home I have to climb a 6% grade for 3 miles going about 30mph or so. Bypassed with just the B&M 70264 the transmission temps got too hot, like 230 degrees or so. Now I'm running in series with my new Denso radiator, and the temps get up to 200-210. Hoping the 699 can keep them under 200 during this climb.
Click to expand...

No cooler is 100% the answer to keeping your trans temp down. You still need to employ other tricks of the trade like turning overdrive off or climbing in 2nd gear. When I'm climbing a grade and able to maintain around 40-45 mph, turning overdrive off locks the torque converter reducing the heat production drastically. If I can't maintain at least 40 mph, I'll climb the grade in 2nd gear which helps reduce the temp as well. When 4wheeling, you can also employ the same tricks. When I'm climbing a sustained steep section a trail, putting the transfer case in 4Lo will take a load off your transmission and keep it at a nice operating temp.

Mount the cooler with brackets instead of the zip ties. It's a better and safer install that way. I've got a video of installing the Hayden 699 cooler on my rig.

<iframe width="560" height="315" src="https://www.youtube.com/embed/34wnfq85_qk?si=ZokIvM8iya49EVAF" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
 
mtbtim said:
No cooler is 100% the answer to keeping your trans temp down. You still need to employ other tricks of the trade like turning overdrive off or climbing in 2nd gear. When I'm climbing a grade and able to maintain around 40-45 mph, turning overdrive off locks the torque converter reducing the heat production drastically. If I can't maintain at least 40 mph, I'll climb the grade in 2nd gear which helps reduce the temp as well. When 4wheeling, you can also employ the same tricks. When I'm climbing a sustained steep section a trail, putting the transfer case in 4Lo will take a load off your transmission and keep it at a nice operating temp.

Mount the cooler with brackets instead of the zip ties. It's a better and safer install that way. I've got a video of installing the Hayden 699 cooler on my rig.

<iframe width="560" height="315" src="https://www.youtube.com/embed/34wnfq85_qk?si=ZokIvM8iya49EVAF" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen></iframe>
Click to expand...

Yeah, I’m familiar with those tricks of the trade. Haven’t had an issue with transmission temps on the highway; I switch off OD whenever I start pulling a grade while towing. It’s going up the mountain back home with my boat I have to lock the transmission into 1st gear to keep the transmission temps below 200. Speed limit is 30mph on that road and 2nd gear was just getting things too hot. I honestly considered putting it in 2wd Low (transfer case in low range, ADD disabled to keep it in 2wd) while going up the mountain with my boat. I did mount my new Hayden 699 with brackets. Curious to see how it does next time I’m hauling my boat.
 
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The trans temp that the '99-'02 ECUs report via OBD-II is the HIGHEST temp the fluid gets - it is on the outlet to the cooler.

Even with my overkill cooler setup (stock cooler in series with large trans cooler), I can get reported trans temp up to as high as 220*F if I'm really romping on it (high load, unlocked torque converter, all controlled by a thermostat) - but it will nearly immediately drop to 190*F or less as soon as the load is removed or the torque converter locks.

So, yeah - it isn't the best, but MOST of the fluid nearly all the time is well under 200*F if the ECU is reporting that under load.

-Charlie
 
My extra cooling 'tricks' were to follow the hayden 699 manual's suggestions - main one is mouning cooling up against AC on condensor makes it Most efffective.

That wasn't enough for me on repeated SG while towing about 2500lbs so I added a fan and use a 5 way relay (signal hot to ignition under hood via an add a fuse and constant hot to another unused 20+ amp underhood source).

That does the trick very well - I added an over ride switch inside cabin so I can turn fan off during winter or when not towing. Luck all.
 
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