JeffMerr

Installing A Transmission Oil Cooler In A 2.5 V6...

32 posts in this topic

I'm having trouble installing my Hayden 403 Transmission Oil Cooler. The tutorial on this site shows the setup for a 2.0 liter motor which has the lines going into the radiator, which you then reroute them into your transmission oil cooler. On my engine (2.5) the lines are going into the motor. My mechanic said there is usually a reason the lines are going into the motor, such as the fluid/pressure is helping something else function. Can someone give me some insite/instruction on what to do? Is it possible to install the tranny oil cooler on a V6 2.5 or is this just for the 2.0 motor? I don't want to cut the line and re-route it and risk damaging something in the engine or making things worse. Thanks!

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It does not go into the engine. They both go into the transmission one on top and one on bottom as they leave the radiator cooler. You will either need to splice in a longer hose or use a longer hose all together to reach the external cooler. Then just follow what you have found for the install. I would not bypass the internal cooler all together, just add it to the return line back to the transmission.

TomK

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There's no way it's going into the motor. The motor and transmission are mated into a single unit so if you're not familiar with the anatomy, it might look confusing. But I can assure you, 2.0L I4 or 2.5L V6, the engine oil and ATF are two completely separate systems. Either your mechanic is massively in error or perhaps you misunderstood his explanation. Either way, we can sort out your solution here.

Perhaps upload some pics and outline exactly where you're confused, then we can help you better.

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JeffMerr can you please post some pics of where the cooler are going into the engine? It's possible that someone plugged the transmission cooler lines and instead used the radiator as an engine oil cooler. Maybe it's that way from the factory I don't know the V6 well enough to say either way. If you believe they are going into the engine I'd really like to see some pics of that.

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Sure thing. Its at a friends house right now so I'll go over tomorrow and take some pics. I haven't seen it yet but my friend is a seasoned mechanic and he was explaining the situation with the lines to me. I printed the tutorial out from this website for him just for reference and he said my lines are different and not going into the radiator at all.

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Ya, post a pic cause I have to see this. If the lines are not going into the radiator what is cooling that ATX?

TomK

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On 93-97, I'm pretty sure there are at least 2 lines that connects the driver side of the radiator and the ATX. They are small lines compared to the big hoses that cools the motor.

trans_zps98997f11.jpg

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The cooler lines do not go to the radiator on the 98+ 2.5's with auto transmission Take a look at the picture I posted here.....http://mazda626.net/topic/37750-where-is-the-thermostat-on-the-v6/?hl=%2Btransmission+%2Bcooler#entry304125... There are 2 hoses comming out of that shiny thing in the picture...that is the cooler. It is right before the thermostat housing. So it kind of does look like it runs to the engine. I also once removed the radiator and only had to disconnect the main coolant hoses...again, no trans lines in the radiator.

I think there are 2 nipples on the transmission that have rubber hoses comming out of them. One goes to that cooler and the other I can't remember but it is where I put my Magnefine filter...it is a short hose with a bend in it. That nipple is on the drivers side of the trans. Sorry its been a few years since I was messing with it..

post-6458-0-98891600-1365639263.jpg

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I have done this job on a '98 Millenia with the same 2.5L and ATX as the 626, and I assure you, the transmission fluid does NOT go anywhere in the engine. The engine gets 4 fluids....oil, gasoline, coolant (anti-freeze & water), and air.

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That said, at least in the AU spec, the 5th gens come from factory with auxiliary ATF coolers, added inline to the radiator one. Basically, they just added from factory what I've always done on 4th gens.

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ok so there are 2 lines coming out of the tranny one line connects to the upper radiator hose mount to the block. Fluid goes in that way and comes out a port on the driver's side of the head back into the tranny. The thought is that the line goes through a waterjacket of some sort in the head. This engine definitely has a different setup than the 2.0 as it does not use the radiator at all. I'm just worried about plugging the 2 lines that go in and out of the head, can anyone who has done this on a 2.5 confirm its ok to reroute it to an external cooler? I apologize for lack of pics they werent clear on my phone.Thanks for the help!

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Is this a United States spec'd car? Something doesn't sound right. Did you look for the cooler in my pic?

I mapped out where I wanted to splice into the lines for a coller but never got around to installing it.... I know it can be done.

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If it were I, I wouldn't plug anything. I'd simply add your extra cooler into the loop, placed immediately before returning to the transmission. That's how it should be done with the radiator cooler as well. You don't block off or reroute from the original radiator cooler. You simply add the auxiliary cooler into the loop as an inline filter, after the ATF has already travelled through the radiator and before it has been returned to the transmission.

I have to admit, your setup sounds strange but I'd love to see some pics or, better yet, a short vid. But in any event, your ATF will be in its own loop, even if it does pass through the engine head as part of its cooling loop. So yeah, don't bypass it or block it off. Just add more cooling capacity to what is already there by adding in that extra cooler. Can't go wrong that way. Just make sure that it's definitely red ATF coming out of the tube that you crack open to splice in your cooler unit. And top up with some extra ATF afterwards because your loop is now bigger than it was.

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Would be nice to remove the airbox and take a picture to get a closer look, especially that top line. Because the picture above is too small and too many parts obstructing the view.

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Ok..This was bugging me so i took a look. THIS IS FROM A 2000 2.5L V6 AUTOMATIC TRANSMISSION. There are 2 hoses coming out of the right side of the cooler in the picture I posted above. There is a hollow bolt with a metal nipple on the top of the transmission (center of pic to the left of neutral safety switch) A hose is attached to that nipple that bends under the airbox.....

post-6458-0-18787400-1365659095_thumb.jp

...and goes to the top part of the cooler(toward firewall) see clamp

post-6458-0-20846700-1365659358_thumb.jp

Here is where the hose comes out of the cooler(toward bumper)

post-6458-0-94970900-1365659804_thumb.jp

and then back to the nipple on the bottom of the transmission. There is another foot or so of hose you can't see here. This is where I put a Magnefine filter.

post-6458-0-29641600-1365660474_thumb.jp

To find the cooler just follow the big hose from the radiator on the drivers side to where there is a clamp under the coil pack...the clamp is holding the hose onto the transmission cooler.

There is a bunch of info floating around that says that the trans lines run into the radiator to cool the fluid on these 626's. I posted that cooler pic in that other thread awhile back to show that on the 2000 2.5l it does not. Hopefully this clears everything up.

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Not seeing any of your pics...

Also, taking into account the fact that I can't see the pics, you're talking about a neutral safety switch. That's an MTX feature. If it's an MTX, then of course there won't be cooler lines going to the radiator. The gear oil in an MTX is not under any real pressure, certainly not under any hydraulic pressure, the likes of which would be needed to pump it through any sort of a cooler. I'm not sure of the anatomy of the MTX, especially on the V6, but I can tell you it certainly doesn't need to, in fact is unable to, flow through the cooler in the radiator.

If you are actually talking about an ATX, then perhaps you meant "transaxle range switch: an not "neutral safety switch"?

EDIT: Pics just showed up for me. And yes, it does look more like a TRS and not a NSS. But also, it's kinda hard to tell what exactly I'm looking at in many of the pics. They're very well focused and all, but also really zoomed in. It's hard to have context for what I'm seeing.

All very interesting, though!! Thanks for the pics. :D

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It is an atx...It is listed as a neutral safety switch locally. Don't know why u cant see pics

For reference the top 3 pics are between the coil pack and the airbox standing at the front of the car. The last pic is lower down in front of the fan and going under the battery.

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Thank you for the pictures. Mine is an ATX as well. I will print this out and give it to my mechanic tonight. What do you guys suggest doing with the original lines after it is rerouted to an external cooler?

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Like I said, don't reroute it. Just add the extra cooler inline with the current cycle.

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Yeah you don't need to worry about what to do with the current lines because if you add the external cooler then those lines should be added to the existing system. You don't cut out the existing system you just add to it. The ATX does have a cooler built into the radiator. By adding another external cooler you're basically running 2 coolers. Just plug the 2nd one into the first one and run them in series.

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DJ..The pics I posted were from a 626 with an Auto Transmission. It does not run through the radiator. I edited my posts to mention the ATX.

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Thank you for the pictures. Mine is an ATX as well. I will print this out and give it to my mechanic tonight. What do you guys suggest doing with the original lines after it is rerouted to an external cooler?

Simply take the line on the bottom of the OEM cooler and run the Hayden between it and the nipple on the bottom of the trans. Easy.

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If you live in a cold climate, I would add the cooler inline as others suggested. The radiator heat exchanger also serves to warm up the transmission faster when it's really cold out.

If you live in a warm climate, I would bypass the radiator heat exchanger entirely. The more stuff you have in-line, the more pressure loss you have, which leads to other problems with the transmission.

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I live in a warmer climate. How do you bypass it? That was one of my questions earlier but seems most people suggest not bypassing it...

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Just take the hoses coming and going from the ATX and plug them into the new cooler. Just be sure to mount it in from of the AC condenser behind the front grill.

TomK

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