2004 Pathfinder - Magnefine Trans & Power Steering Filters

[Ron Co]

'04 Pathfinder - Online sources are inconsistent with respect to hose inside diameters for the transmission oil cooler lines and for the power steering return. Please advise correct hose IDs and recommended sizes for the Magnefine filters for these two applications. Thanks!

[AlanAZ]

Smart of you to double check. I wrote this in the General Info sticky thread:

atraudes wrote:
I bought a ⅜" Magnefine filter but found the connectors to be too large for the [transmission] hose. I got the hose slipped over the end after much stretching with some spreaders, but only barely. I ordered a 5/16" filter instead and it installed nice and snug. I'd recommend that you pull the hose off the radiator and test fit before you go cutting hose in case you end up getting the wrong size too.

Ran into this as well on a '03, but before I saw this post, and had to make the 3/8" work, but barely.

[Ron Co]

Thanks, Alan. Went out this AM, pulled off the splash panel and measured the metal piping with a micrometer. Diameter - .385/.395 inch. Would seem like the 3/8" (.375") diameter filter would work. Perhaps it's the raised ridge (barb) around the OD of the fittings on the Magnefine filter that won't enter the trans hose ID easily. Was your application an '04 Pathfinder or QX4?

[AlanAZ]

A '03 QX4. I remember the hose being quiet stiff and not wanting to stretch over the barb. I did get it mostly on, enough to clamp with fuel line clamps, but not all the way to the filter body. You could check with a Nissan parts supplier/dealership as to whether the hose is the same between a '03 and a '04.

btw: You are aware that they recommend the first filter change at 15K miles, 30K thereafter. I did a full change/flush of the fluid at the time I installed the filter.

[Ron Co]

The hoses on my '04 are still quite resilient and flexible. We're the original owners, and this PF has been ultra reliable. I've done a couple of drain-and-replace jobs on the trans . . . you only get about 3.5 qts out doing that as you know. Fluid is still a nice red. On the last fluid change a couple of years back I wanted to also replace the in-trans filter so I ordered the part and gaskets from the dealer. When I went to pick them up I saw that the filter was just a screen and not a very fine one either so I did not buy it. Really wondered at that time about not really filtering the fluid. Should have done some homework and picked up one of these Magnefine filters then. Now at about 130K miles I am hoping I'm not too late to get out some of the small abrasives that must be flowing happily around with the lube doing their nasty thing. We need to keep this vehicle to around 200K miles as long as it remains reliable. Cosmetically it is in great condition. So keeping this gearbox happy is a primary objective. I might also add an air-oil heat exchanger to the trans cooling system. It gets wicked hot in the summer here in NC. Thanks again for your help.

[Ron Co]

Yes, I am aware of the early change-out recommendation for the Magnefine. Good idea. I'd change it at maybe 10K miles and cut it open to see what crud it may have snared. The full change/flush technique described elsewhere on this forum would likely be a good thing to do. But to use up and toss maybe 8 qts of this costly lube? Hmmm . . . I suppose that's way cheaper than an early failure and rebuild.

[AlanAZ]

I didn't toss more than 1 qt of the new fluid. I used this process to 'flush' the remaining old fluid after doing a drain/replace. The fluid went from a hazy brown color (I had been keeping tabs of the condition of it, and it went from red to brown quickly -- no issues with shifting as yet) to a clear light red using Valvoline MaxLife™ DEX/MERC ATF. If you're not doing a full change of the fluid, it is best to use the exact same fluid as the existing, and not to mix additive packages.

[AlanAZ]

Ron Co confirms in this thread that the filter size required for a trans in-line filter is 5/16.
2004 Pathfinder - Replace Transmission Pan and Gasket

The oil cooler lines though .385/.395" in diameter as I mentioned above, neck down at the ends to 5/16" in diameter.

[AlanAZ]

Ron Co: Did you install a PS filter? Which size is correct for the return hose?

My return hose is weeping (I think the heat from the exhaust manifold in Hot Phoenix degraded it) and while I'm replacing it and doing a full fluid flush, it will be next to no work to add a in-line filter.