Xterra Oil Cooler Bypass

Sharps40

Twelve Pointer
Anybody out there with an Xterra/Frontier done the mod (e.g. eliminated trans fluid flow into/out of the radiator lower tank therby using only the external cooler) to avoid the failure of the transmission due to water in the oil?

I don't have the leak yet, nor signs of water in the oil (checking again tonight and doing the mod in the AM) but at 119000 miles I'm about 20K past the point where the system typically fails and pumps water into the trans destroying it.

Looking for experienced input, i.e. you've don the mod, and experienced/not experienced over heating of the trans on hot days or harsh shifts on cold days, etc.

The factory cooler looks to me bigger and better than even the giant BM coolers I've run in the past on hot rods. So, I doubt that unless towing or wheeling heavy in August I'll ever see the trans hot light come on......

My radiator is still good/I'm not ready to replace. But figured I'd eliminate the potential for a Strawberry Milkshake of Death between now and late fall when I plan to do all the high mileage services (i.e. likely replace the radiator then)
 
Would love to know how it goes. I need to do the same thing to my grandsons frontier.Its a 2006 auto, v6 with 88k in great shape but after reading on the interweb i need to do the same thing.
 

Sharps40

Twelve Pointer
Ill let ya know tomorrow. Should ve doin it righr after a power window fix on the jimmy. On a good note the transmission fluid still looks clear and no milk on the dipstick cap or radiator cap. But i am going to lose the screw that holds the dipstick cap in place.
 

Sharps40

Twelve Pointer
Others who have frontiers and xterras replied to me no troubles after the bypass even when rock crawling and towing
 

Sharps40

Twelve Pointer
Here it is. Successful, 30 minute job. Short ride indicates no leaks and seems to function fine. Monday is back to work, 142 miles a day for 5 days a week. If it ain't a good mod, should show up soon!

Step 1......Remove the Xterra tin foil front skid plate.

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Step 2: Looking from the passenger side front, the two hoses with the backed off connections are the ones that get switched around to make the radiator portion of the trans cooler a dead loop and vector all oil flow to the external oil cooler. (i.e. no more oil flowing through a cracked pipe in the bottom of the radiator). In the photo below the hoses are still in factory configuration, i have only backed off the clamps.

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Step 3: Again, looking from the passenger side front, I have switched the hoses and applied the clamps. The bottom of the radiator loop was blown out with some compressed air and the hose reconnected just for neatness. You could also use clamped on caps. The trans fluid now goes straight from the trans to the external cooler and back to the trans. Starting the motor and letting it come up to temp, check for leaks up by the oil filter. I had none.

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Step 4: Remove the 10mm screw retaining the trans oil dipstick, check fluid levels. Mine was fine. I'll check it again after another drive and I plan to "loose" the 10 mm screw that retains the transmission dipstick.
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Sharps40

Twelve Pointer
Step 5: More examination of the trans fluid.....no water noted in it, but it is varnished. (Trust me, its more red than brown.....camera/lighting does not show it true. But it don't smell burnt and I feel no grit in it.) Not supersizing, 119000 miles and no one ever changes trans oil anyway. (not even the stealer changes it when he lies and tells ya it had a 5000 point check certified platinum pre owned car make ya feel confident it ain't a turd inspection) I'll be flushing 5 to 10 qts through it though.

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Step 6: Properly dispose of the tin foil front skid plate by tossing it on the trailer for the next dump run and later on enjoy the fact that you just cut 20 minutes off accessing your oil filter for a filter change!

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bigten

Twelve Pointer
Contributor
A couple of things Rich. The "cooler" in the radiator on vehicles with an external cooler is actually a heater to warm the fluid in cold weather. Proper temps in the transmission helps maintain the integrity of the internal seals and other various parts.
That "skid plate" is actually an air deflector. Its purpose is to correctly drive air over the engine from the radiator area and also improve air flow under vehicle for fuel economy.
 

Sharps40

Twelve Pointer
Copy. I still have the plate. Plans are a saw to make a bigger access to the oil filter so i can actually get to it with the plate on. I think the japanese must have really small hands. I already have a cover plate for the bigger access cut out and drilled.

As for the bypass, its a hold over till i can get a new radiator in a few months. Ill have it back to factory flow then with much less concern for a failure. I see that new nissan replacements have fixed the issue and dont suppose a quality aftermarket would exhibit the same failure mode.

A friend who suffered a failure and bought a new trans fir his trouble alerted me. Before last week id never heard of any trans failure in a cooler equipped radiator.

I have to pull the entire plenum and rad to change plugs and wires soon so figured id do the mod now and eliminate any catastrophic fail untill then.
 

Sharps40

Twelve Pointer
Speeking of the plate as air deflector....the 37 dodge had one. Lost now and i need to cut another. Thanks for the reminder. I need to get the shop to add it to the final punch list.
 

nccatfisher

Old Mossy Horns
Contributor
A couple of things Rich. The "cooler" in the radiator on vehicles with an external cooler is actually a heater to warm the fluid in cold weather. Proper temps in the transmission helps maintain the integrity of the internal seals and other various parts.
That "skid plate" is actually an air deflector. Its purpose is to correctly drive air over the engine from the radiator area and also improve air flow under vehicle for fuel economy.
I would surmise the Frontier is the same an an X but you can access the oil filter easily by reaching between the frame and the skid plate right where the rubber flaps are. I have had three and it is not a problem at all. In fact I just changed it on my latest frontier and repaired/replaced the bottom skid plate bolts that all the fast lube places always strip out.
 

Sharps40

Twelve Pointer
Been running it a week and no new issues. The slight shudder continued when just coming to a stop, but thats been there since we got it 30k miles back. Checked the oil and it was a quart low so drained the pan and no strawberry milkshake. Topped it off with Global and a bottle of Lube Guard Red. First run out the shudder is about gone and its shifting smoother. I think it'll be okay untill i can get the calsonic radiator out and a new one in place.
 

Sharps40

Twelve Pointer
Nothing wrong with fram. Been running them on all my stuff for all my life for air, fuel, trans and oil. . Usually run the oil filters 5000 miles on the small ones, 10000 miles on the larger quart size filters. 20000 on the air filters. 25000 on the fuel filters usually.
 
Nothing wrong with fram. Been running them on all my stuff for all my life for air, fuel, trans and oil. . Usually run the oil filters 5000 miles on the small ones, 10000 miles on the larger quart size filters. 20000 on the air filters. 25000 on the fuel filters usually.
Cut a fram apart at 5000 miles and see what you thank.
 

bigten

Twelve Pointer
Contributor
^^ As a talking point, possibly in his defense, I've used many Fram filters over the last 45 years with no apparent issues. But, I have been seeing reports lately of failures occurring with the internals of their oil filters. Some have caused catastrophic failure to the engines they were connected to. Reports are that the filter elements are coming loose and wadding up inside the housing, creating oil starvation and engine failure. I cannot verify if claims are false or warranted, so the info can very well be taken at face value.
 

Sharps40

Twelve Pointer
Its possible, anything can fail. The rub is just as you mention, difficult or impossible to locate verification. And especially by an authoritative source. Much fearmongering and complaints (its easy to complain!) on the web and in forums. I have a bad habit of riding forward on experience. Mine, like yours, are quite positive.
 

Sharps40

Twelve Pointer
It would seem that transmission shudder ain't always trasmission shudder. Noted a bit of shudder idling down at stop lights in gear and the idle hovered low around 500 rpm. Seemed a bit low so dropped in a can of fuel injector cleaner and no help. So, looked in the throttle body.....good gosh what a mess.....like my granddaughters bathroom. It seems, Hoppes 9 is a good multipurpose cleaner. A few drops on a patch had the inside spiffy and the butterfly edges shining in no time. Wiped it dry, let it air out and fired it up. Good smooth idle at 750 in gear where it should be and ... no more shudder! Learning stuff every day on these new cars.
 
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