question re: radiator leaking into tranny problems

[thetrance]

for those of us who havent done the radiator bypass yet, has anyone considered putting a lower PSI radiator cap, say 13psi, to reduce the amount of coolant getting into the transmission in CASE it fails?
not 100% sure what the pressure in the tranny line normally is, but i assume at idle its around 20ish psi? so if we reduce the pressure difference, that would technically reduce coolant getting into your transmission, correct?
any thoughts?
Thanks!

[JAHBLESSINGS]

why change the cap when the bypass is a sure way to prevent this issue. i think the problem is that the trans fluid eats away at the seperation between coolant and atf over time.

[eieio]

why change the cap when the bypass is a sure way to prevent this issue. i think the problem is that the trans fluid eats away at the seperation between coolant and atf over time.

+1!
prevention is better than minimizing the possibility

[eieio]

for those of us who havent done the radiator bypass yet, has anyone considered putting a lower PSI radiator cap, say 13psi, to reduce the amount of coolant getting into the transmission in CASE it fails?
so if we reduce the pressure difference, that would technically reduce coolant getting into your transmission, correct?

any coolant contamination, however minimized, will likely result in some kind of transmission issue in the future

[thetrance]

I got this suv used with 156k miles on it. original radiator.. hoping that it would've leaked by now if it was a faulty unit...

[smj999smj]

for those of us who havent done the radiator bypass yet, has anyone considered putting a lower PSI radiator cap, say 13psi, to reduce the amount of coolant getting into the transmission in CASE it fails?
not 100% sure what the pressure in the tranny line normally is, but i assume at idle its around 20ish psi? so if we reduce the pressure difference, that would technically reduce coolant getting into your transmission, correct?
any thoughts?
Thanks!

Of course if you lower the pressure, you also lower the boiling point of the coolant. One pound of pressure equals 3 degrees F. I think the best method is either replace the radiator or do the bypass.

[CPLTECH]

I got this suv used with 156k miles on it. original radiator.. hoping that it would've leaked by now if it was a faulty unit...

The radiators of this vintage were very poorly manufactured, to put it mildly. If you want to gamble and lose it all ($5-7,000. Very expensive & complicated transmission few are qualified to rebuild.) after all have been saying to you, that is your choice. It is just that so many of us on this forum (as well as the Xterra & Frontier) know that this has been a huge problem for Nissan & very, very few escape its grasp. Maybe you like to live on the edge, but after hearing the horror stories, I for one couldn’t stand the high anxiety this issue was causing me, so had a local shop replace the radiator for ~$350. Either that or spend thousands on the alternative. The advice we are giving is: “Trust us. Don’t put it off”.

[dawgn86]

Agree...why spend the $$ on another radiator cap when you can buy the barbed connector, vaccum caps and hose clamps for less and it takes less than a half hour.

[smj999smj]

Also, it's not the radiator cap that controls the pressure but the smaller cap on the coolant reservoir. You might have a hard time finding a cap that size with a lower pressure setting.

[thetrance]

I got this suv used with 156k miles on it. original radiator.. hoping that it would've leaked by now if it was a faulty unit...

The radiators of this vintage were very poorly manufactured, to put it mildly. If you want to gamble and lose it all ($5-7,000. Very expensive & complicated transmission few are qualified to rebuild.) after all have been saying to you, that is your choice. It is just that so many of us on this forum (as well as the Xterra & Frontier) know that this has been a huge problem for Nissan & very, very few escape its grasp. Maybe you like to live on the edge, but after hearing the horror stories, I for one couldn’t stand the high anxiety this issue was causing me, so had a local shop replace the radiator for ~$350. Either that or spend thousands on the alternative. The advice we are giving is: “Trust us. Don’t put it off”.

and how do you know that you are not going to lose your transmission in the long run due to the higher temperatures? there are several posts in other forums showing temps hitting 200+ once you bypass the radiator. I am looking at the big picture here.
What I am saying is, if you "bypass" without implementing additional cooling, you are in the same boat as me. you may not have to deal with it now, but you are reducing the life of your transmission.

[CPLTECH]

To clarify, I did not do the bypass, just replaced the radiator, that way I am using the cooling Nissan designed for engine/trans. I sometimes tow & did not want to risk the trans as you point out. Most automatic cars today have a trans cooler inside radiator as does the PF.