Strange Shifting since bypass

PV2006SE · Postby **PV2006SE** » Tue Dec 13, 2011 12:19 pm

Greetings to all from PR,

Had the radiator/tranny cooler bypass done by a trusted and experienced mechanic about 3 months ago and recently noticed a hesitation to shift when driving at an approximate speed of 40-50 miles. This happens only when truck is fully warm, specially after sitting in stop and go traffic for a long while. Ever since I've been sleeplessly reading most posts (this site has wealth of info. thank you!) about potential lack of cooling in using only the external trans cooler. I am so hoping that I've not cooked the tranny or extremely degraded the fluid in the 900 or so miles since I had the bypass done. Like others, I just ordered a B&M 70297 cooler with fan and a Spal relay harness. Can't wait to receive it and have it installed, hoping that what I am perceiving as erratic shifting changes back to normal again. Please tell me I am not being overly paranoid in thinking that I might have done permanent damage to the tranny.

Thank you in advance for your feedback.

PD
No indication whatsoever of contamination when I check the ATF. Drain and refill done at 20k, 36k and recently at 56k.

Postby **disallow** » Tue Dec 13, 2011 2:08 pm

how much fluid did you lose while doing the bypass?

I would suggest buying 4 quarts and doing a drain and fill.

t

slavabon · Postby **slavabon** » Tue Dec 13, 2011 3:41 pm

Bypass should not degrate the tranny oil in just 3 months. Like the post above says, I would start looking into the oil level. Perhaps you lost some oil during the bypass procedure? Check the level again and if you still paranoid, do another drain and refill. This should make your level to spec at least.

eieio · Postby **eieio** » Tue Dec 13, 2011 4:44 pm

PV2006SE wrote: I am so hoping that I've not cooked the tranny or extremely degraded the fluid in the 900 or so miles since I had the bypass done. Like others, I just ordered a B&M 70297 cooler with fan and a Spal relay harness. Can't wait to receive it and have it installed, hoping that what I am perceiving as erratic shifting changes back to normal again. Please tell me I am not being overly paranoid in thinking that I might have done permanent damage to the tranny.

Thank you in advance for your feedback.

the bypass in and of itself will do no harm to the transmission or fluid unless the truck is subjected to severe use such as maxed out towing loads
i'd be very surprised to hear that the installation of an additional cooler makes any difference in the shifting
though an additional cooler can't hurt, i don't think it will solve an erratic shifting issue

JAHBLESSINGS · Postby **JAHBLESSINGS** » Wed Dec 14, 2011 5:26 am

i think your trans fluid is low.

dawgn86 · Postby **dawgn86** » Wed Dec 14, 2011 7:25 am

first thing I would do check is the ATF fluid. I did my bypass a few thousand miles ago and Im not having any issues. But I can see if one isnt careful doing the bypass, you could lose enough fluid to cause some issues.

eieio · Postby **eieio** » Wed Dec 14, 2011 7:47 am

PV2006SE wrote:No indication whatsoever of contamination when I check the ATF. Drain and refill done at 20k, 36k and recently at 56k.

what kind of ATF are you using, and have you checked the ATF level (per the service manual procedure) since the bypass?
low fluid level could certainly cook the fluid and damage the transmission, but again, the bypass on it's own won't cause damage.

PC05 · Postby **PC05** » Wed Dec 14, 2011 11:23 am

Mine has been doing the same thing with shuddering at 60mph and will not up shift unless you mash the gas. Fluid is fine. Went to a tranny shop they told me to take it to dealer.

PV2006SE · Postby **PV2006SE** » Fri Dec 16, 2011 8:57 am

Sorry folks for the late response.

I am not sure how much fluid was lost while doing by the bypass. It was done by a mechanic who also did a flush and fill with (4) quarts of Nissan Matic S that I provided. I have checked the fluid several times since and it is at the full mark when checked cold or hot. No discernible difference in fluid color since doing the bypass.

The hesitatation to shift at the specific speed (between 40 & 50) happens very rarely and when it does, it has always been after long periods of stop and go traffic. I read various post of similar behavior with locked torque converters. Not sure if this might be the case.

We'll see if the condition persist after installing the external cooler with fan which is scheduled for tomorrow.

Will keep you posted. Thanks.

JAHBLESSINGS · Postby **JAHBLESSINGS** » Fri Dec 16, 2011 11:12 am

when i did my trans service i put in 5 quarts not 4. low fluid might be the issue

Postby **disallow** » Fri Dec 16, 2011 2:18 pm

JAHBLESSINGS wrote:when i did my trans service i put in 5 quarts not 4. low fluid might be the issue

weird. Well I guess I buy in 1L containers, but I couldn't get more than 4L in...

t

eieio · Postby **eieio** » Fri Dec 16, 2011 3:12 pm

regardless of how much fluid is added (under any circumstances), the bottom line is that it measures to the correct level (properly measured per the service manual)
YMMV

Fookn4x2 · Postby **Fookn4x2** » Mon Dec 19, 2011 12:46 pm

Im at 110,000 and never touched the trans other than to do the bypass. Should I do this drain and fill you guys are talking about? 4 quarts to do it?

Postby **disallow** » Mon Dec 19, 2011 1:47 pm

Fookn4x2 wrote:Im at 110,000 and never touched the trans other than to do the bypass. Should I do this drain and fill you guys are talking about? 4 quarts to do it?

I would do it. 4 quarts should be all you need to do one drain and fill. An extra quart on hand wouldn't hurt either.

Rotorian · Postby **Rotorian** » Tue Dec 20, 2011 5:04 pm

disallow wrote:
Fookn4x2 wrote:Im at 110,000 and never touched the trans other than to do the bypass. Should I do this drain and fill you guys are talking about? 4 quarts to do it?
I would do it. 4 quarts should be all you need to do one drain and fill. An extra quart on hand wouldn't hurt either.

Where do I do the draing and fill. I assume the fill is the same port that is measured, right? Which plug do I pull for the drain?

Is the drain and fill described in teh shop manual?

I will go look

.

Thanks,
Regards,