Hot transmission

Shadowfax · 10-11-2007, 11:22 AM

Hello all from a newbie to the Nissan website. I am having a concern with the tranny overheating on my 05 SE (purch. new) equipped w/ tow pkg. Never had a problem before while towing small utility and stock trailers up to maybe 2000#.
Recently bought a 4500# tag-a-long with maybe another 500# of "stuff" so I reckon it's right around 5000# total. Well within the tow capacity. TAL has weight distributing hitch and the truck payload is minimal.
While towing for the first time in the foothills of Kentucky, the tranny gauge heated up and was pegging out on the "hot" side. If any of you have a tranny guage, you will remember there is a mark just before you get to the "H". That's where it was pegging out, never actually got to the "H".
Tranny never heated up on straight and level, only when going up a modest hill and in one of the lower gears. RPM was around 25-2700 and ground speed maybe 45-50. I am no hot-rodder and don't like to abuse my equipment.
I am pretty disgusted right now since I bought this truck to tow with and in 2005 it had the highest tow capacity of any 1/2 ton. I would sure appreciate any input. Add another tranny cooler? (and void the warranty?). Use some other type of tranny fluid (and void the warranty?) Forget it and spend another 40K on a diesel? Thanks for any advice.

NT2005 · 10-11-2007, 11:28 AM

Shift down a gear. That's the same size trailer i tow. You shouldn't have any problem with overheating.

red_rider_elsinore · 10-11-2007, 11:39 AM

Transmissions heat up when they're slipping. Meaning non-lockup situations. Try dropping to 3rd to cool the tranny. With BT Gears at 55mph in 3rd is around 3k rpm. I tow here in California with a lot heavier trailer and in the mountains. I do a 6% grade and my tranny doesn't overheat. If it gets hilly, keep the rev's up or speed up. When towing in the flat I have to tow at 60mph or faster or else my tranny doesn't lock up in 4th gear.

Titan4mde · 10-11-2007, 01:54 PM

Drop a gear FOR SURE!! I bought my truck for the same reason you did; to TOW. I don't pull anything in "D". I always tow in Manual 3 up to 55mph(I'm used to the same type of terrain as you) and then shift to Manual 4 and like another guy said, it won't lock up the converter until about 62mph(computer controled). The only override for the lock-up is matting the pedal. These trucks are towing monsters but they need the RPM's and are very happy revving. THIRSTY, but happy. This will help flood the tranny with freshly cooled fluid and drop the guage from the top of the peramiter. Another thing, that mark just below the "H" is still within design specifications for operating temp.

Shadowfax · 10-11-2007, 04:17 PM

Thanks for the input. My truck has the "tow mode" and is supposed to be smart enough to know when to shift down a gear. While going up moderate hills around here it usually shifts to 4th or 3rd.
Would someone be kind enough to explain about "locking up the converter?" Is this something like having a manual transmission where there is no slippage? Guess it can't be done manually.
Thanks.

red_rider_elsinore · 10-11-2007, 04:39 PM

Quote:

Originally Posted by Shadowfax

Thanks for the input. My truck has the "tow mode" and is supposed to be smart enough to know when to shift down a gear. While going up moderate hills around here it usually shifts to 4th or 3rd.
Would someone be kind enough to explain about "locking up the converter?" Is this something like having a manual transmission where there is no slippage? Guess it can't be done manually.
Thanks.

That's exactly what it means. The auto tranny slips like slipping the clutch on the manual. The thing is the stall speed [measured in rpm] is where the clutches stop slipping and lockout is at a high rpm. The tow mode isn't as sophisticated as other brands. It just holds gears longer. Maybe when we get a tuner for the tranny we'll be able to adjust the gear shifts for better towing performance.

BigJ · 10-11-2007, 05:35 PM

I bought Stillen's Aux Trans cooler!!! I don't tow too much but i just wanted peice of mind with the 35's on the truck. Fairly easy install, you might check it out.

**loufish** · 10-11-2007, 06:03 PM

Quote:

Thanks for the input. My truck has the "tow mode" and is supposed to be smart enough to know when to shift down a gear. While going up moderate hills around here it usually shifts to 4th or 3rd.

The problem is the as you give it more throttle, the first thing it does is un-lock the converter, this is where the heat comes from. It feels like and on the tach looks like a forced downshift to 4th, but it's just unlocking...you should be towing in 4th gear and on hills/grades manually downshift to 3rd as needed...I do the same for other trucks I've towed with, the trans is happier when you downshift your self...

dawgs77 · 10-11-2007, 07:08 PM

A automatic transmission uses a Torque Converter. While accelerating the converter is NO in full locked capacity...they slip. This is how they function.

One day while driving...hit 55 mph and stay steady...a few seconds later you will notice your RPMs drop slightly...you just hit full converter lock up.

Now you put a big ole trailer behind it and try to drive up a hill in D.....you have your foot in it quite a bit...and that converter is slipping a good deal...getting hot as hell.

Do not be affraid of RPMS!!!!!!!!! Remember peak torque for this truck is about 4200 rpms. Drop a gear and run the RPMs up...you'll do more damage then running the low rpms...rpms don't hurt.....they can be your friend!!!!

I pulled a 7k trailer from CA to South Dakota and back....didn't over heat once. But when I hit a hill I dropped into 3rd...and I ran 60-70 mph almost the entire trip.

wiskers · 10-11-2007, 08:33 PM

OMG.....how irronic that you posted this cuz I just got back home from a long trip I had to Cali to pick up a car in my 8.5x20' enclosed trailer. If anybody here has driven on I-5 just past LA you know what mountain I'm talking about here. The first time I drove up the mountain the trailer was obviously empty so I had no tranny issues and I was going about 50mph in 4th.

HOWEVER, on my way back home after picking up the car I had a GVW of about 7,000lbs. Once I started heading back up the mountain I dropped the tranny down to 3rd gear and set my speed to about 45mph this time. After about 2-3miles I noticed my tranny was starting to overheat and it got all the way up to that little line before the "H". What the hell caused this cuz I don't want something to happen down the road while I'm towing in the middle of nowhere? This was a VERY dissapointing experiece cuz I thought the Titan's were better than that.

Titan4mde · 10-12-2007, 07:14 PM

GUYS, Please don't get too hysterical over that little mark below the H. It is still within operating design up to that mark. PAST THAT MARK IS NO GOOD. Anything below is within designed operating temperatures!

wiskers · 10-12-2007, 07:22 PM

Quote:

Originally Posted by Titan4mde

GUYS, Please don't get too hysterical over that little mark below the H. It is still within operating design up to that mark. PAST THAT MARK IS NO GOOD. Anything below is within designed operating temperatures!

Coo.............GOOD TO KNOW!!!!!!!!!!

So would you say my configuration was proper?? Going 45-50mph in 3rd gear and pulling roughly 7,000#? It was about a 6* grade for maybe 5mi (can anyone correct me on that for the big mountain on I-5 just North of LA).

Titan4mde · 10-12-2007, 07:56 PM

At 6% grade, I would maybe drop to 2nd; but if it's that grade with that load, you would probably feel the need to (you know, kinda like the truck was struggling) I'm not familiar with that stretch of road, but we have a 6% grade on I40 west bound at Black/Sugar Mountain. With my camper, it WANTS 2nd gear a couple of times to maintain 50mph. It's also curvy and a very treacherous stretch of about 9 miles or so.

Don't be afraid to let those horses run at 3500-4200 rpms on steep grades, whatever gear. Our engines are happy there; thirsty, but happy. That's where peak torque values are achieved.

Painless · 10-12-2007, 07:57 PM

Sounds like the Grapevine to me. I towed through there, didn't have a problem. I was towing a 25', 9000lb boat doing about 70mph. Hehe, i wasn't in the titan though. I was in a F550 diesel

**loufish** · 10-12-2007, 08:26 PM

Quote:

HOWEVER, on my way back home after picking up the car I had a GVW of about 7,000lbs. Once I started heading back up the mountain I dropped the tranny down to 3rd gear and set my speed to about 45mph this time. After about 2-3miles I noticed my tranny was starting to overheat and it got all the way up to that little line before the "H". What the hell caused this cuz I don't want something to happen down the road while I'm towing in the middle of nowhere? This was a VERY dissapointing experiece cuz I thought the Titan's were better than that.

With that much weight and just 45 mph I'd be tempted to grab 2nd gear...As already stated, running 3500-3800 rpm is NO problem for these engines...