Transmission overheated?

[paulmm]

Had a horrible experience yesterday towing our 1.7 ton van up the Clyde mountain. Half way up all going well and engine light came on and Nav wouldn't rev enough to move. Put into neutral & engine would rev normally but as soon as I put it back into drive no go. I sat there for a few minutes turned engine off after a bit then on again & bingo it would pull like normal but engine light still on. Got to top of hill and pulled over for 10 minutes before taking off again. Engine light still on but everything seemed normal to drive. Took it easy to get home which was only about 15k. Parked van and turned Nav off. When I restarted it about an hour later all good & no engine light.
I'm assuming the transmission got too hot and shut down. Has anyone experienced similar?

 

[Old.Tony]

Obviously having the code that caused the CEL to light up would be beneficial! That code might still be stored in the ECU. Any chance you can get a reading of that? A friendly mechanic, or a $5 bluetooth OBD adapter + free Android phone software will do the job.

I've not had mine light up, and we've towed 1.8T for over 60,000km and 2.5T for about 20,000km. We've hauled the 1.8T van up the Alpine Way in the middle of summer, as well as climbed the hills out of Gloucester to Walcha in summer - just a couple of weeks ago, actually, and with a busted fluid couple (viscous hub).

I do tend to be overly gentle with my car. I'll happily pull the gear back into first and crawl up at 15-20km/h. I have also had the transmission cooler disconnected from the radiator and a new larger unit installed in front of the condensor/intercooler/radiator assembly.

I've also ordered a brand new fluid couple and when it arrives I'll be exchanging it for the current one and then I'll rebuild my current one so that I have a working spare.

 

[paulmm]

Thanks fro the reply OT....... I'll try & get a reading from our local guy. I'm thinking I could have driven it up the hill a little smarter also as I just left it in drive rather than locking it into 1 or 2 even though I didn't push the car the tranny was probably going overtime shifting up & down.

 

[Old.Tony]

I think at the very least disengaging overdrive would help. This would instantly unlock the torque converter, removing the strain from the engine as the gearbox would be completely free to start choosing gears.

There's a small amount of inhibition when the TCC is engaged - unless the engine load exceeds 75%, or the speed falls below 80km/h, or the driver chooses another gear manually, the gearbox will stay in 5th. 75% engine load is actually a significant amount of power. I've noticed mine will trip around 75% load, but will hold down as low as 70km/h. A quick flick of the overdrive button fixes it.

 

[paulmm]

Update to problem have had transmission serviced & mechanic said the fluid was putrid. Transmission has felt much sharper since. Was finally able to get the computer scanned & came up with 2 codes
P1705 TPS signal to TCM problem
P0732 2nd gear ratio problem.
Just hoping these we're caused by dirty fluid & overheating. Codes have been cleared.......fingers crossed.

 

[Foxtrot16]

Is it an auto or manual transmission??

My auto went last year when towing my Campertrailer and cost me $10 000+ to replace. This is due to a design fault that Nissan is aware off but won't do anything about.

Basically the oil cooler is mounted on the front of the radiator and there is an inlet and outlet pipes that go from the auto through the base of the radiator and into the oil cooler.

What happens is that the transmission oil get a lot hotter when towing and fail where it goes through the radiator and you then have transmission oil and radiator coolant mixing and bang!!!

A simple fix to prevent this (as I have since found out) is a bypass mode to re-route the inlet & outlet pipes away from the radiator and also fit a larger oil cooler. I have also fitted a temp gauge to monitor the transmission.

An expensive lesson and one that I could have done without.

Also the new transmission has a faulty torque converter which Nissan are aware of but won't do anything about as 'it is a characteristic of this gearbox and you just have to live with it" and I don't have the money to fight them or repair it myself at this stage so now I just turn the overdrive off.

Karl

 

[Old.Tony]

Karl, if you're referring to a vibration that occurs between 75 and 95km/h, Nissan not only know about it but they were replacing the torque converters at no charge. They were aware that some TCCs were not engaging properly which caused them to rapidly engage/disengage (felt as a vibration). Even some of our overseas users experienced this and had it fixed by Nissan.

I would suggest asking at another dealership. I wish I had the TSB for that problem, you'd be able to shove it in the dealer's face.

I've done that external-cooler mod myself but haven't fitted a temp sensor. Where did you hook yours up to? I've actually found a automatic transmission sensor reading in the ECU but it really closely follows the coolant temp so I'm guessing it's just using that.