Dears,
I have a concern with the gearbox temperature and coolant temperature when i drive only on straight hill road (50 mph) for 5-10 min. The temperature of the gearbox increases to above 230F and the coolant temperature goes to the 3/4 of the gauge. At the end of the straight hilly road, I always face a traffic jam... the gearbox temperature continue to raise and at the end, the gearbox stops to works.
I can drive the car 24/7 inside the city and I never face an overheating problem in coolant or gearbox...
I changed:
1- coolant sensor
2- cleaning the radiator (it was clean)
3- both fans are working
4- changed transmission and oil filter twice

Please advise. I'm LOST

 

Have you checked the transmision fluid to make sure that it is not contaminated with antifreeze? That is what happens if the trans cooler, internal to the radiator ruptures.

 

I see... you mean that inside the coolant radiator, there is the transmission radiator inside, right? and there is a possibility of having a leakage between both radiators... will check tonight. But I doubt since this will be reflected in reduction of the quantity of coolant system (evaporation) or mixing of trans oil with the coolant water... but this is not happening!!! the coolant water remains clear and not being reduced.

 

Might not see any trans fluid in the coolant. I'm not certain of it but I'd guess that the pressures in the trans cooler side might be lower than the engine coolant side. If that is the case you might only see coolant in the trans but not the other way around. Really not sure though. While it happens that the internal barrier in the radiator can start to leak between the two sections I do think that it is not really a very common thing.

 

What are the rpm's while going up the hill versus a flat road? You might have a transmission or converter problem.

Tim

 

say 3000 vs. 1500

can you please elaborate more?

 

If for example you're spinning 3000 rpms going up hill to stay at 60 mph, versus 1500 rpms to stay at 60 on a flat road, you have an issue.

The transmission could be slipping OR you might not have enough line pressure to keep the converter locked up or any number of things.

The temp going up leads me to believe this is you issue.

Tim

 

I got your question now...
I will try to ride 60mph in both scenarios and will check for the RPM.
Since it has a manual mode, I will fix the gear to 3rd and will let you know about the RPM... I doubt that I have slipping...
One guy told me that I may have a problem with the converter since it works as a cooling system... what do you think?

BTW, since it is winter time now, I don't have this problem anymore...

 

There is no reason to not put these trucks in drive and let them run as normal. That might be part of the issues you are having. Running the truck in 3rd gear is just going to cause these types of issues. Your converter needs to lock up in high gear otherwise it will over heat.

Tim

 

But how do you want me for comparison purpose to check the RPM between the hilly road and the flat road for the same speed?
When taking a hilly road, most probably on D, it is 3rd or 4th gear for 60mph while on flat road, it will be 6th gear for 60 mph... no?