| Re: [GMCnet] trans temp sensor [message #153384] |
Sun, 18 December 2011 06:18 |
Gary Casey
Messages: 448
Registered: September 2009
Karma: 0
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Senior Member |
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Rob,
I'm not sure about that. The way the oil system works is that oil if fed directly from the pump to the pressure regulator valve and to the valve body for all the clutches, etc. Pressure is applied to one one end of the valve and spring pushes against it from the other end. When the pressure is high enough to overcome the spring force the valve moves, opening a port that supplies oil to the converter through an orifice. When the pressure rises further another port opens that vents oil to the sump. So it's a priority system - first the clutches are supplied and if there is enough flow the converter will be supplied and finally oil is vented. It is possible, or even probable that during a hot, slow idle the converter supply will be shut off in order to keep pressure in the clutches. But as soon as engine speed picks up the supply resumes. From the converter the oil is fed to the oil cooler and then back to the sump. The converter is
supplied oil at the center, which is the lowest pressure point in the converter. The actual supply pressure the converter sees is a function of the feed orifice and the restriction of the the cooler. I suppose someone might be suggesting that the converter feed orifice be opened up in order to increase the cooling oil flow. But there are lots of other restrictions in the flow to the converter, so the supply orifice has limited effect. All the passages to the converter are in the front pump area and are only accessible with the transmission disassembled.
I guess the bottom line is that possibly the oil flow to the converter can be increased and if the driver insists on putting maximum heat into the converter it might help. Downshifting is easier :-)
Gary Casey
""Gary,
I have "heard" that the transmission or torque convertor can "starve" for oil when pulling hard up a hill and you can fry the
transmission or torque convertor in a heartbeat.
Supposedly there is a "hole" that needs to be drilled out or some other mod to prevent that from happening.
Have I got bad hearing or is this info correct?
Regards,
Rob M.
"" I've never heard of that one Rob--very interesting. The highest temps I see are when I'm stuck in a traffic jam. I suspect the convertor is in total slip mode with very little cooling from the heat exchangers. I'm frequently pulling in the mountains here with max speeds WOT at times of 30 in first gear. Keeping the engine revs up keeps the convertor close to "hydraulic" lockup so the heat generated is less.
--
Bob de Kruyff
78 Eleganza
Chandler, AZ
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