Lock up converter problems

[don282]

Hi all , I have a problem with the Auto in my VS. The convertor lock up works when the car is cold and will stay locked as long as I dont slow down or it needs to drop down a cog ie. climbing a hill. I live in the bush and my most common trip is a run of 38 K, 18K from home I need to slow for an intersection, after winding it up again it wont lockup , if the weather is cold I can sometimes pull it back to 3rd and back into drive quickly and it will lock but if the weather is warm it wont.
Engine temp is normal (for this car) only up to the second division on the temp gauge some times only to the first division. I'm running on LPG but it is the same on ULP, when in the city in traffic it goes above halfway and everything works as it should, fan starts etc. doesn't overheat.
Once its warm it wont lock and when its cold again the same sequence occurs.
It is running a standard temparature thermostat.
Is there an oil or aditive that can be put in that may remove gum that may be causing the TCC valves to stick.
The transmission works perfectly in all other aspects. Car has done 240,000K but I don't know the history, I have run it for the last 80,000K and for about the first 40,000K I never realised that it wasn't locking at all it was only after changing filter and oil that it went to where it is now.
Hope I have stated all the facts that may help someone to pinpoint a maybe common problem. Can't afford a change over as I am having to change the motor this comming week.
TIA,
Regards,
Don....

[hako]

If you read the label of some of those "fix trans in a can" some say they free up gummy valves so you'd imagine they 'may' work in your situation so they'd have to be worth a go. When you did the filter/oil change did it all go smooth - like did you get the "O" ring out from the where the filter sits?....and how was the oil colour and how much crap was in the filter.
Check this link as it may have your problem and/or talk about sticky TCC valves/solenoid.
I'd also doe codes check as the problem may lave logged one.
FYI 4L60E common problems / failures - Impala SS Forum
Checking error codes VR/VS (Revised)
Good Luck.

[delcowizzid]

there is a temp switch in the box too stop it locking if the box is too hot maybe its getting stuffed or the temp of the fluid is getting too high from slip in the box

[don282]

Hi, I have wondered about temp as being a problem but there are no over temp DTC codes set in fact no codes set for the auto. It is not a switch it is a temparature sensitive resistor (Thermistor), when I have the engine & Trans out next week to change engine I will measure it to see if it meets spec.
Also is there a drain plug available that can be fitted to the pan?
Many thanks....Don.

[hako]

I've seen where people braze a drain plug to the pan but I think they just used what was available in their spare junk pile. Advantage of dropping the pan is that you get to see whats attached to the magnet and also the dregs that always stay on the bottom. You can always undo a cooler hose and run it at idle till she stops flowing if you just want to flush although you've still got that crap there.
What delsowizzid says seems logical although I'd imagine that if the car was in O/D the oil would not get hot as there is no slippage.
Good Luck.

[don282]

Thanks hako, comments noted. If necessary I will make one and it will be fitted 1/2 inch up from bottom so as to leave the rubbish on the bottom, I just don't like trying to lower an almost full pan that always seems to end up on me and the floor and it never pours out a corner, always the full length of a side, LOL.
Regards, Don...