Lesson Learned (4L60E)
 

So as most of you know I did a rebuild on my 4L60E recently.
Come to find out after some more tests after the rebuild that there is one thing that will kill these faster than anything else and it is a common problem and that is Line pressure. The specs for this are as follows: Drive, Park, Neutral should have 55psi on the low end and 189 psi on the high end at idle. mine was 50psi which was WAY low but I bumped the EPC a half turn and now I am running 95psi. If you start to have problems with your tranny have the line pressure checked.( it doesnt require a special tool per say) just a 300psi guage and a line, I will do a write up on this later when I install my permenant tranny pressure guage.

Ah so catastrophe averted?

yep thats it a loss of pressure is apparently the main cause of all tranny problems in the 4L60E

Even a clogged tranny filter could reduce line pressure and then.... I wonder if any PSI guage would work. Having that on the dash as front display could tell a lot of how and why the tranny is working. I would have never of thought of that. Good deal friend!

yes any gauge will work as long as it is a 300psi I will get more specifics on what is needed in a couple days and post it here

What you thinkin like spliced inline?

nope.......I am going to use the line pressure port just above the neutral safety switch I still have to go over some "plumbing" requirements but I think copper tube and some brass fittings will work just fine

the worst part is generally you won't notice a drop in line pressure before the tranny gives because the lubrication circuit is the last circuit in the transmission to receive pressure. so all shifting would be occurring normally but you could be starved for lube. good post, its a major issue with these trans.

well.........not fully true.....you would show signs of either a pressure increase or decrease with a loss of lubrication, what is the most common failure point is actually the pressure valve in the pump which flat sides after awhile and causes inconsistant line pressure and fluctuation. which in turn does not apply the clutch packs fully and results in slippage and heat. And most people dont know this but engine problems can kill a tranny just as fast as tranny problems...(just one more reason to keep up on the maintainance) :)

Thats right. The key word is inconsistency.