Driving around everything working great with a rebuilt trans when suddenly loses all gears like being in neutral. Stop on the side of the road shift through all gears and nothing.
Turn key off and wait a minute, start it and works again for a few minutes, then same thing. Got back home by repeating this process a few times.
Then I replaced all the solenoids, pressure switch manifold and the harness with good quality new. The TCC solenoid in the old harness was stuck and seemed to have a short
so I thought I had found the problem. Drove it around a couple 6-8 mile runs today and everything great. It sat for an hour or two, was going out to play on the country roads,
drove about 2 miles and same thing started happening again.
This is a 2004 GTO, 3500 Yank converter. Looked at valve body again on the bench when I did the solenoids nothing unusual or sticking. Why me lord.
EDIT: posted the solution at the end of the thread.

 

Losing motion means you are losing pressure . Short of a broken pump which would not be intermittent . I would suspect a filter or PR valve issue .

 

Thanks Frank, just replaced those parts actually.
I am thinking the fix will be a new computer, unless anybody has any other suggestions?

 

A new COMPUTER/PCM will not fix a loss of movement situation .
They literally is NO PCM fault that will result in no movement period.

 

OK good to know I dont need to down that rabbit hole! So maybe my PR valve in the pump is sticking? It was replaced during the rebuild with a new Transgo valve, springs etc.
I am looking at the install drawing now, boost valve, alum. spacer, big spring, smaller spring, regulator valve. I do not remember seeing the aluminum spacer shown on the drawing.

 

I pulled the boost valve/regulator valve out. They were installed correctly. Boost valve came out pretty easy, the PR valve did not. Took a tug with some long pliers to pull it out.
I plan to polish the valve a little tomorrow until it slides easy, then give it a go.
Strange how it worked for 3500 miles then started sticking, if that is what is happening.
Thanks again Frank for helping me think this through.

 

Valve could be sticking when hot in stroked position. . Polish valve and clean bore out good. Valve should literally go in and fall out in such a way you have to put grease in it t keep it in during install.

 

For future people reading this, the 4L60E/4L65E/4L70E will "work" even if completely disconnected electrically. You will ONLY have 3rd gear, Reverse, Neutral and Park. When electrically disconnected, it also maximizes the system pressure.
This presents a "last resort" option, that if the trans is slipping too much to drive, you might be able to disconnect the trans, which will raise the system pressure and reduce slippage, and possibly limp it home.

However, in this thread it does sound like the trans is loosing pressure when it warms up.

Frank: I do wonder if the valve can drop pressure so low that the car no longer moves. Also, are you referring to the "boost valve"?

 

No I am referring to the actual PR valve and yes i have seen them stick and no movement little to no line pressure.

 

Pulled the PR valve out, bore brushed with a nylon borebrush and blew it out. Polished the PR valve with a piece of used 600 grit until it slid easy. Put in another new filter.
It felt promising shifting from R to D after I filled it with oil, but lost movement again before I could back out of the shop. Rats.
So now thinking I need to pull the pump out and have a closer look? Or could it be a valve body problem? Bad torque converter would fill the pan with metal wouldn't it?
Shifting from R N D in the shop with the car door open I could hear a slight cavitation in R and D. Not very loud but it was there.

 

Check fluid level or trashed up trans cooler?

 

Cooler is internal new radiator. I think the pressure relief check ball in the pump is a long shot but going to look at it next. Maybe a small piece of debris lodged in there,
A small piece of debris tried to kill me once inside an aircraft carburetor. Maybe it is the same one came back to haunt me.

 

I remember a guy posted about a similar situation a couple of years ago (I think he had an S10 Blazer), and @vorteciroc told him to check the AFL valve, that it could be worn severely.

 

I believe I have a crack in the case somewhere, dropped the motor/trans out today.

 

Well I wish I new, but I don't... and My Father is not around to ask anymore.


I'll take a look through his notes, but the books that he wrote everything in are about 9 Inches thick.
I have been slowly trying to re-type it all so I can organize it all by categories/ topics.

Good luck guys!


-Marcello III

 

Marcello: We all miss your dad! He was a smart and generous man, and of course a great contributor here.

 

Not finding any cracks in the case or pump housing, but seeing some metal in the pan that should not be there. I had just cleaned out the pan and more appeared, so must be coming from the converter. The Yank 3600 converter came with the project so have no idea how much use it had, do Yank converters have a roller clutch on the stator? Would that even cause the no movement problem if it was bad?
I will call Yank tomorrow.

 

Thank you!

That is very kind.

 

I am sorry to hear of the passing of your father.
I would have liked to have met him in person. He would always encourage me to have more confidents in my postings. I learned a lot from him and really enjoyed our conversations. The 1st thing I would do in the mornings would be to check in here to see what he would have to say.
He has been and will be greatly missed.
Brian

 

Came back to post the ending. The torque converter is a Yank 3600. The TCC solenoid started sticking. The car would stall at stop lights randomly. I thought it was my tune doing that.
The TC clutch wore down enough that the debris coming from the torque converter that was small enough to get past the filter started to cause the PV valve in the pump to stick intermittently. It would stick in a position that caused no movement. When I would shut off the car and re-start, it would begin working again.
I sent the TC back to Yank and had it rebuilt. Went through the trans and valve body and cleaned all the trash out of it. Replaced all the electronics.
I put 100 miles on in the last couple of days and everything is fine now.
Thank you Frank for directing my attention to the PV valve.