No ATF pressure

[98nhexplorer]

98 XLT, 4.0 SOHV, 55R55E w/220,000mi. I just started to do the DIY trans flush using the running engine and breaking the line at the output of the external trans cooler. Nothing happening except for slow dripping...
I dropped the pan and changed the filter and added back 6+ quarts of new Mercon V a couple of weeks ago. No leaks. Normal reading on the stick. Lost all gearing a couple of days ago. Been sitting ever since. CEL is on and O/D light flashing. Codes are; P0741, P0731, P0733, P0734, P0761. I suspect the valve body gaskets and the EPC at this point but am wondering if the pump could have failed...
Thought Id post up whats gong on before I go any deeper. Up on stands and am about to drop the pan and the VB to see what I can see....
Anyone have any ideas?

Thanks!

 

[koda2000]

I would never try to flush a trans with 220,000 miles on it, especially a 5R55E, which are not know for being particularly long-lived. You're just asking for trouble. Apparently even doing a pan drop, filter and fresh ATF was enough to push it over the edge.

I assume it was driving without any issues before you dropped the pan, or was there a problem with your trans before you attempted to flush it?

Perhaps the reason you had no pressure out of the trans cooler is that it, or the filter was clogged. When you have a lot of miles on an automatic trans the clutches/bands wear out and the clutch material is suspended in the old trans fluid. When the old trans fluid is flushed, or even drained, and replaced with fresh fluid the clutch material is lost and the transmission soon fails. I suppose it's possible that you've blown a VB gasket and it couldn't hurt to find out, but I'd advise against putting money into that trans unless you plan to do a complete rebuild.

 

[98nhexplorer]

Some more info;
Trans was completely re-built in 2006 at aprox. 91K mi. So really, it has been 110Kmi. but w/o any fluid/filter changes that I know of. Other than the occasional, yet getting more frequent 'can of marbles' sound coming from the TC, it has shifted smoothly. When the O/D light started flashing three weeks/700mi. ago, I got the codes read. P0741 was the only one the reader picked up. I dropped the pan, changed the filter and added back 6 quarts of new fluid. O/D light went out but then would come then go off intermittently. When I lost all the gears, I was traveling along at 60mph, in OD. There was a little hiccup then the motor started revving until I let off the gas. I tried 2nd and 1st but nothing. Reverse was the same (after I had coasted to a stop on the side of the road of course!). No clutch slippage had been observed which is why I'm thinking failed gasket(s) and/or solenoids. I'll pull the VB today to see how the gaskets look.

 

[BrooklynBay]

There are two pressure ports for checking pressure. The main pressure port is on the driver's side of the transmission. The EPC pressure port is on the passenger's side of the transmission. A cold transmission which is equipped with a thermostatic temperature valve in the valve body won't allow fluid to circulate through the front cooler until the fluid is hot. There is a bypass kit for vehicles which are used for towing, off roading or just plain driving in areas with a warm climate.

 

[98nhexplorer]

Ah! That explains why nothing was coming out at the break then. Oh well.
Valve body is off now. Gaskets look good. Solenoid(s) then?