Valve Body Rebuild Journal-Disassembly
My ’91 Explorer with 178,00 miles began to have soft shifts and it clocked about 2900 RPM at 70 MPH. My wife’s ’91 with a newly rebuilt transmission shifted much more firmly and held 70 MPH at 2500 RPM. I drove it like this for about 2 months, figuring it was just getting old and hoping to get another year or so out of it – not to be. Just before Christmas I got onto the interstate & it shifted through the gears very strong, and dropped into overdrive, 70 MPH at 2300 RPM. GREAT!! But when I got off at my exit and pulled up to the stop sign, the engine stalled. It acted like it was locked in high gear and kept stalling the engine unless you nursed it carefully away from a stop. I figured on another transmission, but Glacier991 posted an offer I couldn’t refuse. He thought it might be a valve body problem that I could fix, and he generously offered encouragement, assistance, and even some gaskets! How could I refuse? Thus begins my story. On January 12, 2005, I pulled the valve body out and began my adventure:
The patient:
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I used a trick found on these forums for flushing the transmission. In fact, I performed a flush before I posted my plea for help. My “kit†consists of a 5-gallon bucket, a length of tubing, and a short piece of pipe the same size as the radiator stub outs.
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I attach the hose to the transmission line on the right hand side of my Explorer.
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Start the engine and pump most of the fluid out of the pan. I try to gauge about 4 quarts and stop before it quits pumping.
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Now you can drop the pan without getting the “ATF shower.†I was pleased to find the pan relatively clean, with no metal shavings or large pieces lying in the bottom. While I had the pan off, I ran a straightedge down it to make sure it wasn’t dimpled at the bolt holes.
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I decided to correct the oversight of no drain plug. AutoZone had a kit for $7.99. Simply drill a ½†hole and install the plug. I’ve been told the rockcrawlers will want to locate this plug somewhere else, but I put it at the lowest location. These pictures show it installed per the directions. I later cut the large bolt off short so it fit flush with the bottom of the pan on the inside and welded it in, eliminating the nylon washer/gasket.
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I then pulled the valve body and put the pan back on the transmission to keep trash and small rodents out while I worked on it. As you can see, when I pulled the valve body, I found all the crud I had expected to see in the pan.
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I took the valve body into the garage, set up a work table and began disassembly. The A4LD Rebuild Diary in the Useful Threads forum has lots of information and tips on how to do this. I have a couple of comments I will add as I go.
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One of the first things I tried to do was to take pictures of everything to help put it back together. I referred to them a lot as I reassembled it. Here’s the VB with the separator plate removed, but before getting to the gasket. There are two spring loaded valves and 4 check balls. Another great reason to be doing this on a nice large level table.
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The next photo shows a strainer screen in the separator plate. Note the separator plate is upside down. This screen fits down into the VB on what I will call the lower left corner next to the lockup solenoid.
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The reverse servo had a chunk missing out of one ear. This does not affect its operation, but may have been the source of my problem – more on that later.
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I then pulled out all the valves from the bores, using the guidance in the A4LD diary. I found a magnet worked great pulling some of the keepers. The skewer sticks worked great pushing this keeper from the backside, and coaxing sticky valves out of their bores. I was trying to remove the sticky valves by generous applications of Brakleen; I found this only took all lubricant out of the bores and didn’t help. When I switched to PB Blaster (much too late), most of the valves freed up enough to almost fall out.
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I put the valves from each bore into their own individual baggie. Being lazy, I just used a Sharpie and marked them. I used “top left, 1,2,3, and Bottom left, 1,2,3. Any system that will make sense to you as you put it back together. The factory manual labels the bores, starting at 200. (I don’t even care to know where the previous 199 bores are located!). And here’s a picture of the halfway point.
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This is probably already way too much for one thread, so I’ll stop here. I will post the reassembly on a separate thread, as anyone doing this job will be more interested in putting it back together than taking it apart anyway. One more thing before I go, though. I spent over an hour carefully working the gasket off the VB with a scraper and trying not to scratch it, then sanding it smooth on a piece of 600 grit paper laid flat on the table. Then I discovered EZ Off oven cleaner. Applied it to the separator plate, waited 15 minutes, and about half the gasket came right off. Another application got most of the rest. A third application & the plate shined like it just came from the store. I would recommend it. I would NOT use it on the VB itself, as the caustic ingredients in oven cleaner will attack aluminum.
