Transmission Pump Getting destroyed

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russbutcher

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Hello all! My trans recently would slip in Park after being warm at stop lights and didn't like going into reverse and would hesitate to go into gear after start up also while being warm IE leaving car show. So I just assumed a rebuild was necessary, took it out and dropped it off to shop and they found severe wear and the pump had a grove in it. They replaced the pump and did all the bands and seals. I put the trans back in and there is no pressure in the new pump at all. So the guy tells me to take it back out and bring it to him. There was metal shavings galore after only running a few mins to diagnose and circulate fluid. He takes it apart and finds the new pump became severely grooved worse than the original pump. So he ordered a new pump again and new gasket kit. Before we install this trans again we are hesitant because we don't want to ruin another pump. Any ideas of what could be causing this? He has no idea and is confused. The trans is FMX and is mated with a 351C.

 
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I would definitely have a new converter in it.  All those shavings are almost impossible to get out of an old converter.  Also make sure to dump some trans fluid in the new converter before install, You want to spin the converter as you are installing it and make sure it seats all the way. You will here a couple clunks as it seats completely.  If you don't have it seated properly you can easily wipe out a new pump. Once you have the trans bolted to the motor you should be able to move the convert slightly inside the stud holes of flywheel. Should be loose fit, if its bound up at all, your converter isn't seated all the way and you will smoke another pump.  If it is loose in the holes, proceed to install the converter nuts on the studs. 

 
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+1 on that what Kevin said above! Did it exact like that on rebuilding a C6 to a 360 FE in a 1970 F250. Proper seat on the shaft is VERY important! You have to evolve the right feeling to say you have achieved the right seat. Watch some videos out there which explain that very well if you have not had that already done...  :thumb:

I changed the converter and prefilled it too. Too much risk of old shavings and other crud transfering to the rebuilt transmission... 

 
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if you have inserted the converter as it should, rotating freely, you should if you measure from the edge of the casing with a stick, have a 1/4 of an inch on the hub of the converter deeper from that stick. On an FMX, the converter is out gears just 1/4 forward which is really easy to get when you wiggle the trans to mount it back. One thing I'd do is make sure it turns butter smooth when you install it outside the car, then use duckt tape from side to converter to keep it there and rotate it so it kinda match where the holes are on the flywheel. That may sound "non pro", but I'd really do that especially if you have no bridge to work and like me need to crawl on the floor to work.

Here shamelessly using a snapshot of Ken's vid at bad shoe (his videos are excellent and make rebuilding a trans almost a walk in the park, worth every buxx)

edit1: back in the 80's, i've installed a converter on my FMX, and because it was not fully engage, I've broken the center axle. The noise that it made was really scary :O So know that you're not the only one who been biatched and payed the price of a faulty install.

edit2: if you have an external oil cooler, same: replace or purge. Because the filter inside is not really filtering small particles as an engine oil filter would.. Metal shavings are cancer for these trans. if one tiny one enters the valve body: end story.

Screenshot 2021-04-30 at 14.01.49.jpg

 
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Spike Morelli

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If unsure of installation a 3rd time in, why not simply have the transmission shop install the trans. At this point, it would seem that time and money would be saved, and of course, the shop doing the install and repair would warranty it to function properly. I myself, feel confident of much of my  mechanical skills, but that doesn't stop me from out-sourcing those who do it every day, to which there is no shame in doing.

 

Gregaust

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What was the converter to flexplate clearance? Did you replace the  flexplate and by chance get a C6 one ? They are different .

 
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