Tips on c5 valve body removal?

[Doug Burgoyne]

Never did this b4, but removing pan on c5 to replace filter and gasket and do whatever diagnosing I can on this "drove fine but now not working transmission" in my truck. Want to do the air tests described in write up...but need to remove VB of course to perform. Any springs or parts, etc., that could go flying,etc? Anybody know which/how many bolts to remove? May be obvious...but trying to educate myself best I can prior. Thoughts on inspecting VB for possible issues after removing? As always, I appreciate any and all help!!

 

[franklin2]

I would limit myself to pulling the pan and inspecting the fluid and look for any debris in the pan. If you find chunks of debris in the pan and lots of large metal flakes, you are done, the transmission needs a rebuild.

A transmission is not really like a engine where you can go in and replace just certain components. If something fails, it sends metal and debris through the whole transmission, making it difficult to fix one thing and get it back going again.

 

[19Walt93]

There is a spring loaded accumulator that will fall out when you pull the filter but no additional ones above the valve body. I wouldn't recommend taking it out unless you know what you're doing and have an inch pound torque wrench to reinstall it with, though. If you pull the pan and find any metal particles it needs major work, just like franklin said. You could get a pressure gauge and test the pressures in the different gears without tearing it apart, that might point you in the right direction. A C5 is basically a C4 with a centrifugal clutch in the torque convertor and fine threads on the intermediate band adjuster.

 

[Doug Burgoyne]

Thanks guys! Quick backstory. I got this truck for $500 and although started hard (turned out to be bad connection at big ignition plug inside steering column, and no 12v to coil when key in run position)...it drove wonderful over half hour home. Shifted great, trans was smooth and was pleased with how well transmission seemed to perform. Truck sat in driveway for a month or so as I gathered parts for new distributor and non feedback carb setup. Got new ignition and fuel system sorted and starts and idles great now. As soon as I got it running, transmission was not engaging in reverse, and drops in drive, but doesn't want to move forward...much like emergency brake full engaged, but it's not. Very odd behavior for transmission that ran beauty prior to shutting off last time. I will pull pan and inspect fluid, pan, filter, as you suggested. I did replace modulator valve as it was leaking fluid, replaced rubber vac lines, and tested with vac gauge. If not seeing metal, I thought next logical step would be the air tests that confirm proper (or improper) function of clutches, servos,etc as shown on attached video. Thus reason for potential VB removal. If no metal, I'll come back for further advice (rebuild? Replace? Options to get on the road? Etc). Thanks!

 

[Doug Burgoyne]

Ok folks, pulled pan and filter. Inside pan was indeed a few small chunks. Ugh. See picture with dime for reference. A couple little chunks that size or smaller, and then powdered metal in very bottom of pan that looks like metallic paint. Kind of like you see when changing old diff fluid. Pic of that too, you can see if zoomed up on. Also some gritty type business when dumping out filter on paper towel. Like fine ground pepper. That's it, dumped pan through fine mesh paint strainer. Guess this means my trans is toast. Bummer, drove home so well. If you had an 84 with bad c5, what would you do? I'm thinking pull it, take to shop for rebuild, pick it up and reinstall here (cheaper that towing and having them r/r). Or try to find used or rebuilt unit? Tricky with a hundred different versions, bell housings. Etc.

 

[19Walt93]

A used one is going to be at least 35 years old, I wouldn't go that way. If you pull it yourself, make sure to thoroughly blow out the cooling lines and cooler. Did you verify the fluid level before pulling the pan?
If you get it rebuilt, I'd find a reputable independent shop and avoid chains like AAmco.

 

[RobbieD]

*"If it were me"* I'd explore local shops, preferably an independent shop, in hope of finding an experienced rebuilder that knows this transmission well.

In my opinion, there's a lot of advantage in keeping the vehicle with the original drivetrain, if it's feasible to get a trustworthy rebuild on the transmission. I think you'd have a better shot at this with a C5, as opposed say to an A4LD, if you can find a good rebuilder.

 

[Doug Burgoyne]

Yes, verified fluid level, which smells like fresh fluid with no burn smell, foul odor, etc. Like cracking open fresh jug and taking a whiff. My dip stick I'm assuming is model correct, but hard to track down number with so many configs. Viewing from below, tip of stick goes to bottom of valve body almost exactly. See pic. Does that sound correct length for dip? Hard to check proper level as can't drive to bring to full temp. Have to go off of lower/cold Mark's. But as soon as I started to loosen pan bolts, fluid began running out as I would have suspected.