The Stovebolt Site Forums The Shop Area Engine Shop Powerglide fresh rebuild

So, I rebuilt my powerglide, got it all together, in the truck, and it's running. I have forward creeping in R, N, D, and L. But ONLY creeping, under throttle, I have barely any movement, but it puts a little load on the engine.

I filled the convertor with 4 quarts prior to putting it on, made sure it went all 3 clicks back and settled in the pump right, lines are all connected, no leaks, and 4 quarts in the dipstick tube to fill the trans.

I think maybe I just need to adjust the band on the L/R drive?

Any help would be GREATLY appreciated, as I have just got all of it together today, and it's been apart since February.

Tony

My father(a retired transmission man) says it sounds like you aren't getting enough pressure from the pump. There is also a pressure regulator valve in the valve body that might be hung up. He said that to adjust the bands properly, you tighten the band(loosely - not snug by any means) and then back the adjuster off 2 - 2 1/2 turns, and tighten the locking nut. His main thought was that it needed a new pump, but that the valve may be hung up, or even one of the valve body gaskets might be in wrong. I hope this helps.

Is this the aluminum or cast iron power glide?

It do, 54. I'll try to adjust it, I think I probably have it too tight. I appreciate you taking the time to ask your dad.

Roy, it's the aluminum one, but I don't know the year of it, came in the truck, but I don't know if it's original or not.

Be a bummer if it's the pump, but could you ask him which pump he's thinking? There's two, one on the front and one on the rear, although I believe the rear pump is for 2nd gear. I didn't have any issues with the pump before I rebuilt it, I just rebuilt it thinking I'd like to have new and better guts to withstand the higher HP/TQ from the new motor.

Thanks again, and keep the ideas flowing. I won't be able to get to the truck again til tomorrow morning around 9-9:30, so I'll be checking again in the morning for replies.

Tony

I'm pretty sure he was talking about the front pump. If you had no problems with it before, and saw no problems/wear on the pump during the rebuild, it should be fine. He did say that the pressure regulator valve may not be seating all the way, or the band was out of adjustment. As an afterthought, he added that the gaskets on the valve body might be reversed. Check the adjustment of the band and see if that helps any. If not, drop the pan and check the valve body.

Thanks again, 54, and thank your dad. I'm off to see what I can see.

Another thing to check is to make sure the manual valve is attatched correctly to the shifting mechanism. If it is out of place it won't line up correctly in the valve body to direct the fluid where it needs to go.

A pressure gauge would tell a lot if you had one. Did you replace the seals in each clutch pack? If so it is possible that it was cut while installing the piston in the drum. (Been there done that).

Good luck, let us know what you find.

Ok, so I pulled the valve body off, checked for proper alignment of the gaskets, they're ok. Checked for free movement in all the pistons in the valve body, all good. No check balls in the valve body, some people were telling me there HAS to be some, but none were in it when I disassembled it, so my answer to that is, no, there doesn't. Mine has two springs with machined tops on them, they only allow fluid to go one way, so I think they take the place of check balls.

I have a leak on the tailshaft housing where it meets the main body of the trans, thinking maybe it's not seated right and allowing fluid to go haywire at the end of the trans, losing pressure where it needs it? I'm kind of lost at the moment.

Help, please!!
Thanks,

Tony

Dad says you are welcome.

The rear pump is only there so that you can "pop start" the engine(over 20 mph - I think) He agrees with Roy Rodgers, that the linkage to the manual valve could be installed wrong. He said that the band is for low gear, and the clutches are for high gear. If you did bung up the seal on the clutch pack, low should still work OK. Was there any metal in the pan when you dropped it today? If so, your pump might be in backwards. The tabs on the gear should be toward the rear(flush with the pump housing, not flush with the front of the tranny) He said there is also a valve in the pump itself. During the install, you should tighten the bellhousing bolts before you even start the ones on the converter. When the bellhousing bolts are tight, you should be able to spin the converter freely. There should be 1/8 to 1/4 inch clearance between the converter and the flywheel. Dad says he's got one rebuilt(in St. Louis) right now, but the cost of shipping it to Kansas would probably kill you though. He says that he wants to rebuild a powerglide blindfolded some day. I have no doubt that he could - I've seen him pull one out of a car in just 20 minutes before.

I hope that you find the problem without having to pull it. Good luck.

This linkage to the manual valve, I'm not sure I understand what you mean about installed wrong. The pan and fluid were clean, pump is in correctly, as I didn't actually take the pump apart, just cleaned it. I think I need the torque specs for adjusting the band, as in how tight is tight when bringing it in, like in inch-lbs, maybe? And then how far to back it out. Some of what I read says it can do what it's doing from it being out of adjustment. I installed the bellhousing bolts first, so that shouldn't be a problem. I think (can't remember for sure) the convertor spun freely before I put in the bolts to the flexplate.

If I can't get it working, I'll ask you about what he wants for the one he has, I could probably come pick it up if need be.

Meh, can't work on it again until Wednesday, anyways, post shop weekend is Monday and Tuesday.

Thanks again,

Tony

If you had the valve body out of the transmission, then as you put it back in, there is a valve that has to line up properely with the linkage that passes through the case for the linkage outside the transmission. They call the valve in the transmission the manual valve because it has to be moved manually to select what gear you have.

Been tooooo long since I have looked in the powerglide, but that valve may have two grooves close to one end that has to straddle the linkage that comes through the case. (Someone correct me if I'm wrong). If it is not in place you can't select what gear you want. Some transmissions use an "s" shaped link to connect the two.

I'll see if I can find a picture today and post it later to give you a better idea of what to look at.

Thanks for jumping in Roy. It was hard for Dad to explain to me, and even harder to explain it to someone else. I searched around for an image of one installed in a powerglide, but this is as close as I could come. Some people call it the rooster comb.

Dad said that he tightens the band with a speed wrench. It should only take about 10-15 ft/lbs. of torque to tighten.(almost snug - not tight) Then back the adjuster off 2 - 2 1/2 turns and lock down the nut.

I'll call Dad again tonight to try to get a clearer explanation of how the rooster comb goes in right. It's my understanding that you can shift through the different ranges and watch the valve moving to each position to determine if it(the comb) is installed the right way. It can be installed just one or two notches off(on the shaft from the linkage), and cause such a problem I think.

-- p. s.

I just found this on the old car manual project - thanks to Keith Hardy.

Theory and Diagnosis - Chevrolet Automatic Transmissions

It has a good diagnosos section on page 22 and 23.

http://www.tocmp.com/manuals/trans/TTransChev1971/TTransChev19717.html

On this page of the manual you found, #25 is the manual control valve. Maynot be the problem, but if it is it could be a simple fix.

Good luck.

Took the valve body off again on Sunday, but the shop lost power and I couldn't look at it again until tonight.

Everything looks like it's lined up right, the manual control rooster comb was not removed when I did the rebuild, so it should still be right. I talked to a shop on the phone yesterday, he thought the trans took 10 quarts of fluid, and since I only had 8 (4 in torque convertor and 4 in the trans) he thought that might do it. I didn't find anything looking out of the ordinary when I looked at the valve body, so we put it back in.

Tomorrow night, we're going to fill it up while it's running to make sure it's at the right level, and I'll adjust the band like your dad said, 54. Hopefully all will work out.

I'll let you know, and thanks again for the replies.
Tony

That's why we missed it - it's #1 on the diagnostic list. (We tend to overlook the obvious)

No drive in any selector position; cannot load engine.

Low oil level.
Clogged oil suction screen.
Defective pressure regulator valve.
Oil pump defective.
Input shaft broken.
Oil pump priming valve stuck.

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Looks like we might have a winner. Good luck, and happy shifting.

OK. Still no movement.

Fluid is reading full when running, so either the level is good, or the pump isn't working. Gonna check that tomorrow night.

The oil suction screen was clean, check that one off.

Don't know how to check the regulator valve, so *shrug* not sure what to do there.

Oil pump could be the culprit, I'm not sure it's pulling the fluid level down when it's running.

Input shaft definitely NOT broken, scratch that one.

Not sure how to check the priming valve, either, so I'll have to figure that one out, too.

Thanks for the help, please keep it coming, I really don't want to have to take it to a shop, I'm sure it can't be anything THAT difficult, just a case of figuring out what it is.
Tony

When you installed the trans, did it go right up to the engine on the dowel pins without having to pull it up with the bolts? Once bolted up, the torque converter should have been easy to turn by hand to line it up. If not, it is possible that the pump is broken. (Done that too one time)

Also possible that the low clutch seal is bad. Could have cut it while installing it.

Check the fluid level before starting the engine and see how far up on the stick it is, then start the engine and see if the level drops. If it doesn't drop, then something is wrong in the pump. After sitting a few hours, the level should read a good bit overfull on the stick, once running the pump should pull it down to the correct mark if it is working. Also, to get an accurate reading on fluid level the trans needs to be at operating temp, but you can get close when cold.

Beginnning to sound like it isn't developing any line pressure, and the front pump would be the next suspect providing everything else checked out.

I checked the fluid level today when off, then running, then after warming the engine up some. Fluid level isn't moving, which leads me to the conclusion that it's something to do with the pump. Something I found while putting the valve body back on last night: Red rag fibers on the filter- I think maybe the pump may be clogged, or maybe the pump primer, wherever that is. I don't know how that many fibers got in there, I cleaned it originally with them but I washed it with dish soap and water followed by lint free towels to dry it.

Now, to the slightly confusing part about the forementioned conclusion- The engine sounds like it has a load on it in ALL gears, including park and neutral. However, under it's own power, since I adjusted the band to 15 ft/lbs and backed it off about 2 turns, it doesn't move at all.

I towed it home tonight, and my buddy fired it up in neutral on the way. I gestured to hit it, he did, and I felt a drag on my Dodge every time the Chevy revved.

AAAARRRRRRGGHHH!!!

You guys have been incredible help, but if you can stand to keep helping, I can definitely use the help.
Thanks,

Tony

I feel your pain, Tony.

Sounds like you need to pull it back out and go through it again.

Chin up - we're here for you.