Fieroboy_gt

I decided to give a little tune up to my Th425 tranny I changed the modulator valve , filter , an pan gasket. I decided to do this only cause my tranny pan was leaking. I have the tranny mounted to a 454 big block Chevy motor. I'm not sure what the trannys specific year or what it came out of exactly. The tranny was working pretty much fine before I decided to change the pan an filter an modulator valve. It did have to warm up before it would shift in to gear. But once it shifted in to gear it drove 100% perfect.

now I get absolutely nothing when I shift it in to any gear. Im not sure if there may be a special way to maybe prime the pump in the tranny but when I disconnect the tranny lines I don't get any pressure pushing threw the line on the send side or any suction on the return side. There is plenty of vacuum to the modulator valve. I've tried the new and the old valve an it doesn't matter. Is there a way to check the pump. It kinda sucks cause it was running fine till I drained it an changed the normal parts .

MDchanic

Have you checked the fluid level?

- Eric

Fieroboy_gt

Yes which is why I'm trying to figure out if there's a special method to priming the pump so the system maybe isn't air bound. I have a lot of tranny line to fill since the tranny is in a Fieroboy an the lines run from the back of the car up to the front to my radiator. I've got like 6 quarts in the system right now. But it doesn't seem like it's flowing

MDchanic

So you've set the car to idle, warmed it up, and checked the dipstick, and the fluid level is all the way up to the top mark?

- Eric

Fieroboy_gt

Yes it's above the full mark. I filled the tranny it's self an I also filled the lines manually up at the radiator an the radiator as well.

Fieroboy_gt

An yes I wared the car to 180 put the tranny in nutrail an checked the dipstick. I also jacked the rear end up an put the car in drive an disconnected the lines at the tranny to see if I could feel pressure pushing or pulling from the lines or see if I could physically see flow from the discounted lines

MDchanic

I can't really say much more.

Your symptoms are completely consistent with low fluid.

Once you put enough fluid into the transmission, it should work - there's no need to bleed anything.

Considering that you've got such long oil lines, have you rechecked the level to see whether it's gone down?

By the way, the car sounds cool. Pictures?

Welcome to ClassicOlds.

- Eric

oldcutlass

The fluid level must be checked with the engine running, warmed up fully, and in park/neutral. If everything was operating fine before you did your maintenance then it should be fine after. So theoretically its something you did. If the fluid level is fine the you need to drop the pan and reinspect.

Fieroboy_gt

Which is what's perplexing. I did nothing except change the tray filter . An the gasket. There is nothing that could have gone wrong. It's like it's not pumping anything through the lines

Fieroboy_gt

Here's a little video cars in neutral an no flow but Def has a ton of fluid . Then in gear with no flow.


https://m.facebook.com/story.php?sto...00000601624074

TripDeuces

Did you seat the pick up tube on the filter fully in it's bore?

Fieroboy_gt

I think so. It went in incredibly hard. It was the exact same filter but it went in really hard. I'm gonna have to pull the pan again an double check it. Wishe the pan had a drain plug. This thing makes a mess an I just wasted like 40 bucks in ATF. Allwell

MDchanic

I think George may have nailed it.

The filter shouldn't be that hard to install.

And, yes, we've all enjoyed the ATF shower more times than we've wanted to. It sucks.

- Eric

Fieroboy_gt

Hey hopefully it is what it is, cause I'd rather wait 3 or 4 years to rebuild it then do it now

TripDeuces

Only from experience with my TH425. There is a single o-ring on the tube also. Sometimes it doesn't always come out with the old filter. You only want a single o-ring in there, more is not better, so you'll have to look in that hole. Put the o-ring on the tube first, not in the hole first. Lubricate with ATF.
You can easily add a drain plug to the pan with various vendors supplying these kits or you could weld a nut to the pan and use a bolt and washer. Just find an area that won't interfere with the valve body.
Some other things I was thinking of:
The selector lever has come off the gear selector valve in the valve body. I didn't mention it because I don't think it's possible that it can be disconnected without physically dropping the valve body and you never mentioned doing that.
There are two tubes that feed the valve body ATF. They are swedged on one end much like the choke tubes on the manifold. Those I know can be dislodged if you're a bull in the china shop. Not accusing you of that of course but it is something to look at.

Fun71

I added a drain plug to a TH350 pan way back in the 90s. I used a 1/2" nut, turned it in a lathe so the outside was round (removed the hex so someone (me) didn't inadvertently twist it off with a wrench), welded it to the outside of the pan, then used a regular 1/2" oil pan drain plug bolt that threaded into the nut.

Fieroboy_gt

So I dropped the pan an the filter is in as far as it will go. I no longer have a o ring. When I pulled the filter the o ring ripped out, but the filler is staying in place. And it's not pugged. Everything seems to be fine. I'm lost. How often does a pump go bad . There is no reason it shouldn't go in to a gear. Or at least pump fluid

Fieroboy_gt

I'm not sure what the electrical wire on the side plug was for but it was looped together when I got thebtranny

Fieroboy_gt

I finally figured out how to post pictures . The little electrical socket buy the modulator valve was linked like that when i got the tranny . So i hooked up a length of hose to the lines off the top of the tranny an the return line i can freely blow thru. When i hooked up to the send line i wasn't able to blow thru the line . I don"t know if i should be able too or if since that line would be the pump line that i would not be able too . i may just be crazy. i was thinking of hooking up the compressor to it an just blasting a shot threw it of air. Im not going to put it back together till the morning . I will prob get a new O ring at the hardware store then put it together but the Filter blows thru free as well. i'm not going to take any of the valve body apart. I tapped everything with a rubber hammer just to maybe see if i might loosen something up . but while i got this thing drained an what not im open to any suggestions .

MDchanic

Just stand out of the way when all of that ATF shoots out the other hose.



You need to look up there and see whether you have O-rings stuck on the tube, and pull them off, then assemble it from scratch.

Also, I believe that the pickup tube itself is pretty easy to remove - make sure that it's well attached and well sealed.





Really?

So you've never noticed a certain... complete lack of a kickdown function?

Pull that plug off, connect a wire to the terminal that is the base of the "T" that the two terminals make, and run that wire to your kickdown switch.

If Fieros don't have a kickdown switch, you'll need to rig one.

- Eric

Fieroboy_gt

No i ussually Shift threw the Gears pretty much manually . So i just drop it down or up a gear cause it always seemed to like to shift early . an now the filter , filler tube goes in an out of the opening effortlessly. the filter its self didnt come with a O ring an i think to old one was stuck in there cause half of one came out when i pulled the metal filter , pick up tube .

TripDeuces

That may be an early model TH425 with a Switch Pitch torque converter. I only say that because you have the connector on the case with two connections. That could be just a standard item but if memory serves me right they also came with a single connector. Just something to think about. Not having them hooked up won't hurt anything but you do lose the kickdown function as Eric said. The oval canister bolted to the valve body is the kickdown solenoid so hook to that connector to access the kickdown function. If it is a S/P not having the other terminal energized just keeps the trans in low stall mode at all times, doesn't hurt anything.
By what you said you may have ripped the o-ring when putting in the filter. It shouldn't be hard to push into place, lube the o-ring. Hopefully that is what happened and explains it all. Without the o-ring you're just sucking air.

Tell me what that goo is on the side of the filter housing?

Fieroboy_gt

That I's some permate gasket sealer. Apparently when I put the pan on I must have rubed against it. I bought a rubber gasket an then permatexted it as well. The tray pan use to leak a lot so I was just trying to over do the sealing. An yeah I'm thinking that the new filter didn't have a O ring with it so I didn't think to check for a O ring when I installed the new one cause the old one didn't have one come out when I pulled it. When I pulled the new one a old brittle O ring fell out. Or I should say half of one.

MDchanic

Based on the appearance of the wires and the plug (looks like the "T" arrangement of terminals), I believe it's the '71-'72 (give or take) TH425 with the TCS switch.

- Eric

Fieroboy_gt

I'm not really sure what that meaks. I was told when I bought it that it was the stronger of the tornado elder ado style front wheel drive transmistions. I had huge dreams of a 600 hp motor hahahahaha. Oh to dream

Fieroboy_gt

Ok so here is a possiable stupid question for you guys . i pulled the pan changed the o ring an for a short period of time the rear wheels would spin in gear . but they kinda spun as fast as they wanted . it seemed like when i would put it in gear an gas it it seemed like it would speed up but rather slowly. it seems like the pump was working for a breif moment in time i pulled the line an it started to flow some fluid after i manually sucked fluid up threw the line using my mouth. i hooked it up an looped the line just at the tranny an buy passed the radiator just for convience but then it stopped pumping again . so if i can pull fluid through manually could i just run a inline electric pump would that work on a tranny

MDchanic

You may wish to review the operation of an automatic transmission.

Any Chassis Service Manual will provide an excellent description of how the unit works, with fold-out color illustrations.

You have misinstalled the filter and O-ring. It's pretty much guaranteed at this point.

If you can't quite get it figured out, have a buddy who's done these come by and take a second look. Sometimes another set of eyes is all you need.

- Eric

Fieroboy_gt

So after 50 o rings an dropping the pan 10 times today an 4 times yesterday I have figured it out. The canister it's self was suckling air where the drop tube meets it. So no one sells a filterrible an I didn't want to wait 3 to 7 days for one ordered. So I cleaned the he'll out of the filter wire wheeled it an I , cough cough sealed the tube seem where it meets the canister with j b wield. I can't test it till like Tuesday but after thinking bout it. It was only pumping fluid when I way over filled the tranny cause fluid was over the spot where air was sucking. So with any luck I have resolved the issue. Check one off hopefully an then off to another

MDchanic

So the filter itself was defective?

Holy crap.

I find it hard to believe that no auto parts store around you had TH400 filters in stock, though - that's a very common and generic item.

Glad you found the problem, though.

Now we'll all find out how well JBWeld can withstand hot ATF over an extended period...

- Eric

Fieroboy_gt

Well jb wield says that it will sustain long term temp of 500 degrees. Up to short term temp of 600. So I figure tranny under hard load would be like 275 300 tops. So it should in theory since it's not under pressure work. An I though that it was weird no one stocked one but they didnt. And the part numbers didn't match a th400. I always thought that the tranny internals were a exact match for a turbo 400. But I'm not a tray expert on any level

Fieroboy_gt

That was where it was suckling air. I noticed it cause I plugged the end an tried to blow through it an it was letting air buy the rolled seem

MDchanic

Which of these filters did your transmission use, anyway?





- Eric

Fieroboy_gt

More similar to the second picture. The bottom half of the pick up tube is a little bit different.

MDchanic

I see, your transmission uses the earlier style filter. That's probably why nobody had it.

From a bit of searching, it looks as though that particular filter was used through '67, but was also used longer in the TH425.

I agree that the JBWeld will probably work fine, but if it doesn't you'll know it.
I'd recommend carrying a replacement with you, until you get a chance to change it out.

- Eric

Fieroboy_gt

I'm gonna order a spare. I thought it was weird that it wasn't working . After I tried everything I was gonna cut the tube off an just attach a radiator hose. I know dumb idea. I just wanted to test it an see if it would work. I plan on getting the tranny rebuilt in a year or 2. I need to find a shop thou that knows the tranny style . An all the proforma nice upgrades. I figure if I dump 2 to 3 grand in it I want it to be indestructible. I mean supposedly it's pretty much indestructible now which was why I chose to do a longtitudal swap for the fiero. I figure the BBC motor naturally assperated canproduce big power an torque an be reliable. I'd Def like to see 400 whp in the next couple years. My 454 is mildly built. I'd like to get crazy with it tho. The shop that rebuilt an did my block work said that I had one of the better blocks. Said I can go with a big bore of 120 over with out a issue. Which I guess is pretty good . So if I get the tranny built up to participate an the motor really done it should be a cool car.

Fieroboy_gt

An it worked . Now i just need too go and buy another 2 gallons of ATF lol. so it was the filter sucking air from the of the canister. hich is better then having to rebuild a tranny.

oldcutlass

Glad you figured it out and that it was a simple fix.

MDchanic

As we said earlier, it had to be associated with the last thing you did, which pretty much narrowed it down to installation error, such as a misplaced O-ring (likely) or a defective part (highly unlikely), and in the end, thankfully, it was something painfully simple.

I would make one request, as I suggested earlier:
When you finally replace the defective filter with a proper one, please come back to this thread and let us know how the JBWeld held up - was it soft if you pressed it with a screwdriver, could you peel it off if you got a knife under it, etc.
This could be helpful information for someone in the future.

Oh, and post a few pictures of that FrankenFiero when you get a chance - We'd love to see it!

- Eric

Fieroboy_gt

I plan on it, an I accually plan on sticking around this forum. I may only have a oldsmobile tranny but that's like 50% of a running car an u guys are very informative. I will try an get a couple pictures tomorrow morning once I clean up some of this ATF fluid. But I'm Def sure I will have a lot more tranny questions in the future

Fieroboy_gt

Its not pretty or clean yet , an the motor is covered inn antifreeze, tranny fluid and fiberglass dust. but it left the garage. so the tranny is working . It still takes a minute or two for it to go in too gear when you first start it . i was hoping the new modulator valve would fix that but it didnt unfortunately .