TH400 Amateur Build
- Thread starter TXChevy
- Start date
I don't think so, the pump charge circuit has a separate bypass for the cooler lines. Also in this case, cooler and lines are all new and were checked to be clear.
I agree with you, pretty doubtful this was a root cause. I'm ordering a pump from ATI today.
Its a bit of a guess, but I don't want to put the unit back in without more security on the pump itself.
Rick had asked about priming and I think I can verify fluid to the cooler lines and pressure port while on the stand.
I might be wrong, but ID very sparingly (maybe a couple table spoons worth at most) dribble some assembly lube/atf mixed at about a 50%/50% rate over every moving component on the interior of the th400 trans pump, just to be sure nothing starts up (DRY)
I know from experience that doing so on an engine oil pump tends to make it prime much faster than it will with a dry/clean new pump.
it will be almost instantly flush out once the trans fluid start flowing but it should prevent galling or binding in the first minute or two.
I know from experience that doing so on an engine oil pump tends to make it prime much faster than it will with a dry/clean new pump.
it will be almost instantly flush out once the trans fluid start flowing but it should prevent galling or binding in the first minute or two.
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It's not tedious to us gearheads. We like solving problems, especially when it's someone else's.
I read thru both your posts carefully and I don't have anything to add. Buying a new pump would certainly be the easiest route if it's not too expensive.!
Yes I had done that, combo of atf and assembly lube, not packed in there but enough to keep everything lined and to hopefully help the prime. But tons of pumps are installed right out of the box without issue. I'll add fluid to the new assembled pump thru the charge port though.
It wasn't a huge hit but still hated to spend more. Bought the th400 standard pump from ATI. They manufacture or rebuild in-house, and I also got a new PR valve. Total was about $360. I can install the Sonnax booster valve into this new pump.It's not tedious to us gearheads. We like solving problems, especially when it's someone else's.
I read thru both your posts carefully and I don't have anything to add. Buying a new pump would certainly be the easiest route if it's not too expensive.!
As you had mentioned, I'm going to see if I can prime the pump on the stand before installing.
In the meantime, I'm still checking things.
I went through the hydraulic circuits, checked all the valves in the valvebody, everything was correct and moved freely. Air checks from the case side of the VB were all ok and the VB gaskets/separator plate were all ok.
I found an issue with the valve behind the vacuum modulator though. Can't say this was the root cause but I think it would have contributed to the pressure problem.
It was jamming in the case bores. Enough that you had to push it in with your finger. I couldn't remove it with a magnet, I also had to use a small screwdriver to gently pry on it. I then remembered I had noticed this at teardown and noted that I needed to address it. I did not do this, guess I forgot.
This is where it had to be pushed in, wouldn't just easily slide.
And this is fully inserted. You should be able to use a magnet to easily remove the valve, but it would only pull out slightly, then jam. I had to carefully pry on it to remove.
Hard to see but this valve impacts several circuits, including line pressure. If it can't fully and easily move, the line pressure partially exhausts to the wrong circuits.
The lands move in and out of the walls of the VB, allowing fluid to move from one circuit, closing off others.
Doing some research, it's not unheard of, the fix sounded crazy but it worked great. You seat the valve fully, then very lightly tap on the body (not the machined lands). Remove, turn it and repeat. Finish off by giving the lands a light touch of 600 sandpaper lubed with fluid. Didn't take much and this worked fantastic, the valve now moves freely and easily.
I then installed the VB, using the ATSG book as my checklist again, not trusting it all to memory.
Checkballs in place.
VB installed and torqued.
Checked that the gaskets were correctly located. There's a "C" cut into the gaskets that goes against the case.
Also making sure the manual valve is correctly meshed with the selector.
New pump will arrive next week, I'm planning to verify pump priming and get this unit back into the car.
I know I could guess about the pump, but I don't see the modulator valve as the sole problem. I'm ok with getting a new pump - too much work to try the old pump again.
Edit - speaking of the old pump, I installed the gears in the correct orientation, aligned the halves and torqued the bolts. I'll pull the Teflon seals, wrap it up and put it on the shelf. This inexpensive pump clamp works well for the occasional use.
And to be as close to 100% on the suction side, I got a new pickup tube. I know they are made in steel, this one was available, should work ok. Filter is the screen type.
I found an issue with the valve behind the vacuum modulator though. Can't say this was the root cause but I think it would have contributed to the pressure problem.
It was jamming in the case bores. Enough that you had to push it in with your finger. I couldn't remove it with a magnet, I also had to use a small screwdriver to gently pry on it. I then remembered I had noticed this at teardown and noted that I needed to address it. I did not do this, guess I forgot.
This is where it had to be pushed in, wouldn't just easily slide.
And this is fully inserted. You should be able to use a magnet to easily remove the valve, but it would only pull out slightly, then jam. I had to carefully pry on it to remove.
Hard to see but this valve impacts several circuits, including line pressure. If it can't fully and easily move, the line pressure partially exhausts to the wrong circuits.
The lands move in and out of the walls of the VB, allowing fluid to move from one circuit, closing off others.
Doing some research, it's not unheard of, the fix sounded crazy but it worked great. You seat the valve fully, then very lightly tap on the body (not the machined lands). Remove, turn it and repeat. Finish off by giving the lands a light touch of 600 sandpaper lubed with fluid. Didn't take much and this worked fantastic, the valve now moves freely and easily.
I then installed the VB, using the ATSG book as my checklist again, not trusting it all to memory.
Checkballs in place.
VB installed and torqued.
Checked that the gaskets were correctly located. There's a "C" cut into the gaskets that goes against the case.
Also making sure the manual valve is correctly meshed with the selector.
New pump will arrive next week, I'm planning to verify pump priming and get this unit back into the car.
I know I could guess about the pump, but I don't see the modulator valve as the sole problem. I'm ok with getting a new pump - too much work to try the old pump again.
Edit - speaking of the old pump, I installed the gears in the correct orientation, aligned the halves and torqued the bolts. I'll pull the Teflon seals, wrap it up and put it on the shelf. This inexpensive pump clamp works well for the occasional use.
And to be as close to 100% on the suction side, I got a new pickup tube. I know they are made in steel, this one was available, should work ok. Filter is the screen type.
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Of course, I appreciate it!
Just saying I've tried to see where it went wrong, I hate not finding an obvious break lol.
Pump .......
The new pump from ATI arrived (it's actually a refurbished pump with new gears and cleaned up lube channels). I had also bought a new pressure regulator spool valve along with it, although in hindsight, the original one was probably ok. It also included new teflon sealing rings, same as I had put on the old pump during the rebuild.
I set about checking things.
First up was to set the new pump onto the converter to check fit. All was good.
I also verified full seated depth for later when the transmission was in the car.
I poured a bit of ATF into the pump inlet and rotated the pump on the converter in the direction of engine rotation.
Encouraged to see the ATF gurgle out of the line pressure port of the pump.
I then installed the new pressure regulator spool valve and the Sonnax 400-LB1 boost valve/spring kit.
The Sonnax kit had been installed into the old pump.
Here's the difference in the oem boost valve sleeve vs the Sonnax sleeve - you can see the o-ringed Sonnax sleeve, which also includes a larger diameter boost valve inside it.
Everything installed.
Made very sure the snap ring orientation was correct (bevel edge up) and that the snap ring was fully seated into the groove.
New AC Delco pickup tube (bottom) with double o-rings. I was borderline on getting a new one, but wanted to be sure that there weren't any hairline cracks I might have missed. The new pickup tube was a tight fit into the case.
I used the teflon rings that I had, probably nothing wrong with the ones supplied.
Note the plastic thrust washer - I rechecked front endplay with the new pump, used the same .094 thrust washer to end up at .012 endplay.
I would have liked .009-.010 endplay, but didn't have the thrust washer combo to make that work. .012 is still within the .007-.019 spec.
I used the "old" pump gasket, so the endplay was taken with a compressed gasket.
Then, a new gasket, hopefully I won't have to see it again. Pump got a new o-ring.
I could probably have re-used the gasket and o-ring that I had, but these are cheap enough to just get new ones.
And the new pump was set into place.
Before installing the pan, I inserted the converter and put the pickup tube into a small cup of ATF.
I rotated the converter to see if I could get the pump to draw ATF from the cup and maybe get a few drops out of the cooler fitting.
I could hear some gurgling and some fluid was pulled from the cup, but I don't think my spinning was in the realm of 650-800 rpm idle speed.
At this point I felt that I had done everything I could to check and hopefully correct the zero-pressure problem.
The new pump from ATI arrived (it's actually a refurbished pump with new gears and cleaned up lube channels). I had also bought a new pressure regulator spool valve along with it, although in hindsight, the original one was probably ok. It also included new teflon sealing rings, same as I had put on the old pump during the rebuild.
I set about checking things.
First up was to set the new pump onto the converter to check fit. All was good.
I also verified full seated depth for later when the transmission was in the car.
I poured a bit of ATF into the pump inlet and rotated the pump on the converter in the direction of engine rotation.
Encouraged to see the ATF gurgle out of the line pressure port of the pump.
I then installed the new pressure regulator spool valve and the Sonnax 400-LB1 boost valve/spring kit.
The Sonnax kit had been installed into the old pump.
Here's the difference in the oem boost valve sleeve vs the Sonnax sleeve - you can see the o-ringed Sonnax sleeve, which also includes a larger diameter boost valve inside it.
Everything installed.
Made very sure the snap ring orientation was correct (bevel edge up) and that the snap ring was fully seated into the groove.
New AC Delco pickup tube (bottom) with double o-rings. I was borderline on getting a new one, but wanted to be sure that there weren't any hairline cracks I might have missed. The new pickup tube was a tight fit into the case.
I used the teflon rings that I had, probably nothing wrong with the ones supplied.
Note the plastic thrust washer - I rechecked front endplay with the new pump, used the same .094 thrust washer to end up at .012 endplay.
I would have liked .009-.010 endplay, but didn't have the thrust washer combo to make that work. .012 is still within the .007-.019 spec.
I used the "old" pump gasket, so the endplay was taken with a compressed gasket.
Then, a new gasket, hopefully I won't have to see it again. Pump got a new o-ring.
I could probably have re-used the gasket and o-ring that I had, but these are cheap enough to just get new ones.
And the new pump was set into place.
Before installing the pan, I inserted the converter and put the pickup tube into a small cup of ATF.
I rotated the converter to see if I could get the pump to draw ATF from the cup and maybe get a few drops out of the cooler fitting.
I could hear some gurgling and some fluid was pulled from the cup, but I don't think my spinning was in the realm of 650-800 rpm idle speed.
At this point I felt that I had done everything I could to check and hopefully correct the zero-pressure problem.
The Big Day - Round 2 ........
All dressed up for the party.
Before we installed it, I did remove the converter and made sure it was as full of ATF as possible.
It was re-installed and I verified that it was fully seated.
Installation was a repeat of Round 1. This time we left the exhaust off, in case this TH400 was coming back out and taken to a shop!
Converter clearance was 3/16, so I added a 1/16 washer at each bolt to pull converter 1/8 out from fully seated.
So after a lot of work and hair-pulling, here's the result........
Success!!
I'm a happy boy today - my conclusion was that the old pump wasn't working, maybe combined with the sticking modulator valve the result was no pressure. Regardless, it wasn't a parts throw with no results, whew. And I'm really glad we didn't try to continue to run it with no line pressure the first time.
Special thanks to Nick of Nick's Transmissions. Besides his videos, he's helped me directly with lots of advice. If he was closer, I'd have taken this unit to him, but he walked me through dozens of questions.
We started with 4.5 qts, then started it up and continued to add fluid. Line pressure came up immediately.
At 8 or 9 qts, I started to put it through the gear selections. It was slightly slow but remember that all the passages and clutch packs were filling up for the first time. We ended up at about 11 qts and it was going into gear very nicely, no drama, no whiplash. I ran it at a bit higher rpm, pressure changed instantly with rpms. Speaking of pressure, I'll need to go back and run it again. I did see stable 90-100 psi in Park and Neutral but can't remember what the other position pressures were. I think that Reverse yielded about 160-180 psi, but I need to check again. Honestly, I wasn't as focused as I should have been, so I'll do check it all again with a calmer state of mind.
Bear in mind though that this was just up on the stands, not a real driving test. That test remains but it's going to be after my back surgery.
And here's another video of open headers idle sound......
This was a good ending to a long story and I appreciate all the comments and input, hopefully it might help somebody.
I'll update a bit later at that first drive, but it won't be right away.
Thanks!
All dressed up for the party.
Before we installed it, I did remove the converter and made sure it was as full of ATF as possible.
It was re-installed and I verified that it was fully seated.
Installation was a repeat of Round 1. This time we left the exhaust off, in case this TH400 was coming back out and taken to a shop!
Converter clearance was 3/16, so I added a 1/16 washer at each bolt to pull converter 1/8 out from fully seated.
So after a lot of work and hair-pulling, here's the result........
Success!!
I'm a happy boy today - my conclusion was that the old pump wasn't working, maybe combined with the sticking modulator valve the result was no pressure. Regardless, it wasn't a parts throw with no results, whew. And I'm really glad we didn't try to continue to run it with no line pressure the first time.
Special thanks to Nick of Nick's Transmissions. Besides his videos, he's helped me directly with lots of advice. If he was closer, I'd have taken this unit to him, but he walked me through dozens of questions.
We started with 4.5 qts, then started it up and continued to add fluid. Line pressure came up immediately.
At 8 or 9 qts, I started to put it through the gear selections. It was slightly slow but remember that all the passages and clutch packs were filling up for the first time. We ended up at about 11 qts and it was going into gear very nicely, no drama, no whiplash. I ran it at a bit higher rpm, pressure changed instantly with rpms. Speaking of pressure, I'll need to go back and run it again. I did see stable 90-100 psi in Park and Neutral but can't remember what the other position pressures were. I think that Reverse yielded about 160-180 psi, but I need to check again. Honestly, I wasn't as focused as I should have been, so I'll do check it all again with a calmer state of mind.
Bear in mind though that this was just up on the stands, not a real driving test. That test remains but it's going to be after my back surgery.
And here's another video of open headers idle sound......
This was a good ending to a long story and I appreciate all the comments and input, hopefully it might help somebody.
I'll update a bit later at that first drive, but it won't be right away.
Thanks!
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congratulations on making significant progress!
I'm very impressed , I know rebuilding a transmission is far more complicated than what most guys can accomplish
wow, looking at that stacked lumber supporting the vehicle, I hope its sturdier than it looks,
wood stacks can certainly be more than strong enough,
but must be properly built, to support the weight and resist lateral shifting loads
I think it might be helpful if you get a chance, if you might want to buy 4 12 ton jack stands.
maybe I'm just paranoid
I certainly am concerned, but I've known a few guys that have been seriously injured ,
when cars/trucks fell or rolled back over them or on them for various reasons
I'm very impressed , I know rebuilding a transmission is far more complicated than what most guys can accomplish
wow, looking at that stacked lumber supporting the vehicle, I hope its sturdier than it looks,
wood stacks can certainly be more than strong enough,
but must be properly built, to support the weight and resist lateral shifting loads
I think it might be helpful if you get a chance, if you might want to buy 4 12 ton jack stands.
maybe I'm just paranoid
I certainly am concerned, but I've known a few guys that have been seriously injured ,
when cars/trucks fell or rolled back over them or on them for various reasons
under car safety
I had a guy forward me this info "I know we have all read and heard many a times,when you jack your car up to work on it PUT THE DAMN JACK STANDS UNDER THE CARS FRAME. Well I just got a call from my Aunt and Uncle that my cousin 2 years older than I am (and i'm 42)who's name is also Kevin was...
garage.grumpysperformance.com
mechanics creepers
one of the first tools most guys buy is a mechanics creeper,because they usually find it keeps them off the wet ,cold, rough, filthy or oil covered concrete surface thats all too common in many garage work areas, and lying directly on the floor under a car tends to let your shirt and hair act...
garage.grumpysperformance.com
A good tranny jack , makes all the difference.
A good tranny jack ,and decent jack stands makes all the difference. (BTW dont forget to use an engine crane or floor jack to support the engine while working on transmission removal) I recently helped a friend swap torque converters on his car, he doesn,t have a lift, but neither did I for...
garage.grumpysperformance.com
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Thanks Grumpy!
Yes I've got about 8 jackstands, all heavy duty. Those wood blocks are glued and screwed together, a foot square at the base. Super stable.
Rear axle is resting on jack stands and there's 2 more stands at the rear of the frame. Front wheels are resting on ramps. It's not going anywhere.
I always set at least 2-3 support points anytime I lift anything.
Transmission was installed using a proper transmission jack, went in slowly and solidly.
Yes I've got about 8 jackstands, all heavy duty. Those wood blocks are glued and screwed together, a foot square at the base. Super stable.
Rear axle is resting on jack stands and there's 2 more stands at the rear of the frame. Front wheels are resting on ramps. It's not going anywhere.
I always set at least 2-3 support points anytime I lift anything.
Transmission was installed using a proper transmission jack, went in slowly and solidly.
I appreciate your asking, I've done some sketchy stuff in younger days, learned my lesson.
Last Update till a later road test....
Ran the drivetrain again to get pressure readings:
- car up on stands, no back tires installed.
- fluid at dipstick full mark in Park, running.
- pressure gauge on rubber hose, I suspect the flexible (cheap chinese) hose contributes to some gauge oscillation.
- ATI 10 in converter
- Sonnax 400-LB1 boost valve kit
Pressure Readings:
Park - 80 to 100, higher reading is at idle
Reverse - 150 with axle turning, about 800-1000 rpm, 180-200 brakes on
Drive - 80-110 depending on rpm, axle turning
2 - 200-220 same criteria as Drive
1 - 190-210 same criteria as Drive
Momentary pressure fluctuation when shifting between settings, attributable to fluid filling or exhausting clutch packs/modulators.
When it's in Drive, even though it doesn't feel stuck in low gears, it's difficult to really feel 1-2-3 shifts as there's no vehicle weight or resistance.
From Nick's Transmissions:
"Those pressures look good. Shifting through the gears on the stands is only done to conduct the pressure test and validate it engages when shifted into Reverse and Drive...Beyond that, you won't feel much in the way of gear transitions since the vehicle isn't actually on the road surface."
So then, at this point, it looks like all is good. As mentioned, I'll post results later on after an actual road test.
Ran the drivetrain again to get pressure readings:
- car up on stands, no back tires installed.
- fluid at dipstick full mark in Park, running.
- pressure gauge on rubber hose, I suspect the flexible (cheap chinese) hose contributes to some gauge oscillation.
- ATI 10 in converter
- Sonnax 400-LB1 boost valve kit
Pressure Readings:
Park - 80 to 100, higher reading is at idle
Reverse - 150 with axle turning, about 800-1000 rpm, 180-200 brakes on
Drive - 80-110 depending on rpm, axle turning
2 - 200-220 same criteria as Drive
1 - 190-210 same criteria as Drive
Momentary pressure fluctuation when shifting between settings, attributable to fluid filling or exhausting clutch packs/modulators.
When it's in Drive, even though it doesn't feel stuck in low gears, it's difficult to really feel 1-2-3 shifts as there's no vehicle weight or resistance.
From Nick's Transmissions:
"Those pressures look good. Shifting through the gears on the stands is only done to conduct the pressure test and validate it engages when shifted into Reverse and Drive...Beyond that, you won't feel much in the way of gear transitions since the vehicle isn't actually on the road surface."
So then, at this point, it looks like all is good. As mentioned, I'll post results later on after an actual road test.
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