Bonez
Well-known member
Funny I was just wondering if that would work.
Mustang 1700 Reset
- Thread starter jonesallu
- Start date
OP
OP
Hi @stevec,
I'm back and was able to rewatch your videos on a computer screen. I'd like to post some content here on the charge pump and the bypass valve, and what I think is going on - in the hopes that it helps others along the way. If you don't want to read this, here's what I think: I think your by-pass valve is fine, it's not designed to prevent internal leakage, it's designed to keep a steady 50 psi behind it in the direction of flow.
Here's a little technical content on the Ford C-4 transmission - your charge pump (which is normally called a pressure pump), torque convertor, bell housing, etc. are all Ford C-4 parts. The charge pump produces fluid pressure up to 300 psi. **Line Pressure** from the pump can spike to 150 to 200 psi and is used in the C-4 transmission case to control shifting, clutch pressure, etc. In our case, it is killed (0 psi) by passing it back to the final drive cavities. The **charge pressure** is a reduced pressure that is used to fill the torque convertor and keep it "coupled" to the pinion gear. In this case, it's a preset design pressure to maximize performance, longevity (I hope), etc. - it does not physically "lock-up" the torque convertor. What's the pressure? In our case, I think it's 50 psi. It gets a little more complicated in that all 1964 to 1981 charge pumps have a built-in 90 psi by-pass valve to protect the torque convertor from "ballooning". If the torque convertor sees over about 100 psi, it stretches in the direction of the crankshaft and will wipe out the thrust bearing in short order. I think the charge pump cast adapter is way more beefy so I wouldn't expect any damage in that direction. So, OMC installed that little 50 psi bypass valve and that is the pressure used in the torque convertor. That's why they harp on keeping it adjusted. Too little pressure, it will prematurely wear out the friction materials in the torque convertor by slipping too much. To much, and ballooning can occur.
With all that, some fluid leakage across the valve (like years) shouldn't be an issue **as long as there is 50 psi behind the valve** as that is what is feeding the torque convertor through another passage in the cast adapter. From what I could see, the ball in your valve is in better shape than mine. So I think leakage at pressures below 50 psi is fine as long as that pressure is maintained. So I actually think your valve is fine as long you can adjust a constant bypass pressure across it. If you do lap it for a better seal, I think you'll have a better product.
My suggestions for you: First, put your pressure gauge right up at the valve where it needs to be, then increase pressure across the valve and adjust it to 50 psi. Then check the valve up to about 100 psi to make sure it doesn't develop any additional pressure behind the valve. My valve leaked internally too, and it looks like about the same as yours, but that little of fluid bypass shouldn't hurt anything. I've seen pictures on the internet where people permanently install a pressure gauge at that little valve, so that tells me it's that much more important. And yes, JB Weld or do something with the triangular hole in the valve body. I'd suggest removing the fitting, cleaning the body really good and inspect it. You mentioned a crack and now is a good time to address it. I did not see at what pressure your valve was initially set at. Do you know? That would help your diagnosis. I also hope you're aware that all this (pump, valve, convertor, etc.) do not have a formal filter. It's supposed to pass through a screen in a brass housing before entering the convertor stuff. Did you take that apart to see if it's restricted? One guy I talked to said his was and after he cleaned it, it solved a lot of problems. The C-4 transmission has 40 micron filter but the screen is way bigger than that. I guess OMC was going to rely on the volume of filtered fluid through the high pressure hydraulic system.
I hope this detail helps. If you ever have to get into your charge pump, let me know and I'll post more detail and photos that might help. What I know about this stuff is luck. I'm resto-fying a 1971 Ford Bronco for my wife and swapping the manual 4 speed for... a built C-4 transmission, and overhauled the transmission myself. Total coincidence.
If anyone has suggestions, changes or corrections, let me know and I'll make them.
Good luck!
Al Jones
I'm back and was able to rewatch your videos on a computer screen. I'd like to post some content here on the charge pump and the bypass valve, and what I think is going on - in the hopes that it helps others along the way. If you don't want to read this, here's what I think: I think your by-pass valve is fine, it's not designed to prevent internal leakage, it's designed to keep a steady 50 psi behind it in the direction of flow.
Here's a little technical content on the Ford C-4 transmission - your charge pump (which is normally called a pressure pump), torque convertor, bell housing, etc. are all Ford C-4 parts. The charge pump produces fluid pressure up to 300 psi. **Line Pressure** from the pump can spike to 150 to 200 psi and is used in the C-4 transmission case to control shifting, clutch pressure, etc. In our case, it is killed (0 psi) by passing it back to the final drive cavities. The **charge pressure** is a reduced pressure that is used to fill the torque convertor and keep it "coupled" to the pinion gear. In this case, it's a preset design pressure to maximize performance, longevity (I hope), etc. - it does not physically "lock-up" the torque convertor. What's the pressure? In our case, I think it's 50 psi. It gets a little more complicated in that all 1964 to 1981 charge pumps have a built-in 90 psi by-pass valve to protect the torque convertor from "ballooning". If the torque convertor sees over about 100 psi, it stretches in the direction of the crankshaft and will wipe out the thrust bearing in short order. I think the charge pump cast adapter is way more beefy so I wouldn't expect any damage in that direction. So, OMC installed that little 50 psi bypass valve and that is the pressure used in the torque convertor. That's why they harp on keeping it adjusted. Too little pressure, it will prematurely wear out the friction materials in the torque convertor by slipping too much. To much, and ballooning can occur.
With all that, some fluid leakage across the valve (like years) shouldn't be an issue **as long as there is 50 psi behind the valve** as that is what is feeding the torque convertor through another passage in the cast adapter. From what I could see, the ball in your valve is in better shape than mine. So I think leakage at pressures below 50 psi is fine as long as that pressure is maintained. So I actually think your valve is fine as long you can adjust a constant bypass pressure across it. If you do lap it for a better seal, I think you'll have a better product.
My suggestions for you: First, put your pressure gauge right up at the valve where it needs to be, then increase pressure across the valve and adjust it to 50 psi. Then check the valve up to about 100 psi to make sure it doesn't develop any additional pressure behind the valve. My valve leaked internally too, and it looks like about the same as yours, but that little of fluid bypass shouldn't hurt anything. I've seen pictures on the internet where people permanently install a pressure gauge at that little valve, so that tells me it's that much more important. And yes, JB Weld or do something with the triangular hole in the valve body. I'd suggest removing the fitting, cleaning the body really good and inspect it. You mentioned a crack and now is a good time to address it. I did not see at what pressure your valve was initially set at. Do you know? That would help your diagnosis. I also hope you're aware that all this (pump, valve, convertor, etc.) do not have a formal filter. It's supposed to pass through a screen in a brass housing before entering the convertor stuff. Did you take that apart to see if it's restricted? One guy I talked to said his was and after he cleaned it, it solved a lot of problems. The C-4 transmission has 40 micron filter but the screen is way bigger than that. I guess OMC was going to rely on the volume of filtered fluid through the high pressure hydraulic system.
I hope this detail helps. If you ever have to get into your charge pump, let me know and I'll post more detail and photos that might help. What I know about this stuff is luck. I'm resto-fying a 1971 Ford Bronco for my wife and swapping the manual 4 speed for... a built C-4 transmission, and overhauled the transmission myself. Total coincidence.
If anyone has suggestions, changes or corrections, let me know and I'll make them.
Good luck!
Al Jones
I'll have to read this multiple times and give it some thought. I was convinced the valve was causing the weak movement of the machine after learning of this from you. I originally removed the engine and transmission to replace the seals that appeared to be leaking from the charge pump and axle seals coming out of the gearbox. Before I knew about the bypass valve I was thinking this weak movement of the machine was from leaking seals.
I have cleaned out the brass charge pump inline filter screen, it wasent to bad thou.
Thank you for you help. Steve
I have cleaned out the brass charge pump inline filter screen, it wasent to bad thou.
Thank you for you help. Steve
OP
OP
Hi Steve,
Anything to report back on? I'm about to stab my new torque convertor in the bell housing and was wondering if I should give the valve more respect than I have. Anything you can share is greatly appreciated.
Thanks,
Al
OP
OP
Time for an update. I'm still working on the dang brakes. The linings have been a bear to deal with. I thought a propane or MAP torch would melt the adhesive to remove the linings. No way. So I broke out my PPE and am manually removing the linings. Here's where I am, note the new linings were predrilled:
The instrument panels are finished. That took much longer than I thought. I had to de-rust my electrical skills.
Left side:
Sorry, I can't find an underneath picture.
Right side. If you enlarge the photo, you'll see two diodes that were needed to prevent back feeding through the safety system (master override, seat, seat belt, door and backup alarm):
Installed:
Al Jones
Brookings, SD
The instrument panels are finished. That took much longer than I thought. I had to de-rust my electrical skills.
Left side:
Right side. If you enlarge the photo, you'll see two diodes that were needed to prevent back feeding through the safety system (master override, seat, seat belt, door and backup alarm):
Installed:
Al Jones
Brookings, SD
Last edited:
OP
OP
I reached my 10 picture limit on that last one so here are more updates.
I'm working on mounting the other end of the electricals: two load centers, two buss bars, two master circuit breakers, door switch, backup alarm trigger switches (both operator levers need to be pulled back to turn on the backup alarm, unless the override switch is on), backup alarm, camera, and horn.
If you look at past photos, I was using the Ford dark blue on Ford parts. It looked almost black. Here's a photo of all three Ford engine colors. The "Ford Blue" matches the torque convertor and other engine bits so I'm switching to that color.
The seat came in and is installed. It is one inch narrower than stock. It has a switch in the "seat". I wish I could find a reasonably priced in-line delay timer of about 5 seconds to put in that circuit. That's how my New Holland tractor works and I like having 5 seconds to get my butt back in the seat before it kills the engine. Any suggestions?
Note I'm using two right hand operating levers. The right side will have the complicated throttle mechanism in it and the left will have something that looks like this
as I want capabilities for other things down the road. One button is reserved for the horn.
Al Jones
Brookings, SD
I'm working on mounting the other end of the electricals: two load centers, two buss bars, two master circuit breakers, door switch, backup alarm trigger switches (both operator levers need to be pulled back to turn on the backup alarm, unless the override switch is on), backup alarm, camera, and horn.
If you look at past photos, I was using the Ford dark blue on Ford parts. It looked almost black. Here's a photo of all three Ford engine colors. The "Ford Blue" matches the torque convertor and other engine bits so I'm switching to that color.
The seat came in and is installed. It is one inch narrower than stock. It has a switch in the "seat". I wish I could find a reasonably priced in-line delay timer of about 5 seconds to put in that circuit. That's how my New Holland tractor works and I like having 5 seconds to get my butt back in the seat before it kills the engine. Any suggestions?
Note I'm using two right hand operating levers. The right side will have the complicated throttle mechanism in it and the left will have something that looks like this
as I want capabilities for other things down the road. One button is reserved for the horn.
Al Jones
Brookings, SD
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Hi Al, well I've put my machine back together and still stalls the axle when under load. I put an in-line pressure gauge at the high pressure input of that relief valve. After lapping ball and seat and adding a missing o-ring on the backside of the seat it now works well with air test.... but the pressure gauge barley moves with about 3 lbs of input pressure.
I'm going to have to remove engine and pump again and look at the two seals on the back side of the pump did not change. Also I think I'll take converter to a shop to be tested but the real problem is input high pressure. Thoughts...
Stev
