Hello,
I’ve been fighting a leak after installing a RMVB on my 1968 b-body 440. The history is no leaks with the auto valve body for the last four years. After installing the new valve body, there where no leaks when filling it at idle in park, neutral, or in gear. Fluid level was verified in neutral when warm. So I take it out for a ride and return to a trail of fluid up my driveway and 6-8” puddle dripping from the bell housing. I’ve verified it’s all coming from the bell housing and not the pan, dipstick tube, or gearshift seal.

I ended up pulling the trans and as expected the bell housing had a puddle inside below the pump. I’ve pressure tested the torque converter, inspected the bushing and front seal (plan to replace the seal anyway) and checked pump bolt torque with no issues found. On top of that, I find it hard to believe one of these things went bad right when I installed the new valve body.
Did I overfill it and it’s just puking out the vent?
Does the vent need to be moved to the rear with the new manual valve body?
I’m no trans expert, but could there be a pressure problem with the new valve body? I did check line pressure and it’s around 185 in neutral which seems ok.

Any help is appreciated before I reinstall the trans and have the same problem.

Thanks!
Jeff

hi

front seal or over filed or if this is a car that runs 10 sec and you have a heavy braking surge you need to move vent !

Run it awhile and see. No reason for it to start leaking. I've run them with vents in the stock location. Next time the trans is out you can move it to the rear.
Doug

****UPDATE***

Before putting the trans back in, I moved the vent to the rear and replaced the front seal where the torque converter slides in. After putting it all back together, idling it, and driving the car like grandma, there were no leaks. The first time I drive it a little harder, its leaking as it did before I pulled the trans. Still leaking from the bell housing and appears the fluid is being spread by the converter as it is running from the upper right corner where the inspection cover meets the block.

I'm starting to think it has a hairline crack in the converter that only leaks under higher loads? The converter is from Dynamic and is about 4 years old.

Any input is appreciated.
Thanks!

I just went through something similiar. I had the trans in and out 2 or 3 times trying to fix a leak from the bellhousing. Only when the converter made a puddle laying on the garage floor did I figure that out. It was not obviously leaking anywhere but the converter will leak fluid out the engine side when placed snout up. I just put in another converter and it fixed my problem. Frustrating to say the least!

The leak is it coming from the converter pilot do you think?Have you checked the pilot thickness?

Sounds like the time I had a converter snout crack on a 904.
Under power, ATF sprayed out of it.
Never a drop loading the car or warming it up in the pits.

Based on your timeline for the leak, make sure you are checking fluid level in neutral if it is a valve body that charges the converter in neutral. Some race valve bodies don’t.

If you are not sure then check it in gear. If the fluid is high it will leak out the pump vent. I see you moved the vent but did you plug the original?


As for leak disgnosisi, once the leaks start it’s pretty hard to determine where it’s coming from.

I would start by cleaning the front of the converter then get some carb or brake clean and clean the bell housing the best you can and let it dry overnight. Make sure the back of the converter is clean and dry too.

Start it up and see if a leak develops.

Fluid leakage out of the bell but dry converter is either the pump seal, vent, pump bolts. The large perimeter seal can leak too but that’s usually low man on the totem pole.

Wet back side of the converter could be a closure weld (where the two halves of the converter are welded together), cracked impeller hub, and remotely possible but a bad pump seal from a spun pump bushing.

Front of the converter would likely be the pilot to the crank, not very common.


How did you check the converter for leaks. Only time tested method is to pressurize it under water.

One other thing that could cause a leak in the bell area, if someone installed a speedy sleeve on the converter impeller hub and didn't use a sealer between the sleeve and hub, fluid could be forced between them and look like a seal leaking.

Yes, the front vent was plugged when moved to the rear.
The converter is dry but lots of fluid around the input seal, pump seal, and pump bolts.
I just finished pressure checking the converter (up to 30psi) and found no cracks or leaks.
One thing I do notice is the converter snout has some uneven wear. Not sure if this is normal or not?
I guess next step is to pull the pump and replace the bushing and all the seals?
What is acceptable amount of wear on the converter snout before it needs to be reworked?

I would replace the pump bushing and seal. Hard to tell in the picture but the hub looks like it has a lot of runout. Max I think is .008”.

Your first pic has litle wear, then the next has more and so on. The other possibility is when you pull the converter up to the flex plate and in to the crank, that it’s bound in the crank pilot. When you install the converter bolts if it doesn’t seat itself this will contribute to excessively runout as well. Always lightly grease the crank pocket then pull the converter then start the bolts with your fingers but don’t tighten them until they are all statted. Then work your way around while snugging the bolts up.


For runout - hard to check in the field but if you had an old flywheel and laid it flat then laid the converter on it, turned the converter while you had a dial indicator on the hub, you should get < .008”. Of course this won’t work unless the flywheel is held on center.

I also see where the impeller hub has weld that looks like it’s been hitting something, I assume that is old and not new.

You also say leaks at bolts and both seals. Perimeter seal and Input seal are both wet ?

Nice pressure test setup- can’t get better than that.

Yes, I'll replace the bushing and seal. I've never pulled a front pump but I'll see if I can find some experience to do the job or help out. Should I also get the hub of the converter replaced? It does have a small step in it when run my finger across it.

As for the converter pulling up to the flex plate, I noticed recently that the converter bolt blocks are not flush against the flex plate when fully seated into the crank. I can however feel and hear the converter hub bottoming out into the crank. I did a quick measurement, seams excessive ~ .050". I think it needs a spacer added between the two. Are you thinking the excessive run out wear is causing the leak? I just don't understand why it all happened when installing the reverse manual valve body.

I see the weld you are talking about but its just missing the paint. The picture makes it look like it was hitting something. It's an old weld that's not hitting anything.

The pump bolts, perimeter seal, and input seal all had fluid on them. I'm thinking is just the wind inside forcing the fluid everywhere inside the bell housing?!?? Has to be coming from one of the mentioned though. Frustrating.

Thank you on the pressure set up. I wanted to push the pressure higher but wasn't comfortable.

Thanks for all the responses and look forward to additional input.

Jeff

What you can do with the trans on the bench (after cleaning the bellhousing) is to install the converter and pressure test the assembly.
Stick the driveshaft in the extension housing, plug the dipstick tube opening with a rubber plug and c clamp, plug the cooler line fittings then pressure test the trans using the vent tube, don’t go higher than 3 psi. If you hear anything look for an obvious leak. Otherwise spray soapy water all over behind the converter then release pressure and pull the converter. Look for bubbles.

Or make a plug for the pump and pressure test again - you should be a lemon to see where your leak is.

As for the gap between the flex plate and converter bolt pads that is by design. Nothing wrong with .050” gap once the converter is bottomed out. If you can catch a nail on the hub it’s time for a hub.