Big redo of the old bucket

[Gerry]

That's because when you turn the motor off the fluid level rises. It does this on all transmission and its the reason you always check the level with the engine running. The reason they have a vent at the top (or inside the bell housing) is because its gets it away from the fluid.... go figure.

If your vent (breather) was blocked then the fluid would be pouring out of the sight glass as soon as you fired the engine up.

Get rid of the sight glass and stick to a dip stick. Its a nice idea, but it doesn't work. If thats the level without the engine running then its far too low. WOT etc doesn't count for squat. The trans needs the correct level irrelevant of how you use the car.

Course, what do I know?

 

[PotvinGuy]

Blimey, thanks, Gerry. Do we know why the fluid level rises on shut off? I'm gonna guess that the pump suddenly stops sucking, but the converter and tranny guts are still draining back into the pan. Check this professional diagram I found:

I just tried something; I took out the dipstick. Now when I shut off, the trans level (as seen in the sight glass) rises ~1/2" (say 1 cm metric, which we still don't use here in the colonies) and then drops back to the normal level. Pulling the dipstick apparently relieves the internal trans pressure which would normally go out the vent (I don't seem to have one of those). I think if I get a proper vent I'll be OK. Or I can replace the dipstick with a tiny breather....which will make people shake their head. I fancy that.

I've been poking around the net and the consensus seems to be that the fluid level should be around the pan/trans interface. Not sure if that is hot or cold.

 

[Gerry]

I will leave you to it, then

 

[Indycars]

WOT etc doesn't count for squat.The trans needs the correct level irrelevant of how you use the car.

It will if the pump start pulling air!

 

[Lee_in_KC]

The guy who rebuilt my TH350 (he builds drag racing transmissions as a side business... his day job is heavy equipment mech for a local crane and rigging outfit) told me that a TH350 will drain about 3 qts. of fluid back to the bottom of the tranny on shutdown, most out of the convertor. He said the fluid level should be at the pan rail when the motor is running and tranny is in neutral or park.

 

[Snicklefritz]

fascinating stuff. my appreciation to those willing to experiment.

 

[PotvinGuy]

Welcome. Snickle! I live to figure out how things work and how to do new and different stuff. Why be normal? I think many of the bucketeers feel the same.

 

[Pushrod]

I agree with PotvinGuy, learn from other guy's buckets, but don't be influenced by them......make yours to your own individual taste. That's what makes this hobby so great!

 

[T-Test]

STOP!! I've just had a bad experience with my wonder gadget. When I turn off the motor, the trans fluid goes all the way up on the sight glass and spurts out the port at the top. And it spurts a lot! Well, what the what? The fluid is obviously under pressure. Perhaps when the motor is shut off the trans pump keeps spinning for a while? Or the fluid pressure in the body needs time to go away? Any TH400 experts out there please chime in now. And I just noticed that my trans doesn't have a vent on top! That doesn't seem right. Would the lack of a vent cause what I'm seeing? How can I add a vent? Just drill a hole somewhere up top? Or does the vent go somewhere special in the trans?

Yes, lack of vent is the problem. Vent should be on passenger side of tranny at about the top of front pump level on the exterior of the case. Most TH400 have a 90* metal tube inserted in the case. Look for a small indentation(flat spot) on the case and see if it has a plug of some kind or it has been filled in with putty/weld. I have never seen an automatic transmission without a vent for that very reason.

Good luck

 

[Indycars]

Like T-Test said .....check the vent hole!



Maybe you will need to go to a longer/higher sight glass, the one below is 4-1/4 inches. I kinda like these with the drain included.

https://www.mscdirect.com/product/details/56477458
https://www.mscdirect.com/product/details/56477441?item=56477441
https://www.mscdirect.com/browse/tn...ed-Oil-Level-Indicators-Gauges?navid=12107684

 

[PotvinGuy]

Indy, you are hereby promoted to guru status. MSC, of whom I'd never heard, has all kinds of neat stuff and I really like that longer sight glass with drain. Need to get from 3/8 NPT down to 1/8 NPT to fit my pan bung, but big deal. Stand by for more info re my setup and some pan secrets known only to Illuminati members.

 

[PotvinGuy]

Yes, lack of vent is the problem. Vent should be on passenger side of tranny at about the top of front pump level on the exterior of the case. Most TH400 have a 90* metal tube inserted in the case. Look for a small indentation(flat spot) on the case and see if it has a plug of some kind or it has been filled in with putty/weld. I have never seen an automatic transmission without a vent for that very reason.

Yep, someone (who, me?) covered over the vent with epoxy while grinding on the case to make it pretty. But the dipstick tube seems to serve the purpose. More testing and results to follow.

 

[Indycars]

Indy, you are hereby promoted to guru status. MSC, of whom I'd never heard, has all kinds of neat stuff and I really like that longer sight glass with drain. Need to get from 3/8 NPT down to 1/8 NPT to fit my pan bung, but big deal. Stand by for more info re my setup and some pan secrets known only to Illuminati members.

I would have been kissing up alot more if I knew you had the authority to give away Guru Status!

The only 1/8 sight glass is straight and no drain. You would need a street elbow to make it work.

https://www.mscdirect.com/product/details/56476955
https://www.mscdirect.com/product/details/55542609

Did you see the one that have a temperature gauge instead of the drain?
You have to go 1/2" NPT to get a 4-1/4" gauge thou.

 

[PotvinGuy]

I just ordered the 56477441 and MSC had an adapter to go from 1/8 to 3/8. Will post when I get them. Oh, when you create an account with MSC, they give you a promo code for 25% off your first order. More goodies...like Xmas for geezers.

Oh, damn, those ones with temp gauges sure are tempting...

 

[2old2fast]

Yep, someone (who, me?) covered over the vent with epoxy while grinding on the case to make it pretty. But the dipstick tube seems to serve the purpose. More testing and results to follow.

E very so often I ask myself ," Are people really that dumb ?". Here's proof ..

 

[Intrepid]

I need to run a new vent line on my powerglide and I am wondering what did they use on stock vehicles to keep the dust out of the vent tube, I don't want to put some ugly old filter on there.

 

[Indycars]

I just ordered the 56477441 and MSC had an adapter to go from 1/8 to 3/8. Will post when I get them.

I really want to know just how fast it will drain the pan, it's looks like it would be slow, but hey I got the time

Do you have a MSC local or are you shipping to the house? The one I want is in stock and they are also local.

Oh, when you create an account with MSC, they give you a promo code for 25% off your first order. More goodies...like Xmas for geezers.

I better save up a wish list and make that 25% count on the first one.

 

[PotvinGuy]

Shipping to me. Wish I'd thought of that...would've got one with the temp gauge too.

 

[Indycars]

Maybe we were twins that went to different high schools together! hehehe !!!

 

[PotvinGuy]

Maybe we were twins that went to different high schools together! hehehe !!!

Oh, are you a shape-shifting multi-dimensional gelatinous blob, too? I thought I had this planet all to myself...