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Hello,
I'm George from Austria and have the following problem with my Ultramatic gearbox.

After I got my 1951 250 convertible with Ultramatic gearbox out of the winter garage, I noticed that the direct drive clutch in the gearbox was slipping.

I have now checked the oil level and the setting of the throttle valve lever and found no fault.
According to Ultramatic drive trouble shooting and corrective measures, I have carried out the following hydraulic tests:
- Front pump regulated pressure test, OK
- Hydraulic governor pressure test, OK
- Direct drive clutch pressure test, OK

During the converter inlet pressure test, I noticed that the pressure in the converter does not drop to max. 22 psi in direct gear and with the clutch engaged, as described in point 30b on page 46 of the Ultramatic workshop manual, but only drops from 70 to 55 psi (see attached photos).
It says to check the converter inlet valve and clean the converter outlet valve.

Now I have the following questions:
where is the converter outlet valve located, I can find it on the sequence of hydraulics operations, but I can't find it on my transmission?
Where exactly is the converter inlet valve located and what could be the fault?
Is it possible to remove the hydraulic unit when the transmission is installed or is that not possible?

I'm in a hurry as I'm starting next weekend at the Ennstal Classic, a very demanding classic car rally in the Alps!

I hope you can help me here!

Many thanks and best regards from Austria

George

Attach file:

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Ultramatic.zip Size: 2,715.00 KB; Hits: 3

Hello,

If you jack the car in the air, you can drain the transmission fluid then remove the pan. I would advise buying a new pan gasket if yours is the original cork as it probably won't seal well when re-attached. Also on replacement, be sure to follow the torque spec which I think is 11 ft lbs.

Once the pan is off you can take some thin pieces of sheet metal and stick them above the two pistons. Just cut to size and drill a hole in it to mount on a pan bolt hole.

This is explained on p. 27 of this:https://packardinfo.com/xoops/html/modules/archive/content.php?ContentID=49

Then take the pistons and valve body off. Disassemble the upper valve body and inspect all the valves and springs. See page 12 of your service manual.

The converter outlet valve was simply deleted in the later first gen Ultramatics, so yours may not even have one. If you do, since your pressure is too high, yours may have some problem. First see if there is any problem in the upper valve body, as the converter inlet valve / relief valve could cause this problem if it sticks; it would supply full pressure even when the direct circuit is engaged. If you reassemble after service and nothing changed, you may want to try the outlet valve modification here:https://packardinfo.com/xoops/html/downloads/STB/50T-61.pdf

You may also want to blow some compressed air through your cooler lines to check for obstructions. Just set the pressure to no higher than 15 PSI so there is no chance to hurt the cooler.

You asked which valve is which. Please see starting on p. 15 in my link above. Also see these charts:https://packardinfo.com/xoops/html/modules/newbb/dl_attachment.php?attachid=1697223399&post_id=262827

Overall, I think it's most likely that your converter inlet valve is sticking or there is a problem thereabouts.

Also check out the article starting on page 11 about the new torque converters for 52. Your 51 probably has the original design but could have the new style direct drive clutch converter if problems developed in the splines on the old style driving piston plate. If yours is still original the article mentions splines causing problems on release but as I recall there are other articles saying problems with DD engagement could be an issue if the splines on the DD plate were sticking or had developed wear or gouges.