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Need help on an 1950 Pontiac Silver Streak
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By BigAl - Tuesday, May 04, 2010 9:44 AM
Hallo all

I have litell problem. I have an 1950 pontiac silver streak with an 8 cylinder flathead inline engine and with an automatic transmission. I want to change the transmission fluid but I am not really sure how. Perhaps someone of you know how this sould be made and can give some help.

thanks alot.

so long Arnd
By Bill White - Tuesday, May 04, 2010 10:48 AM
That has a drain plug on the converter take the bottum tin plate of and turn the motor over by hand till you see it if my memory is right it is 1/4 pipe size, Then take off the bottum pan on the trans.
If you nead I can look up in a Chilton or Motor manual I have both for that year.

Hope that helps
By BigAl - Tuesday, May 04, 2010 9:25 PM
Hi Bill

thanks for the quick help. OK how to drop the old fluid is clear. My question was not wright. I do not know how to fill the new fluid in and how much of it is need? 

So long Arnd
By john gott - Thursday, May 06, 2010 2:10 AM
I belive it takes 9 quarts (?), there should be a dipstick tube near the firewall for the tranny. Fill with about 5 qaurts, start the engine, let it run for a mniute or two, (allows the pump in the tranny to fil teh fluid coupling), stop the engine and put in the other 4 quarts. Check the level. You can use any DEXRON ATF fluid in the Hydramatic tranny.

John Gott
By BigAl - Tuesday, May 11, 2010 5:41 AM
Hi John

that is all clear but there is no dipstick tube near the firewall. So what then. Is there a special way for pontiac to fill up the trany fluid?

so long Arnd
By Wolfcreek_Steve - Tuesday, May 11, 2010 7:19 AM
My dad had a pontiac with a hydromatic back about 1960. I don't remember a long fill tube on that one either, possibly a removable cover on the floor pan similar to a master cylinder cover with the filler under it. (Just a guess as it was 50 years ago)
By mark h - Tuesday, May 11, 2010 8:35 AM
I have done this in a freind's '48 Pontiac with a straight 8 automatic, but that was a little over 15 years ago. So here it is straight from 1952 Motor's Auto Repair Manual.

1. Cover seat to protect upholstery and raise right side floor mat.

2. Remove transmission inspection floor hole cover. Clean all gravel, sand or lint from floor and around oil level indicator before it is removed.

3. Remove dipstick and wipe it clean. Clean dipstick cap air cleaner in solvent.

4. Pour approximately 8 quarts of fluid into transmission, being sure container, spout or funnel is clean.

5. Set selector lever in N position and apply hand brake. Run engine at a speed equivalent to 20 mph for approximately 1 1/2 minutes to fill fluid coupling.

6. Reduce engine speed to slow idle (carburetor off fast idle step).

7. Add sufficient fluid to bring fluid level up to just below the "L" mark on the dipstick. Again run engine at a speed equivalent to 20 mph for three minutes to heat fluid to near operating temperature, which is indicated by a rise in fluid level to near the "F" mark. Reduce engine speed to slow idle and add fluid to bring level to "F" mark. With engine idling and transmission warm, make a check to be certain transmission is not overfilled.

8. Stop engine, replace dipstick and cover in floor.

Hope this helps,

mark h
By BigAl - Tuesday, May 11, 2010 10:45 AM
hallo Mark

thanks alot for all tha infoprmation I will try it out right tomorrow.

so long Arnd
By Tatra - Tuesday, May 11, 2010 10:56 PM
I'm going to ask what may come out as a stupid question, but do the Pontiac fluid flywheel and tranny have different oil circuits? I have no experience with them but on some English semi-auto epicyclic transamissions (Daimler, SCG) the fluid flywheel was drained and filled seperately from the box (from experience). In some cases, the flywheel used engine oil (Daimler), the box normal transmission oil...

Only asking:)

Cheers & Tschus

By mark h - Wednesday, May 12, 2010 7:31 AM
Pontiac/Gm Hydra-matic transmission is a self-supplied unit. It does have a separate front & rear pump with their own pick up tubes/screens, but both are in the trans. pan. No external lines or cooler. The only engine oil that touches it, is what ever has slobbered out the breather tube.

mark h
By mark h - Wednesday, May 12, 2010 7:52 AM
Tatra (5/12/2010)
I'm going to ask what may come out as a stupid question, but do the Pontiac fluid flywheel and tranny have different oil circuits? I have no experience with them but on some English semi-auto epicyclic transamissions (Daimler, SCG) the fluid flywheel was drained and filled seperately from the box (from experience). In some cases, the flywheel used engine oil (Daimler), the box normal transmission oil...

Only asking:)

Cheers & Tschus


Hi Tatra,

Not a stupid question, While some early American made automatic & semi-automatic trans. used 10w motor oil, they were still self contained units. I was only going by his application. It does have two pumps but supplied from the same source.

mark h
By Tatra - Thursday, May 13, 2010 4:37 AM

You learn something new every day...



PS: So there were US made semi-auto transmissions like the English ones? Who made them?
By mark h - Thursday, May 13, 2010 11:56 AM

After doing some research I found that I misunderstood what you were saying about the flywheel/torque converter using engine oil. I was thinking you meant the oil was supplied by the engine. Also I wasn't thinking of Daimler as being Chrysler/De soto/Dodge like we call their stuff over here. You are right & we were thinking about the same semi- auto transmissions.

 The early style Chrysler which were vacuum operated & had a clutch set up with no sump. Only the flywheel/torque converter held oil. It was filled & drained through the same hole, but was separate from the rest of the trans. These did not have a pump in the rear section.

 The later ones are what you were describing. Over here Chrysler called them "Prestmatic Fluid Drive, De soto "Tip Toe Shift" & Dodge "Gyromatic Drive". They were semi-automatics with a rotary pump & separate front oil sump within the clutch housing (with 10w engine oil) supplying the flywheel/converter. The rear part of these trans. were hydraulic operated, instead of vacuum as earlier, & used a gerotor pump to supply oil for the rear part of the trans.

You are truly right, we sure do learn something new everyday!

mark h
By Tatra - Friday, May 14, 2010 6:15 AM

You misunderstood, but not like you think... I meant Daimler as in the English variety, like this bus below:

That's what all Daimler fluid flywheels more or less look like (the pic is from and there's an explanation provided).


They were usually coupled to an epicyclic pre-selector box. This operated by actautors applying brake bands to sun & planet gear groups. That's what you'd see once you pooled out the inspection box (see more here: To move from stop, you put the gearchange lever (which looked a bit like positive stop Hurst or Allison shifter) on "1" and pressed the "clutch" pedal once, released the brake and the vehicle would move forward, just like an automatic g/box driven one. Then you'd stick the lever on the 2nd gear position, accelerate and repeat... Compared with the crash boxes you had on most English trucks and buses way back then, this was a child's play. Later they fitted air-operated actuators so it was fully two pedal box, only you still had to change the gears yourself, which I prefer. You had similar boxes on Leyland buses and trucks also.


However... You mentioning the Chrysler products made me do a bit more surfing and I found this, with the clutch/fluid flywheel combo you described. No idea whether there was any connection between Daimler and Chrysler back then, but the principle is similar... 

So it seems even when we mean different things we manage to learn something - I had no idea about these Chrysler developments...:)


By mark h - Friday, May 14, 2010 12:09 PM

  Definitely not the Daimler I was thinking of. I guess Chrysler was called Chrysler back then no matter where you were. Funny how the semi automatics we were both thinking of are so different, but in describing them seemed very similar, as are the end functioning results.

 The Daimler fluid flywheel & epicyclic gearbox is very much like a modern automatic (all be it semi automatic). Or even Ford & Gm automatics back to this time frame, with sun & planetary gears & bands. The picture of the Chrysler you have is the exact early version I was talking about. But unlike the Daimler set up, the Chrysler was just a torque converter basically driving a manual gearbox rigged with either vacuum or hydraulic cylinders (early or late style) to select the gears. Being a semi automatic in function more than form, or at least as we see them today.

Thanks for the info & links, they made your description more informative.

Learned something new today.

mark h