Dynaflow Blow Back through Fill Tube in Reverse - Causes and Fixes?

[1957buickjim]

So I have a rebuilt dynaflow in my 1957 Buick, done by the a guy who knows his stuff on this. However, when the car has not been run in a few weeks to a couple months, the transmission is sluggish until warms up, and occasionally when put into reverse (more often then not) will blow about 4-6 oz of trans fluid back out the fill tube. I have had it happen in drive, but rarely. Mostly in reverse. If I drive the car consistently, I don't seem to have this problem. Any ideas as to what the issue might be and how to resolve it so it doesn't happen? My garage floor (and my wife) is not too happy with a red oil spill. I have checked my vent tube on the trans and it is clear, no spider nests or gunk plugging it. Any help would be appreciated. 

[old-tank]

Drive it more often:  it is good for you and the car.

With disuse the torque converter is draining back into the pan overfilling it and when the pump adds fluid back to the converter the air in it blows fluid in the overfull pan out the filler.  Add some STP -- 1-2 bottles-- to thicken the fluid.  It will still drain back but more slowly.  Try to let it idle for a few minutes, run it through the gears briefly.

[60FlatTop]

I would check the brakes thoroughly. Dragging brakes can cause poor performance and cause the transmission fluid to boil and blow out the vent or the dipstick tube.

[1957buickjim]

3 hours ago, old-tank said:

Drive it more often:  it is good for you and the car.

With disuse the torque converter is draining back into the pan overfilling it and when the pump adds fluid back to the converter the air in it blows fluid in the overfull pan out the filler.  Add some STP -- 1-2 bottles-- to thicken the fluid.  It will still drain back but more slowly.  Try to let it idle for a few minutes, run it through the gears briefly.

Thanks Willie! I figured it had to be something like that happening, like an air bubble in the system. I let it warm up usually for 10-15 minutes before I drive it, but this happens mostly when I've driven it (first time in a while type of driving) and then its Moby Dick spouting off when I go in reverse. Is there a reason that it happens mostly in reverse? A pump flow type of thing where the air is moved back and out the tube somehow?

[NailheadBob]

Do you have the rubber seal on top of dipstick by top cap? This dipstick on eBay is very pricey but gives you idea what to look for.

 I was discussing this with @old-tankrecently but his 55’s doesn’t have the rubber seal.

 

Bob

[old-tank]

16 hours ago, 1957buickjim said:

Is there a reason that it happens mostly in reverse?

No answer to that question.  

[NailheadBob]

See Buick bulletin #108 possibly may address your concern, but I think if Jim Hughes did your transmission he would have checked the front pump gear side clearance?

 

 See the assembly of bolt location for converter housing cover to flywheel. 

 

Do you know what the numbers stamped in triangle flywheel at 3 attaching points to converter indicate? example(7,5,6) Indexing triangle flywheel location in relation to engine cylinders?

 

Bob

 

 

 

Edited December 2, 2022 by NailheadBob
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[JohnD1956]

3 hours ago, NailheadBob said:

Do you know what the numbers stamped in triangle flywheel at 3 attaching points to converter indicate? example(7,5,6) Indexing triangle flywheel location in relation to engine cylinders?

 

According to the text of the page the numbers seem to indicate the tightening sequence

[NailheadBob]

13 hours ago, JohnD1956 said:

According to the text of the page the numbers seem to indicate the tightening sequence

John, possibly see location of triangle flywheel, look at lines in photo with tightening sequence to match shape of flywheel also indicated by green paint when engine painted at factory, do you agree?

Edited December 2, 2022 by NailheadBob
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[old-tank]

At this point it is advisable to contact the rebuilder.  Pressure tests as outlined in the service manual (both cold and hot) may be helpful.  Personally I would try the STP even if the rebuilder offered a replacement since it is a huge PIA to R&R a dynaflow.

[60FlatTop]

It is interesting to see all of these references to the shop manual. The shop manual was a major part of my decision to spend my money on tools instead of professional services.

 

In 1988 I bought a new pair of springs for the rear of my '64 Riviera from J. C. Whitney, still in my late 30's and not fully jaded.  They left the car way too high in the rear. They were just the wrong rate although some told me they would squat down after a while.

 

A few years later I bought a correct set from a specialty company. Wanting the best job, I went to a professional spring shop for the installation. I dropped off the car, new springs, and the shop manual. The manual has specific instructions. When I picked the car up it did not sit level. The manual was still on the counter where I left it. They told me I was wrong and coil spring could not be adjusted. I took my book, car, paid them, and went home. I reinstalled the springs as instructed with wood blocks and ends pointing as recommended. The car sat correctly. Another nail in the coffin of "professionals".

 

I did have my Dynaflow rebuilt in a shop a year and a half ago. It was a leap of faith that worked out. I still do fool hardy things. The caution to be advised of is that the professional may reply on his experience more than the manual. Beware of these guys.

 

On transmissions, when I was still in High School we used to go to a shop over in the muck land and I remember talk among the old BSer's about a transmission so good he could throw all the parts of a transmission into a corner and come back months later and put it back together like he disassembled it yesterday. I have remembered stuff like that all my life and can assure you that mechanic who went on the bender is not a guy I want working on my transmission. But the things I heard when I was a kid.

[JohnD1956]

9 hours ago, NailheadBob said:

John, possibly see location of triangle flywheel, look at lines in photo with tightening sequence to match shape of flywheel also indicated by green paint when engine painted at factory, do you agree?

Bob, It looks to me that the original manual calls for the flywheel to be in that specific position otherwise it would cover up the torque converter (TC) drain plugs. Later they added that if it wasn't in that specific position the flywheel bolts would push the TC backwards and score the front pump.  I say later because the TSB says to look at the 58 manual while I believe we are talking about a 57 in this thread.  But it appears to me that if one fails to match the flywheel to TC orientation as required, the heads of the flywheel bolts likely miss the machined depressions in the TC cover and instead ride on the flat lands between those depressions, thus pushing the TC backwards leading to that specified damage potential. 

I guess this winds up clocking the TC to a specific position of the crankshaft.  But I do not think it was for that reason that the flywheel had to be clocked in this position.  

And as I always try to state, I could be completely incorrect.  😵😁

 

[60FlatTop]

That is a pretty interesting bolt tightening sequence, certainly not intuitive. With so many round things in the power plant business even my son and daughter know I eat, sleep, repeat .7854. One of those transmissions would never come back from me correctly tightened without the manual. I am experienced with tightening circular stuff.

Edited December 4, 2022 by 60FlatTop (see edit history)

[avgwarhawk]

No doubt the triangle plate is stamped with numbers for torque sequence. The TC draining ports at 9 and 3 o'clock positions as shown in the picture. The question I have, how is the TC clocked when installing?  Is there any markings on the TC that indicates 12 o'clock? In short, the TC can be 180 out if installed out of clock. Similar to a distributor 180 out and engine will not start. 

[avgwarhawk]

[avgwarhawk]

Rear pump may be leaking air. As Willy suggested, get the front/rear pump pressure reading. 

 

Edited December 4, 2022 by avgwarhawk (see edit history)

[NailheadBob]

4 hours ago, avgwarhawk said:

No doubt the triangle plate is stamped with numbers for torque sequence. The TC draining ports at 9 and 3 o'clock positions as shown in the picture. The question I have, how is the TC clocked when installing?  Is there any markings on the TC that indicates 12 o'clock? In short, the TC can be 180 out if installed out of clock. Similar to a distributor 180 out and engine will not start. 

There is a dowel pin on crankshaft to correspond with flywheel smaller line up hole, what I do not know at this time is when flywheel location at 12 o'clock position as figure 5-107 & 5-108 listed in service manual triangle lines to match shape of flywheel, and notice the green engine paint on lower part of flywheel from being painted at factory, is engine on top dead center?

 

Bob

[avgwarhawk]

53 minutes ago, NailheadBob said:

There is a dowel pin on crankshaft to correspond with flywheel smaller line up hole, what I do not know at this time is when flywheel location at 12 o'clock position as figure 5-107 & 5-108 listed in service manual triangle lines to match shape of flywheel, and notice the green engine paint on lower part of flywheel from being painted at factory, is engine on top dead center?

 

Bob

 

I do not know if the engine at top dead center plays a part when marrying the Dynaflow to the block.  

[1957buickjim]

Thanks for all the details. Just to let everyone know, Jim Hughes did rebuild this transmission, so I'm pretty sure he did it correctly. I did speak to him when it did it after first installation, and he indicated that the transmission fluid expands quite dramatically when hot, and if slightly overfilled, could casue this condition. I drained some and corrected the level, checking it hot, in neutral on a level surface. I do have the correct transmission dipstick as well for the 1957 Buick. 

I think Willie is onto something, as maybe ATF from 1957 had a slightly different viscosity, and adding the STP might change that for a slower or no drain situation. It does seem that it could possibly be an air leak or faulty seal, but I would think unlikely with a Hughes rebuild. I am going to call Jim and ask him what his thoughts are. 

As for lining up the flex plate to the flywheel and torque converter, Jim marked it and provided pretty thorough instructions, which I followed with the transmission install. I will review the product service manuals and chassis manual as you all recommended, just to make sure that it isn't something overlooked. 

[avgwarhawk]

1 hour ago, 1957buickjim said:

Thanks for all the details. Just to let everyone know, Jim Hughes did rebuild this transmission, so I'm pretty sure he did it correctly. I did speak to him when it did it after first installation, and he indicated that the transmission fluid expands quite dramatically when hot, and if slightly overfilled, could casue this condition. I drained some and corrected the level, checking it hot, in neutral on a level surface. I do have the correct transmission dipstick as well for the 1957 Buick. 

I think Willie is onto something, as maybe ATF from 1957 had a slightly different viscosity, and adding the STP might change that for a slower or no drain situation. It does seem that it could possibly be an air leak or faulty seal, but I would think unlikely with a Hughes rebuild. I am going to call Jim and ask him what his thoughts are. 

As for lining up the flex plate to the flywheel and torque converter, Jim marked it and provided pretty thorough instructions, which I followed with the transmission install. I will review the product service manuals and chassis manual as you all recommended, just to make sure that it isn't something overlooked. 

I can assure you that adding STP or Lucas Transmission Stop Slip cures a lot with the Dynaflow and newer viscosity transmission fluid.  My 60 lost prime after a full transmission fluid change.  Dynaflow would not engage after sitting a week.  After about a minute of running it would engage reverse.  One qt of Lucas added and the transmission engagement is immediately felt no matter how long the Buick sits.  Give it a go.  At the end of the day adding the Lucas or STP will not cause trouble. Willie is a plethora of Buick knowledge and direct experience. And to add, he will talk on the phone with you in an effort to resolve a problem.  Definitely a forum member worthy of a gold star!  Willie has saved my bacon and headache more than once. 

Edited December 6, 2022 by avgwarhawk (see edit history)

[1957buickjim]

I totally agree with you about Willie! Absolute encylopedia of practical hands-on Buick knowledge. His recommendations are usually spot on. Thank's Willie!

[Hans1965]

I do have a very similar problem on my 49 Riv. When it is cold, it is pretty normal. All gears work as expected. 

 

When it is hot, I can go forward in D and L as I wish, but when I go into reverse, it gets scary. It shifts into reverse, but as soon as I accelerate only a little the whole car is shaking and rumbling like crazy. Very difficult to locate grom where it origins. I need to shift immediately back into other gears and then it stops this shaking and behaves nicely again. Reverse gear again, shaking restarts after I push the gas pedal a bit. 

 

When it is hot and I stop the engine ca. 3-400 ml transmission fluid comes out of the filling tube. I let it cool down for 5 min and I can normally drive backwards once or twice and then it rumbles again. I stop the engine and another load of transmission fluid comes out.

 

Length of the dipstick seems to be right, about 17 inches.  When I use less transmission fluid (level at lower end of the dipstick) I have considerably worse acceleration, so I like it to be full. The fluid volume to go from minimum to maximum level seems only to be 500 ml. I only refill when warmed up. 

 

Motor mounts good, transmission mounts, thrust pad new. I never really drove the car before the exchange....

 

What I realized yesterday evening after removing the huge floor pan cover to gain access to the transmission is, that the shift rod at the rear end where it meets the transmission has some slippage due to the fact,  that there are no washers to keep it tight. Maybe this potential movement causes some trouble. 

 

But with regard to the normal shifting when cold and stumbling in reverse when hot this cannot be the problem, I believe. Same for the spitting!

 

What I have read here a couple of times is the addition of STP transmission additive to make the Dexron III more viscous to prevent the torque converter to empty itself into the transmission pan after (!) standing for a while. Mine seems to do that while hot and shutting off the engine. So can the viscosity be the real problem here? By the way I had no leaks at all before,  torque ball even nice and tight. I will try the STP for sure.  I just don't understand the problems. 

 

What is the exact function of the breather cap with the short pipe. If this is clocked what is the consequence of that?

 

This is above my capabilities up to now. A little frustrating. ...

 

Next is putting the rear axle on stands to see if the differential causes the shaking....

 

Thanks for any idea what I could try.

Maybe the above makes sense to somebody. 

 

 

[EmTee]

2 hours ago, Hans1965 said:

So can the viscosity be the real problem here?

Purely a guess, but could there be a pump problem (e.g., wear?) that causes foaming of fluid followed by expulsion via the dipstick tube?  If so, and the issue is wear related, then a viscosity improver (i.e., additive) might help make-up for increased internal clearances.  If it is caused by hardened/shrunken seals or O-rings, then a high mileage transmission 'conditioner' (such as the Lucas or STP, or even 3 or 4 ounces of DOT3 brake fluid) could help.

 

Has the transmission ever been rebuilt?  Have you had anyone check the line pressures as Willie and others mentioned above?

[Hans1965]

EmTee, thank you, I have no idea, if the transmission has been rebuilt in the past. Overall it seems to be a low mileage car.

 

To measure the line pressure is for sure something that would be good to accomplish, but honestly where I live I have no clue where to go, so I need to do it myself. Before I walk that way I'd like to understand as much as possible about the problem. Ideally somebody says "hey, these symptoms point to this or that desease." Unfortunately I am not such a technical mastermind, which frustrates me slightly. 

 

I don't think there is any foaming, the fluid is just pressed out over a few seconds. Only the area underneath the dipstick whole is wet.

[EmTee]

1 hour ago, Hans1965 said:

I don't think there is any foaming, the fluid is just pressed out over a few seconds.

Have you ever seen any bubbles on the dipstick when you check it hot?  As I said, I'm just reaching for anything I can think of.  I'm afraid that everything will be pure conjecture unless you are able to get some pressure readings to support a thoughtful diagnosis.

[Hans1965]

I never noticed bubbles on the dipstick.

 

Thank you, appreciate your help! 

[Hans1965]

Opened the cap for the reverse band. Obviously the transmission pan is full. I understand that is not right.

 

There seems to be a drain plug where the red arrow is. No idea what for. 

[NailheadBob]

You might touch base with @Mudbone about that plug and he might be able to give you some advice and pressure tests ideas also, he has Dynaflow videos on rebuilding his 1955 transmission and doing a pressure test

 

Bob

[Mudbone]

On 4/10/2024 at 5:25 PM, NailheadBob said:

You might touch base with @Mudbone about that plug and he might be able to give you some advice and pressure tests ideas also, he has Dynaflow videos on rebuilding his 1955 transmission and doing a pressure test

 

Bob

Be sure the trans is not over full. Make sure you have the correct dip stick. Be sure to test oil level with oil warm and engine at idle on level ground. (How do I know this?)

[KNUT]

Hans 1965. That plug is only for pressure tests. I think your transmission oil looks strange, could it be water infiltrated? The oil is not supposed to be “cloudy”, but clear, though red. You have a drain plug in bottom front of oil pan. In order to drain out all oil, you also need to drain the converter. A total of 10-11 liters.

[50ChevyFrank]

A friend was given his dad’s 56 Chevy equipped with a 235/6 and Powerglide. It would do the same thing. He drove it only occasionally and it puked fluid every time.
Not that this comment helps, it seems to be a common occurrence with the older automatics. 

[Hans1965]

I only see the last comments now. Thanks everybody! 

I still need to check if the length of the dipstick is correct, but when the fluid level is on the low end of the mark I have considerably less torque. Between low and full is only very little difference, maybe half a quart. At full it drives and accelerates very nicely.

I always drive it until warm and only add fluid then in idle. 

The appearance of the fluid might look unnormal, maybe due to the flash light, but seems okay for me. Changed it four times to be sure any water is out. I couldn't open the drain plugs on the converter though. Tried a lot. Both plugs are super frozen. But for that reason I changed the fluid so often.