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Thread: 322 Nailhead and Dynaflow pump failure

  1. #1
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    322 Nailhead and Dynaflow pump failure

    I have a customer that has brought me his 54 Buick Special, he has just bought it and the transmission (Dynaflow) quit pulling shortly after he got it. I determined that the pump has a issue and we removed the trans to take a look.

    Sure enough the pump is toast, but the failure is that the inner pump gear has machined itself into the backing plate for the pump. This has me concerned because I am not sure why this has happened and I obviously don't want it to happen again. The only thing I can figure is the the inner pump gear was shoved into the plate until it failed, and the only way I can come up with why this happened is that the crankshaft is moving back due to a failure with the crank bearings.

    I have run across this before while working on other types of vehicles, but I have always been able to move the crank with a pry bar to conform the crank movement, but I cannot move the crank forwards or backwards at all, and I am using a big pry bar to try to get movement but cant. There is a "clean" spot on the crank right where it goes into the engine so my thinking was that the crank is moving and this is why there is a clean area, but the clean area could of also been caused by dirt or debris that is in this area.

    Looking at the crankshaft set up in this engine it appears that the rear crank bearing has the "thrust sides" that keep this crank from moving.

    For people that are familiar with this engine and or the Dynaflow is this common type of failure?

    Here is a picture of the pump plate with bad wear from the inner pump gear.



    Here is the pump gear itself



    Here is a picture of the "clean area" on the crankshaft.




    Any idea what this is?

    Maybe a attempt to stop a leak from the converter hub?

    It feels like epoxy or glue of some kind..







    Thanks for any input anyone has on this issue.

    James

  2. #2
    You see that ALOT on DynaFlows. I consider this normal wear. The sharp edges of the inner pump gear cause this. I usually bevel the edges of the gear to try & help the wear issues. I have even made the plate out of stainless & it still happens, although it takes longer.


    Tom T.
    Tom Telesco
    Classic and Muscle Automotive
    12 Cook St.
    Norwalk, CT 06853-1601
    Day Phone 203-324-6045 ET
    NailHead Mini-Starters '53-'66
    Adjustable Roller Tip Rocker Arms - All NailHeads
    Custom forged pistons
    Front & rear neoprene seals
    Many other "Nail" parts
    "If I can't get it, you don't need it!"

  3. #3
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    Thanks Tom that makes me feel better about fixing this thing, well kind of... I was just concerned that this guy might have a engine issue on top of a tranny problem.

  4. #4
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    James,

    Is there any evidence that the engine or transmission has been removed or seperated recently?

    Was there any internal damage inside the convertor?

    If the convertor is not indexed properly in the pump drive gear, it will force the pump gear rearward and destroy the pump is short order. Same goes for any transmission in which the convertor indexes through the pump gear. Seen it happen on turbo 400.

    On my 55, the convertor can be assembled and look correct but not be seated in the pump. There is a spec for the distance from the bell housing face down to the convertor face after it is assembled and ready to install. I can't give you that spec, it is not in my shop manual but I have read the procedure to check it and the spec but can't relocate that info.

    The distance from the convertor mating surface on the flexplate back to the face of the block should coincide with that. The point being that you should have to pull the convertor forward about .100" to mate up to the flexplate when the transmission is bolted flush up on the block. This keeps clearances so it does not force the convertor too deep or push the crank forward.

    When I bought my 55, it also had a pump failure and would not move. I was told that it had been freshly built and installed but failed immediately. I don't know that to be fact but believe it to be true, no reason to make up a story. With no other history on the car, I don't know how it got that way or whether it was not indexed when istalled.

    The pump fails quickly and will not necessarily wear out the crank thrust because the convertor may go ahead and drop in after pump failure.


    I have that transmission apart and can not find any incorrect parts or application issues, appears to be all correct for a 55 which has some unique parts.

    If anyone does stumble across those specs for convertor depth when assembled, I would love to know.

    I have heard that a bent flexplate or excessive runout can cause it but moderate runout will be corrected when it is bolted up and conforms to the convertor so I would not worry about minor runout of less that 1/16" although factory specs is alot less than that for maximum. Runout after mating and bolting up is another issue, it should run true, if not , something is in a bind. Those 2 drain plugs must line up and go thru holes in the flexplate. You can't just slam it in, they line up before the trans is flushed up to block.
    Last edited by TexasJohn55; 09-12-2013 at 08:27 PM.

  5. #5
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    Thanks Guys, I feel better about going ahead with rebuilding this thing, well kind of....

    John, You are right about the converter not being fully seated can cause pump failures in a hurry. I have seen that mistake many times over the years. This particular case the trans hasn't been out in a very long time. So I believe I am just dealing with "normal" pump wear.

    I am tempted to install the flywheel, converter, and bellhousing and do a few measurements just for piece of mind. If I come up with some interesting findings I will post them.

    Thanks again
    James

  6. #6

    Dynaflow

    Did they push or tow the car prior to the failure ?

  7. #7
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    Quote Originally Posted by SuperST8 View Post
    Did they push or tow the car prior to the failure ?
    These transmissions had 2 seperate oil pumps, one front and one in the rear driven off tailshaft. At appx 25-30 mph, the rear pump will supply sufficient pressure to operate the transmission independently from the front pump and could be push started. If the front pump was weak, it would slip taking off until the rear pump came online at speed and then pull OK. TexasJohn

  8. #8

    Pump Problems

    Quote Originally Posted by JK080 View Post
    I have a customer that has brought me his 54 Buick Special, he has just bought it and the transmission (Dynaflow) quit pulling shortly after he got it. I determined that the pump has a issue and we removed the trans to take a look.

    Sure enough the pump is toast, but the failure is that the inner pump gear has machined itself into the backing plate for the pump. This has me concerned because I am not sure why this has happened and I obviously don't want it to happen again. The only thing I can figure is the the inner pump gear was shoved into the plate until it failed, and the only way I can come up with why this happened is that the crankshaft is moving back due to a failure with the crank bearings.

    I have run across this before while working on other types of vehicles, but I have always been able to move the crank with a pry bar to conform the crank movement, but I cannot move the crank forwards or backwards at all, and I am using a big pry bar to try to get movement but cant. There is a "clean" spot on the crank right where it goes into the engine so my thinking was that the crank is moving and this is why there is a clean area, but the clean area could of also been caused by dirt or debris that is in this area.

    Looking at the crankshaft set up in this engine it appears that the rear crank bearing has the "thrust sides" that keep this crank from moving.

    For people that are familiar with this engine and or the Dynaflow is this common type of failure?

    Here is a picture of the pump plate with bad wear from the inner pump gear.



    Here is the pump gear itself



    Here is a picture of the "clean area" on the crankshaft.




    Any idea what this is?

    Maybe a attempt to stop a leak from the converter hub?

    It feels like epoxy or glue of some kind..







    Thanks for any input anyone has on this issue.

    James
    HI
    I have never done any of this yet. But have read several accounts of the pump failure. Here are some of the things I compiled on this.

    I wouldn't say it would be easy to damage a front pump, but it could be done. The torque converter is also considered a "pump". Behind the torque converter is a trans pump that could be damaged if your flywheel is bent or is not true, when it spins it will wobble and cause the pump to wear. The key is to not let the trans hang on the torque converter because the flywheel is soft and will bend. I think there is 6 bolts holding the flywheel to the torque converter, make sure they are all out and disconnected before removing trans. A bent flywheel is also a cause of oil leaks because is causes wobble in the torque converter and the seal will leak.

    When you put in the flywheel check the run out of the flywheel. This is super critical, no more than .005" will cause a oil leak or the front pump to be damaged. You can fix a flywheel with a good sized mallet and keep checking it until it is under .005". Also when you put it back in, make VERY sure the drain plugs on the torque converter are lined up with the flywheel openings.

    Flywheels had different part numbers for the '53 and '54, but the only difference is in the teeth. In the '53, they were beveled, and in the '54s, they were square. Buick found that the starter showed less wear with the square teeth.
    They also found a potential problem that would take place at installation, and that was when the transmission is bolted to the block, there must be clearance between the torque converter and the flywheel of between 1/8" and 3/16". If the torque converter can't be pushed back to give this clearance, it will destroy the pump quickly.

    Hope this helps someone.
    Gishmonster
    Gishmonster

    56 Buick 63R
    57 Chevy 2DrHt

  9. #9
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    James, How about an update?
    Did you get the Dynaflow rebuilt and installed without incident?
    Have you learned anything you could pass along to us?

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