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  #1  
Old 09-02-2003, 04:13 PM
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Question Transmission secondary pump

Hi friends. Can someone give me some light about the transmission secondary pump? Does this pump is only active when the engine is turned off and is use only for towing? Will this pump can become engaged (active) at any moment when the engine is RUNNING, as an auxilliary pump. Thank you in advance. By the way the transmission is a 722.361, and I am still curious about a spring I found in one of the port of the secondary pump. If you have any information about the origin of this spring, please let me know.

Thanks!

Darrel
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  #2  
Old 09-02-2003, 06:27 PM
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The rear pump runs off of the tail shaft, so whenever the car is moving, either by the "normal" way, or by towing, coasting, or pushing, the rear pump (auxillary pump) operates.

Gilly
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  #3  
Old 09-02-2003, 06:56 PM
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Don't want to make waves, BUT the rear pump on MB transmissions is there ONLY for a tow start OR push start. & was discontinued in the early 90's as no-one does that any-more. Does nothing for the operation of the transmission. Only allows for starting if the starter is bad.
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Old 09-02-2003, 07:33 PM
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Thank you both, Gilly and M.B. Doc.!!

M.B. Doc. That was what I thought because there is a piston that when activated with pressure it will separate from the governor and the pump becomes inactive. So whenever there is pressure in the main pump, the 2ry is inactive? Also I read that you said that when the 2ry pump comes apart the plastic gear of the governor break. Well in my transmission is a metal pinion but the pin that fix it to the governor broke. The problem is that what caused all this was a piece of plastic (maybe some kind of valve seat) and a spring which came through one of the ports. Do you know what is the nearest structure to that port that has a seat and a spring? I know one of the ports goes directly to the small diameter hole of the filter. Thank you for all the information provided. I really appreciate your help.
Darrel.
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  #5  
Old 09-03-2003, 09:03 AM
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The rear pump drives off of the governor. Many times the spring that keeps the pump drive gear against the governor comes apart. That can cause the rolled split pin on the governor drive gear to shear-off & then you have only LOW gear.
At dealer we either replaced the complete rear pump(if customer wanted) OR just left the rear pump gears OUT, as they aren't needed for the trans to work properly. Then all you need to do is replace the "rolled pin" in the governor drive gear.
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  #6  
Old 09-10-2003, 08:46 PM
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Problem fixed thanks to all you guys.

I want to thank all the good friends that replied to my thread. With the help of Steve, M.B. Doc, Randy, Gilly, Azhari and others, I found that the 2ry pump check valve (part # 126 270 05 89) broke and the top cap along with a small spring inside the valve went into the suction port of the pump gears and locked the drive gear. This broke the 2ry pump drive gear piston (engage the governor with the drive gear) and the split roll pin of the governor worm gear. I bought a used piston, replace the governor pin with a new one (size 5/32") from the hardware store and replace the check-valve ($8.00, although the price list is only $2.00). I followed M.B. Doc recommendation of leaving out the 2ry pump gears.

This problem is reported in the MB Transmission Microfiche for the 722.4. Mine is 722.361 and it happened the same way they describe it. I hope this information can help others with this type of symptoms of no upshift.

I am back on the road again although I am still testing it. I have drove approx. 20 miles and it seems to be back to normal.

Thank you all again. I will post other question about flickering lights later.

Darrel
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  #7  
Old 09-11-2003, 04:39 AM
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Seems like a lot of extra parts just to have the option of push or pull start. If you have a low battery then a jump start would be so much simpler.If your starter suddenly goes what do you do ask the fellow next to you in the parking lot if he would mind pushing or pulling you to 30 mph. and I'll bet very few tow truck drivers would do it either for fear of something going wrong as your steering and brakes are not going to be powered till you drop it in gear at thirty...

But then again that starter just might go when you have parked it at the top of a very long hill........
William Rogers......
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  #8  
Old 09-11-2003, 10:37 AM
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There's an old Redneck joke around here

about the guy who finds his pickup's battery dead and asks a neighbor to push him to start it, mentioning that because it has an automatic trans, he'll have to get up to 30 mph for it to start. So he gets in his driver's seat, puts it in Low, and waves for the other guy to start pushing and nothing happens. Then he looks up in the mirror and sees the other truck coming at his rear at 30 mph.
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