Towing Valve Malfunction Sundstrand 90-1136 ‘69 Charger 12

[BrianKoch 307]

Gentlemen,

 

According to the hydrogear transmission manual, the tow valve on the ‘69 Charger 12 with the Sunstrand 90-1136 is “malfunctioning” because I am able to roll the tractor while it is closed. 
 

To note, the parking brake pawl also seems to be broken, but I believe these issues are independent of one another. 

 

Have any of you dealt with this issue of a malfunctioning tow valve before and can advise? I’ve got the ATF drained out and would like to address this before refilling. 
 

As of right now, I have removed the tow valve and attached a picture of it. The O ring and nylon washer look fine to me, but maybe you see or know something different. 

[Ed Kennell 37,922]

Is this a non runner you are bringing back to life Brian.       

[BrianKoch 307]

39 minutes ago, Ed Kennell said:

Is this a non runner you are bringing back to life Brian.       

Sort of. I bought this one to be solely my mower, but it did not run well so you could say I am rehabilitating it. 

[Ed Kennell 37,922]

Did the tranny work OK when it was running?

[BrianKoch 307]

13 minutes ago, Ed Kennell said:

Did the tranny work OK when it was running?

It worked OK but I didn’t do the “see if the tires spin against an immovable object” test. 
 

 

[daveoman1966 3,745]

As a note: If original, the 69 Charger 12 had Sundstrand Hydrogear model 90-2046.  From the TOW VALVE in your pics, it is clear that a PO has changed this to the Sundstrand Piston-to-Piston model 90-1136.  Here is old vs new Tow Valve.  Yours appears to be serviceable so I'd look elsewhere to resolve the 'easy roll' problem.  As for the non-functioning PARKING PAWL... One should NEVER pull up this lever when moving.  There two styles...shown here:    The CAST one (two piece) has a roll pin to hold it to a separate shaft.  The other one is a formed steel piece welded to the shaft (one piece).  Either of these will wear out from repeated use....WHILE IN MOTION....and the metal filings from this 'abuse' will quickly ruin and/or destroy soft brass components of EITHER a model 90-1136 or the older style 90-2046.  

      

[BrianKoch 307]

@daveoman1966

 

Thank you for the info and confirming my suspicions. 
 

I will service the valve with a new O ring, fill’er up, test and report back. 
 

Regarding the parking pawl damage: 

When draining the old ATF out by opening all 4 drain plugs, I hoped to have at least made a dent in removing majority of the metal filings “floating around”. 
 

Admittedly, tearing the system down and correctly tuning it up is intimidating me to do before mowing season gets here, especially if the benefit doesn’t outweigh the cost of potentially screwing things up more! To reiterate this tractor is just going to be for mowing duty and it mowed OK last season.

 

In this situation, I am thinking, “if ain’t completely broke don’t completely fix it”.
 

Edited March 15 by BrianKoch

[daveoman1966 3,745]

1 hour ago, BrianKoch said:

@daveoman1966

 

Thank you for the info and confirming my suspicions. 
 

Here is what happens when tiny STEEL filings get into the trans fluid and damages the soft BRASS components.  NOTE--- the trans fluid circulates thru the HYD PUMP and the HYD MOTOR.  Accordingly, the soft BRASS components in these will require similar attention.  A rebuild is NOT difficult...so don't let the prospect of doing so intimidate you.  I have available for FREE a .pdf download---with pics---to guide you thru the rebuild---if needed.     

 

[pfrederi 17,617]

Looking at you tow valve there is nothing wrong with it.  The Oring and backer ring just keep fluid from leaking out.  The needle end seals the port and it looks okay.  That you can push her valve closed points to excessive wear as Dave has pictured

[BrianKoch 307]

 

 

@daveoman1966

 

Thanks, I’ll look into your guide.

 

@pfrederi

 

Thanks for clarifying.

 

Do you guys think I can make it through the mowing season? Does the pump/motor continue to wear with each use or does it sort of bottom out its wear and just cause an overall loss in transmission capability?

Edited March 15 by BrianKoch

[pfrederi 17,617]

Ideally I would separate the pump unit from the transaxle so I could inspect and clean the screen.  Alternatively change the ATF fluid and filter draining it as completely as you can,  raise thefront of the tractor.  Run it abit and change again.  Once you get all the metal bits out the problem will not get materially worse.  ...but won't get better either.