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Transmission air modulator?
#1

Not sure what this is called but I have been cleaning the underside of the bus the last couple of days. Today while continuing on my degreasification, I heard and felt bubbling in the transmission oil pan. I believe this fitting is leaking air into the transmission. I have my 120v compressor on so the system is always pressurized. One of the great things of having a pit is finding crap you would never had known was at fault! The piece in question is where the blue air line goes into.


Edit:

After a couple hours of research and cross referencing, I found the part. For those of you with the HT740 transmissions, this is a Williams Controls air modulator. Part number is WM775B or 117830. Prices range from a low of $60 to a high of $407. Found a new one on eBay for $160 delivered. Most places were out of stock or you had to call to see if they were available.


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--Simon
1993 8v92TA #312
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#2

My 110V compressor cycling dropped considerably after I replaced that part!!! I kept hearing a bubbling sound near the engine bay when it was sitting in my shop and all was quiet. I finally found the culprit!

1993 Newell (316) 45' 8V92,towing an Imperial open trailer or RnR custom built enclosed trailer. FMCA#232958 '67 Airstream Overlander 27' '67GTO,'76TransAm,'52Chevy panel, 2000 Corvette "Lingenfelter"modified, '23 Grand Cherokee.
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#3

I am at 22 min cycles. There is a minor airbag fitting leak at the front. Leo will tighten that up when I go back but any air leak found is a good one! It's like scratching an itch good! I don't know what would happen if the modulator would fail. Leave you stuck in 1st gear?

--Simon
1993 8v92TA #312
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#4

Modulator was replaced. I did not drain the transmission fluid but instead swapped it out as quick as I could with my thumb over the hole. Lost maybe 4-6oz of fluid and most of it down my arm. Needless to say I was a mess along with some splash back off the pit steel rail. It was fun. Pit was a mess from cleaning the bottom side. Now I am ready to paint once the floor of the pit dries from washing it down so I can put plastic to avoid an even bigger mess!


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--Simon
1993 8v92TA #312
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#5

Simon,
I can really see how handy your pit has become....a huge time saver!  Think about how long it would take jack, support, creep your way around under the coach and get the coach back on the ground....super nice setup!

Steve & Doris Denton
45' Newell #525, Bath & Half....sold
37' Country Coach, Tribute....Cat C9, 400 hp
2014 Honda CRV Toad
Summerfield, FL
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#6

Thanks Steve! I believe the pit already paid itself off from a saved tow/repair bill!

I am happy to say compressor now cycles every 2 hours from 22 min! that's some serious transmission fluid aeration! I haven't driven it yet but does go into forward and reverse. I'll keep chasing those air leaks

--Simon
1993 8v92TA #312
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#7

Some days I am in my shop next to the MH so I can hear the compressor. Typically it cycles once per day. I don’t know if it cycles during the night or not? That is down from 30 minute cycles a couple years ago!?

1993 Newell (316) 45' 8V92,towing an Imperial open trailer or RnR custom built enclosed trailer. FMCA#232958 '67 Airstream Overlander 27' '67GTO,'76TransAm,'52Chevy panel, 2000 Corvette "Lingenfelter"modified, '23 Grand Cherokee.
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#8

Any tips on what you found that was leaking? By the way, I sent out the refrigerator door seals. Let me know if you didn't receive them.

All airbags are new. Generator airbags are also new along with regulator. The only thing that I am aware of is the front right airbag supposedly has a minor leak that Leo will get to. I don't think it's big enough to leak down that much. But crap, a whole day would be a dream for me to keep that compressor silent!

--Simon
1993 8v92TA #312
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#9

Finding an air leak is like getting a Christmas present I'm up to 4.25 hours. A pit would be a very useful tool your a lucky guy! Do you cover it when not in use?

1999 45'  #504 "Magnolia"
Gravette, Arkansas
1996 40 XL Prevost Marathon 
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#10

Thanks Jack! Yes, It is always covered with a steel open mesh walkable grid.


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--Simon
1993 8v92TA #312
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