C6 NO 3RD GEAR
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4th Gear
Joined: Nov 2023
Posts: 4
Likes: 0
C6 NO 3RD GEAR
Ok so one day while driving it felt like something broke and I lost 3rd gear. The truck has been leaking trans fluid alot and I'm constantly topping it off.
so I after some diagnosis of the modulator valve and vaccum line(check out good)
I decided to put a used transmission into the truck.
this not not change anything.
So I took the original transmission and rebuilt it. I did not see anything standing out to me during the rebuild. All valves in the valve body moved freely and the governor valves moved freely as well. The truck now has a new modulator. Reverse and 1st and 2nd gear shift very smoothly but 3rd just will not engage. I have measured the vaccum at idle to the modulator to be 20 in of vac.(i know i need to do a load test but i figured its getting vaccum with no leaks)
the kick down valve is working properly as well(no binding, not stuck and correctly adjusted)
I flushed the cooler and lines for the used transmission and I replaced it for the rebuilt one.
The things I think it could be:
I did not replace the rings on the output shaft that seal the governor distributor.(so maybe they are bad?)
the governor valve itself
Low engine vaccum
Worn bore in the valve body.
Is there something I'm missing?
I'm lost on this truck at this point
Any knowledge will help
so I after some diagnosis of the modulator valve and vaccum line(check out good)
I decided to put a used transmission into the truck.
this not not change anything.
So I took the original transmission and rebuilt it. I did not see anything standing out to me during the rebuild. All valves in the valve body moved freely and the governor valves moved freely as well. The truck now has a new modulator. Reverse and 1st and 2nd gear shift very smoothly but 3rd just will not engage. I have measured the vaccum at idle to the modulator to be 20 in of vac.(i know i need to do a load test but i figured its getting vaccum with no leaks)
the kick down valve is working properly as well(no binding, not stuck and correctly adjusted)
I flushed the cooler and lines for the used transmission and I replaced it for the rebuilt one.
The things I think it could be:
I did not replace the rings on the output shaft that seal the governor distributor.(so maybe they are bad?)
the governor valve itself
Low engine vaccum
Worn bore in the valve body.
Is there something I'm missing?
I'm lost on this truck at this point
Any knowledge will help
Hotshot
Joined: Jul 2020
Posts: 10,554
Likes: 2,670
From: Near Salt Lake City
You need to check the transmission line pressure
The opposing pressures from the line and the governor make a C6 shift
There are a few good articles about C6 diagnosis online
I got a feeling your governor is the problem
The modulator and its vacuum source just cushion the shift and should not be the problem IMO
Can you check the line pressure?
The opposing pressures from the line and the governor make a C6 shift
There are a few good articles about C6 diagnosis online
I got a feeling your governor is the problem
The modulator and its vacuum source just cushion the shift and should not be the problem IMO
Can you check the line pressure?
Logistics Pro
Joined: Aug 2010
Posts: 3,718
Likes: 586
From: Chillicothe
I am going with the governor here. Is this vehicle 4x4? I ask because if you get high enough rpm it SHOULD force a shift. So if you put it in 4 low you SHOULD be able to go fast enough to force a 2-3 shift and that would confirm the governor.
There is also the reverse trick where you go fast in reverse to force any sludge out backwards..... or you can just take it apart and check.
wardve always put the Transgo valvebody kits in c6s and loved the way they shift. Maybe it needs valvebody work? I know you said the trans is rebuilt, but did you replace any hard parts in the valvebody?
There is also the reverse trick where you go fast in reverse to force any sludge out backwards..... or you can just take it apart and check.
wardve always put the Transgo valvebody kits in c6s and loved the way they shift. Maybe it needs valvebody work? I know you said the trans is rebuilt, but did you replace any hard parts in the valvebody?
Thread Starter
|
4th Gear
Joined: Nov 2023
Posts: 4
Likes: 0
You need to check the transmission line pressure
The opposing pressures from the line and the governor make a C6 shift
There are a few good articles about C6 diagnosis online
I got a feeling your governor is the problem
The modulator and its vacuum source just cushion the shift and should not be the problem IMO
Can you check the line pressure?
The opposing pressures from the line and the governor make a C6 shift
There are a few good articles about C6 diagnosis online
I got a feeling your governor is the problem
The modulator and its vacuum source just cushion the shift and should not be the problem IMO
Can you check the line pressure?
I can check it although i installed a new pump assembly as the old one was worn on one edge. I will check and get back.
Thread Starter
|
4th Gear
Joined: Nov 2023
Posts: 4
Likes: 0
I am going with the governor here. Is this vehicle 4x4? I ask because if you get high enough rpm it SHOULD force a shift. So if you put it in 4 low you SHOULD be able to go fast enough to force a 2-3 shift and that would confirm the governor.
There is also the reverse trick where you go fast in reverse to force any sludge out backwards..... or you can just take it apart and check.
wardve always put the Transgo valvebody kits in c6s and loved the way they shift. Maybe it needs valvebody work? I know you said the trans is rebuilt, but did you replace any hard parts in the valvebody?
There is also the reverse trick where you go fast in reverse to force any sludge out backwards..... or you can just take it apart and check.
wardve always put the Transgo valvebody kits in c6s and loved the way they shift. Maybe it needs valvebody work? I know you said the trans is rebuilt, but did you replace any hard parts in the valvebody?
Thread Starter
|
4th Gear
Joined: Nov 2023
Posts: 4
Likes: 0
Replaced governer
I air checked the governor and it made the right sound.
Reassembled trans and still no 3rd gear
Im lost
Any suggestions?
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