Auto Oil level sight tube?

[mr.n]

Has anyone added an Oil level sight tube? I want one for my next C4 re-build.

Any ideas where to add it on the C4? I'd rather not tap the C4 case and make it weaker.


Pictures of an oil level sight tube on a Atlas t-case.

 

[Broncobowsher]

A sight glass is fairly simple device. Fluid enters a the bottom, top is vented to the same location as the fluid. the fluid seeks it's own level, therefor the level you see on the tube matches what is inside what you are checking for.

In order for it to work the biggest thig to remember is the venting of the top of the sight glass. Since the transmission case is not presurized, as long as the top is open to the atmoshpere it should work. But being used in a vehicle, particurally an offroad vehicle, you can't leave the top open or it will spill and/or take in cantamination. So it must be looped back into the case.

What you will have should look like the Atlas sight tube (the pictures didn't come across on my computer but I know what they look like). You will need the lower tap below the fluid line, pan will be fine. The upper fitting only has 3 choices as you are not willing drill the case (good idea).

1) tie it back into the vent on the top of the transmission
2) tie it into the dipstick tube (least liked by me as you have to still deal with the dipstick, rely on the dipstick not sealing tightly in order to vent and the dipstick tube still enters below the fluid level so it still isn't really vented to the same as inside the transmission as it would in #1)
3) place the vent high enough that you can't slosh the fluid out. Make sure the standard trans vent is still venting correctly or else pressure differential will alter the sight glass readings.

Also pick materials carefully. The cheap vinyl hose that you see working for an Atlas is no match for the heat of a warmed up transmission. Also note that most clear plastic tubing will tend to stain from the dyes in transmission fluid, especially hot fluid. There are some industrial sight glasses that may be able to be adapted.

 

[mr.n]

A sight glass is fairly simple device. Fluid enters a the bottom, top is vented to the same location as the fluid. the fluid seeks it's own level, therefor the level you see on the tube matches what is inside what you are checking for.

In order for it to work the biggest thig to remember is the venting of the top of the sight glass. Since the transmission case is not presurized, as long as the top is open to the atmoshpere it should work. But being used in a vehicle, particurally an offroad vehicle, you can't leave the top open or it will spill and/or take in cantamination. So it must be looped back into the case.

What you will have should look like the Atlas sight tube (the pictures didn't come across on my computer but I know what they look like). You will need the lower tap below the fluid line, pan will be fine. The upper fitting only has 3 choices as you are not willing drill the case (good idea).

1) tie it back into the vent on the top of the transmission
2) tie it into the dipstick tube (least liked by me as you have to still deal with the dipstick, rely on the dipstick not sealing tightly in order to vent and the dipstick tube still enters below the fluid level so it still isn't really vented to the same as inside the transmission as it would in #1)
3) place the vent high enough that you can't slosh the fluid out. Make sure the standard trans vent is still venting correctly or else pressure differential will alter the sight glass readings.

Also pick materials carefully. The cheap vinyl hose that you see working for an Atlas is no match for the heat of a warmed up transmission. Also note that most clear plastic tubing will tend to stain from the dyes in transmission fluid, especially hot fluid. There are some industrial sight glasses that may be able to be adapted.

Broncobowsher, thanks for the long answer!
Can you expand on the industrial sight glass?

Start at the Pan is a great idea, might make it the front so it doesn't catch on sticks. (Well hopefully, and that make a point. I'm not 100% sure on this as if it pulled out that would suck... I mean spill)
What about tapping the cast adaptor plate? near the vent.

I've a 72 case with a plugged hole. See pic. Is this hole to high or to low for the fluid. I guess I'm saying I'm not sure where the fill mark is on the tranny.

1972 C4 2wd case fill, was behind a 351. Used for my 4x4 C4

1975 C4 4wd case fill, used the 4x4 parts. Note no hole in the middle.

 

[Broncobowsher]

I believe that hole in the middle is a pressure tap for diagnosing the transmission. Probably a new machining method deleted it from production.

Tapping the adaptor should be fine.

http://www.grainger.com/Grainger/ww...r=prodIndexRefinementSearch&L1=Sight+Glasses,
is the 30 second internet search

 

[broncnaz]

While a novel idea do you really want to crawl under the vehicle to check the oil level? especaily in a auto tranny where oil level is critical.

 

[mr.n]

While a novel idea do you really want to crawl under the vehicle to check the oil level? especaily in a auto tranny where oil level is critical.

Not a trail ride that goes by that I havn't been on my back looking up at the drive train....

 

[Broncobowsher]

Not a trail ride that goes by that I havn't been on my back looking up at the drive train....

But how often do you do it on flat level ground with the engine running and the transmission at operating temperture?