98 convert A/T 2.73 original gears. I took my car to an incredible vette mechanic because the differential was leaking from the drivers side axle shaft and the seal between the transmission and differential. I had every seal on the differential changed/resealed. 2 months later I see a drop of differential fluid. So I put it up on ramps and on the passengers side coming right down the front of the differential I see this rubber hose hanging down and it is cut on an angle. Looks like a drain hose of some sort. I don't remember seeing it there in the past but it looks like it belongs there because it has a clip, which is held onto the differential under one of the side cover bolts, that holds this hose in place. The fluid is 100% coming out of this hose. Is this hose attached to the vent, what does it do and is it original or did the mechanic add it on? I can't find anything about it in the manual either.

 

There is not hose on the vent unless it was added. I have a DTE rear sitting on my workbench right now and there is no hose. Have you checked the fluid level?

 

Sounds like your mechanic installed the hose on the vent cap, to prevent fluid from getting the differential case all dirty when some fluid is vented out of the rear end. To verify this is the case, suggest you just ask your mechanic if this is one of his modifications.

 

I'm not sure about the hose, but your diff my vent some fluid after long drives for a while if it was overfilled.

 

Spoke to the mechanic this morning. It is attached to the vent on top and directs the fluid down right in front of the leaf spring. He said it was normal but to keep an eye on it. As far as if he added it, I forgot to ask but it is there and this is it's purpose. Thanks All! I think it is a great idea because without it, its hard to tell where the leak is. This way all you have to do is flick it with your finger and you can see it come out.

 

There is a bracket that bolts on the passenger side of the rear differential that holds a vent line from the transmission. Unless you get under the car you may think it comes from the rear end. What color is the fluid? You can almost see the bracket (at about the 4 o’clock position, right where the lower edge of the transmission and the differential come together) in this picture from Mike Mercury's page but the line is out of the bracket.

 

Well, maybe. The vent also acts like a check valve and if the hose interferes with this function it could be a problem source.

 

OK now I am completly confused. Yes this is the line that I am speaking of. The fluid is brown/black not red. This is why I am ruling out trans fluid. So what you are saying is this line that I saw fluid coming from is in fact from the tranny? I guess what is most important to me is what does it mean when fluid comes from this line? Also, if it is from the tranny why is it not trans fluid?

 

Transmission fluid will turn a darker color with age and heat exposure. How many miles on the transmission and has the fluid been changed per the maintenance schedule? The most common cause of fluid coming out of the vent hose is fluid overfill, in other words too much transmission fluid. If it was serviced recently that could be the cause. One little drop of transmission fluid can look like a huge amount on the ground.

 

OK. In early Feb the whole diff was resealed and the trans was opened to fix play in the output shaft (this is why the seal between the trans and diff was leaking) they also changed the 2/4 band. So the fluid was changed in Feb. The only way to really be sure about what is going on now is to drive it and watch. It has been sitting for 2 days now and bone dry. My question to Scotty3 is what is that part the hose is attached to in the photo. It looks like it is not part of the trans at all. Please explain? Something tells me the hose runs behind it and it is an illusion that it is attached to it.

 

The vent hose attaches to the top of the transmission, about mid way down the top to be exact. Its purpose is to allow the fluid to vent out if it expands too much or if there is a pressure problem. The level in the transmission will expand with temperature. The car has to be level, on a lift or jack stands to check it. If your mechanic added fluid when the car wasn’t at the correct operating temperature he could have overfilled the transmission slightly and now the extra fluid has come out of the vent. That’s what it is suppose to do. If it doesn’t happen any more … end of story. Hope this helps.

INSPECTION PROCEDURE

CAUTION: When the transmission is at operating temperatures, take necessary precautions when removing the check/fill plug, to avoid being burned by draining fluid .

1. Raise and suitably support the vehicle.
2. Start and run the engine at idle.
3. Apply the brakes.
4. Shift the transmission into each gear for at least 2 seconds per gear.
5. Shift the transmission into NEUTRAL and continue to idle the engine for 3 minutes to stabilize the transmission fluid level.
6. After allowing the fluid level stabilization time and while still in NEUTRAL (engine still running at idle), check the transmission fluid temperature on the driver information center. Specification Transmission fluid level temperature: 30 to 50°C (86 to 122°F)
7. If the fluid temperature is above specification, turn off the engine and allow the transmission to cool, then repeat the procedure to this point before proceeding.
8. With the engine still running at idle, loosen the check/fill plug on the LH side of the transmission oil pan.
9. Inspect the fluid level:
 Any excess fluid will drain when the check/fill plug is loosened.
 If no fluid drains, remove the check fill plug and fill the transmission with DEXRON transmission fluid unfit the fluid begins to overflow.
10. Install the check/fill plug.
 Tighten the fill plug to 30 Nm (22 ft. lbs.) .
NOTICE: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

11. Shift the transmission into PARK.
12. Release the brakes.
13. Turn off the engine.
14. Lower the vehicle.

 

Really appreciate your help. Sounds great. I will give it some time watch it and take it from there. Basically it seems to be a fill issue adnd checking it does not seem that bad. If you can get leveling and temp right it seems easy. Thanks!