Another ATF Question
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Racer
Joined: Sep 2003
Posts: 353
Likes: 1
From: Long Island, New York
Brian,
After looking through the WSM's I believe the tranny does operate at some significant pressure. There is a procedure for testing the system with gauges during operation. The test procedure uses three gauges - two with a range of 0-150psi and one at about 0-300psi if I remember correctly. This tells me that the system is indeed pressurized some significant amount (the wsm's even talk of the various ranges at various shift points, etc. I think I will see what I can find out and maybe give this a try?? I might reach out for Steve C. tomorrow and see if he has any input.
Doug
After looking through the WSM's I believe the tranny does operate at some significant pressure. There is a procedure for testing the system with gauges during operation. The test procedure uses three gauges - two with a range of 0-150psi and one at about 0-300psi if I remember correctly. This tells me that the system is indeed pressurized some significant amount (the wsm's even talk of the various ranges at various shift points, etc. I think I will see what I can find out and maybe give this a try?? I might reach out for Steve C. tomorrow and see if he has any input.
Doug
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From: Comox, BC
Yes, Doug... I'm sorry to have been somewhat misleading. What I meant to say was that the pan, acting as the ATF reservoir, does not operate under presssure. This is much the same as the oil pan of the engine. Both unpressurized reservoirs provide immersion sources for the oil-pump pickup. The systems are then operating with oil-under-pressure until such time as leakage or valving vents the pressurized oil back into the plenum (casting/pan) where it flows by gravity back into the reservoir. The pressure testing equipment you mention is exactly the same idea as the engine's oil pressure guage. It taps into the pressurized gallery at one (or more) places to provide information about the control circuts in the transmission, which is more a collection of hydraulically controlled mecahnical actions, than it is about only lubrication.
None the less........ the pan is not operating under pressure, and the seals passing through the case are not, either.
None the less........ the pan is not operating under pressure, and the seals passing through the case are not, either.
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From: Comox, BC
Revelation time!! 
It should come as no huge surprize that I was chasing ghosts! I broke down and took the car to Norden Autohaus, here in Edmonton. They put their 928 guy on it...... he's older than ME!!! I spoke to him and told him the whole long sordid story, so he ducked the normal issues of pan gasket and main-seals and headed straight for the obtuse.
He discovered that the Vacuum Modulator Valve seal was allowing a fine spray of ATF to form a small rivulet about 1' forward of the unit. That rivulet oozed over the edge of the case and ran along the pan-gasket. He said it might have fooled him if he wasn't good with the tiny gasket-seal bead that was all around the gasket.
It's a $1.50 seal, readily available from the Mercedes dealer across the street. He'll install it tomorrow morning, and check it over for other leaks, but he says we've got it!
WooHoo!! a $1.50 part and 2 hours of labour!
It should come as no huge surprize that I was chasing ghosts! I broke down and took the car to Norden Autohaus, here in Edmonton. They put their 928 guy on it...... he's older than ME!!! I spoke to him and told him the whole long sordid story, so he ducked the normal issues of pan gasket and main-seals and headed straight for the obtuse.
He discovered that the Vacuum Modulator Valve seal was allowing a fine spray of ATF to form a small rivulet about 1' forward of the unit. That rivulet oozed over the edge of the case and ran along the pan-gasket. He said it might have fooled him if he wasn't good with the tiny gasket-seal bead that was all around the gasket.
It's a $1.50 seal, readily available from the Mercedes dealer across the street. He'll install it tomorrow morning, and check it over for other leaks, but he says we've got it!
WooHoo!! a $1.50 part and 2 hours of labour!
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Joined: Oct 2003
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From: Nova Scotia
Originally Posted by BrianG
Revelation time!!
It should come as no huge surprize that I was chasing ghosts!
It's a $1.50 seal, readily available from the Mercedes dealer across the street. He'll install it tomorrow morning, and check it over for other leaks, but he says we've got it!
WooHoo!! a $1.50 part and 2 hours of labour!
It should come as no huge surprize that I was chasing ghosts!
It's a $1.50 seal, readily available from the Mercedes dealer across the street. He'll install it tomorrow morning, and check it over for other leaks, but he says we've got it!
WooHoo!! a $1.50 part and 2 hours of labour!
. Glad to hear it is solved! 
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From: Comox, BC
Mike, you dork!
You comin' to Kalispell this week-end???
Saturday run down there.......... Sunday run back!
Grab your girl, and come along!!
So far:
3 928's
2 TT Stealth's
3 Nissan Z's
one Bimmer of some kind!
All Couples........ 30..... 50 age group!
ya ya, you'll be the youngest!
Get off your stool and come along!
You comin' to Kalispell this week-end???
Saturday run down there.......... Sunday run back!
Grab your girl, and come along!!
So far:
3 928's
2 TT Stealth's
3 Nissan Z's
one Bimmer of some kind!
All Couples........ 30..... 50 age group!
ya ya, you'll be the youngest!
Get off your stool and come along!
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From: Comox, BC
WooHoo!! 
A nice gentle 1000mi week-end trip on the 4th Annual Logan's Pass "Run to the Sun", and this is the FIRST time in 2 years that the transmission's oil pan has been seen to be DUSTY!!
Not one drip!!
No bloody spot on the concrete parking slab!!
Nuttin' !!
Nadda !!
ONE FOR "NORDEN AUTOHAUS" THE EDMONTON PORSCHE DEALER!!
A nice gentle 1000mi week-end trip on the 4th Annual Logan's Pass "Run to the Sun", and this is the FIRST time in 2 years that the transmission's oil pan has been seen to be DUSTY!!
Not one drip!!
No bloody spot on the concrete parking slab!!
Nuttin' !!
Nadda !!
ONE FOR "NORDEN AUTOHAUS" THE EDMONTON PORSCHE DEALER!!
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Joined: Jan 2004
Posts: 12,620
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From: Boulder Creek, CA
WTG Brian!
So you saved the $$$ of having the guy do all of the obvious stuff... From the sound of things, this is something you probably could have found and fixed yourself if you only had a lift. That's one of my first priorities for my garage, when I build it... plenty of overhead clearance, and a lift. Maybe a pit too.
Anyway, good job, Norden Autohaus! And great effort, Brian!
So you saved the $$$ of having the guy do all of the obvious stuff... From the sound of things, this is something you probably could have found and fixed yourself if you only had a lift. That's one of my first priorities for my garage, when I build it... plenty of overhead clearance, and a lift. Maybe a pit too.
Anyway, good job, Norden Autohaus!
And great effort, Brian!
Thread Starter
Racer
Joined: Sep 2003
Posts: 353
Likes: 1
From: Long Island, New York
Final Installment - I think I fixed the leaking transmission pan 
Last Friday I replaced the fill tank, o-ring at the union , new gasket, and overflow tube and bought one of the fine scale torque wrenches to make sure I had the pan bolts set properly. After a full day's driving and several days of watching the underdise of the car - No leaks. 
Now I'm ready to get the new custom exhaust and get inspected (I hope all goes well).
Last Friday I replaced the fill tank, o-ring at the union , new gasket, and overflow tube and bought one of the fine scale torque wrenches to make sure I had the pan bolts set properly. After a full day's driving and several days of watching the underdise of the car - No leaks. Now I'm ready to get the new custom exhaust and get inspected (I hope all goes well).