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  #1  
Old 09-20-2009, 04:00 PM
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W124 300D Transmission Problem

I drained my tranny fluid, dropped the pan, replaced the filter, cleaned the pan, installed new gasket and tightened the pan bolts.

I thought.

As I was refilling the transmission with fluid and I got to about five quarts, a massive leak started at the pan.

I thought it might have just ran the dipstick tube but I eventually realized that it must have been coming out from around the pan gasket.

From the table I read this transmission takes 6 liters for an oil change.

I wasn't even there yet when this started happening.

The previous owner drove this car through sand and mud and as a result all that is still caked on the underside of the car.

I mention this because that dirt and sand on the top side of the pan bolt holes was binding up the very long winded bolts.

My question is whether or not there could be another source for the leak beside the pan gasket.

If not, I will continue to crank on the pan bolts.

Also, has anybody been able to get an accurate reading from their dipstick?

Mine, with the leak, is reading OVER full.

Thanks for the help.

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  #2  
Old 09-20-2009, 04:05 PM
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You did not drain the torque converter so you overfilled it, you were supposed to drain the torque converter and maybe if you could also open cooler lines to get all the stuff out, capacity should be 7 quarts i believe once all of that is out.
if you torqued to specs and did the correct cross pattern then pan gasket shouldnt be leaking but this procedure can be a little tricky if you havent done it much.
Do not drive it over filled.
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eP
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Old 09-20-2009, 04:14 PM
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You dont want to reinstall the bolts dirty like that, i always clean the pan and bolts with brake cleaner and dry everything nicely so i can get a good grip, it is possible that the gasket maybe pinched or that you didnt tighten the bolts properly, when dirty the bolts can feel like they are going into place but they arent going all the way, you may also have a tendency to over/under tighten when dirty.
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Old 09-20-2009, 04:19 PM
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The manual I read states that if draining torque converter refill with 7.1 liters of fluid.

If only replacing fluid, refill with 6.0 liters.

http://www.ps2cho.net/downloads/MB%20CD/W124/Index/Groups/00Maintenance81-93.htm

On the above page click on automatic transmission fluid and filter change.

I have driven it for about five miles just to hope to get an accurate reading of the fluid at operating temp.

It does seem to shift very differently than it did before.

I'm certain that I didn't put any more in that was required based on the information I had.
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Old 09-20-2009, 04:21 PM
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Quote:
Originally Posted by europower View Post
You dont want to reinstall the bolts dirty like that, i always clean the pan and bolts with brake cleaner and dry everything nicely so i can get a good grip, it is possible that the gasket maybe pinched or that you didnt tighten the bolts properly, when dirty the bolts can feel like they are going into place but they arent going all the way, you may also have a tendency to over/under tighten when dirty.
I did clean the bolts but I didn't clean out the bolt holes.

I didn't do this because I didn't want to risk getting a bunch of sand in the transmission.

I will give the gasket a close look again to make sure it's not pinched anywhere.

Once I've done that I will keep tightening those bolts....
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Old 09-20-2009, 04:36 PM
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Yeech!

1.Do Not Overtighten the Pan Bolts!
Clean,Clean,Clean...
(With my Obsessive "Clean Freak"approach to all things Transmission,I'd be
terrified ,That just as I'd be sliding the clean pan and gasket up to the Tranny
a clump of contaminants would fall on the gasket surface unbeknownst to me.)

I'd drop back and spray the underside of the entire transmission with the
appropriate cleaner and then hose off...repeat until Clean.

Then pull the pan and gasket and check for contaminants.
Then check the Parting surface on the Transmission body for damage.

If I remember correctly this chassis was used to herd cattle?

'Could the Pan or the Tranny Parting Surface be damaged?
'Any evidence the PO used Extraordinary measures to seal up the Pan?
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Old 09-20-2009, 04:53 PM
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#2

When you replaced the Torque Converter and Pan drain plugs did you use NEW
drain plug gaskets(Little COPPER O-Rings)?
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Old 09-20-2009, 05:14 PM
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Quote:
Originally Posted by i-osprey View Post
The manual I read states that if draining torque converter refill with 7.1 liters of fluid.

If only replacing fluid, refill with 6.0 liters.

http://www.ps2cho.net/downloads/MB%20CD/W124/Index/Groups/00Maintenance81-93.htm

On the above page click on automatic transmission fluid and filter change.
I read that as if you drain the pan and torque converter, refill with 6 quarts. If you're filling a transmission and cooler that haven't been in service, fill with 7.1 quarts.

It's safe practice to take an operating temperature dipstick reading before draining and keep track of how much comes out of the pan and torque converter separately. If the car was running before fluid service, give a lot of thought to filling the transmission with more than you drained.

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87 300D
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  #9  
Old 09-20-2009, 05:33 PM
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Quote:
Originally Posted by sixto View Post
I read that as if you drain the pan and torque converter, refill with 6 quarts. If you're filling a transmission and cooler that haven't been in service, fill with 7.1 quarts.

It's safe practice to take an operating temperature dipstick reading before draining and keep track of how much comes out of the pan and torque converter separately. If the car was running before fluid service, give a lot of thought to filling the transmission with more than you drained.

Sixto
87 300D
Well, let me ask you this.

Under normal circumstances, is the fluid level in the pan higher than the pan gasket?
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Old 09-20-2009, 05:34 PM
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Quote:
Originally Posted by compress ignite View Post
When you replaced the Torque Converter and Pan drain plugs did you use NEW
drain plug gaskets(Little COPPER O-Rings)?
I didn't drain the torque converter.

I also didn't use a new washer on the plug.

I didn't have an aluminum one like the one that was on it.

However, it's not leaking from the drain plug.
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  #11  
Old 09-20-2009, 05:35 PM
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Quote:
Originally Posted by compress ignite View Post
1.Do Not Overtighten the Pan Bolts!
Clean,Clean,Clean...
(With my Obsessive "Clean Freak"approach to all things Transmission,I'd be
terrified ,That just as I'd be sliding the clean pan and gasket up to the Tranny
a clump of contaminants would fall on the gasket surface unbeknownst to me.)

I'd drop back and spray the underside of the entire transmission with the
appropriate cleaner and then hose off...repeat until Clean.

Then pull the pan and gasket and check for contaminants.
Then check the Parting surface on the Transmission body for damage.

If I remember correctly this chassis was used to herd cattle?

'Could the Pan or the Tranny Parting Surface be damaged?
'Any evidence the PO used Extraordinary measures to seal up the Pan?
It still has sand and mud caked on it after I have driven it 28K miles and I have cleaned much of it already.

Brake cleaner will eat the gasket won't it?

I have the "non-chlorinated" stuff but I don't recall if it's any safer on plastic/rubber.
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  #12  
Old 09-20-2009, 05:54 PM
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Did you pinch the gasket? or did it roll on you? I think the 2 aft bolts are shorter then the others. Is there play in the pan and the transmission? Do you have a picture? maybe some dirt got between the pan and the gasket? Good luck.
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  #13  
Old 09-20-2009, 06:15 PM
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Quote:
Originally Posted by i-osprey View Post
Under normal circumstances, is the fluid level in the pan higher than the pan gasket?
I don't know for sure but I would guess not on level ground.

How much did you drain?

At this point I would drain the pan and torque converter, drop the pan and reinstall paying close attention to how the gasket is seated to be sure, then fill with 4 quarts. With the engine running, fill in half quart increments pausing to shift through the gears each time until fluid is 1cm (spec for 722.4 is 12mm) below the low mark on the dipstick. At that point, get the transmission to operating temperature (20 min of driving, not idling) then check the level and top off in cup or smaller increments until the level is between the min and max marks.

I don't mean to sound harsh but the same section of manual you quoted for the capacity says to fill with 4 quarts, then start the engine and idle in park, fill the rest gradually, etc. Which could be exactly what you did. I add the safety step of checking the dipstick often over the last couple of quarts keeping in mind the 1cm/12mm below the min mark target.

Sixto
87 300D
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  #14  
Old 09-20-2009, 06:54 PM
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This potential problem with transmission pan gasket installation is usually over torquing the pan bolts rather than under torquing them! Over torquing can actually split the gasket!
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  #15  
Old 09-20-2009, 08:33 PM
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Well, it was overfilled and I apparently didn't see that part about filling 4 quarts and then filling the rest.

I drained some and there are no leaks.

Where was it leaking from?

Is there a breather hose/vent?

It didn't leak at all while filling until I guess I went way over.

Now all is well.

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