71 eldorado transmission pan replacxement

[NORTHPORTGUY]

seem i have a slight fluid  leak from my transmission.  the pan was damaged/dented  and i suspect that's the cause, although the modulator seems leaky too..  anyway i ordered a nice shiny cast aluminum pan with drain plug from autozone via ebay but alas my transmission guy says it is for a 400 trans and not a 425.  so can anyone help confirming if the pans for these two transmissions definitely differ and can anyone recommend a source for a replacement 425  pan?  or offer any comments , informed opinions about changing a transmission  pan in place for at least 35 years. 
thanks

Ken Wiebke

member 23013. 

[The Tassie Devil(le)]

G'day Ken,

They are totally different, as are the Filters.

As for repairing the original pan, unless it is totally trashed, which would also trash the internals of the trans itself, I would have no hesitation in panel beating it straight, which I have done on many occasions.

Now, there are other places for the trans fluid to escape from, and that includes the rear chain cover, shift lever, as well as the Vacuum Solenoid.

If it is coming from the chain cover, then that in itself is a bear to do, as I have't found any replacement gaskets for that, and ended up using Loctite 5900 for the replacement, as this stuff is compatible with Auto Transmission Fluid.   I use this as a gasket replacement, or in conjunction with the gasket, as I have never had a leak since using it.   I found it after consulting with my local Loctite Supplier as I couldn't locate a replacement Chain Cover Gasket for my '72 Eldo.

Bruce.

PS.   My sump required a bit of massaging back into shape as well.

[TJ Hopland]

Yes you have what they called the 425 and the pans are different than the 400.  The 400 has a pretty odd shaped pan, the 425 is close to square.   The pickup and filter is also different.

These guys have a couple options for pans and other hard to find parts for these.  Not cheap.
http://www.appliedgmc.com/level.itml/icOid/482

I have the ragusa pan and am not really impressed.  Don't know if they got better or not.   I had to do some grinding to get it to clear the chain cover and part of the valve body.  I also really wonder if the casting is really porous and it just weeps.

Lots of other places for these to leak.  The dipstick tube leaks and its not quite a standard size oring.   The governer/speedo housing leaks.  The electrical connector leaks (and is the same as the 400).  The shift shaft turned out to be the worst leak on mine last year and in theory it can't come out in the car but I found a shop that managed to do it last year.   Its not a lip seal like many of the 400's its just an O ring.   I replaced the o ring when I had it out a few years ago but it still ended up leaking again.   I didn't ask how the shop fixed it, just wrote the check.

[The Tassie Devil(le)]

The shift shaft turned out to be the worst leak on mine last year and in theory it can't come out in the car but I found a shop that managed to do it last year.   Its not a lip seal like many of the 400's its just an O ring.   I replaced the o ring when I had it out a few years ago but it still ended up leaking again.   I didn't ask how the shop fixed it, just wrote the check.

Actually, the Shift seal can be replaced in the Eldorado, and not the RWD vehicle whilst the transmission is in place.   At least Cadillac thought of that.   It is very easy to do it once the pan is off, and the lever disconnected.   The shaft comes right out and one of the easiest tasks that I have had to do on my car, apart from the mess involved.

Bruce.

PS.   Forgot to mention the other leaking possibilities.   And that it was a TH425.

[TJ Hopland]

The shift shaft must be a year thing, I forget there were small differences.  71-72 may have been slightly different, they did change things slightly to ad the impact bumpers and changed the position of the mounts.  I tried it on my 73 and it hits the frame before you can get it all the way out.  I didn't ask for specifics but I assume the shop had to at least unbolt or remove a mount to get enough angle on the whole driveline to clear the frame.   

[bcroe]

Amen to all the above.  The cast aluminum motor home version works and has
a nice drain (to avoid so much mess).  But I would not use one because there is
less ground clearance, and a good jolt could crack it.  Instead I'd beat mine into
shape, braze a leak if required, and I always braze a square of 1/4" stock against
a side to be drilled & tapped for a 1/8" pipe thread drain. 

Actually the seal of a TH400 can be changed in the car.  But make sure the shaft
is smooth and rust free on the outside of the seal, or it will fail again.  I slide
that nail keeper forward as far as possible, bend it, and slide it out.  At the end
I put in a cotter pin the correct length.  And do the drain.  Bruce Roe

[NORTHPORTGUY]

Thanks for all the input.  .  This forum is so helpful!     

Maybe the answer lies in putting more sand/kitty litter on my garage floor?

I'll consult with my transmission shop  who seems quite good-  and let you folks know...

Ken Wiebke
member 23013 

[bcroe]

Maybe the answer lies in putting more sand/kitty litter on my garage floor?
Ken Wiebke    member 23013     

I get a 3' by 8' piece of duct sheet metal, and bend up the edges.  Extra folds
at the corners; cutting will cause a leak.  A rubber ball hanging down lets me
position the car exactly over it.  The Honda next to it doesn't seem to need one. 
Bruce Roe

[TJ Hopland]

Along the lines of what Bruce was saying there are fancy pads you can put under the car that are a little less messy than kitty litter and parts stores sell a big metal tray that works well.   You can also buy shallow plastic tubs meant for a cloths washer or dryer at a home store pretty cheap.   I have been using a large dog kennel liner I found at a Farm N Fleet sort of a store.  I would think pet stores have em too.   Its fairly large, like 36x48 with only a 1" tall side and its black plastic.   

A 100% leak free car is not easy.  Several years ago now I finally got tired of all the leaks and patches and since I knew the timing chain was on its way out figured it was overdue for a rebuilt.   Spent a lot of money and it was great for a while but was under it last week and noticed wet spots and a few drips again so it didn't last that long.   Maybe my guy and I didn't do a perfect job but I think we get spoiled with newer stuff that has much better designed seals and gaskets. 

My transmission has had varying degrees of leaks for the 20 years that I have owned it.  Even after the rebuild fairly early on there were some drips.  Took a few tires to fix it but not were 100% successful.   At times there were puddles especially after winter storage (like quarts worth).   Last summer when I was moving I finally just took it to a shop I trusted and basically gave them a blank check and said fix it.  Its 95% better now and does not always drip on the ground but there are wet spots on the pan. 

Basically I am saying you can spend time and money and still not get a 100% leak free car.  It could happen but more likely it wont.  It really depends on how bad its leaking and how much time and money you want to invest for how much improvement.

[54 caddy larry]

I have a 74 shovel head harley, when it stops leaking oil I start to worry. Usually means I'm out of oil,lol.

[The Tassie Devil(le)]

Some older machinery worked on the principal of Total Loss.

Went out of favour as the roads began to be sealed.   Okay for the dirt roads of the time, but not bitumen roads.

Bruce.