Alright, just to let you guys know, transmissions are seriously a different language to me. I have no idea what in the world I'm doing when it comes to them. The transmission pan is leaking on my 72 Lark (auto). Is transmission fluid what is leaking (I know, stupid newbie questions)?ou: I honestly don't know what to do. is it basically like changing the seal on the oil pan- drain the fluid, get a new gasket, etc...? Any help will be much appreciated!! Thanks guys.
Its a little more involved than changing your oil. If its a Turbo 350, then youll have to remove the two transmission mount bolts and jack up the tailshaft a bit so the pan can clear the trans crossmember. Just make sure the pan gasket is in fact the gasket leaking. If anything is leaking up higher, it will leak down and make it seem like the pan is leaking. For example the dipstick tube, govennor cover or the modulator O ring could be leaking and not the pan gasket. If your going to replace it, you might consider replacing the pan with one that has a drain plug. Makes life alot easier if you need to do the job again in the future. You'll also need a large catch pan. I took one of my plastic garbage can lids and drilled some drain holes in it and used it in conjunction with my oil drain pan. The fluid comes out of the oil pan like rain so be prepared. Go to Napa and get a USA made transmission filter kit with a cork gasket. You'll need about 5 quarts of Dextron
Is a cork gasket really the best material? Cork sucks on valve covers so I can't imagine it working well anywhere else.
Sometimes they give you a real thin composite gasket. If there is any irregularities in the pan rails, the composite gasket wont cut it. The thickness of the cork usually compensates for a less than perfect pan rail.
Unless you are comfortable under the car while it's up on stands, there is another option. As Jason stated, pan will show a leak that may have started somewhere above. I had a similar problem in my '71. Dipstick tube seal failed, about 2 quarts of Dextron on the floor at the storage facility. Took it to a local trans. shop & left it for the day. This after I talked to the owner a few days prior. Shop dropped the pan, changed the filter. Installed new external seals on dipstick, speedo cable, downshift cable,shifter mechanism, maybe another 1 or 2. Put in new trans. oil after cleaning & reinstalling pan & gasket.Adjusted shifter linkage. I didn't get a drop on me. Out the door for about $250.00. My garage floor has never been dryer.
I will keep this in mind and keep you updated. I will be away at football camp this weekend (yes, I'm only 17 :laugh: ), but hopefully I can get this stuff done next week. Thanks for the help, guys!
Is the oil red? Than it's automatic transmission fluid (ATF). If it's not red (not ATF) it's engine oil. Wich is coming from a leaky rear main seal. If you see a drop of oil hanging from the converter cover (thin sheet metal cover for the converter and flywheel) and it looks like engine oil, it most likely is. You could easily be mistaking it for a leaking transmission maybe. Does your car sit a lot? If so, you might have a normal case of 'convertor drain back'. Nothing serious, and nothing you can do about it really. Except for not letting it sit for too long. But most likely it is your pan gasket that is leaking. A filter kit is the way to go. Now is the time to replace the filter. And those filter kits come with a new pan gasket.
I usually drive my car about 4 or 5 days a week, probably about 55 or 60 miles a week max. It usually only drips when it's just been turned off. it doesn't drip more than one or two drips at a time. The oil is not red, as far as I can tell.
its not a difficult repair at all. Basically a gasket and a few external seals. The only seal you need a tool to remove/ replace is the shift selector seal. Lisle or K-D makes it. No different than swapping an engine oil pan. The engine oil pan is harder to do! I take the trans pan over an oil pan any day
It may not look red on the ground. Stick your finger in the dripped spot on the ground and then check color. I had a pan leak so I bought a nice aluminum pan, with a drainnplug. No more leaks.
Did you get that polished aluminum job with the fins that they have on Ebay? I bought one for the green Riviera because my original Hydramatic pan was bent to hell. Looks trick and the flange is nice and thick. No more bent rails!
Jay show it to me. I went to my local speed shop and we looked through all the catalogs together and picked out a beaut.
the culprit could be the tranny front seal. i had fluid leak from the o-ring at the base of the filler/dipstick tube.
Alright guys... It is transmission fluid that is leaking... and last night while driving the transmission started to slip... I'm assuming the lack of fluid is causing the slipping. Is there any special brand or type of fluid to put in it? I'm going to post a new thread to maybe get some more attention so I can get more help.
Turbo 350s are notorious for leaks at the shifter shaft where it goes through the case; and GM transmissions in general are known for leaks at the modulator O-ring and the speedometer driven gear and housing. Parts are available, but not as readily as they were years ago. The last 350 shifter shaft and speedo gear leaks I fixed required a trip to every parts store and trans shop in a town of 50,000 people; and even then some parts had to be ordered which delayed the completion of the repairs.
Matt, I agree with the above that it may be tricky to locate exactly where the fluid is coming from. I would check all of the suggested areas before getting into any gasket replacement. If you crawl underneath, you can pull the dust cover off and see if there is any fluid coming from the torque converter or front pump seal. Four screws/bolts hold the dust cover on. Otherwise, check the bolts on the tranny pan to see that they were torqued on properly, I think I recall it being around 15 ft lbs of torque. Someone else can probably clarify exact torque specs. If you can tell that it is leaking from the tranny pan, a gasket kit is cheap, and comes with a filter (good idea to change it too if you have it all open anyway).
when changing tranny fluid, is it necessary to flush it somehow or simply warm it up and let it drain out? I remember taking a car to a quick lube once and they offered for an extra charge they, flush the tranny? What is that about and is it necessary?
Just draining it is normal for a gasket/filter change, though there is still transmission fluid in the torque converter that will not be drained. Some torque converters have a drain plug. If not, another method is to disconnect the transmission cooler lines from the radiator. Submerge the intake line in a bucket of new fluid, empty the outplut line (old fluid) into an empty bucket. Run engine until new fluid is discharged into the output bucket. To answer the question about fluid type, just purchase the cheapest Dexron compatible ATF available by the gallon at your parts store. Devon
