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#1
12-07-2015, 04:25 PM
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How much to fix my transmission fluid leak?
My '69 LeMans (350, 3spd auto) has been leaking transmission fluid in my garage for a couple of years. I replaced the cooling lines (which were leaking), but that didn't completely stop the leaks. Is this likely the front seal that is failing? How much can I expect to pay to have a mechanic replace it? Thanks.
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#2
12-07-2015, 04:41 PM
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you have to clean everything off to find the source of the leak, it could be front seal or rear or the pan. If the pan it should be a DIY. If the trani has to be pulled and resealed it's a few hours of work times the labor rate of the shop.
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#3
12-07-2015, 05:23 PM
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1st of all .... bummer ....
this is my observations from the automatics I have worked on ...
1. how much does it leak... a couple drops or a table spoon ..... by the next morning after driving 2. does it drip sitting ther idling ? or does it leak sittin there overnite?? 3. if the tranny has not been power washed or cleaned and it leaks/drips alot..... look for the cleanest area around the pan and lower case... the hot tranny fluid will clean that area of road debris/sand/dirt and leave just an oil film.. and bare metal..check the case around the dip stick tube is there a down hill area that looks cleaner than the surrounding area where the tube enters the case ? your dip stick is bolted at the top correct ? sometimes the spot welds break.. but you would probably notice it wobbbling cuz youve been checkin fluid level with the leak.. 4. if nothing is obvious .... time to power wash the tranny REALLY good with degreaser ... with the torque converter cover off .... take a buddy with your floor jack to the power wash place in another vehicle ..take a big chunk of cardboard to lay on ... get in your grubby clothes and use eye protection ....just barely bump the engine over to get the other side of the torque converter and flexplate too.. 5. bath it hard from the passenger side mostly .... and the rear of tranny too.. hit the drivers side too suspect areas ... passenger side ... hit all the pan bolts good all around a. dipstick tube has an o ring... definately a leaker b. get the torque converter and the front pump area of the inspection cover...clean it while its off also C.... vacuum modulator has an o ring too it can leak d... rear drive line seal is the yoke wet or oily at the rear of tranny ?? e ... if you think your alll washed ... wait 5 minutes and do it 1 more time... really ... clean is good... f ... by the time you get home and jack it back up time to jack it up let the exhaust cool and start touching every above item till you get a little tranny fluid on your finger and your leak should show itself... G if not drop it back down from the jack wait a day or 2 or overnite... check the areas again for weepage... on a tranny with over 40k miles I am leaning towards .... 1 pan gasket and filter change ... when was the last time if you dont know ...its time 2 dip stick tube o ring.... get ahold of me on this there is a fool proof way on this ... 3 front torque coverter seal 4 drive line seal and possible groove on the yoke going into the tranny where the seal rides.. done u joints lately ? might be time to pull the drive line and check 5 resnug your lines witha TUBING wrench 6 vacuum modulator o ring 7 may be coming out the vent on the top of the case thats usually power glides more often 8 possibly the shifter stud coming thru the case not real likely but possible 9 check your tranny mount .... poke it with a srewdriver is it spongee at all ?? recently replaced? cheap 20.00 buy a new one... 10 probably forgot somethin .... large sheets of cardboard from Uhaul rentals will be your buddy dont forget to throw an old towel over the seat and take some ole towels along for the ride good luck ... maybe its rebuild time and then for sure the leak will be addressed 1 way or another youlle be in it a couple hundred to start with going to a shop for a tranny flush fluid and filter change a bath tranny mount drive line drop and check and having the front seal replaced the tranny is 3/4 of the way out already for a rebuild just my 3 $ worth... gotta get back to work .... S T on the side Scott maybe I should have just called yah .............. |
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#4
12-08-2015, 07:49 PM
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How often do you drive it?
My 68 GTO's T400 leaks copious amount of fluid if I don't drive it for a while. Someone said it's something about fluid draining back into the converter, and overfilling it. Driving it regularly seems to stop the leak.
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be a simple...kinda man. |
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#5
12-09-2015, 03:48 PM
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Thanks for all the information. When I had the cooling lines replaced in the summer, they also replaced the pan gasket and filter (but that didn't stop the leak). I drive 1-2 times a week from May-October, and generally I see the leaks after it sits in the garage. I put a piece of cardboard under the car, and it ends up soaked in tranny fluid after a couple of weeks. Unfortunately, I don't have a way to lift the car, so I'd have to have this done by a mechanic.
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#6
12-09-2015, 04:27 PM
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i didnt see it posted but 1 spot to really check is the Kickdown/Detent cable where is bolts to the trans. This is piece being normally plastic, can get a slight crack or the seal can get worn. Now when looking for the fluid it will sometime just run down the housing to the front of the trans an make it look like the front seal or front of the pan is leaking. I have been down that road and swore the front seal was busted, turned out to be a bad kickdown cable. the fact you were replacing the cooling lines recently, the cable housing could have gotten cracked while you were working on those.
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 Jon Peters 66 tempest 3880 lbs with driver 455 .40 over, 6x, XE274H cam, th350,9 inch 3.89, 275/50/15 mt dr 13.04 et / 102.51 mph 11.97 et/ 113.68 mph w/150shot 75 Astre Turbocharged OHC 6, TH350 1/8 mile stats 8.4813 ET / 82.07 MPH |
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#7
12-11-2015, 02:01 PM
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My contribution is porosity of the case itself and overtightening of pan bolts cracks the gaskets and/or deforms the flange of the pan.
Also bear in mind that even changing seals will not necessarily work if the shaft or bore in which the seal is situated has any wear or other scratches or damage. I measure success by the amount of leakage, not its complete absence!
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My Break Away Squad 1969 Fbird (base OHC, 350, 400HO & Sprint Cvt’s - 400HO & TA ht’s) 1969 Custom S 2dr ht 1969 LeMans (2dr & 4dr ht & Cvt) 1969 LeMans Safari wagon 1969 GTO (2 Cvt, 2 ht & Judge ht) 1969 Cat (3 Cvt’s & a 2dr ht) 1969 Ventura wagon 2 seat 1969 Exec 4dr post 1969 2 Bonnie Cvt's & 2 wagons 1969 Bonnie Brougham (4dr ht & Cvt) 1969 Grand Prix 2 SJ’s 1969 2+2 2dr ht (Canadian) |
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#8
12-11-2015, 03:05 PM
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Quote:
One you missed that I have leaking right now is the speedometer cable. I guess there is some kind of seal behind it. mine drips on the cross member makes it way to the trans mount and make it looks like the tail shaft is leaking. |
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#9
12-11-2015, 10:08 PM
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Dipstick Tube Crack
I once had a TH400 leak due to a crack in the dipstick tube down near the o-ring. My transmission guy said he had seen this many, many times. It actually leaked a fair bit with this ailment. We found the crack, repaired it, and it has been good as new since.
Look closely; it can be hard to find. |
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