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#1 |
Registered User
Join Date: Dec 2009
Location: new castle,pa
Posts: 137
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th 400 leaking
Well i am finally at the end of my rope...I have searched the web and the threads on here and ive tried everything they have suggested....and it still leaks..Ive blown out the vent tube...blown air back through the fill tube...all clear...ive put a moroso gasket on...replaced the brand new modulator...kept the fluid level down some...and it still is leaking.....doesnt leak at idle...it starts to leak after you have driven for a few miles....only leaks from the passenger side also....please someone help me......
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#2 | |
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Join Date: Oct 2012
Location: Salt Lake City, Utah
Posts: 3,331
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Re: th 400 leaking
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#3 |
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Join Date: Dec 2009
Location: new castle,pa
Posts: 137
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Re: th 400 leaking
Im willing to try anything at this point...Thank you for the tip...i will post how it works out...
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#4 |
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Join Date: Oct 2012
Location: Salt Lake City, Utah
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Re: th 400 leaking
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#5 |
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Join Date: Jun 2010
Location: Upland Ca
Posts: 4,143
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Re: th 400 leaking
Have you determined where it is leaking from? The passengers side has several spots it could be coming from.
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1972 C10 SWB, Air, PS, PB, 350/350THM. Second owner. 1965 Corvette roadster, 44K miles, 327/365 SHP, 4 speed, side exhaust, knockoffs, teak, second owner (bought in 1970), Have ALL numbers matching components. My frame off restoration thread: http://67-72chevytrucks.com/vboard/s...d.php?t=556703 |
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#6 |
Watch out for your cornhole !
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Location: Azle, Texas
Posts: 14,162
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Re: th 400 leaking
I would suggest pinpointing the leak and repairing with new seal, o ring, or whatever it takes. Adding special fluids is a bit of a band-aid.
Get it very clean and spot where the leak is coming from. Posted via Mobile Device |
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#7 |
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Join Date: Dec 2009
Location: new castle,pa
Posts: 137
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Re: th 400 leaking
Well over the weekend i have eliminated two possible exit wounds here...it is not the breather tube and its not the fill tube.....
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#8 |
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Join Date: May 2007
Location: Southern, Saskatchewan
Posts: 640
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Re: th 400 leaking
Don't forget the kickdown cable entry point on passenger side.
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Kerry My build thread. http://67-72chevytrucks.com/vboard/s....php?p=3657823 1971 Chev SWB with 68 nose, 6.2 diesel th350, and 3.73 rear gears 1988 Chev Extendacab 2010 Honda VT1300CS Sabre 2005 Buick Rendezvous wife's ride |
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#9 |
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Join Date: Jan 2007
Location: Sonoma, CA
Posts: 521
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Re: th 400 leaking
TH400 is electric, no cable.
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#10 |
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Join Date: Mar 2012
Location: Boulder, CO
Posts: 350
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Re: th 400 leaking
All the transmissions I've seen that Lucas was run in them, had, upon tear down, a fine 'patina' of what appeared to be surface corrosion. It was very light, but present throughout. It would seem that the 'slip elimination' is due to roughing up the surfaces of the metal plates, possibly at the expense of bearings and hard parts. We got to look at the guts when the transmission finally stopped transmitting, as the 'magic sauce' cure is a temporary one, at best. As mentioned above, fixing the leak is preferable to 'magic sauce'. Clean it off really good, and check it closely for signs of seepage.
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If 'that which does not kill me, makes me stronger', then I should be Superman by now! |
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#11 | |
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Join Date: Oct 2012
Location: Salt Lake City, Utah
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Re: th 400 leaking
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#12 |
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Join Date: Mar 2012
Location: Boulder, CO
Posts: 350
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Re: th 400 leaking
Whether or not the Lucas accelerated the transmissions' internal failure is always subject to discussion and conjecture. I saw plenty of units that didn't run Lucas, that blew up anyway (usually Mopar, but I digress). I know there are many solvents and chemicals that can react with ATF and any soft parts internally, and that could be the source of the 'patina', no one at Lucas would ever give a straight answer. That being said, the Lucas treatment may gain some time before more severe conditions occur. Leaks, though, are best fixed properly, even when it is a PITA- the 'magic sauce' trick can let go, and the consequence of fluid loss will definitely be more expensive than a leak repair. Clean it up, find the leak, fix the leak- that prevents any uncertainty about what's really going on with the transmission. Pan gaskets are a usual culprit, clean the surfaces nice and dry, don't use any sealer on the gasket and snug the bolts down evenly, but not 'superman tight'. There's an outside chance of porosity or cracking, but that's usually easy to spot. Anymore, whenever I drop a transmission, I reseal it as a matter of course, checking the converter snout and output bushing for wear, too. I only want to do it once!
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If 'that which does not kill me, makes me stronger', then I should be Superman by now! |
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#13 | |
Watch out for your cornhole !
![]() Join Date: Jun 2003
Location: Azle, Texas
Posts: 14,162
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Re: th 400 leaking
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#14 |
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Join Date: Dec 2009
Location: new castle,pa
Posts: 137
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Re: th 400 leaking
Tell me if im wrong...but it seems as though werever the leak is it is under pressure...cause it doesnt leak if i just let it sit there and idle...like i said earlier...it will start to leak after a few miles from the house...i would think that if it was the gasket it would leak at idle also.....so maybe it is the cooling lines only leaking after the fluid is nice and warm do they leak....ive cleaned it off many times so i could check were the leak would be...i get under it and all i see is fluid all over the passenger side....also...my kickdown switch is on the drivers side....
i didnt put the lucas treatment in yet...i bought it...i do want to find were the leak is first....also...thank you all for your continued help...as always you guys are great...
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#15 |
Registered User
Join Date: Dec 2009
Location: new castle,pa
Posts: 137
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Re: th 400 leaking
Is the pan fluid under pressure??? i was told no....
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#16 |
Registered User
Join Date: Dec 2009
Location: new castle,pa
Posts: 137
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Re: th 400 leaking
Well fellows im glad to report that we have found our elusive tranny problem...took the truck out for a ride the other day after changing the cooling lines..thinking they were the culprit...so when i came back home looked under and saw that i had over torqued a bolt and put a crack in my aluminum pan....yikes..
So i found a metal pan to replace the old one and before i put the new one on i noticed the bottom of the fill tube....ah hah...bottom line is i was way overfilling the trans to make it full according to the dipstick....the full on the dipstick is maybe 2 1/2 inches up into the dipstick.....so problem solved...thanks gentlemen....
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