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05-22-2019, 10:17 AM | #1 |
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th350 pan gasket change
Going to change the pan gasket in my trans this weekend. Got a quick question should I put on some black RTV along with the gasket to help with leaks overtime?
Thanks Jeff |
05-22-2019, 12:22 PM | #2 |
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Re: th350 pan gasket change
For some reason they say not too, but I have done it with out issue many times.
I prefer to get the rubber seals as they do not need anything. The cork can have a tendency to leak especially when over torqued. |
05-22-2019, 01:42 PM | #3 |
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Re: th350 pan gasket change
Cork is what I have on there now and im going with the same rubber type. Ill put a small amount of RTV on the trans side and see how that goes.
Thanks for your help |
05-22-2019, 02:03 PM | #4 |
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Re: th350 pan gasket change
also DRY DRY DRY before any install. or if there is atf on the surface anyplace it will most likely leak from there . and if you do want to use rtv let it cure up before you fill the trans with fluid .
i have been using RIGHT STUFF for years now and no problems .
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77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great. |
05-22-2019, 03:23 PM | #5 |
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Re: th350 pan gasket change
Get a one piece oil pan gasket and be done. just a little RTV at the corners at the front and rear.
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05-22-2019, 05:39 PM | #6 |
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Re: th350 pan gasket change
I didn't think about letting it cure. Good advice thanks!
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05-22-2019, 07:01 PM | #7 |
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Re: th350 pan gasket change
RTV clogs valve body passages if it gets loose, that's why some say not to use it.
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05-22-2019, 07:29 PM | #8 |
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Re: th350 pan gasket change
My bad, I was thinking engine. I had issues with sealing a th350 pan and ended up doubling up the gasket and using right stuff to seal it...
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05-22-2019, 08:40 PM | #9 |
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Re: th350 pan gasket change
Put it up clean and dry, I prefer cork. No RTV. Do not over tighten.
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05-23-2019, 10:44 AM | #10 |
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Re: th350 pan gasket change
Do you guys recommend RTV on pan side of gasket, trans side, or little on both?
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05-23-2019, 11:30 AM | #11 |
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Re: th350 pan gasket change
It depends. If the pan is beat up, maybe glue two gaskets together and then put them on dry.
Also, while you have the trans empty, replace the oring on the dipstick tube.
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"Work hard, use your vacation days." 1970 C15 GMC Long Bed 1986 C20 Scottsdale 1983 K2500 Sierra Classic Suburban 6.2 Instagram: C10sofOC |
05-23-2019, 11:48 AM | #12 |
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Re: th350 pan gasket change
Why the dipstick tube? Just curious
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05-23-2019, 03:48 PM | #13 |
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Re: th350 pan gasket change
It's a common leak point, the **** shaft seal is another common area to leak. I hate fighting transmission leaks, I use lube locker gaskets, and cheap summit racing aluminum pans, and that seals things up nice, and the drain plug in the pan is a nice touch also.
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05-23-2019, 05:51 PM | #14 |
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Re: th350 pan gasket change
When I used to work in transmission shops we would first make sure it was the pan leaking and not something above by cleaning and drying the trans and letting it run (in gear) on the hoist for awhile. If the pan was leaking and any time we had a pan off for any reason we would put a straight edge across the pan mating surfaces and pay close attention to any gaps caused by distortion usually at the bolt holes. We would gently hammer the pans straight with a ball-peen hammer. As I recall, we never ever used any sort of sealant on any brand of trans.
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
05-23-2019, 07:11 PM | #15 |
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Re: th350 pan gasket change
if you have the o-ring seal tube clean it and the area of the case good . then rtv around it with your finger after new o-ring installed and tube is in the case bolted in place .
if you have the rubber grommet style clean dry and maybe a tiny bit of petrolium jelly on it is all thats needed . and rubber in case then slide in the tube .
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77-k30lb BIG truck build . 87-k30lb budget beater build . 85-k30lb the plow machine build . 85-c10sb summer fun toy . ----------------------------- HOLLEY SNIPER efi = worst case of p.i.t.a i ever had . EDELBROCK pro flo 4 = best deal going so far . love my setup works great. |
05-23-2019, 10:27 PM | #16 |
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Re: th350 pan gasket change
I always had issues with rubber gaskets leaking. Switched to cork and never had any leaks again. Also, I don't use any RTV.
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05-24-2019, 12:56 AM | #17 |
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Re: th350 pan gasket change
Maybe not obvious but with a sheetmetal pan/cover (1/4" bolts), I think I'd use a nut driver to tighten the bolts so as not to distort the pan, and not shear off a bolt.
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05-25-2019, 08:02 PM | #18 |
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Re: th350 pan gasket change
I have both like the cork better. Less leaks I think I just a small bead around the bolt holes on the pan side dry before you torque it down. When cork gasket time to change or ben one few yr. if the gasket start to look like getting wet it time for a change. should be changed 1yr in most cases. to keep the trans in good shape.
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1977 REG cab Long Bed with a 1984 Front Clip, 82 305 .60 over 9.0.1 flat top pistons, 4bbl, TH350, w/84 SS-intake & cam , w/ 1977 big block rad, 1975 gear box, 1984 master w/ metric fittings top & SAE fitting @ portion block, 1975 3.42 gear open diff. Duel 77-87 Factory air cleaner, duel inlet from rad support . Down sized 9' to new 8' Steel flat bed Was a 77 454 w/308 gear. Taken out 550 lbs. up front with motor clip change. |
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