Operation "Save the driveway"

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Old60Driver

1983 K20 Silverado
Joined
May 17, 2020
Posts
211
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234
Location
Houston
First Name
Michael
Truck Year
1983
Truck Model
K20 Silverado
Engine Size
350
Did a small top end job on my 83K20 (cam, heads, intake), and she's running great! However, I've got some leakage on the TH400. Going to try to pinpoint it tonight. Leaks noticeably more if I let her sit for a bit. Going to wipe everything down, start her up and watch. I don't have any of that leak detector yet. It's on the list. lol I've anticipated shift seal, dipstick, modulator and maybe the speedo. I'm going to double check the pan bolts too. She only has about 67K miles on her, but I know the rubber can harden and all that. Tempted to just change these parts out, but as I'd had to change out a part, when an o-ring would work.

What say y'all? Any other places I should look?

Thanks!
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,369
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3,637
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
Go to your nearest parts store and buy a bottle of A/C oil with the fluorescent dye. You will also need a black light, you can get that at the parts store also. Add a little to the fluid and take it for a drive.

Once the drive is over and the truck has cooled down, crawl underneath and shine the light around. The black light will highlight where the leak is coming from.

If the dipstick tube Oring is leaking, inspect the groove where the o ring is positioned. They are notorious for rusting or cracking. If that’s the case, trash all of ot and get a dipstick that takes the boot type seal. It’s a much better design.
 

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