Yeah, I know, non-Mopar question...

patrick66

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Got a little problem with my 1987 GMC 1500 with automatic trans. It leaks like a stuck pig, and I can't figure out where it's coming from. I did a transmission fluid/filter change on it recently. The capacity with converter is 13 quarts. I put eight in it, as I didn't drain the converter. New filter in. New gasket on. Start the truck and let it idle for a time. Life's good...for a minute or so. Now, I have fluid leaking onto the shop floor like mad! I made sure the dipstick tube had a new O-ring on the trans end, but it doesn't appear to be leaking there. It leaks whether the truck is running or not. I saturated a sheet of cardboard I had stuck under it to try to see where the leak is from, and that was not any help at all.

No leaks at the tailshaft.

So, here is what I figured...either the dipstick seal is crap, despite the new O-ring. Or a loose fitting on the side of the transmission (there are two on the passenger side), or the speedometer cable pinion seal. Or the torque converter??? It has sat for about a week now, and I am not seeing any further leakage, so it's likely dripped below the point of the leak. Gonna start it up tonight, move it around a bit in the yard, and park it over another bit of cardboard and see if I can figure out the leak source.

This is an amazingly straight and rust-free truck. It needs tires, a windshield, and working brake lights to be street-legal. I'm a big fan of the '73-'87 GM pickups, so it's a "work on it when I feel like it" project truck for me. My son can't afford to keep this old square-body going, so I bought it from him and sold him my '01 Ram Club Cab. The Ram is dependable and very clean and solid.
 
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jimmyessbee

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That reminds me of a K5 Jimmy I had. It leaked from the dipstick tube but not when running -- presumably because the fluid was up and moving around and not sitting around by the tube. I just brought a ramp with me everywhere I went and before I shut it off, I drove it up on the ramp on the side with the dipstick. I lost very little.

I probably would have fixed it were it a ramcharger.
 

Justin Plant

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The fluid level raises quite a bit when the vehicle is turned off. Just like the torqueflite in your boat. If it is the trans tube, that side is the unit will be covered with fluid. It should be pretty easy to find. If you start the truck and check the fluid it'll almost certainly be low. If it is the dipstick seal, buy a quality replacement. Viton or something like it, wet it with some fluid and stick it in.
 

haywire 440

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Just stabbing in the dark… is it supposed to be pints?

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patrick66

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Quarts and liters are close enough to be the same
Just stabbing in the dark… is it supposed to be pints?

View attachment 566685

The TH400 and TH700R4 have the same capacity. The above is shown in liters and pints. The 1987 capacity is slightly higher, at 13 liters.

Time to check things again tonight after work. It does appear that I simply over-filled it, according to the chart you provided, at eight liters versus eight pints. I might well have mis-read the specs I had. That's a relief, if I indeed did that! And now, I feel like a knucklehead. I appreciate the info you posted!!!
 
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70bigblockdodge

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GM uses a grommet to seal dipstick tube. Vent is on top behind the bell housing if I remember right. If not, it is at the rear on top before the tailshaft housing/or transfer case adapter. Those seal/grommet get pretty hard and if disturbed will leak.
Square Chevy, one of the best trucks ever made. Of course all 70s/80s trucks are great, save for some 80s electronic ignition and spark control (easily eliminated)
 
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