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Jared D
Jared D, ASE Certified Technician
Category: Classic Car
Satisfied Customers: 1346
Experience:  Shop Supervisor at County Fleet
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I have a 78 GMC K25 4x4 It's been sitting or 6 years. Went

Customer Question

Hi, I have a 78 GMC K25 4x4 It's been sitting for 5 or 6 years. Went to move it and the TH400 isn't engaging and going into gear. Ran fine the last time I drove it. The Trans fluid was very low (none showing on dipstick) and I added 4 quarts +/-. Can move the gear selector out of park through all the gears with the truck running and when I try to go back in park there is a grinding noise. Have to turn off the engine to get back in park.
Submitted: 1 year ago.
Category: Classic Car
Expert:  Jared D replied 1 year ago.

Does the snifter feel loose and wobbly?

It sounds like the shift linkage is out of alignment, but it's strange that it won't move. After idling in park for a few minutes did you check the level again? Sometimes when they are really low you have to run them for a few minutes to get the air out of the system to get it to go into gear.

Customer: replied 1 year ago.
The shifters seemed tight (trans/transfer case). We ran it for a while and kept adding trans fluid until the level stabilized. I was thinking of taking off one of the coolant lines to the radiator to see if it's pumping fluid.I see a lot of forum posts where people are having the same problem when the truck sits for a while and is low on fluid but not seeing any answers.I've never had this happen before. Seems like something is stuck internal given that it worked the last time it ran..
Expert:  Jared D replied 1 year ago.

It's possible that there is tarnish buildup in the transmission lines or in the torque converter that is not allowing fluid to flow. I think your idea of pulling one of the lines to see if it pumps fluid out is a good idea, just be ready in case it is pumping normally; that's a lot of fluid pressure.

You might also have to pull the pan on the transmission to make sure the filter hasn't disintegrated and isn't allowing fluid to pump.

Customer: replied 1 year ago.
Thanks I'll try that.
Customer: replied 1 year ago.
Have a great holiday or weekend if you're outside of the US.
Expert:  Jared D replied 1 year ago.

Thanks you too. Let me know if you need any additional info.

Customer: replied 1 year ago.
Thanks. Sounds good.
Expert:  Jared D replied 1 year ago.

Let me know if you need any more help.

Please don't forget to rate. They don't pay us if we don't get a positive rating.

Expert:  Jared D replied 1 year ago.

Let me know if you need additional information. I would love to help if you still need assistance.

Don't forget to rate. We don't get paid if we don't get a positive rating.

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