Transmission Service-Photos Included

[DixieWASP]

My 1989 Silverado has 123,000 miles and I am the third owner. The truck developed a transmission leak in the last three weeks that appears to be coming from a defective transmission pan gasket. The transmission also has a slow and mushy shift from first to second gear. This morning I removed the cross member to access the pan. I serviced the 700R4 by replacing the old filter and pan gasket with a new filter and pan gasket. I used a parts’ washer to clean the pan very well on the inside and the outside before I reinstalled it. I added around 5.5 quarts of O’Reilly Dexron VI fluid. I don’t know the transmission’s service history but given the color and amount of clutch material in the pan I think it has been serviced by a previous owner. Please look at the pictures and see if you agree. Do you see anything abnormal in the pan? I have not driven the truck since the transmission was serviced this morning but I hope the mushy shift is gone.

 

[PlayingWithTBI]

The transmission also has a slow and mushy shift from first to second gear.

Is your TV cable adjusted properly?

The pan looks good but, a little piece of debris can get stuck in the TV spool and cause sloppy shifts on these transmissions. If it gets stuck, or not properly adjusted, you'll burn up the trans.

 

[Schurkey]

Pan gaskets "can" leak.

At least as often--probably more often--the real issue is something above the pan gasket leaking, the fluid drizzles down and looks like the pan gasket.

Common trans leaks:
Dipstick tube cracked where it's rolled for the o-ring seal into the case. Forming the O-ring groove work-hardens the tube, it cracks at the o-ring groove. The newer "top hat" style seal eliminates this issue.

Torque converter/pump seal

Speedo gear seals

Seal at TV cable housing at case

Modulator O-ring on trans that have a modulator

Output shaft seal

Electrical connector seals





Good luck with the 1--2 shift. Last time I pulled my K1500 trans pan off, most of the 2-4 band material was in big chunks in the pan.

 

[DixieWASP]

Is your TV cable adjusted properly?

The pan looks good but, a little piece of debris can get stuck in the TV spool and cause sloppy shifts on these transmissions. If it gets stuck, or not properly adjusted, you'll burn up the trans.

Thank you for the information and I will check for debris and the TV cable adjustment.

 

[DixieWASP]

Pan gaskets "can" leak.

At least as often--probably more often--the real issue is something above the pan gasket leaking, the fluid drizzles down and looks like the pan gasket.

Common trans leaks:
Dipstick tube cracked where it's rolled for the o-ring seal into the case. Forming the O-ring groove work-hardens the tube, it cracks at the o-ring groove. The newer "top hat" style seal eliminates this issue.

Torque converter/pump seal

Speedo gear seals

Seal at TV cable housing at case

Modulator O-ring on trans that have a modulator

Output shaft seal

Electrical connector seals





Good luck with the 1--2 shift. Last time I pulled my K1500 trans pan off, most of the 2-4 band material was in big chunks in the pan.

Thank you for letting me know about other places to look for a leak. The truck is on a lift in the shop now and I will check for leaks tomorrow and see if I have reduced or eliminated the leaks with the new pan gasket installed.

While I was adding the new transmission fluid this afternoon, my friend was in the truck to put the transmission through all the gears. When he depressed the brake pedal, the left rear metal brake line ruptured sending the pedal to the floor and nasty dark brown brake fluid all over the shop floor! When it rains, it pours. Now I have to repair the brakes before I can do any additional transmission work.

 

[termite]

Thank you for letting me know about other places to look for a leak. The truck is on a lift in the shop now and I will check for leaks tomorrow and see if I have reduced or eliminated the leaks with the new pan gasket installed.

While I was adding the new transmission fluid this afternoon, my friend was in the truck to put the transmission through all the gears. When he depressed the brake pedal, the left rear metal brake line ruptured sending the pedal to the floor and nasty dark brown brake fluid all over the shop floor! When it rains, it pours. Now I have to repair the brakes before I can do any additional transmission work.

On the bright side, it's already on the lift...

 

[GrimsterGMC]

Thank you for letting me know about other places to look for a leak. The truck is on a lift in the shop now and I will check for leaks tomorrow and see if I have reduced or eliminated the leaks with the new pan gasket installed.

While I was adding the new transmission fluid this afternoon, my friend was in the truck to put the transmission through all the gears. When he depressed the brake pedal, the left rear metal brake line ruptured sending the pedal to the floor and nasty dark brown brake fluid all over the shop floor! When it rains, it pours. Now I have to repair the brakes before I can do any additional transmission work.

That was actually very fortunate, imagine if that had happened as you were coming up on stopped traffic. Better to get it all out of the way while it's up on the lift.

 

[termite]

That was actually very fortunate, imagine if that had happened as you were coming up on stopped traffic. Better to get it all out of the way while it's up on the lift.

This is exactly my line of thought and would likely be my luck on when it would fail. I'm more likely to replace the lines when they start showing signs of failure just to avoid it.

My wife had the rear line on her old dakota fail due to rust on I-95 when we were dating and got lucky enough to not get in an accident. I've tried to be vigilant about brakes since then. Steering and stopping are the two areas I won't tolerate likely failures.