Need transmission help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Matt Man · 03-25-2018, 11:09 PM

So I finally got around to installing my deep transmission pan with a drain bolt and I was going to service the trans anyway since I have never done it in the 3 years I have had it. It started to shift more and more firm so I thought I would put the new pan on and have some fresh fluid mixed with the old. I know what COULD happen if you service a old transmission. Anyway, I got the pan off and the fluid was way worse than I thought it was was very dark brown in color and had metal shavings in the pan.

This is not the picture I took, but it looked very similar to this inside:
http://67-72chevytrucks.com/vboard/a...1&d=1522033445

So I put the new pan on and the thing leaks through the casting through a pinhole GREAT. So I ended up pulling the new cover off and just reusing the old one. The shifts are more smooth now but the converter is constantly locking and unlocking which also makes the truck jerk violently. Also, the truck sometimes will die when I come to a stop. So I guess the question is am I looking at a rebuild in the near future? The transmission is a Turbo 350c on my 81 k10.

Irish1941 · 03-26-2018, 12:01 AM

Locking and unlocking? With TH350? That's a 700R4 thing.
TH350 is on all the times. The convertor is not locking and unlocking. I'm thinking that's bad clutch you're feeling. Slip-grab-slip-grab
Like electrical, trans troubles are hard to diagnose online.
Im leaning towards the convertor has cashed out. More than likey pump is going out too thanks to convertor chunks.
If your seeing metal in the pan and with stalling out, convertor is finished. There is no clutch left in convertor so its direct to engine which causes the stalling. Convertor needs to slip at a stop or engine stops.
Im no trans rebuild expert but been down that road more than once.
Best GM trans guy. Hands down
http://www.phoenixtrans.com

**Willowrun** · 03-26-2018, 12:43 AM

TH350C has a locking TC. You could always pull the electrical plug out of the trans if you don't want it to lock.

**kwmech** · 03-26-2018, 12:59 AM

With the amount of debris in the pan, I'd say you were ready for a rebuild anyways. You can increase the clutches in the drums and a mild shift kit and be good to go.

Irish1941 · 03-26-2018, 01:18 AM

Quote:

Originally Posted by Willowrun

TH350C has a locking TC. You could always pull the electrical plug out of the trans if you don't want it to lock.

You are correct.

I forgot about the 350C trans...as did most everybody else.

03-25-2018, 11:09 PM	#1
Matt Man Registered User Join Date: Oct 2009 Location: Buhl, Idaho Posts: 1,438	Need transmission help So I finally got around to installing my deep transmission pan with a drain bolt and I was going to service the trans anyway since I have never done it in the 3 years I have had it. It started to shift more and more firm so I thought I would put the new pan on and have some fresh fluid mixed with the old. I know what COULD happen if you service a old transmission. Anyway, I got the pan off and the fluid was way worse than I thought it was was very dark brown in color and had metal shavings in the pan. This is not the picture I took, but it looked very similar to this inside: http://67-72chevytrucks.com/vboard/a...1&d=1522033445 So I put the new pan on and the thing leaks through the casting through a pinhole GREAT. So I ended up pulling the new cover off and just reusing the old one. The shifts are more smooth now but the converter is constantly locking and unlocking which also makes the truck jerk violently. Also, the truck sometimes will die when I come to a stop. So I guess the question is am I looking at a rebuild in the near future? The transmission is a Turbo 350c on my 81 k10. Attached Images __________________ 86 c30 crew cab dually 454/400 4/6 drop SOLD 1-8-11 1981 chevy K10 short Bed Scottsdale SOLD 10-26-2020 67 GMC Stepside Straight six/3 on the tree "The Peach" 2020 Silverado Double Cab LT Z71 5.3 8 speed Daily Driver K10 build http://67-72chevytrucks.com/vboard/s...d.php?t=671934 The Peach build http://67-72chevytrucks.com/vboard/s...d.php?t=733903

03-26-2018, 12:01 AM	#2
Irish1941 Registered User Join Date: Nov 2012 Location: Los Angeles, CA Posts: 450	Re: Need transmission help Locking and unlocking? With TH350? That's a 700R4 thing. TH350 is on all the times. The convertor is not locking and unlocking. I'm thinking that's bad clutch you're feeling. Slip-grab-slip-grab Like electrical, trans troubles are hard to diagnose online. Im leaning towards the convertor has cashed out. More than likey pump is going out too thanks to convertor chunks. If your seeing metal in the pan and with stalling out, convertor is finished. There is no clutch left in convertor so its direct to engine which causes the stalling. Convertor needs to slip at a stop or engine stops. Im no trans rebuild expert but been down that road more than once. Best GM trans guy. Hands down http://www.phoenixtrans.com

03-26-2018, 12:43 AM	#3
Willowrun Senior Member Join Date: Mar 2013 Location: Ann Arbor, MI Posts: 1,030	Re: Need transmission help TH350C has a locking TC. You could always pull the electrical plug out of the trans if you don't want it to lock.

03-26-2018, 12:59 AM	#4
kwmech Senior Member Join Date: Mar 2003 Location: Colfax-California Posts: 8,650	Re: Need transmission help With the amount of debris in the pan, I'd say you were ready for a rebuild anyways. You can increase the clutches in the drums and a mild shift kit and be good to go.



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