TH350 will not engage after sitting for three months

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Cipriano

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Hello,

So I purchased my '76 K15 "As Is" after it sat for 3 months. I got the engine running today (replaced starter/solenoid and ignition module). Went to take it for a spin but I cant get the TH350 to engage. Tried all the different positions on the full-time 4WD transfer case. Didn't help, tran wouldn't engage in any setting.

My first thought is possibly an extreme case of torque converter "morning sickness" after sitting for 90 days. Any thoughts or tips on how I get the TH350 to engage?

Thanks!
 
78C10BigTen

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Not to sound rude but start simple... have you checked the fluid level? Maybe its low. I know my 78 leaks and is low after extended sitting. If you give it some rpm's will it try to move?
 
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I'll check the fluid in the morning. And, no offense taken regarding simple recommendations! :)

I know there was "some" fluid on the dipstick when I was kicking the tires. But that was before I got the engine running.
 
Smtty58

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Did the trans work before you bought it? Sounds like it wasn't running when you got it, so that could be an unknown. My first thought was "morning sickness" also. Run through all the gears, letting it spend time in each gear. Also, odd, but make sure the converter is bolted to the flexplate.
 
78C10BigTen

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Cipriano said:
I'll check the fluid in the morning. And, no offense taken regarding simple recommendations! :)

I know there was "some" fluid on the dipstick when I was kicking the tires. But that was before I got the engine running.
Click to expand...
Theres usually fluid on the stick when not running because the pump isnt pumping fluid. Thats why it says to check in park while hot.
 
78C10BigTen

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Smtty58 said:
Did the trans work before you bought it? Sounds like it wasn't running when you got it, so that could be an unknown. My first thought was "morning sickness" also. Run through all the gears, letting it spend time in each gear. Also, odd, but make sure the converter is bolted to the flexplate.
Click to expand...
On that note! The ears may be busted off the TC too...(highly unlikely). Thats how my dad got our 73. Guy said it needed a trans and dad found out it needed a TC cus the ears were broke off. Just so happened there was one in the back of the truck.
 
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Smtty58 said:
Did the trans work before you bought it? Sounds like it wasn't running when you got it, so that could be an unknown. My first thought was "morning sickness" also. Run through all the gears, letting it spend time in each gear. Also, odd, but make sure the converter is bolted to the flexplate.
Click to expand...
The kid I bought it from said the transmission was okay when he parked in 3 months ago due to the solenoid and ignition module. He seems trustworthy but then again nowadays...who knows.
 
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It was towed to my house, rear axle elevated, front axel on ground. Could that have done something?
 
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I once had a '78 van with a th350 and if it sat for a few weeks, the fluid level would get low enough that the transmission would no longer transmit anything. I don't remember if it would act up at only 1 qt low, or if I would just simply dump in another qt of fluid to make it do transmixer things again.
 
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78C10BigTen said:
On that note! The ears may be busted off the TC too...(highly unlikely). Thats how my dad got our 73. Guy said it needed a trans and dad found out it needed a TC cus the ears were broke off. Just so happened there was one in the back of the truck.
Click to expand...
I've seen flex plates crack, also.
 
Smtty58

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Cipriano said:
It was towed to my house, rear axle elevated, front axel on ground. Could that have done something?
Click to expand...
Been a long time since I owned a 203, but IIR, if you towed with the front wheels on the ground, and the Tcase wasn't in neutral, the back tires would spin also. How far was it towed?
Also, with the truck in park, Tcase in gear, will the truck roll? I would consider Tcase problems here also.
 
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Cipriano said:
Hello,

So I purchased my '76 K15 "As Is" after it sat for 3 months. I got the engine running today (replaced starter/solenoid and ignition module). Went to take it for a spin but I cant get the TH350 to engage. Tried all the different positions on the full-time 4WD transfer case. Didn't help, tran wouldn't engage in any setting.

My first thought is possibly an extreme case of torque converter "morning sickness" after sitting for 90 days. Any thoughts or tips on how I get the TH350 to engage?

Thanks!
Click to expand...
If you haven’t figured this out yet, first thing id do is install a mechanical transmission pressure gauge, fire it up and see if you have any line pressure at idle. I’d also check vacuum signal at the modulator as well - you want at least 13-15Hg.

If no line pressure is showing on the gauge, drop the pan and see if the filter is clogged up. If so, replace the filter, put fresh fluid and repeat the line pressure test. If still no pressure, yank it for overhaul.

If you’ve already solved the problem, disregard….
 
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