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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: dburbach85 on February 14, 2017, 09:01:28 am

Title: No 3rd gear?
Post by: dburbach85 on February 14, 2017, 09:01:28 am

Hi guys, checking back in after a very long (about 10 months at this point) 1987 R10 project. The truck was originally a 4.3 V6, but that engine died and I just finished swapping in a nice new 350. Everything seems to be working just fine, except my transmission (Turbo 400) won't shift into 3rd. Or rather, it will when I'm coasting, but as soon as I get back on the gas it downshifts to 2nd and stays there. 1st, 2nd and reverse all work perfectly. Any help?

Title: Re: No 3rd gear?
Post by: bd on February 14, 2017, 12:06:01 pm

Check the transmission fluid level and inspect for ATF leaking from the modulator valve vacuum nipple.  Then make sure the vacuum line is securely connected at both ends to the intake manifold and modulator valve.

Title: Re: No 3rd gear?
Post by: dburbach85 on February 15, 2017, 08:12:09 am

The transmission fluid level is good, but I'll check out the modulater valve. Thanks!

Title: Re: No 3rd gear?
Post by: Irish_Alley on February 23, 2017, 12:38:03 pm

dont forget to check the hose also