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Discussion Starter · #1 ·
I got a 78 K5 Blazer for Christmas. Cool huh, new paint and 76,000 miles. The car sat for 11 years and we knew the tranny stuck a bit. Well it is very hesitant in going into drive and pops out easily. It seems to go in when cold, but once warm, it won't. 1st, 2nd, and reverse are all fine, and shifting is great also. Is there anything I should check? Oh yeah this is a TH350 bolted to a 400 and is a 4x4 with a NP203 transfer case. I do plan on changing the fluid and I hope i don't find chunks just wondering if there is anything I can check or fluid I can dump in.
Thanks,
CHris
 

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Look for any rust first,if you find some the rust might have pitted some of the spools an would keep them from moving back an fourth.If you see rust you should take the valve body off an look on the other side for rust on the spools. I bought a junk yard 700r4 an I had to replace 2 spools because of rust pits. Also the bores could have pits in them to,if they do your gona have to get a rebuilt valve body.
 

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Theirs alot of seals & some o-rings that sat around for 11 yrs. that won't seal any more. This is the real problem,you have atf that is leaking past seals so their not enough pressure to push pistons an spools.Something more or less like internal bleeding.
 

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Discussion Starter · #6 ·
Been busy but curiosity got the cat. Took the K5 out and she will go into drive at about 3600 RPM which I do not like. I kept driving her and it got easier, but still not normal. Suggestions, or just keep driving her?
 

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Been busy but curiosity got the cat. Took the K5 out and she will go into drive at about 3600 RPM which I do not like. I kept driving her and it got easier, but still not normal. Suggestions, or just keep driving her?
If you keep engaging the tranny at 3600 rpm, something's gonna give- the u-joints come to mind.

You may have a split O-ring, this happened to me w/a TH250 in a Buick years ago. Took the pan down and a chunk of the O-ring (square cross section) was laying there.

I hesitate to even say this, but you could try some of the canned rebuild that swells the seals. This might get you a few miles before it take a real dump, but if it was me, I'd bite the bullet and rebuild it NOW before that happens.
 
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