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Let me rephrase this:(86 F250 C6 trans)

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Jak

03-31-2006 14:12:37




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What will a faulty modulator valve's symtoms be on a 1986 F250 C6 automatic transmission?Can it affect the second to third shift?




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Doc 2

03-31-2006 22:17:24




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 Re: Let me rephrase this:(86 F250 C6 trans) in reply to Jak, 03-31-2006 14:12:37  
You will get delayed upshifts, 1-2 and 2-3, but the 2-3 is most notable. The modulator is the most likely cause. Pull the vacuum hose off the modulator and if it is bad there will be transmission fluid in the hose. There could also be other problems. FIRST thing to check with any transmission problem is fluid level and condition. Start with these things and go from there.



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Josh H

03-31-2006 18:09:52




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 Re: Let me rephrase this:(86 F250 C6 trans) in reply to Jak, 03-31-2006 14:12:37  
I'm no expert on auto transmissions. I have an 84 f150 with a c4. It has always hesitated going into 3rd. If you are on the gas hard it shifts well, but if you aren't accelerating hard it revs for a second before it goes in. It started to shift both gears only at high rpms, and downshift everytime you touched the gas. I replaced the modulator and it fixed the shifting at high rpms but didn't fix the hesitation shifting into 3rd. They are only about $20 and go on in a minute. Replace it if your unsure.
Josh

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rustyj14

03-31-2006 18:08:57




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 Re: Let me rephrase this:(86 F250 C6 trans) in reply to Jak, 03-31-2006 14:12:37  
to find out, using a pump oil can, squirt a bit of brake fluid into the tube where the vacuum hose goes on it, let it sit for 10 minutes, then try it! If that cures it, go buy a new vacuum modulator, and install it! You'll need a thin open end wrench to install it, and to remove the old one! I heard from a friend, who on a trip out west with his 1966 Ford, got taken by an unscrupulous transmission shop in Indianapolis! $500 to squirt brake fluid in the modulator--100 miles down the road, same thing! A guy at a little old gas station fixed it right for "peanuts"! A new modulator fixed it up! I'd of gone back that night and lit the place up! Rusty

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Billy

03-31-2006 15:09:35




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 Re: Let me rephrase this:(86 F250 C6 trans) in reply to Jak, 03-31-2006 14:12:37  
First I'm not an expert on automatic transmissions,
but I have seen several bad modulators..The ones I'm seen will not shift gears at normal speeds, always at high speed.. it affects first to second and second to third shifts... A vacuum leak will do the same..



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Bob

03-31-2006 15:39:54




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 Re: Re: Let me rephrase this:(86 F250 C6 trans) in reply to Billy, 03-31-2006 15:09:35  
Sounds right. Also, a bad modulator or a problem with the vacuum line to it will cause HARD shifts from park or neutral to "R" or "D".



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