Mark axed the right question...does it shift all the way into 3rd, and then stays there, or does it "neutralize" when it should shift into 4th?
If it simply does not make the final shift into 4th, there are a couple of things that could cause it. The T.V(throttle valve) cable could be out of adjustment, or frayed.
The 3-4 shift valve could be stuck in the valve body.
In
rare instances, the servo seals(on the pass side) for 4th could be damaged.
If it does shift 1-2-
3 with no problems, that tells us the 3-4 clutches are good, as they are applied for 3rd
and 4th.
And...if it has a good 2nd gear, that tells us the band is good, as it applies in 2nd
and 4th.
Sooo...if the above is your scenario, then we are looking at a cable problem, a stuck valve, or possibly a check-ball(in the valve body) that has hammered it's way thru the separator plate.
More info is needed...how fast have you(or he) driven it to see if it will eventually shift into 4th?
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Joel Adams
C3VR Lifetime Member #56 
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