My truck sat for a couple of years and then I had the engine rebuilt. Engine running great now but i'm running into some transmission problems. I've noticed that it doesn't seem to start out in first gear and on cold mornings it won't shift on it own. I have to manually shift it until it is nice and warm. This evening I have finished changing the filter and put a quart of Lucas oil while refilling it after the changeout. After driving it around a bit i still get the same problem. Has anyone seen this problem? I have read a few things that have told me to tighten some bands. Should I take this to a local transmission shop to have it looked at or is this something I can still work on? Any suggestions?

Thanks

 

Sorry this is a 1978 Ford F-150 351M C6 transmission 2WD reg cab

 

At this point, considering the unit does shift fine when it's warmed up? I believe that the bands are correctly adjusted. Bands when they start to get out of adjustment will normally happen at all temps. (sometimes worse when hot or warm)

It could be a build up of varnish and crud in the valve body and the servos. This would create tight valves in the valve body and would create resistance when the fluid attempts to push against the valve. When the unit is cold, and you shift manually? You are doing more of the fluid direction..and not relying on the gov. or vacuum modulator.

You mentioned it does not start out in first gear? Does the truck attempt to go forward in 2nd gear....or maybe 1st gear--but slipping? This could be quite a few different things.... There is in the rear part of the unit a one-way roller clutch. If that is acting up? That would keep the unit from going into first gear--until you put it manually into first--then a servo kicks in doing the job the one-way clutch would normally do. (it's designed that way for heavy duty operation. Normally one would dump it to manual first for heavy load starting or 'rocking' the truck when stuck--the roller clutch might take to much stress--so the valve body kicks in the 1st-reverse band/clutch (sorry--can't remember which one LOL) That keeps that extra pressure off the roller clutch to keep it from breaking.)

It's a crap shoot at this point. Without having a shop tear the valve body apart and cleaning all the varnish out? (and ensureing the valves move freely)...This is all guess work.

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Maybe it is starting off in first but slipping. When I start from a stopped position it is very slow when it starts moving. I noticed this evening also sometimes it wouldn't go in to 3 without letting off the gas and i'm guessing allowing the vacuum to build up to switch to 3. If i smash on the gas it tries to step down a gear but never completely makes it. What does it normally cost for a shop to remove the varnish and get something like this working again correctly?

 

Not even sure that's the problem at this point. Although I'm sure a transmission shop will probably suggest just rebuilding the whole thing. Can't really say any $$ amount as the shop will have to diag. the problem and then kickup an esti. Might be cheaper to buy one already rebuilt or a used one with a warr.

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