I recenlty purchased a 78 F-150 4x4 with a 400/C6/205 combo and tonight the tranny wouldn't shift. It was doing fine earlier, but than as soon as the vacum line for the modulator valve got knocked off, it wouldn't shift, i put the vacum line back on after i noticed it had been nocked off and it is still not shifting. Any suggestions or need any more info, just ask, i'm new to the auto's, and it was rebuilt under 2,000 miles ago.

 

Is there vacuum at the modulator?

 

Yeah, there is vacum now, it's shifting at higher rpms now after this and you have to let off gas and it'll shift, but it seems like it's shifting hard and it'll cackle when it's in 3rd while deacellerating like a manual and also uses the engine to slow it down for a bit.

 

oil / filter change time? try a quart of lucus trans fluid additive and that might help

Matt

 

I'll try the addative allong with new oil. How hard is it to change the filter and any specific dirctions on how to do this? This might be a good idea since the truck was sitting for a while.
While i'm replacing tranny oil, should i also replace the differential oil and put lucas in the tranny and diffs?

thanks for the help

Dustin

 

It's very easy. Take the pan off the bottom of the tranny. You'll see the filter right there, it's bolted in. Kind of a weird shape too. Take that and the gasket off, put new one on. Clean the old gasket off the pan very well and put it back on. Simple as changing engine oil and filter.

 

i wouldnt worry so much about the diffs. getting them to seal up is an out right b****. i do see that ur in linsborg. im going to school at ksu. ill be going through salina on thursday night. would u like some help on changing ur filter around 5-6 thurs night?

changing the filter is pretty painless but hella messy. id reccomend getting a filter kit from the auto part store, as well as some floor dry. then pop the pan off and take it to your bench and clean it well. then scrape all the old gasket off. next pull the filter which is prolly held on by a small bolt. make sure to get the old o ring out with it. then install the new filter and bolt it in. then id reccomend putting the lucus in the pan as its thick and doesnt flow down the filler tube well. then rinstall the pan and pour fluid in till full (THIS WONT BE FULL FULL!!) then start your truck and let it idle and keep an eye on the fluid level. when it stableizes pull the truck forward and backwards till it starts to move normal. then let the truck warm up and fill it up when full. make sure not to put too much fluid in as too much is bad.

Matt

 

wow i just realized that this truck is basically the same truck as my old one. the interior looks exactly the same (cept mine was a manual)

Matt

 

Sure, the help would be nice, i don't work the rest of the week so it'll work out and i'll get the lucas, filter kit, and tranny oil. I'll send ya my address in a pm. I'll also make sure to get a pan so we can drain the oil in it.

 

yea, id recommend a pan and mabey some kittly litter or a spot where u can make a mess. cardboard is also nice to crawl around on. i get out of class at 3:45 ish and it will take prolly an hour and a half to get there. also give me a phone number in the pm and ill be glad to stop by. make sure that you get the correct filter kit at the store. crawl under ur truck and see the shape of the pan and that will be the shape of the pan gasket.

Matt

 

Sounds like a plan, i get outa school at 3:30 and i'll be home getting everything ready. I sent you a pm with address and phone numbers. I'll see if i have any cardboard around, may not since we're moving this weekend but the trucks gunna be used if we can get anything lifted that high...lol. I'll make sure everythings correct.

Dustin