1978 F150 Help
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Joined: Mar 2008
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1978 F150 Help
I just recently bought a 78 f150 4x4. I believe it has a 351m with a c6 transmission. I just want to use the truck for wheeling. However it has a few issues that I was wanting to get some advice about. The engine cranks and idles fine, however it seems to have a bad oil leak between the motor and transmission. I believe it is a rear seal but have read a lot on this forum about these trucks having other causes for an oil leak and would like to see where you guys think I should start. It also seems to be running a bit rich and don't know whether to rebuild the carb or put a new one on it. Also the transmission is giving a bit of problems. It will go into reverse fine but when i put it in a forward gear like D 2 1 it will not go into gear till i give a pretty good bit of gas and then it will grab. Should i just get that transmission rebuilt or buy one?
Any help would be greatly appreciated. Thanks.
Any help would be greatly appreciated. Thanks.
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Joined: Mar 2005
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From: Lake Havasu, AZ
Have the Trans rebuit by a shop that is local to you, I just have the one in my 94 f150 rebuilt and had issues with it, one of the new moduals they put in was faulty out of the box, they had to replace it again and then everything work perfect. The key to this is local shops go by word of mouth and will continue to work with you if there is probles after the rebuild.
Back several years ago when I have my C6 rebuilt in my 78 the local shop replaced the rear main seal and also let me know that I had some bad wear on one of the crank bearings so I could get that fixed while they have it torn apart. So that should fix your rear main oil leak.
Does it have an aftermarket oil gauge on it. My hooks at the rear of the motor and if that leaks it will look like it might be the rear main.
Back several years ago when I have my C6 rebuilt in my 78 the local shop replaced the rear main seal and also let me know that I had some bad wear on one of the crank bearings so I could get that fixed while they have it torn apart. So that should fix your rear main oil leak.
Does it have an aftermarket oil gauge on it. My hooks at the rear of the motor and if that leaks it will look like it might be the rear main.
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Well none of the gauges work and i just have found the oil sending unit on the back of the motor but haven't had a chance to further inspect it and don't really see a place that should hook to it in the area.
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From: lino lakes, mn
Wash the engine bay the look for your oil leak. Places to look are valve covers,oil sending unit,back of intake manifold and rear seal area drop the inspection plate between the block and transmission to check rear seal. For the carb first make sure your choke is opening all the way. Then look inside to see if fuel is spilling into the venturies at idle the most you should see is a few drips. Try adjusting your idle mixture screws go in until the engine stumbles then back out until you get the highest idle or if you use a vacuum gauge until you reach the highest vacuum should be steady at about 20 in do this with both screws until the max is found sometimes you will have to reset the "curb idle" to get it down to the 6-750 rpm range.For the tranny check your fluid level try changing the filter and flushing the fluid the fact that it takes some rpm to get it to move means either a pressure problem or not enough fluid. A rebuilt tranny is expensive try some cheap stuff first.Most fords have a drain plug in the converter so you can get rid of most of the old fluid just by draining the pan and converter when you refill put in 5 quarts run it through the gears then 2 more and so on till the level is right.
