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rear main seal on 1978 F-250 with 351m engine

sparky18

sparky18

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what style of rear main seal is on a 78 351m engine(1 or 2 piece)?

and can it just pop right out and puke oil everywhere?

on mine,oil is pouring out between the motor and auto tranny.(motor oil)

could it be one of the plugs on the oil ports on the back of the motor?

are they screw in plugs or brass type push in ones?

kinda wanna know a couple things here before the tear down begins,lol.

thanks,Mark
 
but would the rear main just start pouring oil like that?it's coming out at about a cup or more a minute.must have rolled it out somehow i guess.
 
I doubt the cam. You didn't say mileage but the seal is old and hard and blew out.

cam plug is metal, and would have to either rust out or the cam would have to push it out,and if you have that kind of cam walk it probably wouldn't run.
It would have walked off the lifters.

If this was vegas I would take any odds.

Let us know what you find.
 
Should be pretty easy to drop the pan and rear main cap to get a new one in. Or does that motor have to be jacked up for the pan to come out?
 
robzombie4551 said:
I doubt the cam. You didn't say mileage but the seal is old and hard and blew out.

cam plug is metal, and would have to either rust out or the cam would have to push it out,and if you have that kind of cam walk it probably wouldn't run.
It would have walked off the lifters.

If this was vegas I would take any odds.

Let us know what you find.
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I have seen sbc's push out the cam plug and still run.
 
i'm hoping next time that i get home i can take the inspection plate off and shine a light in there to see if i can get a visual of where the oil is coming from.
 
I have seen sbc's push out the cam plug and still run.
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This is no sbc, with all due repect. I've run them with 5lbs. of OP, try that with a ford for a month,and see whats knocking. SBC are the most forgiving of all engines except {let me reveal my age] The slant 6 225 dodge.

Has to be jacked, ford has the double hump pan.

Just face reality, it's 95% percent rear main seal. not trying to be a know it all, but with the limited info given that will likely be the out come.

Put this to rest, look and see if oil is coming from mid block or above the flywheel or below it. look thru the insp. hole after cleaning it out from all the oil being thrown around. start it and if on stands you can shine a light and confirm location of said leak.

Please more than ever, now I gots to know.
 
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i too am getting more curious as this goes on,but am pretty sure i will find it being the seal.i got this truck from someone that owed me money and have no idea how many miles are on it (as in if speedo worked all it's life) or much else for that matter.just know it was sitting there idling while i put fuel in it and it all of a sudden started puking oil out.never seen a seal do that before is why i started asking questions.being a chevy man i don't know much about these engines.
 
Most likely the rear main seal, you can pull the pan but you have to jack the engine and pull the pick up tube off the oil pump to slide the pan out. I have seen the oil gallery plug come out on the older FE's and they are a PITA to re-install. The last one i did i gave up and tapped out the hole and screwed in a plug with locktight. But i did not find that oil leak until i pulled the pan and replaced the rear seal, man that thing would dump the oil in a stream too.
 
SBC!!!:rof: I would rather run a tired 300six than one of those things and i hate the 300six! No GM will take the abuse that a Ford engine will take, there are a many GM lovers around here who would just shake their heads at the abuse i put my old Fords through. Even they would admit they knew of no engine that could stand the abuse i put them through, with the exception of the old Dodge slant-6. Everyone who knows engines know the reliability of those engines :thumbsup:

Another Ford engine i hated was the 400M, heavy gutless turd if you ask me. They do not like abuse a lot either though, not like an FE or a Windsor engine. Like a Chevy they would spin bearings or break pistons, i had one that broke the cam off so the last 2 cylinders were dead but the junk still ran and got me home.
 
I haven't met a six cyl. from the big three you couldn't abuse.

We were talking V8's and they all have there weaknesses and strengths.

As far as running your tired 6 go for it, love to see one plow a foot of snow or tow anything over 10lbs. LOL.
 
Well.....now that I got home lastnight,I find the truck buried in a snow bank.Not sure I will get at this project till spring now.I pretty much think I will just pull the tranny and have a reall good look at everything.I'm not scared of the work.Kinda like it actually,lol.I gotta heat the shop to get my dually clutch changed,so I might roll the old bugger in there and have a look see.

One thing I would like to know is what are the diff's between the 351w and the 351m?I have a 351w here,and it has a loose wrist pin makin noise and i herad they are bad for that.What are the 351m's bad for?
 
Just saw this. I have a pretty good knowledge of these as they were something I was very into. OK First off...The 351/400m was well KNOWN for rear main seal leaks. In fact it was pretty much a mathematical certainty. it is 2 piece and can be done in the truck. In fact pulling the pan is real easy. You will need a tool to get the old one out and thread the new one in. IIRC they used a rope seal. KD makes the tool. It's a small corkscrew that scrws into the old one to pull it out. You may need to loosen all the main caps if it is stubborn. then there is a hmmm how do I describe..Maybe I'll look for mine tommorow and take a pic but it threads the new one in.

Now as far as a 351w and 351M they are completley different engines. The W stands for Windsor. The M stands for Clevland Modified. Basically an M motor is almost idnetical to a Clevland except that Ford made the block wider on the M motors to have the same bolt pattern as a Big Block (429/460). The True Clevland has the same pattern as the Windsor. The M/Clevlands could turn alot of HP stock with just a 4bbl upgrade and a decent manifold because the heads breathed really well. The 4v heads from a Clevland were the best and would bolt to an M. However the 351C 4bbl motor also had a 4 bolt main and was a very tough coveted engine in the race circut but not really a good motor for a truck. Not enough low end torque. The 460 is the best choice for a truck as it's a brute. L&L adaptors used to make the conversion kit. Don't know if it's still available but probably. The M motors had weak low ends and often spun bearings. They had poor oiling circuts and IIRC the oil went to the upper end of the motor first. an M motor needs well over 45 psi of Oil Pressure. In fact 60+ is ideal. The Melling High Volume Oil Pumps of the era were a guarateed crank killer as they did not put out enough oil pressure. The M Motors particularly the 400M ran hot as well.
a 351W is almost the same as a 302 although IIRC the rotation was different or something stupid on the cam/dist..not sure. Long time ago. They were junk too. Best engine ford ever made was the 429 SCJ.
The FE series were pretty tough engines too. The 4bbl clevland was a good motor for racing. The rest were junk.
 
Acesneights1 said:
BTW a cool swap would be a 6.9 diesel with a banks. Would not be hard to do.
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holy hell,like i said i'm not scared of hard work,but i really don't even need this truck,so that much work i really don't want to do,lol.

sad part is that this truck is in INCREDIBLE shape for the year,now it sits in a snow bank drooling all over itself.

if i needed it as a regular farm truck,the big block swap would be cool,but it may just be for sale in the end as it just sits around most of the time.

it's a damn shame to let it sit around when someone somewhere might be able to use it.
 
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