Possibly "stupid" questions...F-250
demonmaster
07-22-2009, 12:11 PM
Hi, I have a 1978 F-250 w/ 351 mod that wasnt running right (missing/ruff idle etc) that we took the valve covers off and found M.I.A. pushrods...and began taking the motor apart (heads, timing cover, the works) finding the missing push rods down below/not in the motor and no apparent head/valve/ piston damage. ALSO has had an oil light staying on when running, oil was always full.
Now for My questions...1) do the rocker arms have to go back in the exact same place on the motor and 2) could a low/weak oil pump have caused this problem?
Also, the timing chain and gears looked good w/ just a lil play and was wondering if I should change the oil pump just to be safe/avoid Murphy's law?
Any and all help info would be appreciated as I am relearning to be My own mechanic again.:banghead:
Now for My questions...1) do the rocker arms have to go back in the exact same place on the motor and 2) could a low/weak oil pump have caused this problem?
Also, the timing chain and gears looked good w/ just a lil play and was wondering if I should change the oil pump just to be safe/avoid Murphy's law?
Any and all help info would be appreciated as I am relearning to be My own mechanic again.:banghead:
toddman67
07-22-2009, 12:28 PM
No questions are stupid! Ask away.
The rocker arms do not have to go in the same place, however it is a recommended practice considering wear patterns.
I would put a mechanical oil pressure gauge on the engine before pulling pan. Pull the plugs and just spin the engine over and see what you have.
If you suspect oil pump problem and removal of the pan is in the works, pull a couple of rod bearings and look for damaged and unusual wear. A new pump will not repair worn out bearings or a scorn crank. If the bearings look worn and the crank looks good you may be able to replace the bearings on the vehicle.
Replacing the timming chain would'nt hurt, provided everything else is in check.
Measure the push rod throw on the one that came apart and compare it with the others to rule out worn cam.
The rocker arms do not have to go in the same place, however it is a recommended practice considering wear patterns.
I would put a mechanical oil pressure gauge on the engine before pulling pan. Pull the plugs and just spin the engine over and see what you have.
If you suspect oil pump problem and removal of the pan is in the works, pull a couple of rod bearings and look for damaged and unusual wear. A new pump will not repair worn out bearings or a scorn crank. If the bearings look worn and the crank looks good you may be able to replace the bearings on the vehicle.
Replacing the timming chain would'nt hurt, provided everything else is in check.
Measure the push rod throw on the one that came apart and compare it with the others to rule out worn cam.
MagicRat
07-23-2009, 08:46 AM
-check for bent pushrods.... place them on a flat surface, like a glass-top table or mirror and roll them.
-Even if you mix-up the pushrods, you can at least put them back the right way up. The rocker end of the rods has a larger wear pattern (shiney spot) than the lifter end.
A new oil pump is cheap insurance and worth putting in. I have found that with older Ford small blocks, the oil pump wears out before anything else does in the engine.
As noted above, check the bearings. New bearing shells (check to see if they are oversize, its stamped on the back) and a light polishing of all the journals with fine emery paper is a great idea.
Finally, get a book on SBF engine rebuilding, if you can.
I have this book, its great, not just for Fords.... many of the instructiuons are applicable to any engine:
http://www.amazon.com/How-Rebuild-Small-Block-Ford-Engines/dp/0912656891
-Even if you mix-up the pushrods, you can at least put them back the right way up. The rocker end of the rods has a larger wear pattern (shiney spot) than the lifter end.
A new oil pump is cheap insurance and worth putting in. I have found that with older Ford small blocks, the oil pump wears out before anything else does in the engine.
As noted above, check the bearings. New bearing shells (check to see if they are oversize, its stamped on the back) and a light polishing of all the journals with fine emery paper is a great idea.
Finally, get a book on SBF engine rebuilding, if you can.
I have this book, its great, not just for Fords.... many of the instructiuons are applicable to any engine:
http://www.amazon.com/How-Rebuild-Small-Block-Ford-Engines/dp/0912656891
demonmaster
07-24-2009, 08:43 AM
Thanx Guys for ALL the info...the mechanical oil pressure gauge was already in mind/thought to do and the oil pump replacing as well...Murphy's law and I are very close friends LOL.
We are replacing ALL the push rods w/ new just to be sure and probably the timing chain and gears (timing kit was reasonable) to be sure as well, even tho it does NOT appear to be loose/worn.
Looks like I got a lil more tearing down to do but better safe than sorry.
Thanx very much again ALL...and I am sure I was be hollaring again...Demonmaster :biggrin:
We are replacing ALL the push rods w/ new just to be sure and probably the timing chain and gears (timing kit was reasonable) to be sure as well, even tho it does NOT appear to be loose/worn.
Looks like I got a lil more tearing down to do but better safe than sorry.
Thanx very much again ALL...and I am sure I was be hollaring again...Demonmaster :biggrin:
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