460 rebuild

[injun joe]

ok traded some guy my 1986 f-250 diesel for a 95 f-350 gas. i traded because the 350 had the 1 ton axle and it was more pleasing to the eye.ok ran a few compression checks and found out 4 cylinders are well below 150#'s so my question is anyone rebuild a 460 from the ground up. my dad just told me if its out i can half ass it and im gunna replace practically the while motort which makes sense. but the rebuild is gunna cost me over a thousand so is it worth it in any of your experiences or just drop a smaller ford block into it. oh its a fuel injections FUUUUN i know.

 

[TDunk]

Rebuilding engines isn't that hard, but with that said it's real easy to screw something up and have it grenade on you. You can buy a re-ring kit (with main/rod bearings, oil pump, gaskets etc.) for a few hundred, have the heads done for a few hundred and do it your self. BUT, if memory serves those motors had a problem with cracked pistons. As for dropping a different size motor in, there always a pain in the arse.

 

[Outlaw5.0]

Pistons are not that much, you should be able to buy a set for $200.00 or so. Have a machine shop measure the bore for size, taper, and out of round, this will let you know if it needs to be bored oversize or not.

 

[injun joe]

well my dad is a good mechanic so i wont be doin this alone or else i wouldnt even think about even touching the egine.looked at just a ring kit it was close to 500$.well like i said i would want to replace most of the stuff so i dont really have to be replacing stuff in the future. or i at least want to replace the essestial stuff like crank. so if i got 25#'s of compression in 3 cylinders would this mean more than just the rings.theres also a master rebuild kit for 1000$s.

 

[TDunk]

If two of the low compression cyl.'s are right next to each other then i'd say possibly a blown head gasket (but there would be other symptoms if that was the case) I'd be betting on a problem with the valves in the heads rather than bad rings. With rings that bad on 3 cyl.'s you would have pretty bad blow-by and be burning oil. How miles are on the truck?

 

[injun joe]

well the truck has only 123,000. and the 2 dead cylinders are directly across from each other i think cylinders 3 abd 4. when i pulled the plugs they had a bridged gap of black crap what i assume is oil it looks awfully close to one of my 3-wheelers that pulls oil to. well we did the old timer check for leaky valves and nothin came up. i did a compression check on 4 of the 8 cylinders and the numbers were 25,25,90,120. i was getting ready to do a leakdown test but i figured whats the point those 2 cylinders are pullin oil.

 

[ND_ash]

I have a 84 with a 460 and most of the oil it was getting came through the valves. Unless the the cylinders are scored most of time oil comes from the top.
Take the valve out of the compression tester and put air pressure in the cylinders that are low with a air compressor. You can find out wear it's leaking to by check for crankcase blowby or if it has a gasket out, or a bad valve.
Some 460 don't have a lot of compression but it should be within 15 percent on all 8

 

[TDunk]

Rule of thumb on the old school big blocks was at 100k they were due for a re-build. This doesn't apply to every big block and especially not new vehicles, but rather a guideline. First thing i'd do is check the rest of the cyl.'s for compression, squirt oil in the holes and re-try the compression test. If the rings are bad the numbers should increase by a little bit. The engine neads rebuilt with out a doubt, but if you know what cyl.'s have low compression you can take a closer look at those cyl.'s, rings, valves, etc. and see what might be the culprit.

 

[injun joe]

yeah rite now is just sittin and yeah gunnna have to do the leakdown test and see where the air is comin from hopefully just from the exhaust.

 

[jnl502]

Sounds like there was no maintanace or the truck has a crap load of miles on it that did not show. Also over heating or over reving will break a ring or two. That is what it sounds like to me. If so get ready to bore. My 97 f-350 crew cab has 151,000 miles on it and has pulled a 28 ft camper most of it's life. I also have a 97 f-250 ext cab utlity bed and it has over 200,000 on it and neither one uses a qt on 3000 miles. I did not buy them new but they were good trucks. Newer motors run longer usually run longer because the oil we have today is better. I have run the 429-460's for years with good luck but bad millage to boot. If you plan to keep the truck a complete rebuild is the best way. You can rering it but it won't last. If you turn crank,bore,rebuild heads it will live long and run good. Hope this helps you god luck
jason

 

[stihlcrazy20]

sounds like you have a few sticking valves or the springs are shot. if you head gasket was bad you would be able to smell it coming from the exhaust because it would allow coolant into the cylinders(would smell sweet and blow alot of white smoke). also sounds like either the rings are shot or stuck in the piston groove. i just finished my rebuild in a 79 f250 high boy. i wouldnt for see where you would need a complete rebuild, 9 times outta 10 all that is needed is a top end rebuild.

 

[cuznguido]

If the rest of the truck is in good shape you will money and time ahead to buy a complete "long block" and stick it in there. Assuming your goal is to use the truck for work and you need it on the road and running. If you have the time and inclination you can overhaul it yourself, but with a long block you will get a warranty and you will have it down a day or two instead of two weeks.

 

[TDunk]

If the rest of the truck is in good shape you will money and time ahead to buy a complete "long block" and stick it in there. Assuming your goal is to use the truck for work and you need it on the road and running. If you have the time and inclination you can overhaul it yourself, but with a long block you will get a warranty and you will have it down a day or two instead of two weeks.

Jasper or Marshall would be the only two manufactures i would even consider using for getting a re-built engine. We just had a sales rep from Jasper stop in and said that they were able to lower there prices by (on average) $300.

 

[TDunk]

sounds like you have a few sticking valves or the springs are shot. if you head gasket was bad you would be able to smell it coming from the exhaust because it would allow coolant into the cylinders(would smell sweet and blow alot of white smoke). also sounds like either the rings are shot or stuck in the piston groove. i just finished my rebuild in a 79 f250 high boy. i wouldnt for see where you would need a complete rebuild, 9 times outta 10 all that is needed is a top end rebuild.

Not always true with the head gasket. I've seen more than a few gaskets blow between the Cyl.'s and that's where all the compression goes. If it were mine, i'd just plan on doing a re-build. Flat rate on replacing the head gaskets is just shy of 11Hrs. Personally, i think the rings are shot on a few cyl.'s plus there is a valve problem. So if it were me, i'd just pull the whole engine out. If there was more room under the hood, i'd say yank the heads off, but for as tight as it is under there i'd be pissed if i spend all that time pulling the heads off to find out that the rings are bad/stuck and it needs bored. Just my 2 cents.

 

[injun joe]

well like i said i would wanna rebuild the engine anyways cuz my dad just told me ''you aint gunna half ass it.'' but i wanna put in mostly new parts in anyways that way i know most of it is new. but yeah it was a for service truck huge truck its got the quad cab then the long bed so its a beast around turns. i would just use it for delivering loads of wood,pulling, and hauling most of the time just a good work truck. i like the truck alot il try to get you guys pictures if i can. i like it a lot because it stands out a lot too with the for service green. earned the name jolly green giant.