460 engine noise

[Anonymous-0]

I am trying to decide if I should even begin to tear into this thing. So I would like some advice from some experienced folks on here.

The oil pressure is about 25 psi. The compression on the front five cylinders is 135lbs, the sixth is were the issue lies. It reads 85 psi, placing a tablespoon of oil brings it up to 125 psi. It makes a distict hollow knocking sound when its running especially after it warms up to operating temp. Removing the spark plug wire makes it quiet down but it is still noticable.

I'm thinking I have a combination problem, bad rings, and a bad wrist pin. The noise does not sound like its coming from the bottom of the engine. The tractor starts right up and runs well with the choke half way closed. It does blow blue smoke under load.

So what do you all think is the issue? Any advice besides tearing it down all the way?

Thank you!

 

[Anonymous-0]

I have a 706 gas with the 263 cubic inch engine which is very similar to yours that might make the same noise as your 460. A long-time IH mechanic told me that I had a scored piston/cylinder. I guess the scored piston/cylinder would be worn some, therefore as the piston is moving up and down it pivots on the wrist pin depending on which side of the crank the rod is on. As the piston pivots in the excess clearance it makes the knock as the piston skirt hits the cylinder wall. Yes, it varies if the engine is cold or hot. I have been told that some people have ran their tractor that way for years with no problems. They probably aren't plowing or using it extremely hard.

 

[Anonymous-0]

Thank you for your response!

 

[pete 23]

Yup, most likely scored piston. This causes skirt to collapse and excess clearance makes it rap. I would not run it very much, maybe into the shop to tear it apart.

 

[d282]

Rebuilding a 460 c-221 right now because of the same problem, scored piston. When I took the pan off a broken off piston skirt was laying in it. When you take the head off note what the bore sizes are for each cylinder. If marked A-B you can buy a standard oh kit if they are stamped C-D-E you better make sure you can get the oversize sleeves before you pull them all and find out you can't find them.

 

[Anonymous-0]

Thanks again for all the good advice. Don't want to spend a lot of money on this tractor just wanting it mechanically sound before it becomes a rolling piece if scrap. Everything else works except the engine noise. Is it possible to just replace the one sleeve, piston, pin, rings and rod bearing? Can this be done in frame on this tractor? Have attempted to sell it as I am already restoring my Grandpas 860 Ford and that's where the money is tied up now. No one wants a 460 with engine noise at any price around here. If I can get it fixed I plan to keep it and someday restore it as well. A full tear down is just not in the cards right now or a priority.

 

[pete 23]

Sure you can replace just one sleeve and piston. Raise fuel tank, support and all, pull head and see what you got. You can tip head out from under fuel tank but to me it isn't worth that hassle getting it back in. You have to temp hold push rods up with clothes pins or some other means. Just me. Also, if you do pull head, when pullig the push rods, jiggle them loose out of tappets or them may well come out of their bore and make more work for you.

 

[Anonymous-0]

Thanks for all the input! Going to buy a shop manual so I can get started on this one.

Any other tips tearing it down and putting it back together will be greatly appreciated!