856 with a knock

Every once in a while I think I must have to prove that I don't have good sense. I have 3 tractors I need to work on and am thinking of buying an 856 with a knock! Price don't seem too bad at $3500 but what do I know? I hope T.V. or one of you other guys with a wealth of knowledge will comment. The guy says he bought it from a farmer who was plowing with it when it started to knock. This guy replaced the main bearings and in 3 days it started to knock again. It doesn't knock at idle but does as engine speed increases. Now my question,I can get another 407 with a good crank for $800 or I can put a 5.9 cummins in it. Thoughts and comments appreciated. Lee

Well i can't hear the knock so here your on your own . Would i put a Cummins in it ???? probable not . would i buy and engine i know nothing about but what someone told me Nope . Would i fix what is in there YEP . How would i fix it ?? I would find out why it is knocking . Does it have a bad crank ?? maybe a bent crank , bad oiling ?? i would have to look first before i would make a move . Then if it called for a tear down it would be a total tear down and a major rebuild with line boring decking with new sleeves pistons and rods reconditioned hear totally gone thru and valve set to correct spec. When working on a D-Dt 361 -407 it is wise to hand fit each piston to the hole and before you start fitting you want to make sure that the sleeves did not wrinkle while you were installing them . as you will get a little but a ridged hone will dress then fit the pistons . So ok ya spend 3500 three would be better . and ya put three more into a top notch rebuild add in a new T/A and clutch you now have a tractor that will out live you . and you will still be ahead of the game .

Thanks T. V. I greatly value your opinion/knowledge. I keep hi test gas in my 560 and Super M tractors because of your posts. I have read your posts on the 407 being difficult for a novice to build is part of why I am considering the cummins. The other reason is that I have a good cummins and a guy that has done work for me and does cummins swaps for a living offered to swap my cummins in an 806/856 for 2 to 3 thousand. I love a cummins but nothing sounds better than an 856 407 pulling a load. I have rebuilt M's and put pistons/sleeves in a 460D but don't know if I am up to doing a 407. The bad part is I don't know anyone locally that would have the knowledge for a 407 either. More comments if you have them?

That sounds more like rod knock than mains. I'm wondering if it was low on oil or something to cause those bearings to go down. I've never had one just do it suddenly. I have heard they do but I have never seen it.

I take that back I did have an engine that I got so hot that it melted the rod bearings and fused leaves of them to the crank. It was fascinating to tear down but I had just spent bucks rebuilding it and that was down the drain.

It sounds like one of those deals where it might punch a hole in the block driving it on the trailer. I wouldn't be afraid of it, though.

The 856 is a great tractor - maybe my favorite depending on my mood that day. I'd buy it and plan on putting a crank in it.

You must be in Ga. If I didn't have a 756 I would be considering it.
It looks pretty good.

I am in northern middle Tn.

I guess i am getting lazy as i would rather rebuild the 407 then go thru all the work of a swap. swapping out a engine in a Oil All Over is a piece of cake doing a swap on a Farm all takes a lot more fabbing and machine work . Last spring my one buddy and i did a swap on a 2150 as the herc. that was in it sucked a sleeve and trashed the block , could we fix it yea we could have but i do not have the one special tool for working on a herc. After a month of trying to find the tool with no luck we talked about ti a little and Vernon wanted to just dump a 5.9 in it and i said WHY lets put and 8.3 in it . So he and i went on the scrounging run to find and engine . we found just what we were looking for with the correct pump and bell housing . So all we needed was a starter for the NEW flywheel move the fan hub up to the next location and make a modification to the oil pan to clear the ft. drive shaft, make four motor mounts and hook the hoses and wires up and it was a done deal. Gave three grand for the engine a grand for the new flywheel and about forty bucks for some steel to make the motor mounts and mods to the pan and it is in there .Now he has a 210 HP ft wheel assist tractor with only a total of 65oo total including the price of the tractor. olivers are a lot easier . Plus that 407 If done wright will live a long time . The biggest thing about doing the 361 and 407 is making sure that you check everything and hand fit the pistons to each sleeve and make sure that you do not wrinkle the sleeves when pressed in. Ya don't beat the sleeve in . One guy that lives around here did not want to pay me to rebuild his 806 because i charged tomuch well after blowing up five engines and the longest lasting one when fifty hours He finally gave in and had me build the long block and he installed it in the tractor , then had me make a service call to install the pump correctly as here again he did not know what he was doing .

T.V. I wish I was close enough to let you build the 407 for me. I thought about a friend about 90 miles away that might do it.He worked in an IH dealership and loves tractors of that era. He has a small shop and does a few jobs like that. Thanks for your help. I have several things covering me up right so I am having a tough time making these decisions. It always helps me to get on here and get knowledge from you guys. Thanks again Lee