Smoke out the breather...something is seizing up, rod bearing, main, or a piston, all of the above will cause it. As Oil Slick said, don't run it!! That kind of noise can get a LOT worse, real fast...

Does that engine have inspection covers on the side of the block? Might be a way to relatively quickly get a handle on the damage if you don't find metal in the filters.

If you would consider doing an overhaul, if the crankshaft and bearings check out (knock is related to a piston problem) you would be looking at a lot less expense, possibly an inframe overhaul, than if you find a bad rod or main bearing that would require a complete overhaul, crankshaft grind or replacement etc.

The D318 I referred to earlier was run with fuel in the oil until it started knocking. Working through the inspection covers, I was able to tell the owner that it was a bad rod bearing as we expected and more importantly, that the crank would not be able to be reground as it has already been ground 0.030 under. That points down a completely different set of tracks than when you are thinking about overhauling, and it's good to know ahead of time.

With the sudden increase in blow-by from the crankcase breather, I wonder if a chunk might have come off a piston top and be stuck so it's knocking every time the piston comes up. I will try to attach pictures of the pistons we took out of our D7E a couple years ago. No knocking, but about the worst blow-by flow I have ever seen on a running engine.

Happy new year gentlemen,
Dad and I went over end looked at that D7 a while back, we're glad to see you got it. Sorry to hear that the engine may be smoked. Over here in Placerville (40 mins away) we have a D7 3T engine, good running condition out of a tractor that we parted out. The engine is available if you want to come over and check it out. Matt Veerkamp 530-409-0857

"rjh-md" wrote:

Sounds like your clearing operation was very shoddy ,and hap hazord ,if you keep the clearing neat by wind rowing or piling trees and stumps as your clearing ,so the machine is engaged to the land rather than traveling over trash ,also filling stump holes and keeping the land graded as you clear,and establish working room , things may have been different ,especially on hill sides . An experienced operator would have felt the root ball raising the front of the tractor ,and imediatly threw the tractor in reverse backing off as the root ball came up . Also this same experienced operator would have pushed the tree with the center or lower side of the blade so that as the root ball raised the tractor it would throw the lower side up keeping the machine more level throwing the tractor into the hill ,rather than down the hill

As to the engine .I would remove the oil filters ,and cut them open to see how much bearing material is deposited in the filters .If the filter are still clean you may luck out by hooking up a brake bleeder filled with oil under air pressure to the gauge line at the block and try to pressurize the oil gallary while barring over the engine to see if this will free up the bearing s ,and adjust the pony clutch as OM recomended

gotta keep in mind...some dont do this professionally.....everything i have seen here not only could have been preventented with a little more experience...but at the samwe time....i have been...as we call in the logging world...stump fucked....many times myself lol......runnin a old cat on grades like this requires a dying skill.....for instance....how many here know how to cross steer......probably not these gents....but thats ok....this is how you learn lol....i used to run hillsides like this skidding logs...in a D7G....sitting on the arm rest....trying to roll a cig...in my early 20s lol......glad no one got hurt...but the lesson was learned none the less

"Casey wrote:

Hi dcrobira
Until all have operated a dozer on the west slope of the Sierra Nevada I can only hope that the criticism is tempered. I'm glad all is OK.
I have owned and operated crawler tractors since 1962 in all venues including 5 days on the Las Palitas fire in 1985 that nearly burned San Luis Obispo. I have found nothing as challenging as working a dozer here in the Sierra, where the granite domes rise up and take your tracks right out from under you without warning. I've ridden my D6C sideways 15 to 20 feet on a gentle slope that I would have never expected. New seat covers were ordered. It was a 10 on the pucker factor. Also the Buckeyes, Liveoaks and Manzanita combined with unseen boulders can high center a tractor with a 1/3 a turn of the track or less.
My neighbor was clearing several hundred acres with a 10K D6C. Was doing a nice neat job of a methodical clearing. While backing up a steep hill, the right track slipped forward, turned the tractor sideways and it rolled at least 8 full revolutions down through the brush. He said it was a slow roll and he thought it would stop three or four times but kept going. The ROPS held and seatbelt and helmet held well, though the ROPS had to be replaced before the tractor was put back in service. His biggest concern was having a branch spear him in his house while it was going over.
I hope that your repairs are not too costly and you are able to resume your work. Be careful and enjoy yourself.
Casey

i ran that D7G....just outside of Chester California...i would start my morning....just at dawn....clawing my way up this rock nob on the East side of lake Almanore....to have my coffe and Cig as the sun came up....there is no terrain like the Sierras....ran D6D in the rubicon area...that was fun.....QUincy....Westwood.....Georgetown...Feather Falls....and the Bambi Inn....this is the area I grew up logging in.....the things i have seen cats do in the sierras would blow your mind lol...