Farmall Cub

Does the knock still go away when you operate the pump.....Dave

pickerandsinger wrote:Does the knock still go away when you operate the pump.....Dave

yes, but I think this could just be from the slight rpm drop.

To Sum up where things stand right now: I pulled the oil pan and wiggled the rod bearings, there was no play aside from a tiny bit side to side on all of them. that of course doesn't rule out the mains (is there a way to check them easily?).. I found no metal in the pan aside from the nut and washer that go on the hydraulic pump. I removed them (and about 1/4 inch of gray sludge), and replaced the oil (30 wt) and new filter (fram... it's all i could find on short notice). ----> knock still there but oil pressure is now much better. I also pulled out the pump and put a new all-metal locknut on the shaft with some loctite. ----> knock still there. My next step is to check the timing, valve lash, and do a vacuum test before deciding on a tear-down.

The gray sludge worries me the most actually... water in the oil? can 1/4 inch be from years of condensation? I changed the oil 3 times and it didn't flush it out, so it could have been building up a long time. I'm going to keep a close eye on my coolant level.

The oil pan drain hole is higher than the bottom of the oil pan. That stuff never really comes out of the bottom during an oil change without pulling the pan and mopping it out. Most likely, the goo is hydraulic oil due to an oil leak out of the hydraulic pump into the oil pan along with some metal residue from normal engine wear.

Now that you have fixed the hydraulic pump, make sure your hydraulic oil reservoir is full.

outdoors4evr wrote:The oil pan drain hole is higher than the bottom of the oil pan. That stuff never really comes out of the bottom during an oil change without pulling the pan and mopping it out. Most likely, the goo is hydraulic oil due to an oil leak out of the hydraulic pump into the oil pan along with some metal residue from normal engine wear.

Now that you have fixed the hydraulic pump, make sure your hydraulic oil reservoir is full.

thanks! that's what I was hoping. TC reservoir is good and full now. I didn't replace the gaskets when i took it apart (they looked quite good), so i'm going to be keeping a close eye on it. for now it seems to be working perfectly.

Aside from the engine knock of course...

The Electrical system is in pretty sorry shape as well.. though i doubt that has much to do with the knocking. my battery won't hold a charge (it's pretty old looking), the lights don't work and there's an awful lot of wires that have come loose and go nowhere.. she runs and starts fine though (when there's a charge in the battery)

Check your hydraulic fluid levels as well.

Eoghan wrote:doesn't rule out the mains (is there a way to check them easily?

The best way would be with plastigauge, as Eugene already suggested:

Eugene wrote:While you have the pan off, suggest purchasing plastigage from auto parts store and gauging the rod and main bearings. Guessing plastiqage will cost about $7- for two sticks, one stick measuring .001" - .003" and the 2nd stick measuring .003" - .006".

I've gotta say, you're after it like a good beagle chasin a rabbit... Keep in mind these tractors are 50/60 years old and depending on what your intentions are for using it, its easy to put a lot of money in one....It may do you better to look for a good used spare engine (from someone like Boss Hog, if he has one) and run the one you got as long as you can rather than shell out 1500 or so in yours if your not looking for a restoration piece....Unless of course thats the avenue you wish to do...Above all its your tractor, do what you want by all means...It don't hurt to run down the problem before you make a decision for sure....Just throwing out a scenario...May as well check your mains, like Eugene said....It sure don't sound like its knocking beyond hope, thats for sure...Dave

I wish my dog were as eager to get rabbits as I am to get this tractor working! I got the cub to plow and cultivate my little vegetable fields (about 3 acres total), as well as mowing a couple of acres of rough grass. I'm not aiming for a restoration by any means, just a working tractor that i can fix up little by little, then maybe when I have a few bucks down the road either rebuild or replace the engine so she'll be with me for years to come.

Anyways, after I get the basics out of the way, I suppose I'll get myself some plastigauge and spend another day with my head up her skirt. bearings aren't that expensive, right? and I can replace them with the engine on, right? Better to do it now than scuff up the journals and have a real mess on my hands later.

As long as she can pull a plow by garlic planting season (without blowing up)!

Alright, I'm gonna offer a suggestion that some may not agree with. It is likely a main bearing knock, and worst case, we've had a few cracked crankshafts that would knock, but still run. However, one other thought, it could be a carbon buildup on top of the piston. You might only be hearing it at full throttle because that is when you take up all the slack and/or "stretch" the connecting rod enough for it to hit the head. Now if you have located it in the bottom of the engine, then it's likely something else, but it's worth a shot. Buy a can of seafoam, and locate a spray bottle. Put some of the seafoam in the spray bottle, take the air hose off the carb, and put the engine at close to full throttle. While running, spray seafoam into the carb until you bog the engine down, then stop and let it catch back up. Ignore the white and black smoke, as well as the particles that this dislodges, but be prepared for them. Repeat this 4 times, on the 5th time keep spraying until you kill the engine. Let it sit 30 minutes, then restart. With luck, this will dislodge all carbon traces. It is best to do this on a warmed up engine. I think you have little or nothing to lose to try this, and it's about $10.

As my father use to say, always check the simple stuff first so would start with the timing. However if that does not clear it up quit running it and pull the oil pan to inspect.

I scanned the original posters posts and found no mention of low oil pressure. Plastigage will provide an indication of rod and main clearance and general condition, along with the visual inspection.

We already have the oil pan off and have found one possible reason for the knock. Has the source of the knock been found or will be found by plastigaging the bearings - unknown. Plastigaging, inexpensive but a bit time consuming, will either confirm or eliminated another possible knock source.

I would let the engine get to oporating temp. run at high idle to where it knocks. short out one spark plug at a time. This can isolate if its a rod knock.If no change on any plug then it could be and most likely is a main bearing knock. It also could be piston slap...or all the above..

Look at the #1 rod. That is the last bearing in the oil supply feed and usually the first to go. I figured you would get to this point when you mentioned low oil pressure. Good luck.

Thanks guys, It's probably going to take me a few days to get things narrowed down and also to collect the necessary tools/gaskets/etc, but i'll probably have some questions if it comes down to replacing bearings. it's nice to know you guys are here!