General Engine Rebuild Advice

Clarkbug · Dec 29, 2008

Hello All.

For those of you that dont frequent the Farmall board, I have a pair of BN's that I picked up, and am now tearing into as they are both stuck. Drained water or antifreeze out of both of the pans, and one had cylinders full of water. I pulled the head off of that one, and have it in on the work bench.

I picked up a valve spring compressor, and pulled out the valves tonight.

I guess I need to know what to do next. Im guessing I should have a shop check the head and magnaflux it, but what else? Do they need the valves in it as well? How can I tell if I can just lap the valves in or if I should get a valve job done? I was able to pull some of the valves right out once the keepers were removed, but others I had to tap out with a brass drift.

If I get the head worked over (assuming its not cracked) and can un-stick the pistons, whats next? Im guessing I should drop the pan, but what do I look for once I do?

Sorry for the novice questions, but I usually just tinker, and this is a bigger job than I figured it would be!

teddy52food · Dec 29, 2008

I would not spend anything on the head just yet. Get the rest apart & see if you have a rebuildable block. Get the crank out and if you can't check it, have a machine shop mike it.

Janicholson · Dec 29, 2008

Keep every valve and pushrod in order from front to back. The valves can be cleaned with a rotary wire brush (Bench wheel). They cannot be damaged this way, so clean them well. Wear a respirator or mask to avoid the (possibly lead containing deposits). Use a wire brush on a drill to clean the combustion chambers as well.
De grease and get it ready to take to a machine shop for a valve grind. The guides and stems of the valves should have .001" clearance (max) measured with a micrometer, and ball micrometer.
The sleeves can be bumped out from below with a wooden hardwood block and a hammer from below.
Be sure to keep the rod big end from damaging the crank journal. You will need the rods, so getting the pistons out will be necessary. JimN

msb · Dec 29, 2008

Chase ALL threads(internal & external) before you reassemble the thing is one suggestion I would make.

John B. · Dec 29, 2008

Tear it completely down and take the block, head, valves,valve springs, crankshaft, camshaft, rods, to the machine shop let them hot tank the block and head then they will check it for cracks etc. Let them install new wrist pin bushings and order any bearing that you will replace. They can measure the crank and get the right bearings. Let them measure the cam and install new cam bearings in the block. This way you will have a good engine to work with. It'll be like new. You may want to try to save money but in the long run you will wish you spent the money to do it right.
You will be looking at around $1,000.00 with all the parts and labor to do what I mentioned above.

Rusty wheel · Dec 29, 2008

It helps to take pictures as you go so you have a reference to look at when you put it back together. rw

Clarkbug · Dec 29, 2008

Thanks for the tips Jim.

I have a shoebox with 8 holes punched in it to keep the rods in the correct order, and as I pulled out the valves, I was putting the valve, keepers, spring retainer, spring, and the heavy washer all in a plastic bag marked 1 through 8 to keep things in order.

Ill wire wheel everything up tomorrow, and see what it looks like. I know one of the valves I pulled had all sorts of rust and "stuff" piled on top of it, most likely from water getting in the exhaust stack.

I have a set of vernier calipers and a micrometer, but whats a ball micrometer? Im guessing it has a ball at the end instead of a flat surface?

From the replies that I see here, its looking like this is getting to be a more expensive proposition than I had hoped for... I do want to do this right, but I was hoping to do as much as I could on my own before getting too expensive.

So since I have two BNs, how do I tell which engine is the one in the best shape? Or is that really like asking someone in Florida to tell me the weather here in NY?

Thanks for the advice, and please keep it coming.

banjo · Dec 29, 2008

As far as i know there are no cam bearings in the block , machined surface is what my manual states.

old · Dec 29, 2008

If it where me I would not do much till you have the engine freed up. The reason is you could end up with a couple $100 in the head just to find out the block is bad and then you would have a good head and nothing to put it on. Also if you rebuild the head you better figure on rebuilding the engine or you will probably just blow the bottom out of the engine because of having a rebuilt head and old parts in the bottom
Hobby farm

buickanddeere · Dec 30, 2008

Clean, clean and clean.
Pull the plugs from the oil galleries and rifle brush them out.
Put a dial indicator and degree wheel on the camshaft.You will be shocked at how a "good enough" looking cam & follows set are worn. The cam controls timing and the engine can never run 100% with each cylinder seeing different lift and timing.
Fortunately getting the cam and lifters trued up doesn't cost any more than a set of rings.
New valve guides or bronze sleeves. Nice fresh new valve seats & valves don't seal and don't last with the valves wobbling around loose.
A set of "LP style" pistons while you are at it. With todays gasoline why run 4 or 5 to 1 compression when the engine will run fine on 87 pump gas with 7 or 8 to 1 compression.
Tell your cam grinder what compression ratio so the cam duration will match the piston's compression at stock rpms.

Janicholson · Dec 30, 2008

The ball mic is an adjustable device that is placed in a hole and expanded to ft. It is then measured out of the hole to assess the size. When using the same instrument to actually measure the inside and outside Diameter, one gets a good measurement.
With rust in the cylinders, it will be necessary to disassemble the engine. If it is light surface rust, and the engine is basically able to be turned over, it deserves looking at the wear on the sleeves to see if they are usable.
If you can feel a step in the bore of the sleeves where the top piston ring stops on its travel upward, it needs to be measured. THis spot is the heaviest wear location in the cylinder. If the step measures more than .005" in diameter difference (measured at the very bottom of the cylinder, compared to the widest at the ring wear) it will be necessary (and cheaper) to buy a kit for the engine (about 650 or so fro m this site, or other sources. Shop.
RIngs, pistons, and a bore/hone on the existing cylinders will be more than the kit. Best of the season, and of luck. JimN

John B. · Dec 30, 2008

I've never seen an engine that didn't have cam bearings. Even the F12's had cam bearings. You need to look a little closer.

glennster · Dec 30, 2008

another thing to do thats real helpfull, get some 1 quart zip lock freezer bags. as you dis-assemble something, put all the fasteners in a bag and mark what they are for, also identify any special bolts ect and where they go. get a spiral note book and make notes and drawings as you dissasemble. makes it a lot easier when you go to put it back together.

Anonymous-0 · Dec 30, 2008

A ball mike has a ball on the fixed anvil. You seem to be explaining hole guages or something like that.

Anonymous-0 · Dec 30, 2008

Your engine has replaceable wet sleeves. Just press them out with the pistons then you can salvage the rods as your new kit will be sleeves pistons and pins and rings so there is no need to unstick the pistons as they are junk.

trucker40 · Dec 30, 2008

You want to get it unstuck first,then look at the rod and main bearings,the condition of the crankshaft.Then after you have an idea of what you need there take your head to have the valves ground and checked for cracks.

teddy52food · Dec 30, 2008

A's B's and C's came without cam bearings.

rrlund · Dec 30, 2008

Read everything below. No mention of oil the pump. Take that apart and clean it up,especially the relief valve. Just learned a hard lesson on that on a BIG engine. Had to spend another day dropping the front axle back off that one to get the pan off to do what I should have done the first time. Relief valve must have been stuck open and had very little oil pressure.

Clarkbug · Dec 30, 2008

Thanks for all the advice everyone. There is a little bit of conflict, but thats to be expected when you have so many folks providing input.

I do appreciate the information, and the value of everyones experience. I have read about whats involved in a rebuild, but havent gotten my hands dirty with it before now.

The wind is pretty strong here today, so thats going to get in the way of me doing much to the machines outside. Ill spend today cleaning up the head I do have and electrolyzing some of the parts for my other Farmalls.

And I guess the one other question Im curious about is if this can be done in-frame, or if I need to pull the whole engine from the tractor. I dont really have a good place to work on this thing right now, nor do I have an engine stand. I guess its time to look for both, or maybe I can steal a garage from someone for a few weeks if I had to...

relaurain · Dec 30, 2008

I'm a certified engine builder and I wouldn't spend dime 1 on this project until I had the head off and looked at the cylinder walls. If they had water in them, there is a good chance that motor will never "free up". I've had motors where I had to pound the pistons out of them in little pieces! If there was oil in the pan the bottom should still be good unless water came out too. Good luck - lotta good tips on this posting so far.

Anonymous-0 · Dec 30, 2008

There is NO CHEAP way of returning a junk yard really stuck engine to running. There can be much wrong, like pitted cylinder sleeves (inside and out) to say nothing of bent rods from trying to turn the engine and cracked head and block from freezing without antifreeze.

At best you have a discarded sow's ear and you want a silk purse. It is gonna cost.

Gerald J.

PaulW_NJ · Dec 30, 2008

I've been enjoying this thread, because I am going thru a similar situation with my 240U. I began trying to resolve a frozen valve in the head, and the project has taken a life of it's own. One thing I've learned is that the moment you repair and "tighten up" one part of the engine, you will immediately place increased pressure upon the next "weakest link" in the engine,and cause it to perform worse than it did before. For example, for me at least, a rebuilt head led to replacing the rings, and while I was there I discovered all of the bearings were down to the copper layer, and then the rear seal was oozing, and then . . .

A good overview book is a welcome guide. For example this one is $15 well spent. Two things to remember: (1) how often will you use the tractor at full laod, and (2) you're not running it at Daytona. Things can really get out of hand . . . fast.
Amazon Book

Janicholson · Dec 30, 2008

Everything we know is defined by who taught us to call it what. I stand modified. Jim

trucker40 · Dec 30, 2008

You could most likely do an inframe if your crank is good.I dont know anything about that tractor myself,but it could be possible to do an inframe if you can get get the clutch out and the flywheel off and the front cover off,without splitting the tractor,you could do an inframe even if the crank was bad.Working on the ground is a lot harder than on concrete,and inside with a concrete floor is like heaven compared to outside in the mud.Especially if you have to split it.Nothing is impossible though.Sometimes if outside is all you have,it works fine.If you have jacks,blocks,some thick plywood to put under it a tarp and some heat you can get it cozy outside.

Clarkbug · Dec 30, 2008

Paul,

the funny thing is that I actually got that book for Christmas last year, and I left it down in Virginia, not thinking I would need it up here in NY.

Lesson learned there!

Its about to get quite chilly here in NY, so I may have to hold off on too much tinkering for a few months until I get another break from work. Im thinking of filling the block up with some old diesel to just keep it from rusting at all and to maybe help things loosen up somewhat.

Again, I really thank everyone for their input and help so far, since this is all new to me. Im sure Ill have more questions soon!

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