I have a 1942 Allis B.  That stopped running while cutting hay yesterday.

It looks as though the oil pump stopped working and the connecting rod bearings are destroyed. The bearings probably have .060 of play on the crank shaft.

In the oil pan there was what looked like lots of chunks and blobs of melted lead.  I didn't have a magnet to test if it was magnetic out in the field and forgot to bring a piece home to test it so I am not sure it was lead but it sure looked like it.

Is that lead(probably babbitt) the facing from the bearing inserts in the connecting rods?  Or is it from somewhere else in the engine?

Is there babbitt anywhere in  a B engine?  Is there aluminum in a B engine?

Is there a facing on the connecting rod bearings?  Something has allowed there to be about .060 of play between the crank and connecting rod insert and I am guessing it is whatever the bearing inserts are faced with, but I don't know if they have a facing.

Thank you.  That is what I assumed was where the material came from but I couldn't find information online or through the manual saying that the bearings were lined with babbitt so I figured I would ask here where someone would know for sure.

So now that I know where the metal is coming from, would it do any more damage to the engine to polish out the scratches with some fine emery paper on the crank and slap new bearings in and run it? 

I know it wouldn't be the best for the new bearings but I want this tractor up and running NOW and don't want to pull the engine until winter to have the crank ground and replace the oil pump.  (it looks like the pump still works as long as I prime it)

I would look at the MAINS also ......... cam shaft bearings a brass, not babbit ... you might see that it turns smoothly.

ALso this is a BYPASS FILTER system... and it is SPLASH LUBED.. the cam is hollow and has holes in it that SHOOT oil toward the bottom of pistons and run down the rods.. Not direct oil pressure to the bearings.... and the filter just takes 15% of the total oil flow, filters it, and dumps back to sump.....

#1 MAIN has a thrust built into the bearing.. You might check END SHAKE of the crank and make sure it is not excessive... suppose to be around .005 inch.

I would prefer not to take the main bearings apart. The crank shaft has no up and down or side to side play(that I can tell) But it does have excessive end play.  I am assuming the main bearings are still OK, and the end play was that way when I bought the tractor.

I will have to take a closer look at how the cam shaft is mounted and its bearings.

Can you explain the splash lubed part a bit better?  The only splash lubed engines I have first hand experience with small engines where there is a dipper on the connecting rod or  the gear for the governor throws oil on everything.

I kept them all facing the direction they were when the came out of the engine.  However I think the front one may have been in backwards.  All the pistons have a small notch in the skirt and on the rear three that notch was facing the front.  On the front piston it was facing the rear.  I don't know if that notch is supposed to be lined up in a specific direction(I know a similar notch matters on two cycle engines)

The 85% of the pump output goes down the hollow cam.. Cam has holes in it that point at the bottom of the pistons.. Oil SHOOTS out the holes at the piston, onto the wrist pin, and drips down onto the connecting rod bearings.

The cam also has holes in it to lube the 3 cam bearings directly... and there are 3 passage ways to the mains , from the cam, to lube the mains directly.... You maintain about 10- 15 psi in the system at the FILTER... The filter is stuffed with cotton and has HIGH restrictions (backpressure)... If the filter center tube is gone, or the filter is paper instead of cotton, you might have 50% of the oil LOST thru the filter and back to sump.. That is stealing FLOW from the hollow cam shaft...

main and rod bearings are SHIMMED for clearance....

Check the filter for the little "Stand Pipe" up inside it that's part of the filter Base housing. Someone should be able to post an image please. 

If that is missing, don't run it until you block off the filter infeed line, or replace the pipe. 

Otherwise, it'll continue to starve the engine if it is missing. 

The pipe is in there and it is the correct filter.  My guess is the check valve on the pump is damaged.  When I primed the pump it worked began working again.

I think the check valve in the pump is what caused the pump to stop working.  When I prime it it works fine. 

It isn't a money issue, it is more of a "I don't have enough hay for the winter yet" issue.

getting the right clearance on the bearings with the shims is most important.

steve(ill) wrote: If you know you are going to have excess clearances and you want more oil flow / spray to the bearing, you could block off the filter and get an extra 15% more flow internal... I would retain the pressure gauge so you can see what you really got, and look for pressure loss ( like the original problem).

There are two holes on the tube going into the filter,  one on the tip and one near the tip but on the side.  My thought was I if I could find a screw that fit snug in one of those holes I could use it to temporarily block the flow.  Another option was a piece of thick shrink tube to block the hole on the side of the pipe.

I have to do some reading in the manual to figure out how to get the cam out and the cam bearings.

To remove the cam does it just pull out the front of the engine? 

It was getting dark when I got to that point so I just tried to give it a small pull and when it didn't come out I assumed there was more to getting it out.

your getting in pretty deep when you pull the cam out...

The spec for oil clearance for the cam is .002"-.004", .015" is way out of spec. But given your situation, you will have to run it the way it is.

Where are you in WI? I am between Green Bay and Wausau and run an unofficial Allis-Chalmers dealer. I have some .0025" rod bearings here that will work better than STD for the specs you measured. I also have gaskets, reground crank and lots of other parts to get you back going asap! I don't have a running engine to drop in though.

At this point all that is still in the  block is the crank, cam and tappets, magneto and oil pump.

When I tried to pull it it was getting dark so I didn't try very hard but there was no end to end play with just hand pressure.  I assumed I wasn't hitting the tappets yet because I figured there would be at least some play before they starting giving resistance.  I'll have more time tomorrow to work on it. 

Although at this point I think I am only a few bolts away from removing the block from the torque tube so if the cam has toooo much play I may just pull the engine completely.

Whether you remove the cam or not, your oil clearance from the cam to the cam bearings is too much at .015". You will lose lots of oil pressure there. The only way to remedy that is to remove the cam and replace the cam bushings. You may need to go to 0025" undersize bushings on the cam also.

If you take the block out of the tractor, then you may want to consider just swapping out the crank also.

Rice Lake.

What do you mean by .0025 rod bearings?  Are they oversized by that amount?

I would be interested in getting parts from you if you have them in stock.

At the moment I need:

 a head gasket,

thermostat housing gasket, (the one between the housing and the head)

oil pan gasket,

timing cover gasket,

and a governor cover gasket. 

As well as the connecting rod bearings and crush shims.

It feels like I am forgetting something in that list but I don't have the tractor here to look at and see what it is.

I was pretty sure .015 was way out of spec, but in your experience do you think an old, well used engine can get that worn and still run or would you guess that most of that is from running without oil?

steve(ill) wrote: probably hard to get a good measure of bearing wear with the cam installed.. The pushrods and rocker arm are pushing DOWN from above so you will not notice much  movement by hand ............ if your going to pull the cam, i would suggest pulling the motor and turning it upside down / rocker arm off / push rods out.

The head is off.  Just the camshaft and crank shaft are left in the block at the moment so the .015 isn't a super accurate measurement because I only measured the front bushing but it is close.

Sounds like you are working out at the farm ?  If the motor was out and HOME in the garage, you might have more time and easier job to overhaul ?

The oil pump drives off the back of the cam shaft.. If you pull the motor, check the pin drive in the shaft.

At the moment it is out in the hayfield where it stopped running.  Unfortunately I don't have any place to work on it at home other than the living room.  And no work shop at the farm either.  

If I end up pulling the entire engine I will want to do a full restoration on it, which I would like to do, just not now when I should be baling hay.  So at the moment I just want to get it back up and running for another 20-30 hours and then I will have all the time in world to work on it this winter.

My project for next week was going to be to put up a shed that I tore down and moved to the farm so I have a place to work in the winter, but now my project for next week is to get the tractor running and bale hay.

If your PUMP is good, you really dont need much oil pressure, just a lot of FLOW....... still question what ORIGINALLY caused the problem.

Might be worth putting a THICKER oil in to try to fill up some of the clearances and retain oil film.

I don't know what caused the pump to stop working.  I  put the mower on, added a quart of oil then made three or four rounds mowing.  Then shut it down to make sure nothing on the mower vibrated lose and then made a few more rounds.  After checking everything and restarting I had to have the throttle one notch higher than I did at first.  I watched kept a close eye on the temp gauge because early in the summer when working it hard it would start to loose power when it was up to temp(condenser, plugs and adjusting valves mostly fixed that).  It never got much above 170 so I wasn't too concerned about the need to have the throttle a bit higher.  It stalled out going up a small hill.  When I tried to restart it is when I first noticed it wasn't building oil pressure when cranking it.  I took the oil filter and valve cover off to confirm it wasn't pumping oil instead of the gauge just not working.

My guess is when I shut the tractor down to check that everything was tight the check valve on the oil pump got stuck open and the pump lost prime.  I don't watch the pressure gauge that closely and I must not have noticed it didn't have pressure.  Once I primed the pump through the filter tube it pumped oil just like it should while cranking it with the starter.

The screens on the oil pick up were clean of debris when i pulled the oil pan so I don't know if something got stuck in the check valve or just build up over time was finely enough to hold the valve open.  Now that I have the engine apart it looks like the last person to be in there was a fan of silicone.  My first thought was a chunk of that got stuck in the valve but it would have had to get past the mesh on the oil pickup.

Yes, the .0025" are 'oversize' bearings for 'undersize' crankshaft. .005" are available also but I don't have any in stock right now. Looks like I have all the other items here that you listed.

For your time constraint, I would see running the cam as is if you have to. But the rod bearings need to get better clearances to avoid spinning a bearing. With adjusting the shims you should be able to get close to spec as long as the crank journals are not galled from the bearings. Its possible a VERY tired engine could have that much wear on the cam bearings.

Pretty much all of this is based on the hope that the pump stays working even if I have to prime it before every time I start it.  I'll have to watch the gauge very closely and hope it keeps working.

VALVE clearance was right in the ballpark .010 hot/.012 cold.

Was the tractor sputtering or missing when it was 'lacking power'? Did pulling the choke halfway or all the way have any effect?

I am thinking fuel or electrical problem but need more info to make accurate diagnosis

Loose valves / bearings / worn parts, normally dont keep an engine from RESTARTING after it has run 30 minutes .......... See if it restarts when cool.... See if it has spark.

It wasn't sputtering, but when climbing hills in thicker grass it felt like it was bogging down almost to the point of wanting to kill.

Pulling the choke was how I killed it(kill switch wasn't hooked up yet)  It took a good 4 or 5 seconds for it to shut off with the choke fully closed.

At this point I am leaning towards not getting fuel is the next thing to look at as well as triple checking the timing.

The condenser is new(less than 10 hours on it) and all four plugs had really good spark last night at which point we couldn't get it to run  for more than a  30 seconds to a minute.

Fuel is getting to the carburetor for sure, the fuel is only a few weeks old and the float is working, and there is no water in the fuel.  I opened the drain on the carburetor and drained it into a glass container so that is how I how I know all of that,  I don't know what the inside of the carb looks like.  It could be a plugged jet,  the reason I didn't dig into it is lack of gaskets and the carburetor has never been a problem before other than water getting into the tank.  It just felt unlikely that the carburetor would choose 30 minutes after rebuilding the engine to stop working.

Most likely.

I have a question about the timing.  When I turn the engine over very slowly by hand the number one plug fires(from the snap coupling) when the piston is very close to top dead center.  Is that correct?  Or should it be firing 30degrees before?

I read that when it is turned slow it should fire at  top dead center.  I just don't know if that is correct or not.

mags were setup that way to work with HAND CRANK systems.... Still works OK with electric starter.

iF YOUR tractor was not sputtering or missing when you thought it was 'lacking power' than your problem is not in the carb. If you had spark off the coil wire when the tractor would no longer start, then the electrical components should be okay too.

If you have a magneto, to check the timing proceed as follows: Disconnect pug wires from plugs. Hand crank the engine very slowly until the magneto impulse snaps. At this point, the setscrew on the front crankshaft pulley should be pointing all the way up or all the way down. If the mag snaps when the setscrew is before or after vertical, loosen 2 mag attaching bolts and tilt mag so it snaps when setscrew is vertical, either top or bottom. Your static timing is now correct. This setting would have to be pretty far off to have that much affect on engine power.

I've had rust in the tank cause the same problem. intermittent plugging of the filter and tube. 

What I did was remove the sediment bowl assembly from the tank, drill the top just a little and install a piece of copper tubing to come about a half inch up into the tank and drill the sides to allow fuel to enter there as well. That way you have more unobstructed places for fuel to enter. 

at the front left of the motor, disconnect the governor cross rod from the rod going to the carburetor.. pull the throttle forward and back and watch that the governor arm is moving  smoothly across the front of the motor..(behind the radiator) .. Put the THROTTLE lever at FULL OPEN... go to the carburetor and pull the rod FULL FORWARD... now see that the carb rod lines up with the hole in the  governor cross shaft.... if not, bend the cross shaft forward or reverse until it fits.

If that dont work, then you MIGHT have a  governor problem.... and there is a SPRING on the governor rod at the housing , right ?