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Z134 No Compression in Cylinder #2

C

Craig L

Member
I've got a mid 50's MF 50 with a Z134 Continental engine with "0" compression in cylinder #2. I noticed the engine was running rough, pulled the plugs and did a compression test. Cylinder #1 at 95, cylinder #2 at "0", cylinder #3 at 95 and cylinder #4 at 80. Just looking for some advice as to why may cause this and is there anything I can check or do before I tear into this. I did notice that there was some antifreeze in the oil. Even with this running rough I really haven't seen any white smoke out of the exhaust. What's the first step to diagnosing this issue.
Thank you
 
I would agree, think you have a valve stuck open, antifreeze in oil is serious, but probably not related to this issue.
 
Any suggestions as to how to unstick a valve? I can see in the cylinder but it's a bit hard t see if one of the valves are not seating properly.
 
Had that once on a farm all. Took the valve cover off and found a pushrod had came out of the adjuster.
 
You've already done the first step, running a compression test.

Next step is to get the valve cover off, look things over.

For it to suddenly lost all compression is a sign of a sudden failure, like a broken valve spring, stuck valve, seat come out, pushrod bent or broken.

Once the cover is off you can probably see the problem and determine if it can be repaired without pulling the head.

The coolant in the oil can be a head gasket, or it can be leaking orings at the bottom of the cylinder sleeves. I would suspect the orings if there were no other problems like overheating, coolant froth under the valve cover, or coming out the breather tube. Changing the orings is no small job. The liners will have to be removed and the bottom of the block thoroughly cleaned. If the rest of the engine is getting tired, might be time to do the whole job and be done with it.

If you are not going to replace the orings, and are taking the head off, be sure to clamp the liners down with bolts and flat washers. Otherwise they will ride up if the engine is turned. If any ride up, the seal will be broken and will for sure leak.
 
Rev the engine up and shut off ignition while engine is still spinning full speed , listen for air
escaping out of exhaust, intake or crankcase breather. Poor man's quick and dirty test for loss of
compression, normally burned valve.

Best way is cylinder leakage test but takes a little more time and effort. Beats compression test
as it indicates where loss of compression is going and also can tell if leaking into cooling system
 
Stuck valves are common on an engine that has been stored, but for one to stick running is not.

Probably a good reason it stuck, and it needs to come apart and find out why.

Or could be the seat fell out and is holding it open.
 
My plan is to get the tractor in a good place to work on it today and pull the valve cover off. Wanted to thank everyone for their suggestions. Once I have the valve cover off and I have some more info I'll you guys know what I've found.
Thanks again.
 
My plan is to get the tractor in a good place to work on it today and pull the valve cover off. Wanted to thank everyone for their suggestions. Once I have the valve cover off and I have some more info I'll you guys know what I've found.
Thanks again.
 
I remove the valve cover and found the valve cap for one of my valve stems for cylinder #2 had come off and was just sitting there. See the photo's. Not sure why it slipped out but I'm going to loosen- up the rocker are adjustment and put the cap back on and re-adjust it to I believe .015 thousands and see if I get compression.
Any suggestions before I attempt that tomorrow?
 
I remove the valve cover and found the valve cap for one of my valve stems for cylinder #2 had come off and was just sitting there. See the photo's. Not sure why it slipped out but I'm going to loosen- up the rocker are adjustment and put the cap back on and re-adjust it to I believe .015 thousands and see if I get compression.
Any suggestions before I attempt that tomorrow?
 
I remove the valve cover and found the valve cap for one of my valve stems for cylinder #2 had come off and was just sitting there. See the photo's. Not sure why it slipped out but I'm going to loosen- up the rocker are adjustment and put the cap back on and re-adjust it to I believe .015 thousands and see if I get compression.
Any suggestions before I attempt that tomorrow?
 
I tried to upload the pictures but this site is not allowing me to do it.
mvphoto54246.jpg
 
It may have just hav4 had enough clearance to fall out.
I would adjust all the lifters while you have the cover off.
pull that push rod out and see if its bent. If that valve is sticking it could have bent the push rod. It may be a good time to rebuild the head.
Only you can decide.
 
Upon further review, I notices that I can not rotate the push rod for cylinder #2 so it sounds like it maybe bent. Also, I noticed that cylinder 4 had one of its push rods offset, almost like its ready to do the same thing as to what happened to cylinder #2. If you look at the last photo you'll see the push rod is over to the right and not centered. That may explain why that cylinder had lower compression the #1 & 3. It only had 80. Maybe it's not opening all the way.
1 had 95
2 had 0
3 had 95
4 had 80
 
Took off the rocker arm assembly and found that I have 3 bent push rods. I can't imagine what would have caused this. Does any one know were I can get 3 used push rods? I'd like to try to put this back together to see if this will work for awhile?
 
Wanted to give an update on my Z134 engine with no compression in cylinder #2. After taking off the rocker arm shaft assembly and having it soak in my parts washer, I noticed that some gunk was dripping out of the bottom of the shaft. Took the shaft apart and noticed inside the shaft and the oil holes were almost completely clogged. Also, after removing the head, cylinder #2 intake valve was stuck closed from carbon and a little bit of sludge. Cylinders 3 & 4 that had the 2 other bent push rods, those were carboned up as well. I figured that after years of running this the oil slowly began to almost NOT get to the rocker arms even though the top of the head had oil. I surmised that the oil not traveling down the inside of the rocker shaft caused the gunk and carbon build-up ultimately causing restriction of the valve movement and thus bending the push rods. Now, I'm at a cross-roads! Do I pull the pan and remove the pistons and push rods, pull the sleeves and clean everything and replace the original sleeves with new O-rings? I did notice under the valve cover there was a bit of froth, not much. Not sure if its recommended to re-use the original sleeves and just replace the O-rings but this engine is very quite and doesn't burn any oil and has decent power.
 
(quoted from post at 08:12:18 05/10/20) Wanted to give an update on my Z134 engine with no compression in cylinder #2. After taking off the rocker arm shaft assembly and having it soak in my parts washer, I noticed that some gunk was dripping out of the bottom of the shaft. Took the shaft apart and noticed inside the shaft and the oil holes were almost completely clogged. Also, after removing the head, cylinder #2 intake valve was stuck closed from carbon and a little bit of sludge. Cylinders 3 & 4 that had the 2 other bent push rods, those were carboned up as well. I figured that after years of running this the oil slowly began to almost NOT get to the rocker arms even though the top of the head had oil. I surmised that the oil not traveling down the inside of the rocker shaft caused the gunk and carbon build-up ultimately causing restriction of the valve movement and thus bending the push rods. Now, I'm at a cross-roads! Do I pull the pan and remove the pistons and push rods, pull the sleeves and clean everything and replace the original sleeves with new O-rings? I did notice under the valve cover there was a bit of froth, not much. Not sure if its recommended to re-use the original sleeves and just replace the O-rings but this engine is very quite and doesn't burn any oil and has decent power.
Click to expand...



The froth could be from if you large temperature/humidity changes during the day. Also if it doesn't get run really long enough to get nice, and hot it won't burn the condensation out of the engine. I wouldn't hurt to pull the rods/pistons to check the piston rings to see if any are collapsed, or stuck to the pistons.
 

Replacing the sleeve orings is a good idea while you are in there. You can check the ring end gaps, the ring lands, and the skirt clearance, if all are in spec go back together with them or replace the rings and hone it.

But the bent pushrods are a mystery. Has the tractor been stored for a long time? Stuck valves are almost always the reason for bent pushrods. It looks like one of the adjuster screws is worn away too??? Possibly that was caused from a bent pushrod.

I don't see evidence of lack of oiling though. Usually loss of oil results in the rocker shaft and bushings burning up long before the valve stems loose oil.

You may want to disassemble the rockers completely. The clearance specs on the shaft bushings is very tight, few will be in tolerance. A reconditioned rocker assy may be in order. You can buy the components to DIY, but the bushings have to be honed to size. Be sure the cork plugs are in place in the ends.

But while the head is off, and you are considering going into the bottom end, roll the rear main bearing out, be sure it has not spun. That is where the rocker shaft gets a metered oil supply, through the hole in the top half of the rear main bearing. You can also blow down through the oil galley while the bearing is out to be sure it is clear. Sometimes if someone used gasket sealer on the head gasket it will clog the oil galley to the rockers.
 
Each year I run the tractor but it does sit at times the remaining part of the year. I agree, cylinder #2 intake valve was stuck and I couldn't pull it from the head at first. I backed-off the adjustment screw and tried to get the bent push rod out, that's way that adjuster looks like that. Just before dunking it in my parts washer I looked and saw all of the crud in the shaft and the holes along the shaft were plugged as well. I did disassembled the shaft completely and cleaned it. You mentioned cork plugs, my shaft didn't have them and my MF 50 manual for this motor doesn't even list or show cork plugs at all. You mentioned going into the bottom half and that's where I'm at. If I were to take off the pan I was going to just pull the sleeves, clean them up and replace the O-rings. This motor is pretty quite, no bearing noises. I'm sure the proper way is to tear this down completed and rebuild it but I'm thinking the rocker shaft wasn't really lubricating like it should have possibly causing the stuck valve then ultimately bending some of the push rods. Can those sleeves be re-used if pistons and cylinders wall are not damaged?
Thank you.
 
I have misspoken, my manual does show cork plugs but my shaft didn't have them at the time I pulled it down to clean it. Can I make my own plugs and does it have to be cork?
 
Wanted to give an update on my progress. Pulled the head and cleaned the valves and guides (the guide in cylinder #2 intake valve was gummed-up causing the valve to stick). Looked it over and the head looks to be ok. Lapped the valves and cleaned the block. After looking at the head gasket I don't see any signs of it leaking to cause one of my issues (a very small amount of antifreeze in the oil). I don't remember hearing that a head gaskets causing antifreeze in the oil (only entering the combustion chamber). The cylinders sleeves look to be in really good shape so now do I pull the pistons and sleeves to replace the sleeve O-rings? This MF 50 has a Superior Loader and is really not so easy to work on and I don't have a sleeve puller or piston ring installer. Has anyone re-used their old sleeves if they are decent and is there anyone in the Southern Nevada area that I can use their sleeve puller & ring installer? If I have to purchase a sleeve puller I will but probably never use it again.
Thank you
 
Wanted to give an update on my progress. Pulled the head and cleaned the valves and guides (the guide in cylinder #2 intake valve was gummed-up causing the valve to stick). Looked it over and the head looks to be ok. Lapped the valves and cleaned the block. After looking at the head gasket I don't see any signs of it leaking to cause one of my issues (a very small amount of antifreeze in the oil). I don't remember hearing that a head gaskets causing antifreeze in the oil (only entering the combustion chamber). The cylinders sleeves look to be in really good shape so now do I pull the pistons and sleeves to replace the sleeve O-rings? This MF 50 has a Superior Loader and is really not so easy to work on and I don't have a sleeve puller or piston ring installer. Has anyone re-used their old sleeves if they are decent and is there anyone in the Southern Nevada area that I can use their sleeve puller & ring installer? If I have to purchase a sleeve puller I will but probably never use it again.
Thank you
 
Got the head back on and she runs well. After I ran it for a few cycles I re-torqued the head. Now I'll run it for a bit then drain the oil to see if I have any antifreeze in with the oil and do another compression test. I ran through the governor adjustment procedure but it really doesn't seem to be working all that well. I don't believe this has worked properly since I've owned this. Also, my serial # plate on the motor says ZB144663366, I contacted the guys at Montes Equ. in Illinois to ask help with decoding my serial #. My question to them was "is the B in my serial # mean that its a Hi-Altitude motor"? Their answer was a bit confusing. This was his answer, "Those only made certain enignes and that ZB part is peculiar to me... could be High attitude...l Spece the spec". I'm wanting to know so I can check the engine timing and the settings are different for the 6.6 to 1/Standard or 8.1 to 1 compression ratio engine. It seems as though I may have the Hi-Altitude motor with the higher compression ratio.
 
My mid 50s TO-35 did the same. Pulled the valve cover and #4 exhaust pushrod is missing. I assume its in the oil pan. I plan to put a new pushrod in until I can drop the pan. Valves need adjustment once in a while or will slip out from under rocker arm.
 
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