Rolled my Yanmar EX3200 and have questions

whodat526 · Aug 26, 2011

SSdoxie said:
I have found that tacky stuff before in some diesels. It is partially burned/unburned fuel. I really suspect your #2 cylinder has a slight bow in the connecting rod. Here is a way to check without a compression guage.
use piece of electrical solder (solid stuff, not flux filled), remove the injector and feed it down into the cylinder bowing the solder slightly so it is close to horizontal. Then rotate the engine by hand, don't use starter, 1 revolution. Repeat this with all 3 cylinders and see if the solder is compressed equally. This will tell you if piston rise is different in 1 cylinder.

Unless you can find a service manual, your going to have to take to a shop anyway to get torque specs. Check with a Yanmar dealer. Read your model number so they can compare it to correct engine. Any numbers at the end after the dash are only equipment specifications as to intake & exhaust configuration but same numbers 3TN????- are all the same internally.

i would have to agree i believe he would have a bent connecting rod before a bent valve

irwin · Aug 26, 2011

The following is not for those of you that already know this.. it's for those that don't.

Hydrolock is a very common result when attempting to start an engine without first verifying there is no liquid in cylinders. [Driving through high water will stop an engine instantly (water is sucked into the intake).]. Perhaps a injector is stuck open at the wrong time and fills a cylinder...or maybe the vehicle rolls on it's side and oil fills one or more cylinders...

Fuel, oil or water will not compress, so when attempting to crank an engine with a liquid in cylinder(s) the piston can only go so far before the liquid stops it cold, if the starter has enough torque (and it often does) it will bend something.. ie: piston rod, push rod, valve stem(?)..it might even damage the rod bearings or crank journals.. most of the time (but not all the time) the engine is repairable without a complete rebuild (unless the engine stopped when above an idle, serious damage then)..however once the engine is open any questionable components should be replaced.

The possiblity of a damaged injector was mentioned, I'm not an expert in diesel engines so I'll say maybe (pretty easy to swap injectors, so what the hey).. gas engines though .. the possibility of the injector getting damaged durring a hydrolock is not high.

art · Aug 26, 2011

Do you have a harbor freight near you? I don't use special tools often but they have cheap injection compression testers for diesels! I use it in glow plug holes normally.

TDR · Sep 4, 2011

Hi all. Finally a break in the work schedule so now back to the tractor. First a couple of updates on past challenges: bought the compression tester for diesel motors but lacked the adapter for the 3TN motor so that is a bust but did find a 3TN service manual on the Internet.
The #2 connecting rod is bent. Several of you experts were confident of a rod being bent and you were correct. My humble apologies for skirting around and being hopeful of a simple fix. After pulling the cylinder head and hand rotating the motor it was obvious #2 piston was lower than the other 2. The dial indicator validated it was in fact .070" lower. Pulled the piston and found the rod has a distinct bend in it. I will order the parts Tuesday (a rod is $225 and the head gasket $105) and put back together next weekend. Fortunately I could get to the rod cap through the small access plate on the pan so I did not have to break the tractor in half.
I did document the whole process with step by step photos and tips in case anyone experiences the same mistake. I will post something after I complete the repairs. Thanks again to all.

kebo · Sep 5, 2011

Been reading this one with interest and have learned some from it about diesels. It was very fortunate that you could access the bottom of the #2 rod without having to split the tractor. The Yanmar diesel on my JD 790 has a very similar access panel on the bottom of the oil pan so I know what you're referring to there. I hope that your repair goes well and that it runs like a champ after replacing the rod. Good luck!

aebsmithcreek · Sep 5, 2011

i just found this thread, very interesting to follow, espsecialy for somebody as challenged by these things as me. it is obvious there is a lot of expertise here. TDR, all the luck in the world to ya and hope you are back to tractorin soon. if ya ever get tired of your current digs it sure would be nice to have a neighbor with your mechanical skills

keep us informed.

earl.

TDR · Sep 13, 2011

Hi all. A quick update on the EX3200. Installed the new connecting rod and reassembled the engine on Friday night. Saturday morning I was SAFELY moving dirt again. Here are 3 pictures to show the smoking tractor, the #2 exhaust port and the bent connecting rod. Thanks to all for your help!