Yanmar Nightmare

[Lary-74426]

This one is going to take awhile to explain....I have a Yanmar 3 cylinder diesel tractor. The side covers read "F235" while the instrument panel reads "F255" I purchased it with 23 hours on the clock, it now is approaching 400 hours. The Summer of 2014 we took it to Kansas to do some work on the family farm.. it started overheating. About every hour I would have to stop and hose down the radiator to cool it down, but it was never short on water.
Brought it back to Oklahoma for the Winter, and last Spring noticed a water leak at the radiator. Pulled the radiator and the top tank had separated, thought that I did not get enough antifreeze in it, and soldered the tank back on. Next it blew the top radiator hose. Next it blew the seal in the water pump. Finally dawned on me that it was building to much pressure, but the cap never blew by. Tried running it with the cap off when I noticed that exhaust was coming out of the radiator. Ordered up a head gasket and head bolts. Upon removing the head I found that the new gasket had a rubber "O-Ring" molded into the gasket, old one was missing. Cleaned up the block and head, installed new gasket and torqued the new head bolts. Stupid me, while installing the rocker arm assembly, I did not properly align the push rods, and broke two rods, both center cylinder. Ordered up new push rods. Upon initial start up I could hear a weird sound coming from the intake, and it had decreased power. Pulled the head again and found that I had bent both valves, but did not see any piston damage. Ordered up two valves and another $70 plus head gasket. This time it ran good but wanted to overheat again. Finally found that the radiator was partially plugged with exhaust. Soaked the radiator overnight in Super Clean, back washed it and it has not overheated again. NOW the problem is that it is burning oil, so much that it is dripping out of the muffler, about a pint an hour. Decided that valve seals were to blame, so ordered and replaced all six. Same problem. There is no blow by, nothing coming out of the breather, so I am assuming that the problem is top end.
I am at my whit's end...what am I missing?
Any help would be greatly appreciated.

 

[Coyote machine]

An exhaust based leak, and paragraph breaks for us readers. You'll have to unzip the head again and this time verify it's straight with no cracks, etc. Same with the block, it HAS to be perfectly straight with no defects, cracks, etc.
I don't know your engine build, whether it's sleeved or a parent block. You've overheated it so much it's hard to guess what the problem is. You need to find the cause to fix the problem, so taking it apart is necessary, then find cause and effect.

 

[California]

... And post this over in the Yanmar forum where somebody familiar with that model might see it.

Massive oil in the exhaust and none from the crankcase breather?

That sounds like there is an opening from the oil line that goes up to the rockers, that dumps oil into the exhaust ports. On the older YM's this was a bolted on external tube. If that passage is cast into the head on yours, a leaking head gasket or worse could be the unintended path. But it seems to me that any interconnection there would put exhaust into the valve cover and out the breather, and you aren't seeing that.

Different model #'s shown on the side covers and dashboard? Only 23 hours on the tach? Bad radiator cap, split radiator tank, bad head gasket? This might be one of those infamous VN 'rebuilts' assembled out of unrelated used parts. ('rebuilt' with zero access to genuine Yanmar parts). Look down on the side of the engine by the starter, for the engine model #, to see what you really have. Then look on TractorData . com to see what models used that engine.

It's rare but we see the occasional FrankeinsteinMar - assembled out of who-knows-what, in the Yanmar forum. These are assembled in VN sweatshops after the tractor completed one lifetime in Japan, a second lifetime in the paddies of VN, then when it won't run any more it gets 'rebuilt', painted nicely, and sent over here to be sold as 'new rebuilt' with its age misrepresented. Meanwhile good used Yanmars imported here straight from Japan, and the US Yanmars imported legitimately 30 years ago, keep on running flawlessly without drama. The FrankensteinMars caused so much trouble to Yanmar's reputation that Yanmar-USA sued all those bogus importers and put most of them out of business, as a first step before re-entering the US market a few years ago.

Yanmars are top-tier quality. A Yanmar that is simply used, of any age, will never show problems like this one.

I suspect a cheap non-OEM headgasket and radiator cap used for the 'rebuild' were where all this trouble started.

 

[Jerry/MT]

This one is going to take awhile to explain....I have a Yanmar 3 cylinder diesel tractor. The side covers read "F235" while the instrument panel reads "F255" I purchased it with 23 hours on the clock, it now is approaching 400 hours. The Summer of 2014 we took it to Kansas to do some work on the family farm.. it started overheating. About every hour I would have to stop and hose down the radiator to cool it down, but it was never short on water.
Brought it back to Oklahoma for the Winter, and last Spring noticed a water leak at the radiator. Pulled the radiator and the top tank had separated, thought that I did not get enough antifreeze in it, and soldered the tank back on. Next it blew the top radiator hose. Next it blew the seal in the water pump. Finally dawned on me that it was building to much pressure, but the cap never blew by. Tried running it with the cap off when I noticed that exhaust was coming out of the radiator. Ordered up a head gasket and head bolts. Upon removing the head I found that the new gasket had a rubber "O-Ring" molded into the gasket, old one was missing. Cleaned up the block and head, installed new gasket and torqued the new head bolts. Stupid me, while installing the rocker arm assembly, I did not properly align the push rods, and broke two rods, both center cylinder. Ordered up new push rods. Upon initial start up I could hear a weird sound coming from the intake, and it had decreased power. Pulled the head again and found that I had bent both valves, but did not see any piston damage. Ordered up two valves and another $70 plus head gasket. This time it ran good but wanted to overheat again. Finally found that the radiator was partially plugged with exhaust. Soaked the radiator overnight in Super Clean, back washed it and it has not overheated again. Any help would be greatly appreciated.

"NOW the problem is that it is burning oil, so much that it is dripping out of the muffler, about a pint an hour. Decided that valve seals were to blame, so ordered and replaced all six. Same problem. There is no blow by, nothing coming out of the breather, so I am assuming that the problem is top end.
I am at my whit's end...what am I missing?"

DO you have lots of blue smoke? If you are really getting a pint an hour out of the exhaust, then you have lost oil control on a piston(s). The oil control rings are worn, clogged with carbon and not scraping oil off, or they are broken. Diesels can get the "slobbers" when they operate at idle or low rpms with light loads and that is mostly unburned fuel that looks like oil. But not to the tune of a pint an hour. I doubt if it's the valve seals. Diesels don't have a throttle plate to control airflow like a spark ignition engine so there is little pressure difference across the intake valves to cause oil to be drawn into the manifold.

As far as overheating, did you clean the air side of the radiator? It can get clogged and cause an overheat. So can a collapsing lower rad hose when the engine is reved, a loose water pump drive belt, a clogged air filter, leaking injector, rad cap not holding pressure, etc

How is the engine for making horsepower? if it feels weak, your compression rings may also be worn or your air filter clogged.

hope this helps.

 

[Agvg]

Can you have a oil leak on the rocker shaft that fills the top of the engine with oil? If the oil return holes are small in the head this can happen.

 

[Lary-74426]

Sorry, new here did not know that there was a separate area for Yanmar

 

[Lary-74426]

I am wondering why you are questioning the original clock hours...I was told that to be sold in the USA without all of the required safety equipment, the tractor had to be "used" IE Grey Market

 

[oldpilgrim]

I bought a Datsun PU back in the 70's that had similar problems after being overheated. I bought it for practically nothing, knowing it was bad. It was a warped head, as I suspected. i had it milled flat and drove it many miles after.