I will have all new bearings in my starboard-side rollers by tomorrow lunchtime, so that meant we were a bit bored today so we broke down the body of the machine. I was looking for a leaky hydraulic radiator, but couldnt see any obvious signs of leakage. My hydraulic level has dropped a couple of litres, but i have also bled out all the air by repeated use (not cracking a fitting) so i suspect this lowering of hydraulic levelcould be attributed in some part to this. There was some wetness on the hydraulic pump and about 1/2 an inch of caked on mud/oil and other crap covering the entire inside. If a seal on a cylinder is leaking, is it obvious?
What i found is that the smoke exiting via the fan/radiator is actually from the cylinder head breather. I am sure this will need a strip down as we found a lot of carbon in the cylinderhead. How serious is this heavy amount of smoke leaving from the breather (at idle and straight from startup)? My engineer reckons its just a seal that needs replacing. But i'd like to get my 1st project finished and the excavator back down to ground level before i start on a full strip down...
Hmmnh, sounds like you have a typical Japanese machine, generally speaking in Japan machines are bought for a specific project, receive very little maintenance because they are only required to do a certain amount of work and then are auctioned/sold off to a second hand equipment exporters.
It really is pot luck when buying an ex Japan machine. Some have had luck and others have had to spend a lot of money on a machine with little hours.
Far as your machine goes, smoke from the breather is generally blow by, in other words the piston rings are not sealing that well, this is generally worse when the engine is cold and when it is idling because there is not as much pressure on the rings/not sealing as well as they should.
My guess is that there is a build up of carbon under the piston rings, which is making them stick.
Another thing that causes blow by is cylinder glazing, whereby the cylinder walls have a thin film of stuff that is polished and thus the rings can't 'bite' into the cylinder walls and seal well, this caused by extended idling and operating a Diesel under light loads. Sometimes glazing can be removed by working the engine hard for an extended period of time. You may well hear the engine working hard as you dig, in Japan it is likely it sat on a job site idling for most of the day because the operator was too lazy to shut the machine off when not required to work. Not sure how many hours on your machine but I would guess that most of them where done at idle.
Hopefully a proper mechanic can elaborate on this.
I am thinking your mechanic is referring to the valve stem seals when he talks about seals? Unless he is talking about the head gasket?
Carbon/sludge in an engine means that the oil has not been regularly changed, maybe never.
There are three ways that I know of to get rid of sludge, firstly is the slow method of changing the oil often and using a high detergent oil (which Diesel oil is), secondly is the more dramatic and potentially dangerous method of using an engine flush product (problem is that you may dislodge a big chunk of sludge which could block up an oil line in the engine causing damage) or thirdly is pulling the engine apart and physically cleaning it.
I really don't want to recommend one method over another, the flush method is the cheapest but given that you have blow by, I would advise that an engine tear down and inspection is your best option, yes it is the most expensive but it is the proper one.
What about your exhaust smoke? Exhaust smoke is a good indicator as to the health of your engine, if we know what it is like we should be able to narrow down what is going on.
If the exhaust smoke is what can be considered normal, then your mechanic could be correct in his diagnoses of a failing exhaust valve stem seal but this is somewhat unusual.
However if your oil pressure is good, you should be able to keep using the machine until such time as you can get it pulled apart.
The hydraulic issues are a bit puzzling, the system is sealed and the only place it comes in contact with air is in the hydraulic tank. Anyway all you can do at this stage is clean the machine well and then use it.
