The State of Head

The head of my Yanmar 1GM10, with my custom-fabricated valve-spring compressor
fashioned for me by a local machinist, Eddy.  Worked like a charm.

If you're going to rebuild an engine, it is pretty convenient that you can hold the head in your hand. Put aside the sludge factor and it would almost be cute.  Nothing this oily fits in that category, though, and when you get over that, the next emotion is awe.  This 9 horsepower engine turned turned over 110,000,000 times just on my Alaska trip.  Another 350,000 times last year... never mind all the other shorter seasons it has seen.  Half the horsepower of a John Deere lawn tractor, it has pushed a 6,000 lb boat 5,000 miles in the last couple years. Try riding your lawn tractor to New York and halfway back. Diesel engines rock, and this 20+ year old Yanmar has put in some time.

So why quit now? The hour meter has clocked a mere 2500 hours since the last rebuild (I'm assuming it has been rebuilt, but I don't even know that for sure).... That is very low for a diesel, and unless I can find the answer, I wonder if I can ever be confidant in it again?

I have the head off, and have extracted the valves, push rods, rocker-arms, and thermostat. Everything I've measured thus far is well within spec.  Some carbonization, for sure, but nothing outlandish.  It is early days, but I confess my greatest fear is NOT finding an obvious explanation for overheating and burning 2.5 liters of oil in 5 hours.

I will bring the block up from the boat to my workshop in the next days, and what I am hoping to find is obvious evidence of oil blowing by the rings and being burned in the combustion chamber.  If it isn't that, then the only possibility that I can conjure is the governor, and even at that, I have no explanation for how the governor could suddenly start behaving like a self-destructive despot intent on amplifying fossil fuel consumption.  No reason in that.

By the numbers:

Valve stems:
     Nominal at installation:     .2756
     Measured:                          .2740 (wear tolerance = 2717)

Valve Springs:
     Intake:
     Measured free length:       .4010   (wear tolerance = .3850)
     tilt value:    .533/.4010 =   .0133   (wear tolerance = .0350)
     Exhaust:
     Measured free length:        .4010
     tilt value     .203/.4010 =    .0051

Rocker arm bushing                .4728 (wear tolerance = .4724)




Comments

Post a Comment

Popular posts from this blog

Connecting a Chart Plotter, VHF, AIS Receiver and Tiller Pilot using the NMEA 0183 protocol

Image
NOTE: An updated version of this posting that includes an AIS transceiver is now available here. Ripple's complement of communication and navigational electronics now includes: Standard Horizon CP390i chart plotter  Digital Yacht AIS receiver   Raymarine ST2000  tiller pilot  Standard Horizon VHF/DSC radio These devices can all be networked, so installing them includes making decisions about whether and how to connect them.  As with most everything on a boat, there are tradeoffs.  The benefits of additional functionality are always at war with the unanticipated dangers of creeping elegance and the instability that arises from proliferating connections (natural failure points). My four devices, like most modern electronics, can talk to one another using the well-established NMEA 0183 protocol.  NMEA 0183 falls short of a full-blown network, but it meets the need for point-to-point connections such as are appropriate to my configuration..  The NMEA 2000 protocol provides
Read more

Re-powering s/v Ripple

Image
My Summer, 2017 Adventure An irregular sound, a vibration untuned to the sum of your experience: this one was a momentary drop in RPM... 25, maybe 50 rpm. I bumped the throttle, right? Then it happened again, and denial shades into anxiety. The opening hours of a 6 week cruise: Seattle, up the inside passage, over the top of Vancouver Island and a leisurely meandering through the inlets that indent the west side. But this journey ended just as it began. A series of intricate diagnostic rationalizations, fuel filter and impeller changes availed us not at all. Lots of oil gone missing! Limping into Kingston Harbor, Ripple’s Yanmar 1GM10 turned the last of some 300,000,000 revolutions in my service. Broken-hearted 1GM10 Only slowly did I surrender the hope of rebuilding my faithful one-lunger.  As it happens, Yanmar does not make an oversized piston for the engine, as they enlarged the size of the cylinder when the 1GM transitioned to the 1GM10, and given that the
Read more

Installing and Networking a Class B AIS Transceiver with a Chart Plotter and VHF Radio using NMEA 0183

Image
In 2015 I purchased an AIS receiver for a trip up the Inside Passage.  This posting is largely an upgrade of the  posting for that installation . I suspected at the time I might look back on purchasing only a receiver as a false economy, and that turned out to be the case. I want to be SEEN as well as to see others. This year  I purchased a Vesper XB 8000 AIS transceiver to replace the perfectly functional Digital Yacht AIS receiver that I had benefitted from over the previous three seasons.   My decision to go with Vesper was based on the reputation of their product and their customer service,  and also because the device makes the data on my network visible via a WiFi gateway.  This should make it easier to pull off tracking and route data, and to display AIS targets on tablet or phone as well as the chart plotter. The XB-8000 also provides an easily managed anchor alarm, accessible by tablet or smart phone.  I won't have to sit in the cockpit all night watching the chart plotte
Read more