ONAN Generator Fixed?

18 February 2019 – Yacht Haven Marina, Phuket, Thailand

Big news – our generator is fixed, or so we think ……

First, let me talk about the Volvo. While dockside, making repairs to the generator and waiting for parts to arrive, I decided to talk to the local Volvo mechanic about oil pressure and the life of our Volvo. Well, the engine is now 20 years old but has about 2650 hours on it. It could last to 6,000 or more hours, but age is a factor. Parts are also getting difficult to source as this engine is obsolete. What is good about it though is that it has none of the fancy bells and whistles (or sensitive crap that can shut it down) that the modern engines have. I like this engine, but over the years, the oil pressure has been slowly weakening. The mechanic suggested that rather than an expensive refit, which is not needed for any other reason – its time to start using STP or Slick 50, or one of the many oil additives that are designed for older engines. So, this is what we’ve decided to start doing, use an oil additive when changing oil.

While looking over our engine, he noticed that the heat exchanger had leaked a little salt water and proposed to remove it and make repairs. While doing that, he then noticed that the oil cooler was leaking oil, and that had to be repaired as well. So, over the past few weeks, we’ve had both of these things looked at, and we’re happy to have done it here in Phuket. This is the reconditioned heat exchanger, it looks like new.

Our ONAN 6KW generator has been repaired, and we’re undergoing testing to verify its reliability. We had the slip rings and end bearing changed, as well as the Voltage Regulator – both parts came from North America. Damien at Electrical Marine (Northern Lights dealer) did the work and had his technicians remove the stator and rotor. Both components were bench tested and found to be in good condition. Despite installation of these new parts, the generator was still reluctant to produce sufficient AC voltage a few days ago. I have been “flashing” it for about a year, as I’ve read that these generators tend to lose their residual magnetism over time, although that’s not true of all generators. Flashing it involves injecting 12V into the F1/F2 field coil at startup, just for a few seconds. Over the past two years, I’ve probably done this fives times. However, when the generator quit two months ago, flashing it didn’t help, it was DOA – probably because the Voltage Regulator was burned out. Damien discovered that there is a circuit path described with a dashed line in one of the ONAN detailed diagrams – that wasn’t actually fitted. This circuit, if fitted, would provide a “flash” of 12V directly to the field coil from the starter relay – every time the generator is started. Damien discovered that this circuit is sometimes described in both ONAN and Northern Lights literature – perhaps to provide the necessary boost when the machine gets older. He fitted the two wires and single diode – and presto, it WORKS. When starting, I have to make sure that I hold the switch down just a second or two longer after the diesel has started, in order to have enough boost to start the AC portion of the machine. Wow, this is progress! We are now dockside for a few more days to verify this is working properly and to check on reliability. A lot of people will probably have their eyes glazing over by now, but this description is mostly for Jimmie Thom and a few other techies out there who love this stuff. 

We are now seriously planning for our departure, both from dock and from Thailand (clear out at Ao Chalong). We’ll soon take on two crewmembers, Gabriele De Rota (Italian, age 27) and Mariona Gil De Biedma-Galofre (Spanish, age 29). Here is Mariona on the left and Garbirele on the right. 

They are currently on another boat and have been looking for passage “out of SE Asia”. Our plan is to sail to Sabang Indonesia (North Sumatra) (about 220nm), stay for “about a week” and then head on to Cochin India (about 1280nm). Both voyages are weather dependent, and we’re starting to look at the weather now. We think we have about 6 weeks left in the NE monsoon. The winds might be light but at least it is very unlikely there will be storms. 

Leave a Reply

Your email address will not be published. Required fields are marked *