Diesel Tune Up – #94

I’ve been getting questions about oil and filter changes and diesel fuel bleeding. There are a few tricks I’ve learned over the years (if you have more, please let me know).

The basic oil change goes something like this: Warm engine. Stop engine. Put down rags. Remove drain plug, oil, and filter. Spin on new filter. Replace drain plug. Put in new oil.

After checking the manual for your engine’s specific needs, consider the following. You warm the engine to make the oil flow out more easily. Some engines will drain better if the dipstick is out. The best ‘rags’ are those oil-sorbent sheets they have at marine stores. They suck up oil and repel water which makes them great for bilges too (keep them clear of the bilge pump intake).

My favorite system for removing old oil is to attach a hose to the oil drain hole (using fittings, found at big marine outlets). You can then pump the oil out using a hand or electric pump. Be careful with your pump selection, pumps with plastic parts may melt (info gleaned from first hand experience). With a reversible pump you can send the new oil back into the engine when it’s time. Be sure and keep the oil line securely capped when not in use.

Before removing the oil filter tape a ziplock freezer bag to the side of the engine so it will catch the oil as you unscrew the filter. Then drop the filter into the bag. Oil and diesel tend to burn through some plastics so put a strip of sorbent sheet in the bottom and double up the bag as convenient. Remove the filter by hand or with a filter wrench or, in a pinch, with a screwdriver driven through the middle. Make sure the replacement filter is the right one before implementing this last method. Dip your finger in the new oil and run it around the rubber seal on the new filter before installing. I install mine tight hand tight for easy removal next time around. Fill engine with new oil until the stick shows almost full – done.

Save empty oil containers for the next oil change. Drop off when full at next marina/fuel dock/boatyard (for recycling!). Be aware that the oil filter will take up some oil when you next run the motor. Avoid running with too much oil. This can harm a diesel. Check oil level often. This might be a good time to check your impellor (salt water pump).

Most professional yachts change oil every 100 hours. Coming to cruising yachts near you: instead of constantly buying new oil and having to cart the old ashore, clever yachts use synthetic oil which resists break down. At oil change time they send the dirty oil to an onboard polisher which removes the impurities and leaves the oil like new for use in the next oil change.

My fuel tanks get me about 150 hours worth of motoring and so I align my oil filter changes loosely with my fuel fill ups. Before filling the boat with fuel, knowing that I am about to change out my primary fuel filter, I run whatever fuel I have left through the old filter and into an empty tank. This way I know I am starting with clean fuel. Always splash a little diesel additive in while fueling. Biocide is good but enzymes are better – Star Brite makes a good one.

Racor. I know of no better primary filter system. Get the kind with the clear bowl on the bottom so you can see water and dirt when it collects. Filter changes are easy. Wrap a sorbent sheet around the middle of the housing. Unscrew the top, pull out the old filter and slide in the new. Replace the gaskets and wet with fuel. Flip on the fuel pump switch until the housing is nearly full (priming). Replace the top.

The secondary filter is mounted on your engine and is usually a two micron and a bitch to change. I use two micron filters on the primaries, the Racors, (instead of 10) so that I don’t have to change the secondary as often. Racor makes fuel pressure gauges which mount on the filter and show you how dirty the filter is. I’ve had a Racor water sensor go off on a yacht once that saved us some trouble. Want to be able to change filters without shutting down the engine? Install two Racors, with Y valves, so that you can switch filters while running. Install the electric fuel pump before the Racors. Sounds obvious right? I have worked a few boats that had their fuel pumps between the Racors and the engine making filter priming very difficult. Mount the pump switch nearby. Want to do some fuel polishing while dockside? Put a Y valve between your Racor and the engine to route the clean fuel back into the return system. When installing Racors orient the in/out fittings fore and aft to prevent air from getting to the engine after a knockdown.

If you ever run a tank dry or create an air leak in your fuel system you will wish you had practiced your bleeding proceedure at the dock. Check your manual for the process for your engine. You should keep the tools you use for bleeding mounted in the engine room. Bleeding Low Key’s diesel takes about thirty seconds. Again, the electric fuel pump makes things much easier. Do you know what your engine sounds like when it runs out of fuel? You should know this and be comfortable in the bleeding procedure early on in your cruising career.

Capt Woody – You mention a radar detector in several articles. I am in the process of equipping my boat for cruising, and have a few questions about the detectors.
1) Who makes them? 2) Where do you buy them? 3) What is their range? 4) Are they loud enough to wake you up? 5) What is the power draw, is it less than leaving the radar on? Thanks for your answer – Brian S.V. Luna Si

Brian – I got my radar detector from C.A.R.D.. You can get them straight from the manufacturer http://www.survivalsafety.com/. I don’t know what they claim but I was picking up boats from a couple miles to over the horizon. I put my antenna under the dodger but there was enough wire to have mounted it higher. Radar can be a huge amp consumer. In my opinion, radar is for fog. I had fog for 1 hour on my circumnavigation. Staring at a screen when we should be scanning the horizon is an accident waiting to happen. The detector was a great thing for me. When singlehanding I would set it up and go to sleep and the alarm would alert me to ships approaching from any direction. It has two loudness settings and a sound off setting when ships are everywhere. The loud was plenty loud enough to wake me up even with the engine on. They claim .045 amps. Whatever it was, I couldn’t detect it with my mounted amp meter.


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