The engine is a Westerbeke 40-108, built in 1980, s/n ED 22432U 559349F. Cylinder head number 37116500/3.

Rebuilt the engine March 2006. Had the cylinder head, exhaust manifold, injector pump, injectors, transmission, heat exchanger, and oil heat exchanger rebuilt.

The drain plug on the oil sump is a 1/2"-14 BSPP thread plus a 13/16" washer (copper or phenolic)

Engine water discharge hose 5/8" ID.

Engine develops 37HP @ 3,000 RPM. Cruising RPM ~2,000. According to Westerbeke, with a 2:1 transmission, the ideal prop size is 18x10 (2 blade) or 18x8 (3 blade). For each 1" reduction in diameter, increase the pitch by 2".

The engine holds 5½ quarts of oil. I'm using Shell Rotella T6 5W-40. The engine burns ½ quart/25 hours at about 1,650 RPM. Changed to this heavier weight oil to minimize engine oil leaks.

In 2001, changed all the hoses, the heat exchanger, and the oil cooler.

I created a cross-reference list between Westerbeke W40 and Perkins 4.108 parts. I've found that the Perkins parts are anywhere from two to 10 times less expensive than the equivalent Westerbeke parts. The cross-reference list is here.

In 2009, added a remote oil filter system to make oil filter changes easier and less messy.

Service Schedule

Rule of thumb: Rebuild the engine when the oil consumption (not leakage) exceeds one quart per eight hours per 100 horsepower.  So, with the 40 HP engine, when the fuel consumption exceeds one quart every 20 hours, then rebuild.

Placed all the engine wires inside flame-retardant split-convoluted (split loom) polyethylene sleeving. The two sizes used were 3/8" and 1/2".

Replacing exhaust hose

Heat the end of the hose with a heat gun being careful not to burn the rubber. Once warm, take a 2" wooden bung (e.g., an emergency seacock plug), put it in the heated end and start hammering it until the top of the bung is 2" below the end of the hose. Turn the hose over and use a broom handle to bang out the bung. Do the same thing with the other end of the hose.

To install the hose, feed one end of the hose down between the engine and engine bed on the port side just forward of the oil filter. Feed the other end of the hose over the exhaust manifold fitting while putting a bend in the hose near the exhaust manifold. Bending it is the secret to getting it straight on to the fitting. I used a hi-temp RTV (silicone) gasket maker to cover the fitting before slipping on the hose. Once hose is all the way on the fitting, put on two hose clamps to hold it in place.

Remove the four screws that hold down the Hydro-Hush muffler. Align the hose with the Hydro-Hush and put the hose on the hitting (make sure to first put RTV on the fitting). Then, adjust hose angle to get the Hydro-Hush back to its mounting position and screw it down. Put two hose clamps on this end of the hose.

To create enough room to maneuver the hose between the engine bed and the engine I carved away about 3/8" of material on the top edge. There's a 1/4" stainless steel plate inside the fiberglass that I cut away.

Random Temperature Readings (°F)

Conditions: May 8, 2011, seawater 68°F, air 74°F, 1,600 RPM, in gear, tied to dock.

I installed in 2006 an electric fuel pump between the tank and the Racor filter to make it easy to fill the Racor. The pump I used is a Mr. Gasket Micro Electric Fuel Pump model 12S. With the pump off, fuel still flows through it pulled by the engine's fuel pump. The inlet fitting to the pump is a 45° brass flared fitting 1/8 NPTF to 5/16" tube OD (1/2"-20 thread). The outlet is the same size, except a right angle fitting.

The new tank (2006):

Capacity: 50 gallons
Usable: 49 gallons at up to a 20° heel
Weight: 52 lbs. (empty)
0.125" 5052 Aluminum with 0.188" side plates

Deck fill: 2" Sea-dog 351331. Uses an O-ring under the cap (2.0" OD x 1/8" thick, neoprene)
Fuel lines are 1/4" ID with compression fittings

Fuel tank vent: 5/8" hose to a Perko (0509DP4CHR) tank vent fitting (replaced 2016)

Tank designed by me, built by Carter Fabrications in Millersville MD.

Draining all the liquid out of the tank via a siphon, the remaining liquid measured 0.75" from the tank bottom, which I'm guessing is about a quart. The calibration was done pouring one gallon at a time into the tank.

The Plexiglas cover in front of it is 9⅜" x 5⅝" with a 2⅛" hole for the key (full-sized drawing and dimensioned drawing). Replaced 2022.

The cutless bearing sits inside the fiberglass stern tube. Two screws (10:00 and 4:00) are set in the stern tube with stainless threaded inserts. Set screws are used. The screws have putty over the tops of them. The bearing is turned down from 1.5" to 1.40" and then knurled. There are dimples where the set screws go.

I replaced the 3-blade 14"D x 11"P (reconditioned 3/1998 Buedel's #25226, Manufactured 3/1980) prop with a 15"D x 11"P Michigan Prop 3-blade. I also had the yard fair the water entry into the prop by removing the "shoulders" on the deadwood in front of the prop. The reason for this was to get rid of the cavitation and to put more power into the water to fight choppy seas.

The small nut goes against the prop and the large nut behind it.

The easiest way to install the packing:

1. Wrap three turns of TefPack packing around a 1" diameter cylinder. Cut two circles with a diagonal cut from the packing.
2. Take the green Drip-Less Moldable Packing and warm it in your hands. Then, roll it between your fingers into a long "log" that's the same thickness as the TefPack packing.
3. Make two logs of the Drip-Less Moldable Packing, with each being the same length as the TefPack packing.
4. Remove the old packing from the hex spud nut.
5. Insert the first TefPack circle into the nut, carefully noting where the split is in the circle. Push it down into the nut either with a pushing tool or gently tighten the spud nut on the packing gland until the gland touches the TefPack packing material and then back off the hex spud nut.
6. Insert the two circles of the Drip-Less Moldable Packing, taking care to make sure that the splits in the circle do not line up with each other. Again, push it down all the way into the hex spud nut, as above.
7. Insert the last TefPack packing circle into the hex spud nut.
8. Hand-tighten the hex spud nut on to the packing gland.

Changed from using a takeoff on the alternator to using the mechanical take-off on engine (above dip stick). This was done because of interference problems between the electronic tachometer and the Link 2000-R voltage regulator.

Teleflex 82430P electronic tachometer, including hour meter (installed 11/98).
Teleflex 1A96042 sending unit (voltage out)
Teleflex 52776P 0.104" square drive tang

The tachometer has an error with its readings:    True RPM = 84 + 0.858 * Tach reading (4/2000). I determined this with a photo-tach. I corrected the tach calibration by setting different switch settings on the tach (ratio of wrong reading over true reading — 4/2000).

I also had made up a 6" long mechanical drive cable (1998) because of the sending unit was too wide to screw onto the engine. The cable was made at a speedometer shop. On the engine side, the cable has a female 7/8"-18 thread. On the sending unit side, the cable has a male 7/8"-18 thread. Replaced the cable in 2006.

The previous hour meter had 1258 hours on it. (11/98)

Hurth HBW100-2R, Nr: 09-08324, manufactured in 1979, rebuilt 1/06

ALL BOLTS ARE METRIC!

Gear ratios: Fwd 1.790, Rev 1.860

Holds 12 oz. of ATF fluid.

There is 1.75" clearance between the end of the flange and the compression nut on the stuffing box.

Hurth bought by ZF Industries in 1995.

Damper plate had a number on it: 1866 061001