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Catalina
36 #849 – Engine Overhaul We bought our 1988 Catalina 36, named “Dutch Boy”, in January 2001 in the Galveston Bay, Texas area, where we still keep our boat. From some of the records that came with the boat, it appears it has always been in the Gulf of Mexico coastal regions and was first commissioned in Fairhope Alabama in early 1988. Since
buying our C-36, I have made various improvements and many needed repairs
to keep all systems going. Although
the Universal M25XP engine appeared mechanically in pretty good shape, the
high heat and salty humidity of the US Gulf Coast region sure was doing a
trick on the engine paint and unprotected parts, resulting in a lot of
flaking paint, rust and corrosion. So
I knew I would have to pull the engine someday to clean it, sandblast it
and repaint it. In 2003,
after studying “Marine Diesel Engines” - 2nd Edition by
Nigel Calder, I decided it was time to do the work and de-carbonize the
engine at the same time.
De-carbonizing and fuel injector overhaul may be needed after about
1000 hours, and our engine was now up to about 1370 hours. Various books on the subject make the point that most
sailboat diesel engines expire early due to rust and corrosion rather than
mechanical wear and I certainly concur.
By this time I had also acquired Universal’s Parts Manual and
Repair & Maintenance Manual for the engine and a Kubota Engine Parts
Manual. I am a Dutch born
Naval Architect by profession, so I am quite familiar with marine systems,
but I never quite got interested in working on engines until we got our
C-36.
In early December 2003 I drained the engine oil and coolant and started to disconnect all hoses and wiring from the engine. Photo #1 shows the engine while draining the coolant. I labeled all wiring, disconnected the exhaust elbow, removed the foundation lag screws and disconnected the propeller shaft. With the help of my stepson, the engine was lifted out using a 2-ton wire pull attached near the end of the boom using choker sling, and with the main halyard on a winch serving as the boom topping lift. I did not want to hang the engine lift system more forward along the boom for fear of bending the boom. We used another halyard as a backup and kept that backup tight at all times.
Photo #2 shows the engine swung over the finger-pier ready to be placed on a purpose modified furniture dolly. One of the reasons we bought the C-36 is its excellent access to the engine, which is important to older guys like myself, and lifting the engine out proved to be quite easy. We bolted the engine to the dolly and rolled it down the floating dock, up the ramp, up a concrete footpath and onto the parking lot. There we rolled it onto a small trailer, and secured the engine for the trip home in Sealy Texas, see photo #3.
I
worked on the engine, in the garage at home, during weekends for about 2.5
month before re-installing it early March 2004.
I installed overhead hooks in the garage ceiling to lift the engine
in the garage and also built a wooden A-frame to lift the engine in the
driveway for cleaning and sandblasting.
The following is my (almost complete) list of overhaul work:
1.
With the engine hanging in the A-frame, I completely degreased the
engine using spray-on engine degreaser, and I water-blasted it with our
high-pressure washer. This,
obviously, was done after all openings and fuel connections were fully
capped. The combination of
spray-on degreaser and pressure washing really worked well, and what used
to be a lump of greasy dirty iron (and aluminum) became a clean engine one
could actually touch. The
high-pressure water blasting also took-off a lot of loose paint.
After that it went back in the garage for mechanical work. 2. I removed the exhaust manifold and air inlet manifold and degreased, cleaned and de-carbonized them thoroughly.
3.
I removed the valve cover, rocker arms, push rods, and injectors
and removed the cylinder head. Checked
the head bolt torques before removing the head and found out they were a
little low. I will check them
more regularly in the future. Photo
#4 shows the engine without cylinder head, while photo #5 shows the head,
valves, valve springs, injectors, etc. arranged on a temporary table,
consisting of a sheet of plywood on saw horses.
I could not really find an affordable and sturdy valve spring clamp
for valve removal, so I modified a woodworker’s clamp with some
customized oak jaw extensions to do the job.
A little primitive but it worked.
4.
The cylinder head, valve stems and piston tops had quite a bit of
carbon deposits, so I cleaned this off as recommended by Nigel Calder in
Chapter 7 of his above-mentioned book.
Especially the exhaust valve stems had significant carbon deposits,
and I believe I would have found some serious valve stem damage had I
waited much longer to do this job.
The valve springs; rocker arm assembly, etc. were in very good
shape, so no need to replace any. 5.
I also cleaned the carbon off the cylinder walls and found that
there was remarkably little wear in the cylinders.
I used Mobil-1 synthetic oil since buying this boat (I checked with
Westerbeke first to get their OK) and I swear by that stuff.
We have been using it in our car engines for many years.
Considering the boat engine oil is typically changed once a year,
the small amount of extra money is well spent.
6.
After putting the cleaned valves + springs back into the cleaned
cylinder head, I tested the valves for leaks by pouring kerosene in the
ports (one at a time), as recommend in Nigel Calder’s book on page 122. That gave me quite a surprise, since most valves leaked and
some quite badly. So I had to
lap the valve seats to try to improve the situation.
Since the valves have a groove for a flathead screwdriver no
special lapping tool is required, other than grinding paste and polishing
paste. I worked on this for a
while, without trying to grind the valve seats down too much.
I put the valves back in the head regularly to check for leaks.
I never could get rid of all leaks and some valves continued to
have some small amount of kerosene dribble, but it was a lot better than
before. I had to accept what
I got since the valve’s recess in the cylinder head was getting awful
close to or slightly beyond specified tolerances. 7. I installed a new cylinder head gasket, reinstalled the cylinder head and covered all ports with plywood covers in preparation for sandblasting. I had to use sandblasting, since large amounts of the old “Universal Bronze” paint were still there, and brushing or grinding did not get it off very well and many areas were not well accessible.
8. My stepson had given me a 5.5hp Air Compressor for Christmas, and I bought a simple $50 Sears sandblasting kit and Grade1 blasting sand, and proceeded to sandblast the engine, gearbox, exhaust manifold, seawater cooling heat exchanger, and various small parts, outside on our driveway. Since we live out in the country this was not a problem, but it sure was nasty work. Photo #6 shows the engine partially sandblasted, waiting for me to get more grade1 blasting sand at Sears in Houston. I could only find grade 2 and 3 blasting sand locally, which did not work with the small Sears gun, and was to coarse for this work anyway. I had to stop and wait regularly for the compressor to catch up, but it worked very well in the end. Despite covering myself with a full coverall, gloves, face mask, goggles and a hat, I had sand all over my body after each blasting session.
9.
Sandblasting uncovered two leaks: One pinhole in the oil pan next
to the dipstick attachment and one in the heat exchanger near one of the
hose fittings. I had the heat
exchanger repaired at a radiator repair shop in nearby Waller, TX.
And I ordered a new oil pan + gasket + dipstick tube assembly from
the local Universal Dealer. The oil pan simply had too much corrosion to
be repaired. The oil pan
itself had to come from a dealer somewhere in the Midwest, since the
dealer nor Westerbeke had one in stock, so it took about 4 weeks to
deliver. Photo #7 shows the engine from the bottom with the oil pan
removed. I did not find any significant wear and no damage to the
crankshaft assembly. By that
time I had already repainted the engine and the old oil pan, while the new
oil pan was still on its way to Texas.
10.
I replaced any and all gaskets with new ones, but the removal of
the old ones proved to be cumbersome. I used sharp wood workers chisels
and fine Dremel type grinding and polishing tools to get the surfaces
clean and smooth before installing the new gaskets.
No leaks, no drips, no errors with any of the gaskets. 11.
After putting most of the engine back together it was time to
repaint. I never liked the
old “Universal bronze”, since it is so dark and does not show oil or
fuel leaks very well. I like
to know if I have any. I used
a high temperature “aluminum” engine paint purchased at local
auto-parts stores. I could
have used the new Universal blue-gray engine paint, but I developed an
aversion to paying the high prices charged by Universal dealers, although
I used them for some parts such as the new oil pan and dipstick tube
assembly. 12.
I installed new flexible engine mounts since most of the old ones
were badly corroded. The new mounts came from the local Universal Dealer
and were, thankfully, reasonable priced.
13. I installed a new seawater pump impeller and a new thermostat.
14.
Photo #8 shows the engine mostly re-assembled and re-painted with
some of the new hoses already installed, and almost ready for loading on
the trailer for the trip back to the boat. 15.
With my stepson’s help, I re-installed and re-aligned the engine
in early March 2004, and after that I spend about two weekends
reconnecting the electrical wiring, the exhaust elbow, replacing all
cooling water hoses, all fuel hoses and all hose clamps with new stuff. 16.
I had some problems restarting the engine and found out that the
nylon vent screw on the Racor primary fuel filter was cracked, letting air
in the system. Since this
Racor filter appeared to be as old as the boat, it was time to replace it
also. I am refurbishing the old one for a spare.
17.
When I got the engine going after working, what seemed like hours,
to get all air out of the low pressure and high pressure fuel lines, it
would only run on only 2 cylinders. Although
Nigel Calder suggests servicing the injectors after about 900 hours, I had
hoped in vain that they would still work OK.
So it was time to replace the injectors since overhauling them did
not appeal to me. I bought 3
new injectors from the Houston Kubota Industrial Engine dealer.
At about $66 each, it is not worth messing with the old ones.
Two of the old ones are still OK so they are now emergency spares.
Someday I get a complete set of new spares. 18. Photo #9 shows the engine back in the boat. Even with ~1370 hours on it now looks (and feels) like new. It starts promptly and the new injectors sure improved the way it runs and idles. The engine compartment is now clean and much brighter with the aluminum colored engine. It also helps that I replaced the engine box sound insulation about 2 years ago, when the old stuff really started to crumble.
Photo #9 also shows the end of a flexible aluminum air duct just above the engine, which is part of the outside air supply system that I installed in late 2001. Most people do not realize how HOT it gets along the Texas Gulf Coast in summer. During the summer of 2001 I had some serious engine electrical wiring overheating, almost causing an engine room fire. I found out that the temperature in the fully closed engine compartment got as high as 150º to160º when running the engine at nearly full power in the 95º to100º summer heat. That is way too high in my book and should also significantly reduce engine output. So I installed an air scoop in the outside face of the port cockpit coaming, I ran a flexible air duct along front of the galley’s rear bulkhead, installed a 12V in-line bilge blower on the bulkhead and continued the duct down through the countertop, along the front of the back cabin and into the engine compartment. A plywood cover with sound insulation covers the blower and much of the ducting in the galley. This system really works. During a hot day I can blow 70-80cfm of outside air into the engine compartment, and when the blower is off, the engine can suck the fresh air more easily through the same air duct. I put a three-position pull switch in the engine control panel and ran the necessary wiring. In 1st and fully in position, all blowers are off, 2nd position runs the engine air supply blower only and when fully pulled out both the air supply and air discharge blowers are running providing forced circulation. I also use an electronic temperature gauge in the cockpit with a remote sensor in the engine compartment to monitor how hot it is. With the forced air supply I can now keep the temperature in the compartment below about 135º during our very hot days. I tried two brands of blowers; one runs at too high speed and sounded like a jet engine. The other one, now in use, is much better and less noisy.
One more thing I have to fix is the pitch on my 3-blade PYI Max-Prop feathering propeller. The boat came with this Max-Prop installed and the original 3-blade fixed one stored on board. The Max-Prop had a lot of vibration at certain engine speeds, so I took it off and put the 3-blade fixed propeller on in 2001 in preparation for a long trip through the Intra-Coastal Waterway to Rockport and Port Aransas. Since the fixed propeller sure slows the boat down when sailing, I cleaned all barnacles and multiple sloppy layers of anti-fouling paint off the Max-Prop and overhauled and re-installed it in June 2003 (see photo #10). I painted the Max-Prop with the “Petit” Zinc Barnacle Barrier paint now recommended by PYI. Rather than following the Max-Prop instructions, I gave it a higher pitch of 10.3” (20º blade angle) than the 9.2” (18º) I should have used to match the 9” pitch fixed blade propeller. Although the Max-Prop is now clean, performs well and has much less vibration, the engine will only run at maximum 2500-2600 RPM, even after the overhaul. During the next haul-out I will reduce the blade angle to 18º, which should increase full throttle engine speed by about 15% to 3000 RPM. My engine manuals say that my M25XP should run at maximum 3200 RPM, but actual maximum is 3000 RPM when I run it at full throttle in neutral. So I guess the governor is set at 3000, which is OK with me, I am not going to change that. Hans Treu |
