Bayliner 4550 / 4588 Pilothouse Motor Yacht
Built 1984–1993 by Bayliner Marine
About the Bayliner 4550 / 4588 Pilothouse Motor Yacht
Researched from public sources for this model. Any individual boat may have been modified or repowered — confirm before relying on any figure.
- Built
- 1984–1993
- Builder
- Bayliner Marine
- Length
- 45.33 ft
- Beam
- 14.92 ft
- Draft
- 3 ft
- Displacement
- 28,000 lb
- Hull
- fiberglass-cored
- Hull / keel
- planing
- Propulsion
- inboard
- Fuel
- 444 gal
- Water
- 200 gal
- Holding
- 48 gal
- Water heater
- AC + engine
- Stern thruster
- not fitted
- Steering
- hydraulic · Hynautic
Tank capacities — where the figures come from
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Fuel 444 gal
“Fuel ....444 gals.” — spec database, cdn.denisonyachtsales.com · “444 gallons of fuel capacity” — search excerpt (1991), dmgboat.com · “Fuel Capacity (US Gallons): 444 gal” — search excerpt (1991), yachtx.com · “Fuel Tanks #: 2; Fuel Tanks Capacity: 250 gal” — broker listing (1987), s3.amazonaws.comDenison's model guide and two 1991 listings give 444 gal. A 1987 listing brochure describes two aluminum tanks of 250 gal, but it's unclear whether that is per tank or in total, so it isn't used. No builder document was found online.
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Water 200 gal
“Water ....200 gals.” — spec database, cdn.denisonyachtsales.com · “two 100 gallon freshwater tanks” — broker listing (1987), s3.amazonaws.com · “757 liters (199 US gallons)” — search excerpt, yachtdatabase.com · “160 gallons of water capacity” — search excerpt (1991), dmgboat.comA 1987 listing brochure describes two 100-gal plastic tanks, 200 gal in total, and Denison's model guide agrees. One 1991 listing says 160 gal.
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Holding 48 gal
“Waste ....48 gals.” — spec database, cdn.denisonyachtsales.com · “48- gallon holding tank with dockside pumpout and electric overboard macerator” — broker listing (1987), s3.amazonaws.comA broker's model guide and a 1987 listing brochure agree, but neither is a builder source.
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Water heater AC + engine
“Two 11 gallon hot water heaters with heat exchangers” — broker listing (1988), westwindyachtscanada.com · “Two 11 gallon hot water heaters and tank with engine heat exchanger” — broker listing (1987), s3.amazonaws.com · “We run a pair of Force 10 water heaters in the original location.” — search excerpt, baylinerownersclub.orgTwo separate listings (1987, 1988) describe two 11 gal heaters (22 gal total) with engine heat exchangers, in wording that looks copied from a Bayliner spec sheet, and an Owners Club post confirms a pair of heaters in the original location. No builder document was found, so the size isn't confirmed.
Tanks are often replaced or added on older boats — check the tank labels or a survey for yours.
Thrusters and steering — where this comes from
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Bow thruster unknown
“Sidepower Bow Thruster with Wireless Remote Installed 2013” — broker listing (1989), yachtr.comNo builder equipment list was found. One 1989 4588 listing shows a Side-Power bow thruster added in 2013, and a Bayliner Owners' Club thread debating adding one to a 4588 suggests they came without, but that isn't enough to say how they were built.
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Stern thruster not fitted
“One bayliner 4550 found only has a Vetus 9.5hp STERN THRUSTER w/dedicated 8D battery” — search excerpt, tapatalk.comOur earlier figure of none has no source. An owners'-club post mentions one 4550 with a Vetus stern thruster, a single boat and presumably added later.
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Steering hydraulic · Hynautic
“Stainless steel steering wheel with Hynautic Steering (upper and lower helm)” — broker listing (1989), yachtr.comOnly one broker listing (a 1989 4588) was found, naming two-station Hynautic steering and Hynautic engine controls. It agrees with our earlier figure, but a listing alone can't confirm it. No builder document was found online; a 1990 owner's manual exists but couldn't be checked.
Thrusters and steering are often replaced — check the units on your boat before ordering parts.
Called 4550 Pilothouse 1984-88. Low-deadrise (6 deg) fully cored hull with a shallow keel; cruises 16-17 knots near 1 nmpg with the Hinos. Three staterooms, raised pilothouse, transom door, flybridge davit. Succeeded by the lengthened 4788. Build count (approximate, not stored): HMY: over 350 built.
Engines fitted
-
Hino 220 hp diesel (MerCruiser-marinized) — 220 hp, diesel, twin
standard
Standard through 1990; Japanese Hino blocks marinized in the US by MerCruiser. Cruise 16-17 knots near 1 mpg. The water-jacketed exhaust manifold/heat exchanger is prone to galvanic corrosion.Sources: hmy.com · boatnation.com
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Hino 250 hp diesel (MerCruiser-marinized) — 250 hp, diesel, twin
standard
Uprated Hinos from 1991.Sources: hmy.com · boatnation.com
Boats of the same model can differ — check which engines yours actually has before ordering parts.
Generator
12.5 kW diesels appear on a 1993 4588 (a Westerbeke, reported by an owner on the Owners Club forum) and a 1988 listing (an Onan). A 1987 listing has an upgraded 21.5 kW Westerbeke and a 1989 listing a replacement 12.6 kW Westerbeke. No builder or review says standard or optional; 12.5 kW looks typical, but makes differ.
Known problems for this model
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Hino turbo, aftercooler and heat-exchanger service engine
Owners flag turbos (early dry-type especially), aftercoolers, manifold coolers, heat exchangers, injectors, raw-water pumps and harmonic balancers as the Hino items to inspect or budget for.baylinerownersclub.org
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Exhaust elbow/riser deterioration exhaust
Exhaust elbows and risers corrode; owners prefer one-piece cast replacements.baylinerownersclub.org
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Wet deck core deck
Foredeck and flybridge deck core can delaminate or rot, with water entering around the radar arch, cabin eaves, bow pulpit and poorly bedded hardware.baylinerownersclub.org
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Window gaskets and caulk interior
Rubber channels around the pilothouse and salon windows harden with age and need replacement to stop leaks.baylinerownersclub.org
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Very tight engine room engine
Engine access through cockpit hatches is widely described as one of the tightest in its class, complicating maintenance.hmy.com
Engines & parts
MerCruiser 5.0 (305) / 5.7 (350) V8 gas parts: good
Factory standard engine — you entered “Hino 250 hp diesel (MerCruiser-marinized)”
GM small-block Chevrolet base engines, so internal parts are everywhere. Marine exhaust manifolds and risers for 1983–2002 small blocks are sold by many aftermarket makers (Sierra, Barr, Osco and others) through Power Boat Supply, Hardin Marine, Basic Power Industries and similar stores; Mercury sells genuine parts through dealers.
Parts sources: Power Boat Supply, Hardin Marine, Basic Power Industries
Common problems (2)
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Manifold/riser failure and water in cylinders exhaust
Cast-iron manifolds and risers rust internally or their gaskets fail, letting water back into the cylinders; small amounts cause hard starting and rough running, large amounts hydrolock and wreck the engine. Service roughly every 7 years in fresh water and about 5 in salt.powerandmotoryacht.com · forums.iboats.com · justanswer.com
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Overheating from scaled manifolds cooling
Rust and scale inside the manifolds restrict cooling flow and cause overheating under load.powerandmotoryacht.com
Maker’s service schedule (8)
| Engine oil & filter change | 100 hrs or 1 yr | “Most four-stroke outboards and sterndrive engines require an oil change either annually or every 100 hours of operation.” — manufacturer, mercurymarine.com |
| Fuel filters & water separator | 100 hrs or 1 yr | “The fuel filter on your engine should be inspected or replaced per the maintenance schedule in your owner's manual, usua” — manufacturer, mercurymarine.com |
| Raw-water pump impeller | 300 hrs or 3 yrs | “How often should my seawater pump impeller be serviced? Every 300 hours or 3 years, whichever comes first.” — manufacturer, mercurymarine.com |
| Spark plugs inspect / replace | 300 hrs or 3 yrs | “How often should spark plugs be changed? Every 300 hours or 3 years, whichever comes first.” — manufacturer, mercurymarine.com |
| Coolant replacement & freeze-point test closed (freshwater) cooling only | 5 yrs | “How often should coolant be changed on engines with closed cooling? Every 5 years.” — manufacturer, mercurymarine.com |
| Transmission fluid change sterndrive gear lube | 1 yr | “Gearcase lubricant in outboard and sterndrive lower units should also be changed annually or at the service interval spe” — manufacturer, mercurymarine.com |
| Lubricate steering linkage and check power-steering fluid sterndrive | 100 hrs or 1 yr | “Mercury Marine recommends lubricating the steering linkage and checking the power steering fluid level in ... MerCruiser” — manufacturer, mercurymarine.com |
| Check power trim fluid level sterndrive | 100 hrs or 1 yr | “Power trim and tilt fluid level should be checked annually or every 100 hours.” — manufacturer, mercurymarine.com |
Service part numbers (6)
| Oil filter | Mercury Quicksilver 35-866340Q03 | “Part number: 866340Q03 ... for MerCruiser sterndrive and inboard engines except V6 engines with the oil filter mounted o” — manufacturer, mercurymarine.com · “Includes: Oil Filter Oil Filter 866340Q03 Fuel Filter 802893Q01 ...” — dealer, midnightmarine.net |
| Fuel filter carbureted engines (Rochester 2-/4-barrel, MerCarb 2-barrel): filter inside carburetor fuel inlet |
Mercury 53336T | “For use on MerCruiser 3.0L, 4.3L, 5.0L , 5.7L and 7.4L engines with Rochester 2- and 4-barrel and MerCarb” — manufacturer, mercurymarine.com |
| Fuel filter MPI engines with Gen III cool fuel module (filter page: 2004 and newer; kit page: 2002 and newer) |
Mercury Quicksilver 35-8M0093688 | “Fits 2004 and newer Mercury/MerCruiser sterndrive and inboard engines with Gen III (3) fuel cooler” — manufacturer, mercurymarine.com |
| Raw-water impeller Bravo sterndrive and inboard engines with engine-mounted sea water pump (2-piece plastic pump per Mercury) |
Mercury Quicksilver 47-59362Q01 Also: Sierra 18-3087 |
“For MerCruiser engines with engine mounted, 2-piece, plastic sea water pumps.” — manufacturer, mercurymarine.com · “Water Pump Impeller 59362Q01” — dealer, midnightmarine.net |
| Thermostat standard cooling, 160 F |
Mercury Quicksilver 807252Q5 | “Thermostat 807252Q5 is for V6 and V8 MerCruiser engines ... made by General Motors (model year 1987-2016)” — manufacturer, mercurymarine.com |
| 100-hour maintenance kit (oil filter, fuel filter, drive seals) MPI engines with Gen III cool fuel module (2002 and newer) |
Mercury 8M0147053 | “Mercury 8M0147053 MerCruiser 5.0L, 5.7L, 6.2L, 8.1L and 8.2L V8 MPI ... 100 Hour Maintenance Kit” — manufacturer, mercurymarine.com |
From the engine maker’s parts lists, or two independent parts dealers. Numbers change with serial number and get superseded — check yours before ordering.
Steering
Hynautic — K-series pressurized hydraulic steering (H-series helms, K-series cylinders) parts: obsolete
SeaStar bought Hynautic and kept making components and rebuild kits for years; after Dometic bought SeaStar, Hynautic pages and parts were removed from Dometic's site. Helms H-21 through H-52 and cylinders K-6 through K-31 are discontinued. Seatech Marine Products publishes SeaStar direct-replacement equivalents (e.g., H-50/H-52 replacement kits usable in the pressurized system with a non-vented fill plug) and offers rebuild services; independent hydraulic shops rebuild helms and cylinders for roughly $250–350 each. Kobelt/Accu-Steer also supply steering and power-assist equipment used on larger boats.
Parts sources: Seatech Marine Products (Hynautic alternatives & rebuilds), Kobelt (marine steering systems)
Common problems (3)
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Helm pump shaft seal leaks steering
The upper helm shaft seal deteriorates from sun, salt and dirt and weeps oil; raising system pressure is only a stopgap, and the helm must be removed and resealed.samsmarine.com · trawlerforum.com · youtube.com
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Cylinder rod seal leaks steering
Damaged wiper/rod seals let fluid out the end of K-6 type cylinders.facebook.com
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Olive-type tubing fittings leak steering
Some owners dislike Hynautic's olive compression fittings on plastic tubing because they are prone to leaks.trawlerforum.com
Model sources (10)
hmy.com · baylinerownersclub.org · baylinerownersclub.org · hmy.com · boatnation.com · cdn.denisonyachtsales.com · s3.amazonaws.com · westwindyachtscanada.com · s3.amazonaws.com · yachtr.com
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Other Bayliner models
- Bayliner 2855 Ciera Sunbridge 1994–1999
- Bayliner 3270 / 3218 / 3288 Motor Yacht 1981–1995
- Bayliner 3870 / 3888 Motor Yacht 1983–1994
- Bayliner 3988 Motor Yacht 1995–2002
- Bayliner 4788 Pilothouse Motor Yacht 1994–2002
Researched from public sources. Spotted an error? The sources are listed above — tell us what they got wrong.