Volvo Penta MD22 Rebuild, common faults and everything you need to know
Direct predecessor to the D2 series. Direct-injected with a rotary pump and mechanical governor, aluminium OHC cylinder head, cast iron block. Naturally aspirated in the MD22L/P and turbo in the TMD22.
The MD22 is one of the more rebuild-friendly marine diesels of its era. Mechanical direct injection with a rotary pump, no electronic dependencies, a robust cast iron block and an aluminium OHC cylinder head. When an MD22 fails, it is almost always one of two main faults: the seating surface of the cylinder liner leaks (coolant in oil) or the cylinder head has cracked from overheating - cracking that the lightweight aluminium head is particularly prone to. We carry out cylinder head reconditioning with pressure testing, cylinder boring, crankshaft reconditioning and complete engine reconditioning in our own machine shop with 12-month warranty. See also our boat engine rebuild hub page.
The MD22 in brief
Data from Volvo Penta's original brochures for the MD22L (2000) and MD22P (2001) plus the Hallberg-Rassy Club engine reference.
Variants in production
| Variant | Power prop / crank | Aspiration | Period |
|---|---|---|---|
| MD22 (base) | 59 hp crank | NA | 1988-1994 |
| MD22A | 59 hp crank | NA | 1994-1995 |
| MD22L / L-A / L-B | 49 / 50 hk | NA | 1992-2002 |
| MD22P / P-B | 58 / 59 hk | NA high-revving | 1995-1999 |
| TMD22 Turbo | ~78 hk crank | Turbo | 1997-2002 |
NOTE - the variant names: The letter denotes aspiration / power calibration, not a generation step. L = low-revving NA (49 hp). P = high-revving NA (59 hp). T = Turbo (TMD22, 78 hp). The common misspelling "TDM22" does not exist.
Common faults on the MD22
Cross-verified against Volvo Penta's original brochures, the Cruisers Forum, the YBW Forum and the Hallberg-Rassy Club service archive. For a complete engine reconditioning we follow a standardised strip-down sequence.
Cylinder liner leaks - water in oil
Catastrophic • Critical- Symptoms
- Milky oil, dropping oil pressure, coolant loss with no visible leak, possibly white smoke.
- Cause
- The lower seal of the cylinder liner lets go. Coolant from the water jacket runs down into the oil sump. A classic MD22 killer if missed - the big-end bearings fail from diluted lubricant.
Cracking of the aluminium cylinder head
After overheating • High- Symptoms
- Water in oil or oil in water, white smoke, coolant drops between runs.
- Cause
- The MD22's cylinder head is cast in aluminium alloy while the block is cast iron. Thermal shock from overheating (usually a raw water pump failure or a blocked heat exchanger) causes cracks between valve seats or between a water passage and cylinder. Pressure testing is required for diagnosis.
The rotary pump leaks
Common • Medium- Symptoms
- Diesel-smelling oil at the pump mounting, oil seepage on the side of the engine, dropping injection pressure.
- Cause
- The rotary pump's shaft seal ages. Diesel leaks out under running and the oil is thinned by the fuel.
Heat exchanger clogged
15+ years • Medium- Symptoms
- Dropping operating temperature or overheating, reduced coolant flow.
- Cause
- Limescale and salt deposits on the raw water side. Aluminium passages corrode internally.
Cylinder liner wear
4 000+ hours • Medium- Symptoms
- Oil consumption, blue smoke under acceleration, dropping compression.
- Cause
- Natural wear at high operating hours. The liners can be replaced or bored to oversize.
MD22 rebuild prices
Prices based on MD22 specifications (4 cyl, 84 mm, 8 valves OHC). Excl. VAT and parts. All main operations - cylinder boring, crankshaft grinding, cylinder head resurfacing - carried out in our own machine shop.
Cylinder head reconditioning
Bottom end
Full rebuild
Injection pump service
Cylinder machining
| Service | Price |
|---|---|
| Cylinder boring 4 cyl (84 mm) | 3 318 kr |
| Cylinder liner replacement 4 cyl | 6 800 kr |
| Plateau honing 4 cyl | 1 050 kr |
Cylinder head reconditioning (aluminium OHC)
| Service | Price |
|---|---|
| Resurfacing aluminium cylinder head 4 cyl | 1 330 kr |
| Cylinder head pressure testing | 1 876 kr |
| Valve seat cutting 8 valves | 910 kr |
| Valve guide replacement 8 pcs (aluminium) | 1 274 kr |
See also
Other Volvo Penta marine diesels we service and related services.
Questions and answers about the MD22
Is the MD22 IDI or direct injection?
Direct injection (DI). Volvo Penta's own original brochures for the MD22L (2000) and MD22P (2001) describe the engine as direct-injected. IDI circulates incorrectly in third-party sources.
Is the MD22P turbocharged?
No. The MD22P is a high-revving naturally aspirated variant (4000 rpm, 18:1 compression, 59 hp). The turbo variant is called the TMD22 (T = Turbo) and delivers ~78 hp at 4500 rpm. The common misspelling "TDM22" does not exist.
What is the difference between the MD22, MD22L and MD22P?
The letter denotes aspiration / power calibration. MD22 (base, 59 hp NA, 1988-1994). MD22L = low-revving NA (49 hp, 3000 rpm, 17:1). MD22P = high-revving NA (59 hp, 4000 rpm, 18:1). All share the same block (1 994 cc, 84 × 89 mm) and the same OHC aluminium cylinder head.
What does it cost to rebuild an MD22?
Cylinder head reconditioning 6 000-8 000 kr in labour. Complete engine rebuild 26 000-38 000 kr in labour, plus parts typically 7 000-15 000 kr depending on condition. Pump service is often added.
How long does a rebuilt MD22 last?
15-25 years or 6 000-8 000 operating hours. A mechanical design with no electronic dependencies makes the MD22 long-lived. It is the heat exchanger, the rotary pump and the aluminium cylinder head that typically need maintenance, not the block itself.
What is the water-in-oil fault?
The lower seal of the cylinder liner lets go. Coolant from the water jacket runs into the oil sump. A classic MD22 killer - if the fault is missed, the oil is thinned out and the big-end bearings fail. Treated with cylinder liner replacement.
How long does an MD22 rebuild take?
Cylinder head reconditioning: 1-2 weeks. Complete engine rebuild: 3-5 weeks in the workshop. The winter season is the busiest - book well in advance.
Do you have an MD22 that needs looking over?
Call us or send a quote request. Reply within 24 hours. Quote after inspection. We service all types of boat engines - see the boat engine page. All rebuilds with 12-month warranty.