Yanmar, Volvo Penta, Cummins marine diesel turbo rebuilds

3JH, 4JH, 4LHA, 6LP, 6LY Series

Yanmar

Yanmar's sailboat and light-cruiser diesels run compact MHI and IHI turbos that live inches from a raw-water exhaust mixing elbow. When the elbow clogs or corrodes through, exhaust backpressure and water intrusion take the turbo with it. We rebuild the turbo; make sure the elbow gets replaced or you will see us twice.

KAD32, KAD42, KAD43, KAD44, KAD300

Volvo Penta

The compressor-plus-turbo KAD series is a masterpiece with a maintenance appetite. The turbos are KKK/BorgWarner and Garrett units under Volvo part numbers, and complete assemblies from Volvo cost eye-watering money when available at all. Rebuilding the original is the sane path on these engines.

TAMD and D-series (D3, D4, D6, TAMD63/74)

Volvo Penta

The TAMD workhorses and modern D4/D6 common-rail engines power everything from trawlers to pilot boats. Holset, Garrett and BorgWarner units by application. High-hour commercial engines respond especially well to scheduled turbo rebuilds rather than run-to-failure.

6BTA 5.9, 6CTA 8.3, QSB, QSC, QSM

Cummins Marine

The 6BTA and 6CTA dominate sportfish and trawler repowers, running Holset H1C/HX35/HX40-family turbos with marine-specific housings. Cores are plentiful, corrosion is the enemy, and our Holset bench experience runs deep. QSB and QSC electronic engines follow the same pattern with later Holset hardware.

4045TFM and 6068TFM PowerTech

John Deere Marine

Deere's marine PowerTech engines power workboats, gensets and displacement cruisers with Schwitzer S2BW-family turbos under RE-prefix numbers like RE502857. Same tough hardware as the ag units, plus marine corrosion. Fully rebuildable.

Series 60 marine, Cat marine

Detroit + Larger

Series 60 marine conversions run Garrett units like the UTW7801, and Cat 3126/C7/C12/C18 marine engines carry familiar heavy-truck-family turbos in marine trim. If it is on a boat and it spins, we can likely rebuild it; send the tag photos through the form.

Saltwater ingestion through the exhaust elbow

The signature marine killer. A corroded or clogged mixing elbow lets raw water siphon or surge backward into the turbine housing. Salt attacks the wheel and shaft, and if water reaches the cylinders the engine is next. Turbine-side rust on a marine core is the fingerprint; we always report it because the elbow, not the turbo, is the root cause.

External corrosion in the salt atmosphere

Even without ingestion, the salt air of an engine room corrodes actuator rods, clamps, fittings, and water-cooled housing passages. Seized wastegate hardware and crumbling coolant fittings are routine on cores from coastal boats. We replace corroded external hardware as part of the rebuild.

Carbon choking from underloaded running

Sailboat auxiliaries and trawlers that never see full load soot up their turbines and elbows. The turbo never reaches self-cleaning temperature, deposits build, and boost fades. After the rebuild, run the engine hard periodically; marine diesels want load.

Coked bearings from hot shutdown at the dock

Run in on plane, tie up, shut down. The heat soak with no idle-down cokes the oil in the center section exactly like a farm tractor. Three to five minutes of idle before shutdown is the cheapest turbo insurance a boat owner can buy.

Raw water cooling passage scale

Water-cooled turbo and manifold passages scale up with salt and mineral deposits, insulating the very parts the water is meant to cool. Local overheating warps housings and cooks seals. Rebuilds include descaling water passages where the design allows.

Long layup corrosion

Boats sit. Months of humidity inside a salt-loaded exhaust system corrode the turbine shaft right at the seal, and the first start of the season grinds the rust through the bearings. If your boat winters ashore, fogging the engine and sealing the exhaust makes the spring survey kinder.