Twin Disc MG-514B Troubleshooting

The chart below shows the areas boat owners have most common questions on when trying to troubleshoot why their Twin Disc ® marine transmission MG514B underperform. It categorizes areas of possible malfunction, likely cause and recommended action to bring your new, rebuilt or used Twin Disc ® marine transmission back to proper operation. The chart will give you confidence when speaking with your Twin Disc ® marine transmission mechanic or ordering parts. As a quick reference guide only, the chart must not be thought of as a substitute for the use of your Twin Disc ® marine transmission MG514B Owner's operating or service manual.

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AREA	PROBLEM	POSSIBLE REASON	RECOMMENDED ACTION	CHECK
OIL PRESSURE	Low oil pressure	Partially clogged oil strainer	Remove and clean.
		Stuck pressure regulation piston in selector valve assembly	Remove selector valve assembly. Disassemble the valve and clean piston.
		Broken piston rings on clutches	Remove the manifold and dissemble the clutches. Replace piston rings.
		Come-home setscrew loose or missing	Remove the some-home access pipe plugs. Tighten a loose come-home setscrew by turning counterclockwise, or replace setscrew.
		Damaged or worn oil pump assembly.	Remove and replace oil pump .
		Incorrect linkage installed on selector valve assembly	Adjust linkage so that selector valve stem is indexed properly by detent.
		Clogged or plugged orifice in orifice plate of selector valve assembly	Remove orifice plate cover. Clean parts.
	No oil pressure, or erratic low pressure at control valve tap	Low oil level or empty sump.	Check gaskets and seals for leakage. Find parts causing leakage fill marine gear and replace them.
		Fully clogged oil strainer	Remove and clean oil strainer.
		Damaged or worn oil pump assembly.	Remove and replace oil pump .
	High main oil pressure	Stuck pressure regulation piston in selector valve assembly.	Remove selector valve assembly. Disassemble the valve and clean piston.
	Overheating	Insufficient heat exchanger capacity.	Find a heat exchanger of sufficient capacity and replace it.
		Insufficient cooling water flow.	Inside diameter of water lines too small. Replace lines with larger inside diameter hoses.
		Clutches Slipping.	Low oil pressure will cause a clutch to slip. Adjust clutch.
		Oil levels too high	Correct oil level.
		Improper oil sump.	Drain marine gear, and fill with proper oil.
		Clutch plates warped	Replace Clutch plates .
	Excessive noise	Worn splines between reverse driving and driven gears and clutch shafts	Remove marine gear, dissemble marine gear, and replace worn splined parts.
		Bearing failure	Remove marine gear. Dissemble marine gear and replace damaged or worn parts
		Worn or damaged rubber blocks	Remove marine gear and replace worn or damaged rubber blocks
	No neutral	Clutch plates warped	Replace Clutch plates.
	Harsh engagement	Steel ball in selector valve not seating properly.	Remove orifice plate cover clean parts. Replace parts if necessary .
CLUTCH	Clutch slips	Improper adjustment	Adjust Clutch.
	Clutch will not remain engaged	Clutch adjustment too tight	Adjust Clutch.
	Clutch will not remain engaged	Improper remote engaging linkage.	Adjust linkage as required to assure proper travel of operating lever. Engaging force must be removed after complete engagement of the clutch.
	Power Take-off continues to drive when clutch is desengaged	Warped or welded clutch plates	Remove power take-off and replace clutch plates .
	Power Take-off continues to drive when clutch is desengaged	Bearing failure	Remove power take-off and replace clutch plates .