809922410 Mercruiser NUT

Table 1
Tools Needed
Part Number Part Name Quantity
1U-5470 Engine Pressure Group 1
Illustration 1 g00295554
1U-5470 Engine Pressure Group
Air Inlet Restriction
There will be a reduction in the performance of the engine if there is a restriction in the air inlet system.
Inspect the engine air cleaner inlet and ducting in order to ensure that the passageway is not blocked or collapsed.
Inspect the engine air cleaner element. Replace a dirty engine air cleaner element with a clean engine air cleaner element.
Check for dirt tracks on the clean side of the engine air cleaner element. If dirt tracks are observed, contaminants are flowing past the engine air cleaner element and/or the seal for the engine air cleaner element.
Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts.When working on an engine that is running, avoid contact with hot parts and rotating parts.
Use the differential pressure gauge of the 1U-5470 Engine Pressure Group.
Illustration 2 g00808208
Air inlet piping
(1) Air Cleaner
(2) Test location
(3) Turbocharger
Connect the vacuum port of the differential pressure gauge to test location (2). Test location (2) may be located anywhere along the air inlet piping after air cleaner (1) but before turbocharger (3).
Leave the pressure port of the differential pressure gauge open to the atmosphere.
Start the engine. Run the engine in the no-load condition at high idle.
Record the value.
Multiply the value from Step 4.d by 1.8.
Compare the result from Step 4.e to the appropriate values that follow. The air flow through a used engine air cleaner may have a restriction. The air flow through a plugged engine air cleaner will be restricted to some magnitude. In either case, the restriction must not be more than the following amount: Maximum restriction ... 6.2 kPa (25 in of H2O)The air flow through a new engine air cleaner element must not have a restriction of more than the following amount: Maximum restriction ... 3.7 kPa (15 in of H2O)Exhaust Restriction
There will be a reduction in the performance of the engine if there is a restriction in the exhaust system.Back pressure is the difference in the pressure between the exhaust at the outlet elbow and the atmospheric air.
Hot engine components can cause injury from burns. Before performing maintenance on the engine, allow the engine and the components to cool.
Making contact with a running engine can cause burns from hot parts and can cause injury from rotating parts.When working on an engine that is running, avoid contact with hot parts and rotating parts.
Use the differential pressure gauge of the 1U-5470 Engine Pressure Group in order to measure back pressure from the exhaust. Use the following procedure in order to measure back pressure from the exhaust:
Illustration 3 g00808215
Exhaust piping
(1) Muffler
(2) Test location
(3) Turbocharger
Connect the pressure port of the differential pressure gauge to test location (2). Test location (2) can be located anywhere along the exhaust piping after turbocharger (3) but before muffler (1).
Leave the vacuum port of the differential pressure gauge open to the atmosphere.
Start the engine. Run the engine in the no-load condition at high idle.
Record the value.
Multiply the value from Step 4 by 1.8.
Compare the result from Step 5 to the value that follows. Back pressure from the exhaust must not be more than the following amount: Maximum back pressure ... 10.0 kPa (40 in of H2O)