864435 Mercruiser HOSE, Port Exhaust Elbow to Thermostat Housing

Periodic inspection and cleaning is recommended for the turbocharger compressor housing (inlet side).Fouling of the compressor can contribute to loss of engine power, increased black smoke and overall loss of engine efficiency.If the turbocharger fails during engine operation, damage to the turbocharger compressor wheel and/or to the engine may occur. Damage to the turbocharger compressor wheel could allow parts from the compressor wheel to enter an engine cylinder. This can cause additional damage to the pistons, the valves, and the cylinder head.
Turbocharger bearing failures can cause large quantities of oil to enter the air inlet and exhaust systems. Loss of engine lubricant can result in serious engine damage.Minor leakage of a turbocharger housing under extended low idle operation should not cause problems as long as a turbocharger bearing failure has not occurred.When a turbocharger bearing failure is accompanied by a significant engine performance loss (exhaust smoke or engine rpm up at no load), do not continue engine operation until the turbocharger is repaired or replaced.
An inspection of the turbocharger can minimize unscheduled downtime. An inspection of the turbocharger can also reduce the chance for potential damage to other engine parts.Note: Turbocharger components require clearances that are precise. The turbocharger cartridge must be balanced due to high rpm. Severe service applications can accelerate the wear of the components. Severe service applications may require more frequent inspections of the turbocharger.Removal and Installation
For options regarding the removal, installation, repair and replacement, consult your Caterpillar dealer. Refer to the Service Manual for this engine or consult your Caterpillar dealer for the procedure and specifications.Cleaning and Inspecting
Remove the exhaust outlet piping and remove the air inlet piping from the turbocharger. Visually inspect the piping for the presence of oil.
Turn the compressor wheel and the turbine wheel by hand. The assembly should turn freely. Inspect the compressor wheel and the turbine wheel for contact with the turbocharger housing. There should not be any visible signs of contact between the turbine wheel or compressor wheel and the turbocharger housing. If there is any indication of contact between the rotating turbine wheel or the turbocharger wheel and the turbocharger housing, the turbocharger should be reconditioned or replaced.
Check the compressor wheel for cleanliness. If only the blade side of the wheel is dirty, dirt and/or moisture is passing through the air filtering system. If oil is found only on the back side of the wheel, there is a possibility of a failed turbocharger oil seal. The presence of oil may be the result of extended engine operation at low idle. The presence of oil may also be the result of a restriction of the line for the inlet air (plugged air filters), which causes the turbocharger to slobber.
Inspect the bore of the turbine housing for corrosion.
Clean the turbocharger housing with standard shop solvents and a soft bristle brush.
Fasten the air inlet piping and the exhaust outlet piping to the turbocharger housing. Inspect the Exhaust Bypass
The exhaust bypass is a wear component that is sensitive to the load cycles of the engine. Replacement of the exhaust bypass is predicted at the top end overhaul for a general "C" or "D" load profile. Applications that have frequent cycling of the engine will increase the wear rate of the valve in the exhaust bypass. Applications that have extended periods of operation at the opening position of the valve will increase the wear rate of the valve. The valve stem should be inspected periodically for wear of the valve stem. A reduced service interval may be required if the inspection reveals heavy wear of the valve. This will ensure proper operation of the exhaust bypass. Use the following steps in order to inspect the exhaust bypass.
Pressurized System: Hot coolant can cause serious burns. To open the cooling system filler cap, stop the engine and wait until the cooling system components are cool. Loosen the cooling system pressure cap slowly in order to relieve the pressure.
Drain the cooling system to a sufficient level below the exhaust bypass in order to remove the cooling lines that attach to the exhaust bypass. Refer to the maintenance section of this Operation and Maintenance Manual, "Cooling System Coolant - Change" for instructions on draining the cooling system.
Illustration 1 g01174063
(1) Exhaust bypass
(2) Boost line
(3) Coolant line
Disconnect the boost line (2) and the two coolant lines (3) from the exhaust bypass (1). The coolant lines (3) attach to both sides of the exhaust bypass (1).
Illustration 2 g01173813
(1) Exhaust Bypass
(4) Nut
(5) Housing
Remove the nuts (4) that fasten the exhaust bypass (1) to the housing (5).
Remove the exhaust bypass (1) from the housing (5).
Illustration 3 g01173915
Inspect the valve stem (6) for heavy wear.
Replace the exhaust bypass (1) if the valve stem is excessively worn.