228701 Mercruiser SCREW, CARBURETOR MOUNTING (3 1/2")

Keep all parts clean from contaminants.Contaminants may cause rapid wear and shortened component life.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, PERJ1017, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products.Dispose of all fluids according to local regulations and mandates.
Note: The following oil pressure measurements are taken between the oil filter and the engine lubrication system. Before you begin this procedure, ensure that the area around the oil pressure port is clean and dry. Be careful not to introduce any form of contamination into the lubrication system during this procedure.
Illustration 1 g00296486
1U-5470 Engine Pressure Group
The 1U-5470 Engine Pressure Group measures the engine oil pressure in the system. This engine tool group can read the engine oil pressure inside the oil manifold.Note: Refer to Special Instruction, SEHS8907, "Using the 1U-5470 Engine Pressure Group" for more information on using the 1U-5470 Engine Pressure Group.Note: The engine oil pressure can also be measured by using an electronic service tool. Refer to Troubleshooting for information on the use of the Caterpillar Electronic Technician (ET).
Remove the plug from the appropriate location for your engine. Install the appropriate bushings into the fitting for the pressure tap. These bushings will reduce the size of the tap to the correct size for the 1U-5470 Engine Pressure Group. Install the fitting for the pressure group into this port.Note: The fitting for the pressure tap is a metric size. Do not use a SAE or an NPTF fitting in this port.
Start the engine. Run the engine with SAE 15W40 oil. Refer to Operation and Maintenance Manual, "Engine Oil" for the recommendations of engine oil.Note: Allow the engine to reach operating temperature before you perform the oil pressure test.Note: The nominal engine oil temperature at rated rpm is approximately 95° C (203° F). The engine oil temperature must not exceed 115 °C (239 °F).
Record the value of the engine oil pressure when the engine has reached operating temperature.
The normal engine oil pressure at rated rpm is approximately 627 kPa (91 psi) to approximately 731 kPa (106 psi). The maximum engine oil pressure must never exceed 850 kPa (123 psi). The minimum engine oil pressure at rated rpm must never drop below 500 kPa (73 psi). The specification for the minimum engine oil pressure at low idle rpm is 248 kPa (36 psi).Note: A record of engine oil pressure can be used as an indication of possible engine problems or of damage. A possible problem could exist if the engine oil pressure suddenly increases or decreases 70 kPa (10 psi) and the engine is not at normal engine oil pressure. Inspect the engine and correct the problem.
Compare the recorded engine oil pressure with the engine oil pressure indicators on the instrument panel and the engine oil pressure that is displayed on Cat ET.
A faulty oil pressure indicator or a faulty oil pressure sensor can give a false indication of engine oil pressure. If there is a notable difference between the engine oil pressure readings, refer to the Troubleshooting manual for troubleshooting details.