Under the hood

Turbocharger Faults
Wires within the smart remote actuator (SRA) connector located on the right-hand side of Mack MP7, MP8 and MP10 engines below the turbocharger are subject to vibration during engine operation.

This vibration can result in terminal fretting which produces very fine dust particles and can be seen as a fine green dust inside the connector. When these particles migrate between the female and male pin connectors, intermittent contact problems will result and be made evident by SID 27 and PSID 232 fault codes.

Installing a connector back shell (Part No. 3985620) on the back of the male (mounting bracket side) SRA connector and securing the harness wires by installing a tie wrap around the fabric cover as shown in Figure 1 will correct this condition by dampening the vibration to reduce terminal fretting.

If you encounter multiple instances of logged SID 27 and PSID 232 fault codes, install the connector back shell and secure the wires as follows:

• Disconnect the SRA connector (the bottom connector on the mounting bracket) and then unscrew the bulkhead nut to remove the connector body from the mounting bracket.
• Clean both the SRA side and engine harness side of the connector with a high-quality electrical contact cleaner.
• Install the plastic back shell (Part No. 3985620) over the back of the connector (male side), making sure the fabric cover extends inside the shell.
• Secure the wires by installing a tie wrap (Part No. 948211) around the fabric cover immediately behind the plastic back shell (within 10 mm of the rear of the shell).
• Reinstall the connector body to the mounting bracket and then reconnect the connector. Road test the vehicle and recheck the system for faults.

Top 7 Tips for Engine Rebuilding
Mahle Clevite Inc. offers a list of the Top 7 Tips for engine rebuilding. This list covers a wide range of technical recommendations, including how to achieve successful engine start-up and prevent future failures.

Here are Mahle Clevite’s top seven tips for engine rebuilding:

#7. Determine and correct the cause of failure before rebuilding the engine. Check to be sure the radiator is not plugged, and the oil pump is putting out the correct amount of pressure. Not all components that cause failure can be seen. The air intake and cooling systems need to be examined and repaired as well.

#6. Know that you have the right parts for the engine before installation. Many parts look very similar, with differences that cannot be easily detected. As a matter of good practice, compare the new parts to the old parts before installation. This also will ensure that a part which cannot be replaced is not discarded.

#5. Follow all of the manufacturer’s recommendations for engine rebuilding. These recommendations can be specific to a particular engine. This is essential for proper torquing/retorquing, clearances and start-up procedures.

#4. Be careful when using RTV. Know when and where RTV should and shouldn’t be used. And in cases where RTV is required, use the appropriate amount.

#3. When using oversized and undersized items (i.e. pistons, bearings and oil rings) confirm that you are using the correct size for the block and crank.

#2. Prime the engine oil system before start-up, and lubricate all parts well during assembly. If the engine is not pre-lubed properly, it can experience a great amount of damage in the first few seconds during start-up. If the engine is not started shortly after assembly, it’s a good idea to conduct a second priming of the oil system. Since a common error is forgetting to add engine oil, check the dipstick. Also check to see if there is coolant in the cooling system.

And, the number one most important tip to remember when rebuilding an engine is:

#1. Always operate in as clean an environment as possible. Contamination is the number one cause of engine failures. Roughly 40 percent of engine failures can be traced to dirt, honing grit, machining chips, blast media, shop towels and abrasive wear.