Case Study: Ford F-150 screeching noise after engine replacement

Dec. 15, 2022

This F-150 was originally brought to the shop because the engine was producing excessive vibration and internal noises.

Related To:

Vehicle: 2008 Ford F-150, 2WD, V8-5.4L, Automatic Transmission/Transaxle

Mileage: 172,556

Problem: This F-150 was originally brought to the shop because the engine was producing excessive vibration and internal noises. The shop installed a remanufactured engine. Soon after starting the replacement engine, it began making a screeching noise from the bell housing/torque converter area. After running for 10-15 minutes, the noise stopped. Upon restarting, the noise returned and lasted for about 10-15 minutes, then stopped. It didn’t matter if the engine was hot or cold. The technician was just about to remove the transmission to diagnose the noise but decided to call ALLDATA Tech-Assist first for some advice.

Case Details: A Tech-Assist consultant recommended checking all PCV and EVAP hoses on the back of the intake manifold to make sure they were not crossed. If they were crossed, the engine would pull manifold vacuum through the rear main seal and could cause a screeching noise. As it happens, both lines have the exact same snap fittings, so they could easily be mixed up. Using Rescue Lens to help guide the technician’s inspection, the Tech-Assist consultant helped the technician identify the vacuum lines. Sure enough, the EVAP purge line, and PCV vacuum line were crossed at the back of the intake manifold.

Confirmed Repair: The technician removed the lines and reinstalled them in their proper location. After the repairs, the screeching noise was gone. The technician was happy he didn’t have to remove the transmission. Problem solved!

Reprinted with permission from ALLDATA.

About the Author

Richard Diegle | Senior Automotive Editor for ALLDATA

Rich Diegle has been in the automotive industry since 1978. After graduating from a local community college, he began working at a Nissan dealership as a used car technician. Since then, he’s worked as a Nissan and ASE master automotive technician, shop owner, marketing copywriter, automotive editor, public relations manager, instructor, ALLDATA Tech-Assist team manager, and a senior automotive editor.