ASE A1 Engine RepairEngine Block AssemblyMedium
A technician is performing a pre-assembly inspection of an engine block. They notice that the cylinder bores have a slight 'ridge' at the top of the cylinder, just below the deck surface. What is the MOST appropriate next step for the technician?
- AApply extra oil to the cylinder walls to lubricate the rings over the ridge.
- BInstall new pistons and rings, ensuring the rings are compressed tightly.
- CUse a ridge reamer to remove the ridge before piston removal or installation.
- DProceed with assembly, as the rings will seat themselves past the ridge.
Show answer & explanationAnswer & explanation
Correct answer: C. Use a ridge reamer to remove the ridge before piston removal or installation.
A ridge at the top of the cylinder bore is caused by normal cylinder wear where the piston rings do not travel. This ridge must be removed with a ridge reamer before attempting to remove or install pistons, otherwise, the piston rings will strike the ridge, potentially breaking the rings or damaging the piston.
Why the other options are wrong
- A. Extra oil will not prevent mechanical interference between the rings and the ridge.
- B. Installing new pistons and rings without removing the ridge will almost certainly result in broken rings or piston damage.
- D. Proceeding with assembly without removing the ridge will cause damage to new rings and pistons.
Cylinder Ridge Reaming
Cylinder ridge reaming is the process of removing the wear ridge that forms at the top of a cylinder bore due to piston ring travel.
- Essential when servicing or replacing pistons/rings in a used engine block.
- Prevents piston rings from catching on the ridge, which can lead to breakage or piston damage.
- Performed with a specialized tool called a ridge reamer.
Memory trick: Ridge 'R'eamer for the top 'R'idge.