We were overhauling a Caterpillar engine in the workshop the other day when we came across some significant damage – which is not an uncommon sight on engines with wet liners.
We’d removed the cylinder liners and inspected the crankcase, and this is what was found:
You’ll see the damage caused by fretting on both the liner and the crankcase e-bore.
Whilst the liner was going to be changed as part of the overhaul, there are different options for the crankcase e-bore:
1) Replace the crankcase
2) Use a specialist repair composite
3) Fit a sleeve, and machine back to original ID, ensuring the liner will be correctly aligned
If you find this on your engine, the right solution is going to depend on the extent of the fretting, class requirements and costings.
There are multiple potential causes (or even a combination), but commonly it is due to failure of the liner o-rings, incorrect use of inhibitor in the coolant, or even as a result of prolonged maintenance intervals.
If you do experience this type of fretting damage, you are at risk of water leaking into the engine oil leading to the type of problems highlighted above.
Alternatively, you could end up with a broken liner and fragments around the engine in the lube oil system.
Protect yourself by ensuring the coolant is maintained at the correct strength and any maintenance schedules are adhered to. Furthermore, ensure the e-bores are checked anytime the liners are removed.
