Engine/Transmission (1998.5 - 2002) When is "broken in"? ;-)

[DMather]

Had to pull head to replace head gasket (rust intruded from side and compromised water jacket seal)



There is no ridge on any cylinder and the cross hatching from the factory hone is still looks fresh. I've seen less in a vehicle with 30K on it.



So... almost at 400K ..... when should I expect this engine to be broken in? :-laf:-laf:-laf

 

[MCharlebois]

these motors are truly amazing!!!!!

cheers marcel

 

[Vaughn MacKenzie]

On my '96 when I had the head off at 432,000 miles all cylinders but #6 had hone marks and #5 nearly gone. Still no ridge at the top. I am told with the blocks being hard the rings will likely be worn out before the hone marks are gone.

 

[Mikey-KE7LBB]

I had a little over 250k on my 92 when I ended up needing to replace the head gasket due to a bad idler pulley that chewed up a new belt in a matter of 200 miles towing on a very hot and very bad day #@$%!

I was very impressed that all of the cylinders looked as if the block left the assembly plant the day before!!

Good quality oil and keeping the EGT's and coolant temps in check will yield many miles before these things get worn out.

 

[Skydiver]

Got to have the cross hatch pattern for oil to flow in. I'm not a rebuild specialist but I have done a few and been around dozens more. Back in the 60s and 70s a new engine or newly rebuilt engine sometimes used a quart in 500 miles, that is until the rings seated. Nowadays engines are sold new with little breakin required. AND the tolerances are tighter than they used to be. HINCE 5w20.
Anyone know what the factory ring gap is on a newer Cummins?