Quote:
Originally Posted by funola
subetealabici, ...... that you have to abide by every little bit in the FSM etc. etc........
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Here is the value to having and following the specific instructions in the manual produced by the people who made the engines and have millions of dollars to spend on R and D...
Pistons are almost always aluminum.... there are typically three or four rings grooves around their outside.... obviously for the rings... which do not sit inside the rings until they are compressed by the piston being INSIDE the bore...
So as you try to put the piston into the bore.. you have these ' fingers' wanting to stick out past the bore.. so you use a tool meant to keep them flush with the edge of the piston... while you slide the piston into the bore..
But all it takes is one tiny slip ... the ring compressor not exactly down to the top of that bore...and you are tapping on the piston to get it in...
and you risk breaking the ring LAND... the part between the rings... which can be fairly narrow depending on the piston length and the number of rings..
The ring compressor does not usually go into the bore at all..
so the Chamfer at the top of the bore needs to be of a design ( ramp) which will allow the rings to be further compressed to slide into the bore...
If they are not.. you can break the ring... or the land.... or both...
This might not be TOO much of a problem on the 616 pistons.. .as they are relatively reasonable in price compared to the turbo 617 pistons..
But if you ruin that piston... which... if you followed the FSM procedure to get the bore to piston distance correct by measuring the piston and boring the sleeve to fit it...
You have a new piston NOT measured and fitted to the bore.. ...
Luck is not the way to increase your chances of getting 300,000 miles out of a rebuilt Mercedes Diesel engine...