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Hi,
How did you determine that it’s only piston slap?
Does it stay knocking and not clacking there is a difference in sounds.
The clacking of piston slapping the cylinder wall usually goes away once the engine is up to operating temperature because the piston expands and oil deadens the sound quite a bit.
In 1993 some of the 240 Volvos got BMW oil squirters directly under the Pistons. I suspect they were turbo models first.
How much it helps I don’t know?
On earlier engines, this noise is common with these engine after a reasonable high mileage and go on for a very long time. It just doesn’t sound good on cold starts ups and the cold varies the events severity.
Connecting rod issues do not generally go away.
It’s a wee bit more mass to control flying around in there.
Excess clearance any place just gets worse.
On the big ends, the Babbitt material gets more wiped away as time goes around and around on them.
Wrist pins are not usually a problem unless the engine was totally mistreated by the lack of regular oil changes.
But since the big ends are first to get oiled, they also get the worst of the first pumped in oil!
Now the question whether do do all four or not is not because of the .010 of piston diameter causing a weight problem of balancing of a few grams. As it was said, the piston is not very tall!
But rather, doing the work without tearing the engine completely down to get access to only one cylinder properly!
You need a round straight bore from top to bottom and a hone does not make a bore “more round,” just bigger!
When boring your hole is only as round as the bearings holding the boring bar true!
Taper is induced only because as the boring bar extends out it loses support at the cutting tool.
Honing can take out taper and produce a finish, but that’s it!
Then you have to ask, where does the “swarf” go!
I was never an automotive machinist and I’m sure they have their “special” ways but the quality of work done varies tremendously during short cuts!
With “In” mass production procedures, things are done quite differently than the way I described them above!
Tooling investments with Measurements taken from several directions of thought.
But one has to consider their intent and that’s an end product, to stay in business!
That is, we hope?
I personally would evaluate (:) “ think it over well” (:) to what you expect to have “after” tearing it down half way, when actually, it’s one-fourth of a good job!
So the answer is “no” you don’t have too!
The engine will take whatever you give it and respond accordingly.
Life is that way, you know!
Phil
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