Quote:
Originally Posted by Charlievee
There's really nothing conclusive from doing that because if your mains spin, it's almost certain your rod bearings will fail unless you pick it up early. So unless everyone in that thread did an engine tear down, you can't conclusively say the rod bearing failures were not due to a main bearing failure.
If I was to do a rod bearing change, I'd save a bit more and get the mains done together with OEM coated bearings. The chances really are you should hear a knock if it's your rod bearings, or your crank and rods can be replaced. Unless you're unlucky and a rod goes through your block or you have a secondary main failure. Again, I like my chances the more thought this gets.
There's a fallacy in logic here, if you deadset believe the wear is causing the failure on rod bearings, it's the same wear on the mains!!! In all your research, have you seen an engine which has mains with no wear compared to the rod bearings?
|
Re your 1st point, err no, because very, very few people have come back reporting mains & rod bearings failing subsequently. Your logic fails there.
If the mains were failing at that point then the engine wouldn't last long at all after that, think in terms of a few hundred miles if you're lucky.
Main bearings aren't a bit more to do than rod bearings, as I've already told you they're a lot more.
About the rod knock, I thought so too, but some people (including at least 1 engine builder, Malek,
photos here &
report here) report just a light ticking or nothing at all (as in Maleks case).
If the crank gets irreparably damaged due to a rod bearing failure, then I know a new crank alone costs at least ~£3k (here in UK).
Also,
Deansbimmer reported that when people here a knock it's usually already too late for the crank, IIRC he said he's managed to save 2 engines which had got to that stage.
Re strip down to look at mains when doing rod bearings, true most people don't so that. But as I said above, if it was as big a problem then their would have been plenty of people reporting that back too by now!
There's a fallacy in logic here, if you deadset believe the wear is causing the failure on rod bearings, it's the same wear on the mains!!!
Nope, your logic is flawed here too, you're assuming the mains are under the same conditions as the rod bearings, they are not, any number of differences could explain why they fail (so far that we've seen in this not new problem) far less often than rod bearings. And, as I've said before, so far from what I've seen reported of
failed engines, rod bearings are by far the more common cause. If I find that later in the list mains are more often reported as the cause of failure, I'll let you know (& others) know! (in that thread)
.
Although the rod bearings are easier to do than the main bearings by far, that doesn't mean they are easy per se, seeing as it takes 8-10hrs+!!
If you could simply drop the sump off to get to the rod bearings (like you could on many older cars, some newer), then yes that would be easy!
And again you're focusing on the <1% engine failure rate & ignoring the large number (but yes, not all) of rod bearings showing
significant premature wear (even if you don't include the ones with marginal wear). I at some point am going to collate links & photos of rod bearings (from any engine) with normal wear with at least several 10s of thousands of miles on them for comparison.
I mean that's clearly what all the reliable (non-subjective and biased) evidence suggests - no it doesn't! lol
Anyway, I'm not trying to force you to do your rod bearings, I'm just trying to give you a clearer picture of the gamble you're taking, IMO you're being overly optimistic (and illogical) about it. Anyway, your choice & I don't want to expend anymore time on this discussion really
.
I'll keep my fingers crossed for ya.