Je me demande pourquoi on n'entend pas parler des roulements principaux, mais seulement des roulements à tige. Je suppose que cela est dû en partie au fait que les gens ne veulent pas reconstruire complètement un moteur, mais ne sont-ils pas fabriqués à partir du même matériau? Ne subiraient-ils pas la même usure ?
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09/04/2019LAST POST
bmwlover0725 a écritJe me demande pourquoi on n'entend pas parler des roulements principaux, mais seulement des roulements à tige. Je suppose que cela est dû en partie au fait que les gens ne veulent pas reconstruire complètement un moteur, mais ne sont-ils pas fabriqués à partir du même matériau? Ne subiraient-ils pas la même usure ?
Le jeu des roulements est en cause, pas le matériau (si la prépondérance des avis d'experts est correcte). Bien qu'il y ait eu quelques défaillances publiées des roulements principaux, en particulier sur les voitures FI (la soufflante met une contrainte supplémentaire sur le roulement principal n ° 1), ils n'ont pas été au degré des roulements de tige.
serranot a écritLe jeu des roulements est en cause, pas le matériau (si la prépondérance des avis d'experts est correcte). Bien qu'il y ait eu quelques défaillances publiées des roulements principaux, en particulier sur les voitures FI (la soufflante met une contrainte supplémentaire sur le roulement principal n ° 1), ils n'ont pas été au degré des roulements de tige.
a m'a frappé après la publication. Je me sens comme un idiot maintenant. Le nettoyage a toujours été le problème. Il semblerait que BMW change le matériau ne fasse presque aucune différence. En fait, il semble que les nouveaux roulements durent encore moins longtemps que les plus anciens.
every now and then you hear about main bearings. I think that's what took out my engine but we'll see whenever I get around to tearing it down
Main bearing failure rates are lower. There have been failures on non-forced induction cars.
It is a concern, but the solution is costly and the chances are lower then a rod bearing issue so many choose to deal with it if it happens.
It is a concern, but the solution is costly and the chances are lower then a rod bearing issue so many choose to deal with it if it happens.
It would also be cheaper and less labor intensive to replace your whole engine.
SYT_Shadow wroteWhich RB did you have in it?every now and then you hear about main bearings. I think that's what took out my engine but we'll see whenever I get around to tearing it down
bmwlover0725 wroteThey didn't change the bearing material due to admitting they had a rod bearing issue. In 2011 Europe mandated against lead/copper bearings so BMW switched to tin/aluminum. They increased the clearance very slightly but not enough to keep 11+ engines from having rod bearing failure.It hit me after posting. I feel like an idiot now. Clearance has been the issue all along. It would appear as though BMW changing the material makes almost no difference. In fact it seems like the newer bearings last for even less time than the older ones did.
TheRussski wrotelook at the DIY in my sig. Again, main bearings != rod bearingsWhich RB did you have in it?
Interesting information. I never knew that they changed the bearing material due to a mandate from the EU. I know there is a lawsuit going on regarding bearing failure. See below:
https://www.carcomplaints.com/news/2018/bmw-m3-rod-main-bearings-lawsuit-new-jersey.shtml
https://www.classaction.org/media/urena-v-bmw-of-north-america-llc.pdf
https://www.carcomplaints.com/news/2018/bmw-m3-rod-main-bearings-lawsuit-new-jersey.shtml
https://www.classaction.org/media/urena-v-bmw-of-north-america-llc.pdf
It's not as common as rod issues but it happens. Had one dropped off last week that's sitting here with main failure waiting for full tear down. Usually see half a dozen or so per year, just at my shop.
Assumingly less stress on the mains sitting still and also having the load to some extend spread, vs the rod shells being hammered on directly by the rod?
deansbimmer wroteWhat mileage range you see them come in for mains failure?It's not as common as rod issues but it happens. Had one dropped off last week that's sitting here with main failure waiting for full tear down. Usually see half a dozen or so per year, just at my shop.
What the cost to replace a main bearing?
Is it double the rate of the RBs?
Just curious, that's all...
Is it double the rate of the RBs?
Just curious, that's all...
Bemo wrotehttps://www.m3post.com/forums/showthread.php?t=1504062What the cost to replace a main bearing?
Is it double the rate of the RBs?
Just curious, that's all...
SFCM3 wroteThanks, I've perused the referenced thread before but, unless I missed it, it doesn't delve into associated costs.Bemo wrotehttps://www.m3post.com/forums/showthread.php?t=1504062What the cost to replace a main bearing?
Is it double the rate of the RBs?
Just curious, that's all...
TheRussski wroteThey're all over. From the 30's to over 100k.What mileage range you see them come in for mains failure?
Costs also vary and are a case-by-case assessment. At my shop, the best case scenario would be a preventative service (no symptoms) which can run around $7k including rod bearings (engine out). This will obviously vary depending on location and shop.
If the bearings have already failed, there's no assumption that the motor can be saved. Usually the lowest cost solution is replacement with a used engine from a donor car.
Maybe this has been discussed before as there are various rod bearing threads and I've read through various bits and pieces since 2015 when I joined but if mains and rod bearings seem to wear, wouldn't it make more sense that the issue is not the tolerance but rather the oil weight spec'd for the car by BMW to lubricate said tolerances?
If a thinner weight had been specified would we possibly not be seeing the issues to the degree that they occur? Even if BMW internally determined that they goofed, even fairly shortly after release of the car, they would not come out and admit it as it would put them on the hook for a HUGE cost in liability. Better off letting it play out and take their chances that it isnt significant enough or that owners don't keep the car long enough to care or at least not care enough to go through the large monetary burden to pursue trying to prove it in court. Odds are in their favor.
I realize there is at least one court case that I've heard of but not sure how much broad benefit this will bring to the rest of us.
If a thinner weight had been specified would we possibly not be seeing the issues to the degree that they occur? Even if BMW internally determined that they goofed, even fairly shortly after release of the car, they would not come out and admit it as it would put them on the hook for a HUGE cost in liability. Better off letting it play out and take their chances that it isnt significant enough or that owners don't keep the car long enough to care or at least not care enough to go through the large monetary burden to pursue trying to prove it in court. Odds are in their favor.
I realize there is at least one court case that I've heard of but not sure how much broad benefit this will bring to the rest of us.
deansbimmer wroteThank you. I’ve read here too that supercharger adds extra load on the mains as well as driving style. But then again same thing can happen to any car, just not in this frequencyThey're all over. From the 30's to over 100k.
Costs also vary and are a case-by-case assessment. At my shop, the best case scenario would be a preventative service (no symptoms) which can run around $7k including rod bearings (engine out). This will obviously vary depending on location and shop.
If the bearings have already failed, there's no assumption that the motor can be saved. Usually the lowest cost solution is replacement with a used engine from a donor car.
M43S7RO wroteMaybe, but not necessarily. The clearances are too minimal to maintain an adequate hydrodynamic oil wedge and that's one of the biggest reasons why we see wear.Maybe this has been discussed before as there are various rod bearing threads and I've read through various bits and pieces since 2015 when I joined but if mains and rod bearings seem to wear, wouldn't it make more sense that the issue is not the tolerance but rather the oil weight spec'd for the car by BMW to lubricate said tolerances?
In the context of main and rod bearings, you can't simply consider the bearing clearance as only a space for oil to flow and lubricate surfaces (thus suggesting a thinner oil might always be better). The oil at pressure creates a "solid" hydraulic wedge (hydrodynamic bearing) that supports the rotating assembly and prevents contact wear. Too little clearance and the oil wedge would be weak and shear. Too much clearance and the wedge would require too much oil flow volume to maintain form and the pump might not be able to keep up.
The VANOS system requirements must also be considered. BMW did not arbitrarily arrive at the 10w60 spec.
