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How do these bearings look? No major scratches, nothing that you can catch a finger nail on. Surface is smooth on all. Some dark discoloration on a few.
Add to this: how do the crank journals look (and measure)?
The wear on the lower mains is an interesting illustration of where the pressure is applied by combustion. The wear patterns at the areas 45º from bottom center tell me that it's a 90º V engine. Without measuring/feeling it's hard to tell if that's just a little mottling of the tin on the surface or wear into the second layer a little. On larger equipment I'd be carefully examining oil flow, but on the larger equipment I visit there's always oil flow prior to rotation, including additional heated "lift oil" to pick up the rotating part before a full film dam can be formed on the bearing faces. Wear on your crankshaft will tell you more about the telltale patterns on bearings. Make sure the journals are still round.
Thanks for you input fellas. The block is now at Beaty and Woods to have it decked and most likely we will do the cylinders as well (they do tons of Alusi blocks). New rings and new bearings as well. And all will be measured.
I dont think they look good at all. the copper showing is bad, and a mirror finish isnt good either. (looks like copper on #6 and a couple of others) a very smalll film of oil stays on the matted finish. when its shiney, they are goners! change them out and have a new engine!
the mains dont look bad, except for the bottom of the #3 journal. you (I) couuld use those. rod bearings... i dont think they look that good. my 84 with 175,000 miles on it, and 5 years on the track, rod bearings looked MUCH better and i still tossed them.
The wear in the main bearings shows why modern bearings are grooved differently. I am using the bored out factory bearings as spacers in my new engine and fitting 140 degree grooved bearings into them to avoid this type of wear and extra friction. Many engines including the GM LSX are using smaller grooving these days.
The wear in the main bearings shows why modern bearings are grooved differently. I am using the bored out factory bearings as spacers in my new engine and fitting 140 degree grooved bearings into them to avoid this type of wear and extra friction. Many engines including the GM LSX are using smaller grooving these days.
I would be cautious just adopting the practice of newer engines bearing designs. There is alot more going on in those engines than just a groved bearing and you are reducing the surface area of the bearing. Since the stock design is fine, why alter it?
The wear in the main bearings shows why modern bearings are grooved differently. I am using the bored out factory bearings as spacers in my new engine and fitting 140 degree grooved bearings into them to avoid this type of wear and extra friction. Many engines including the GM LSX are using smaller grooving these days.
There is no friction in the bearing unless steel on steel. During running there is (should be) no contact whatsoever. It rides on a film of oil.
Originally Posted by Imo000
I would be cautious just adopting the practice of newer engines bearing designs. There is alot more going on in those engines than just a groved bearing and you are reducing the surface area of the bearing. Since the stock design is fine, why alter it?
This.
Be VERY careful about grooving anything in the bearing area. As Imo000 says, it reduces the surface area and as such reduces the load carrying capability. Automakers are hesitant to make .1 mm changes to these kinds of things as even that much will affect the functionality.
The wear in the main bearings shows why modern bearings are grooved differently. I am using the bored out factory bearings as spacers in my new engine and fitting 140 degree grooved bearings into them to avoid this type of wear and extra friction. Many engines including the GM LSX are using smaller grooving these days.
Guessing that the use pattern for most of our cars, with extended time between drives, is a major contributor to that kind of bearing wear. The time it takes to get oil to those bearings on dry start is critical. Especially after hibernation, there's a good case for spinning the engine with the fuel pump fuse removed for a few seconds just to get everything filled up again before adding combustion pressure.
03-22-2016, 12:49 AM
Crank + Rod Bearing Wear - 88 S4
