BREAKING: GM is officially recalling the L87

[WalleyeMikeIII]

No 'support' is the right word. As in reaction forces developed in an eccentric rotor and hydrodynamic bearing system.

Video essentially says go up in viscosity if you need to.

View attachment 458253

L and C haven't changed since the LS days. But viscosity has dropped yet power goes up.

What provides the support, the reaction force, for this? The oil film.

Well, I’d argue, based on the bad machining admission from the manufacturer, that C has indeed changed, and this is the difference. From a design perspective, L and C haven’t changed, but given the out of tolerance manufacturing, the real world C is not as designed…so, run the numbers with C a bit larger and again a bit smaller, and see what we get?

Would be nice if we knew which way these things were out of tolerance…

 

[blanchard7684]

no, the sizes of the liners are different, the liners from L86 sit tightly on the crankshaft, and the liner from L87 sits with a gap of 0.15 mm. He has more freedom. Plus, the L86 liner has a red coating similar to rubber, which does not wear off, and the L87 liner erases the coating immediately increasing the gap. I personally held them in my hands and compared them when they assembled my engine.

Ok so even though the journal dimensions haven’t changed, the bearing sizes have changed?

That is a good one.

 

[jfoj]

https://www.enginebuildermag.com/2021/08/engine-bearings-to-coat-or-not-to-coat/

 

[viven44]

Ok so even though the journal dimensions haven’t changed, the bearing sizes have changed?

That is a good one.

I'm not seeing that at all.

Per RockAuto, same rod bearing part numbers for L86/L87 6.2L

See below comparison of part numbers for a 2019 vs 2022 Suburban w/6.2L

2019 CHEVROLET SUBURBAN 6.2L V8 Connecting Rod Bearing | Shop Now at RockAuto

Engine Parts and More for Your 2019 CHEVROLET SUBURBAN at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

2022 CHEVROLET SUBURBAN 6.2L V8 Connecting Rod Bearing | Shop Now at RockAuto

Engine Parts and More for Your 2022 CHEVROLET SUBURBAN at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

If Vlad can post part numbers for the red coated bearings, we can figure out which application it's from, but it's not L86

 

[Vladimir2306]

Ok so even though the journal dimensions haven’t changed, the bearing sizes have changed?

That is a good one.

The landing size is the same, but the internal one is different.

 

[Vladimir2306]

I'm not seeing that at all.

Per RockAuto, same rod bearing part numbers for L86/L87 6.2L

See below comparison of part numbers for a 2019 vs 2022 Suburban w/6.2L

2019 CHEVROLET SUBURBAN 6.2L V8 Connecting Rod Bearing | Shop Now at RockAuto

Engine Parts and More for Your 2019 CHEVROLET SUBURBAN at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

2022 CHEVROLET SUBURBAN 6.2L V8 Connecting Rod Bearing | Shop Now at RockAuto

Engine Parts and More for Your 2022 CHEVROLET SUBURBAN at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

If Vlad can post part numbers for the red coated bearings, we can figure out which application it's from, but it's not L86

Their number is 12656817
The photo shows the bearings, the red one on the right is from L86, the silver one is from L87. The red one has 140 thousand km on the mileage, and the silver one has 15 thousand km, wear, scratches, and burrs are visible on the one on the far right.

Amazon.com: Michigan Motorsports Gen V LT Connecting Rod Bearings -Fits 2014-Later Gen V LT1 L86 LT4 6.2L GM 12656817 (1) : Automotive

Buy Michigan Motorsports Gen V LT Connecting Rod Bearings -Fits 2014-Later Gen V LT1 L86 LT4 6.2L GM 12656817 (1): Bearings - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

[DuraYuk]

The bottom end rotating assembly of these engines is virtually identical going back to the LS days. Journal sizes have not been changed. The first oil spec for a truck based LS was 5w30. This is found via a simple google search.

Asking for proof of this is like asking for proof that the sky is blue. You can find this out for yourself.

But if you want to nit pick based on 6.2 alone then we can do that too.

L92 vs L87 details

L92 6.2L Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More

From cylinder heads to the camshaft, here's a complete rundown of all the vital engine specs you need for the 6.2L L92 LS engine.

www.onallcylinders.com

L86 6.2L EcoTec3 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More - OnAllCylinders

The L86 is a Gen. 5, 6.2L, small-block engine powering 2014-present GM trucks and SUVs. They are known as the EcoTec3 6.2L engines. These engines use a longer intake runner than its …

www.onallcylinders.com

As far as engine bearings and crankshaft go these two engines are identical. journal size, rod ratio, bore and stroke.

So the L92 was out in 2007 in an Escalade. The oil spec for a 2007 escalade was 5w30. See example below. You can find this in about 3 dozen other ways with a simple search.


View attachment 458252

Not the same engines. Sorry try again.

 

[DuraYuk]

different part numbers but dimensions aren't.

LS1 crank journal specs: https://www.onallcylinders.com/2017...ormance-bore-stroke-cylinder-heads-cam-specs/

L87/L86 (posted for the second time)

L86 6.2L EcoTec3 Engine Specs: Performance, Bore & Stroke, Cylinder Heads, Cam Specs & More - OnAllCylinders

The L86 is a Gen. 5, 6.2L, small-block engine powering 2014-present GM trucks and SUVs. They are known as the EcoTec3 6.2L engines. These engines use a longer intake runner than its …

www.onallcylinders.com

2.559, 2.11 journal diameters, and stroke is 3.6. Same connecting rod length of 6.098. Same deck height 9.24.

These are the core dimensions in configuring the engine bearings.

They are the same.

Original oil was 5w30 for trucks.

CAFE also plays a role here.

Corvette and Camaro have 0w40 as a spec because their sales numbers are rounding error compared to trucks and suvs.

So they don't have to get 0w20 to juice up the cafe numbers.

They may be similar but they are not the same. That does not prove your point. Your really weaving here. Not even the same displacement lmao.

 

[blanchard7684]

Not the same engines. Sorry try again.

explain how they aren't the same from the point of the rotating assembly. Specifically the journals and the bearings.

 

[blanchard7684]

They may be similar but they are not the same. That does not prove your point. Your really weaving here. Not even the same displacement lmao.

This is baseline factual information that you are taking exception to.

Refusing this information disqualifies you for a continued response.

Next up: the sky is red.

 

[DuraYuk]

explain how they aren't the same from the point of the rotating assembly. Specifically the bearings.

Seriously? I thought you were an engineer? I dont mean offense by this.

They are similar. Same family. You cannot say they are the same engines and designed the same. And take the same oil.

The parameter changes. Period. What else is same? The oil pump? The displacement? The stroke? The bore? The liner? The cam profile? The valves? The max rpm? The caps? The torque specs for the main bearings? You cannot say it's the same engines because the bearing is similar.

These engines have familiarity because they are part of the same family but they are different. Every engine out there by every manufactuer has similarity by design. But they are different. Designed for different parameters. Its that simple.

I dont know why this is the hill you wanna die on when its black and white..

If you think the 6.2 is the same as an ls1......well you are wrong..

You said it yourself. Different part numbers lmao. Jesus.

 

[blanchard7684]

Seriously? I thought you were an engineer? I dont mean offense by this.

They are similar. Same family. You cannot say they are the same engines and designed the same. And take the same oil.

The parameter changes. Period. What else is same? The oil pump? The displacement? The stroke? The bore? The liner? The cam profile? The valves? The max rpm? You cannot say it's the same engines because the bearing is similar.

you are not addressing the question: how are the journals different? This is the key component for bearing design that call into question the oil viscosity.

Journal width is the same, journal diameter is the same. The materials are the same.

Show me exactly how the crank is so different between these two.

The other components are a distracting irrelevancy.

 

[viven44]

Their number is 12656817
The photo shows the bearings, the red one on the right is from L86, the silver one is from L87. The red one has 140 thousand km on the mileage, and the silver one has 15 thousand km, wear, scratches, and burrs are visible on the one on the far right.

Amazon.com: Michigan Motorsports Gen V LT Connecting Rod Bearings -Fits 2014-Later Gen V LT1 L86 LT4 6.2L GM 12656817 (1) : Automotive

Buy Michigan Motorsports Gen V LT Connecting Rod Bearings -Fits 2014-Later Gen V LT1 L86 LT4 6.2L GM 12656817 (1): Bearings - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Ok thanks.

12656817 appears to be the stock replacement for a 2014-2016 6.2L used on Silverado 1500s. Not sure why GM went to 12683811 in 2017

Interestingly 2014 is when they switched to 0W-20, and perhaps out of an abundance of caution they may have used this bearing. It is still good info, and I think your mechanics may have done you right by going to those bearings.

 

[DuraYuk]

you are not addressing the question: how are the journals different? This is the key component for bearing design that call into question the oil viscosity.

Journal width is the same, journal diameter is the same. The materials are the same.

Show me exactly how the crank is so different between these two.

The other components are a distracting irrelevancy.

So if a house uses the same beam its the same house ? If the truss is similar in design its the same ? Nevermind that the roof is completely different size, shape, and pitch?

The bearing can be similar but all the external forces are different not to mention material composition.

Gm engine designs have largely been the same displacement for a long time doesnt mean that the engines are anywhere similar even if the displacement is the same.

Timken makes bearings for many vehicles. Dimensionally many are similar but they are in different applications. Does that mean that everything that uses that bearing is essentially the same thing even tho one is a car one is heavy equipment and one is a roller on a assembly line ?
I get what your saying but outside of only trying to prove your nuance it isnt relevant here.

 

[blanchard7684]

So if a house uses the same beam its the same house ? If the truss is similar in design its the same ? Nevermind that the roof is completely different size, shape, and pitch?

The bearing can be similar but all the external forces are different not to mention material composition.

Gm engine designs have largely been the same displacement for a long time doesnt mean that the engines are anywhere similar even if the displacement is the same.

Timken makes bearings for many vehicles. Dimensionally many are similar but they are in different applications. Does that mean that everything that uses that bearing is essentially the same thing even tho one is a car one is heavy equipment and one is a roller on a assembly line ?
I get what your saying but outside of only trying to prove your nuance it isnt relevant here.

I never said they were the same engine. I said the rotating assembly was virtually identical.

And specifically the journals which is where the viscosity discussion becomes pertinent.

These engines may have changed valve covers, pcv valves, throttle bodies, etc...whatever irrelevant component you want to bring up...it doesn't change the fact that 1) the original LS engine has the same crank journal dimensions as current engines and 2) first 6.2 and current 6.2 had same crank journals and was even a forged crank 3) these engines were orginally spec'd with 5w30.


In terms of your house analogy: house A made in 1999 has the same wood, same number of beams, same cross section of beams as house B made in 2014. Yet the 2014 house has much smaller nails. 2021-2024 houses are based on 2014 design with small nails. 2021-2024 houses have added weight on the roof (more load). Now the load bearing joints are failing. The remedy is to use the larger nails.

The bearing can be similar but all the external forces are different not to mention material composition.

You might have noticed that GM put more power through these engines--on the same bearing design. They also changed transmissions and the resultant transmission mapping.

So the "external forces" have increased when dimensions haven't changed.

 

[vcode]

Here are the actual facts as we know them released in GM's recall report.... "Engine teardown analysis identified two primary root causes, both of which are attributable to supplier manufacturing and quality issues: (1) rod-bearing damage from sediment on connecting rods and crankshaft-oil galleries; and (2)out of specification crankshaft dimensions and surface finish." Absolutely no where does it mention oil as being an issue, and to claim it is, is 100% opinion and speculation at this point.

 

[blanchard7684]

Here are the actual facts as we know them released in GM's recall report.... "Engine teardown analysis identified two primary root causes, both of which are attributable to supplier manufacturing and quality issues: (1) rod-bearing damage from sediment on connecting rods and crankshaft-oil galleries; and (2)out of specification crankshaft dimensions and surface finish." Absolutely no where does it mention oil as being an issue, and to claim it is, is 100% opinion and speculation at this point.

If that is the case then there would be no recall effort regarding 0w40.

 

[vcode]

If that is the case then there would be no recall effort regarding 0w40.

Again, no where does it say the oil is the problem. Replacement engines and newer vehicles will continue to use 0W20. Why is it so hard to comprehend that manufacturing defects caused the problems?

 

[blanchard7684]

Again, no where does it say the oil is the problem. Replacement engines and newer vehicles will continue to use 0W20. Why is it so hard to comprehend that manufacturing defects caused the problems?

it isn't. But it is equally hard to see how people are ignoring the big glaring 0w40 aspect of this recall.

 

[vcode]

I never said they were the same engine. I said the rotating assembly was virtually identical.

And specifically the journals which is where the viscosity discussion becomes pertinent.

These engines may have changed valve covers, pcv valves, throttle bodies, etc...whatever irrelevant component you want to bring up...it doesn't change the fact that 1) the original LS engine has the same crank journal dimensions as current engines and 2) first 6.2 and current 6.2 had same crank journals and was even a forged crank 3) these engines were orginally spec'd with 5w30.


In terms of your house analogy: house A made in 1999 has the same wood, same number of beams, same cross section of beams as house B made in 2014. Yet the 2014 house has much smaller nails. 2021-2024 houses are based on 2014 design with small nails. 2021-2024 houses have added weight on the roof (more load). Now the load bearing joints are failing. The remedy is to use the larger nails.



You might have noticed that GM put more power through these engines--on the same bearing design. They also changed transmissions and the resultant transmission mapping.

So the "external forces" have increased when dimensions haven't changed.

The original engines did call for 5W30. SM grade conventional dino oil. Pre-Dexos. Oil has come a long way since 2007 and I would guess that a fully synthetic 0W20 would spank a SM grade 5W30.....