2019 Sierra 6.2L PIP5606- Bent Pushrod

[Thomcat]

On 5/15/2019 at 12:51 PM, Sierra Dan said:

Because the engines are the same architecture.

Only real difference is instead of shutting down 4 cylinders with (AFM)  L83, L86...… the T1 engines

with (DFM) L84, L87 can run on as little as 1-2 cylinders.

Not the same architecture, changes in internal design and operation.

 

Half the AFM cylinders use collapsible lifters and half solid, all the DFMs use all collapsible and it is the solid ones that are more susceptible to bending.

 

AFMs use a LOMA, a separate plastic manifold located in the V of the engine feeding the collapsible lifters of the 4 deactivation cylinders. DFMs eliminate the LOMA and feed the oil directly to solenoids within the block, directly feeding all 8 cylinders for faster more reliable response. Most importantly it eliminates the LOMA discharge valve in the sump which in the past has been responsible for clogging lower oil rings sets on the 4 dead cylinders turning them into smokers. DFMs cucle all cylinders so there are not the same dead cylinders running for a prolonged duration.

 

In addition the DFMs use a modified design of the PCV system in the valve covers rounding the tops and adding internal baffles to greatly reduce oil vapor entering the PCV hose and precluding the need for an external catch can.

 

https://gm-techlink.com/?p=11880

 

 

[RE1]

17 hours ago, f8l vnm said:

WOW! Last time i heard this was on my 2001 Camaro LS1!!!!  Good luck brother! 

I'm gonna guess it was a missed shift on a manual transmission. User error. Not the engine's fault.

[grapedrinkesha]

3 hours ago, Thomcat said:

Not the same architecture, changes in internal design and operation.

 

Half the AFM cylinders use collapsible lifters and half solid, all the DFMs use all collapsible and it is the solid ones that are more susceptible to bending.

 

AFMs use a LOMA, a separate plastic manifold located in the V of the engine feeding the collapsible lifters of the 4 deactivation cylinders. DFMs eliminate the LOMA and feed the oil directly to solenoids within the block, directly feeding all 8 cylinders for faster more reliable response. Most importantly it eliminates the LOMA discharge valve in the sump which in the past has been responsible for clogging lower oil rings sets on the 4 dead cylinders turning them into smokers. DFMs cucle all cylinders so there are not the same dead cylinders running for a prolonged duration.

 

In addition the DFMs use a modified design of the PCV system in the valve covers rounding the tops and adding internal baffles to greatly reduce oil vapor entering the PCV hose and precluding the need for an external catch can.

 

https://gm-techlink.com/?p=11880

 

 

Where did you read that information on the PCV system on the L84 engine? That's great to hear for longevity, and makes me love this truck even more!

[f8l vnm]

11 hours ago, Colossus said:

How did you manage to do that on a LS1 Camaro?  Good grief!  What were you doing!? 

Not sure how it happened exactly but i may have missed a shift at red line..that is what mechanic told me anyway . Literally 20 years ago. 

[RE1]

22 minutes ago, f8l vnm said:

Not sure how it happened exactly but i may have missed a shift at red line..that is what mechanic told me anyway . Literally 20 years ago. 

I had a ‘97 (LT1) and then a ‘99 Z28 (LS1). Both 6 speed manual transmissions. 
 

I remember reading countless threads on the LS1 boards about people missing the 2-3 shift and going from 2nd at or near redline to 1st instead of 3rd and manually overreving the engine. No rev limiter is gonna save your ass. Bent pushrods resulted. 

Edited January 29, 2020 by RE1

[f8l vnm]

LS1's dominated untill 2003 when the 03 Cobra came out.  Man i miss those days . Too bad GM still cant make a interior  

Remember the HUMP on the passenger side?  lmao 

[RE1]

3 hours ago, f8l vnm said:

LS1's dominated untill 2003 when the 03 Cobra came out.  Man i miss those days . Too bad GM still cant make a interior  

Remember the HUMP on the passenger side?  lmao 

Yup. Fun cars. 

[BlancoSilverado]

7 hours ago, grapedrinkesha said:

Where did you read that information on the PCV system on the L84 engine? That's great to hear for longevity, and makes me love this truck even more!

Im still pulling 1/3cup of oil/water every 4,000 miles. 

[grapedrinkesha]

13 hours ago, BlancoSilverado said:

Im still pulling 1/3cup of oil/water every 4,000 miles. 

How many miles do you have? Have you checked your valves with a borescope?

[L86 All Terrain]

It was common on the L86, which is very similar but with AFM instead of the new DFM. Both cause more problems than the fuel they help save but this is what EPA regulation has got us. Unreliable vehicles caused by unrealistic economy demands. Help save you $500 in gas before the system fails and you need $3,000 heads, nice thanks EPA. Here's and L86 thread started this morning. Makes me think anyone planning on keeping these trucks should do a AFM/DFM DOD delete. Or buy new heads from someone like TSP. 

 

 

[BlancoSilverado]

3 hours ago, grapedrinkesha said:

How many miles do you have? Have you checked your valves with a borescope?

I have now 16,000 miles, 

I have not done that yet, primary reason i do not have a good bore scope to check. I will be borrowing one in the next month from a friend. 

[grapedrinkesha]

5 minutes ago, BlancoSilverado said:

I have now 16,000 miles, 

I have not done that yet, primary reason i do not have a good bore scope to check. I will be borrowing one in the next month from a friend. 

I am going to buy one to keep an eye on mine. I've done a lot of research on this topic but there isn't a lot on our engines specifically that I can find. I will be sure to run full synthetic as I've heard that is the best precaution to take along with a manual cleaning when the valves start coking.

[BlancoSilverado]

5 minutes ago, grapedrinkesha said:

I am going to buy one to keep an eye on mine. I've done a lot of research on this topic but there isn't a lot on our engines specifically that I can find. I will be sure to run full synthetic as I've heard that is the best precaution to take along with a manual cleaning when the valves start coking.

Im running a RXP catch can. there are tons of reviews stating that its better then some of the others out there. 

I have been running Amsoil SS since the 500 mile mark.

[grapedrinkesha]

2 hours ago, BlancoSilverado said:

Im running a RXP catch can. there are tons of reviews stating that its better then some of the others out there. 

I have been running Amsoil SS since the 500 mile mark.

Hopefully you got one of the legit ones, there seems to be a lot of knock offs out there for the RX cans. I have an extended warranty that isn't worth me losing or I'd be running a can as well. 

[BlancoSilverado]

15 minutes ago, grapedrinkesha said:

Hopefully you got one of the legit ones, there seems to be a lot of knock offs out there for the RX cans. I have an extended warranty that isn't worth me losing or I'd be running a can as well. 

Oh yes i did,  I teamed up with RXP to make sure i got a legit one. The video below is Blanco getting the RXP installed.