GM service bulletin for faulty valve springs

Terry Swensen · December 10, 2020

So I went in and talked to the service manager today. He didn't deny that he knew about the TSB. He said he has only had one that he had to repair so far. He said corporate GM said if a spring hasn't broke by 300 miles they probably won't break.

He also said GM told them to run every new vehicle with a V8 for 4.5 hrs at 1800 rpm. If no springs break the the engine should be good to go.

Larry CG · December 11, 2020

54 minutes ago, Terry Swensen said:

So I went in and talked to the service manager today. He didn't deny that he knew about the TSB. He said he has only had one that he had to repair so far. He said corporate GM said if a spring hasn't broke by 300 miles they probably won't break.

He also said GM told them to run every new vehicle with a V8 for 4.5 hrs at 1800 rpm. If no springs break the the engine should be good to go.

Heard the same thing about running above idle to test. Seems like "testing in production" to me, which is really the best way in many cases. Problem is once they've rolled off the line, then the lot, costing the customer money, time, and risk that could be avoided. General waste for everybody involved. A good step, but would hope/think there would be a better way to identify which plants/batches installed in what engines and could be dealt with proactively. Cost of doing business, I guess.

Terry Swensen · December 11, 2020

1 hour ago, Larry CG said:

Heard the same thing about running above idle to test. Seems like "testing in production" to me, which is really the best way in many cases. Problem is once they've rolled off the line, then the lot, costing the customer money, time, and risk that could be avoided. General waste for everybody involved. A good step, but would hope/think there would be a better way to identify which plants/batches installed in what engines and could be dealt with proactively. Cost of doing business, I guess.

It was all plants, I asked. They put out 65 trucks per hour per plant and I dunno what percentage have V8's. This was over a 105 day period according to GM. That's a lot of trucks and that's not including Cadillacs, Camero's Corvettes, Suburbans, Tahoe's etc.

Edited December 11, 2020 by Terry Swensen
Wrong word

tbbqwebber · December 28, 2020

2020 AT4, 6.2L, with around 7,000 miles (heres y'alls evidence for higher milage problems). I dont know the exact build date but purchased around 8/15/20. Truck died at hwy speed on Christmas eve. Just got the call that a valve spring broke. I believe they said they're only replacing the one spring. I'm no mechanic so I just accepted it until I did a little homework. So from what I've read here, I should be asking for all springs to be replaced per the TSB?

Rob Mugs · December 28, 2020

3 hours ago, tbbqwebber said:

2020 AT4, 6.2L, with around 7,000 miles (heres y'alls evidence for higher milage problems). I dont know the exact build date but purchased around 8/15/20. Truck died at hwy speed on Christmas eve. Just got the call that a valve spring broke. I believe they said they're only replacing the one spring. I'm no mechanic so I just accepted it until I did a little homework. So from what I've read here, I should be asking for all springs to be replaced per the TSB?

To backtrack....

First, they should be scoping the cylinder to make sure none made it down that far/run a compression test

If all is good, then replace all springs

If there is cylinder scoring/compression loss, replace engine

Edited December 28, 2020 by Rob Mugs

Transient · December 29, 2020

Yep. 6.2s called for replacing all valve springs. 5.3s called for replacng only the 1 broken valve spring.

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tbbqwebber · January 12, 2021

Update - dealer did replace all valve springs without any encouraging from me. Fully covered under warranty. Took about 4 days to get the truck back.

*this post didn't quote. This is for the 2020 AT4, 6.2L, with 7,000 miles

Edited January 12, 2021 by tbbqwebber
Tried to quote post above but didn't. Edited for clarity

Rob Mugs · January 14, 2021

On 1/12/2021 at 1:03 PM, tbbqwebber said:

Update - dealer did replace all valve springs without any encouraging from me. Fully covered under warranty. Took about 4 days to get the truck back.

*this post didn't quote. This is for the 2020 AT4, 6.2L, with 7,000 miles

Ouch.. 7,000 miles is a long time to be in the "unknown"

@kodiakdenali

kodiakdenali · January 14, 2021

26 minutes ago, Rob Mugs said:

Ouch.. 7,000 miles is a long time to be in the "unknown"

@kodiakdenali

I'm having mine replaced, proactively, with aftermarket dual springs instead of factory style bee-hives. this whole thing stinks...but its not worth the stress of the unknown for the next 2-3 years (at the rate I add miles to my truck).

Billynstephanie · April 27, 2021

20 LT with 5.3-had 8400 miles b4 valve collapsed and bent a push rod-dealer replaced all valves on one side and was out truck for 11 days-build date 09/20