2015 GMC Sierra 1500 - Help with cylinder valves requested

Maintenance/Repairs
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1

#7 CYLINDER valves stuck open engine running very rough

2

How was this diagnosed . . . ?!

I’m assuming your check engine light is illuminated at idle . . .

what are your fault codes?

what engine?

how many miles?

3

Since #7 is part of the cylinder deactivation system, I’d say your engine has been destroyed. When the system fails it very often sends metal shavings into the oiling system destroying your bearings.

Without more information about your truck, its engine and any error codes, I can’t give you better news.

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Don’t mechanics handle these sorts of issues?

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Ask your shop if they can recommend an additive to the oil designed to de-carbonize the valve guides. If so, that’s probably worth a try. I am not able to post a link (b/c this post would almost certainly be flagged & removed as spam, still might be), but you might try Googling “how to clean carbon deposits from valve guides” for some ideas. If you are able to temporarily resolve the problem this way, probably makes sense to change the oil and filter more often than you have been doing.

6

A engine with a stuck valve is beyond the help of oil additives, in my opinion.

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Am I the only one that’s skeptical of the “stuck valve” diagnosis?

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8

The customers interpretation of the problem doesn’t matter, they will have to rely on local repair facilities to perform the repair.

Here is a bulletin about broken valve springs, seems entirely possible:

MC-10160640-9999.pdf (nhtsa.gov)

BTW, the OP didn’t ask for help, they only stated they experienced an engine malfunction.

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Nope! (here’s to making 10 characters…)

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Are you asking a question or just making a statement??

Valves as in both intake and exhaust, or just one valve??

Typically (on an interference engine) if/when a valve sticks open it contacts the piston and that makes a mess of things, minimum a borescope will have to look for damage, but probably head and oil pan, maybe even a main and or rod cap will have to come off to see the damage…

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The title of this topic is: “2015 GMC Sierra 1500 - help with cylinder valves requested” so I’d say they’re asking for help.

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The titles for Ask Someone threads are created by the moderator. They are trying to generate activity to make this forum appear relevant.

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So what is your recommendation for OP’s first step? Take the GMC to a GMC dealership?

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…allow their repair shop to follow through with the repair. They understand that there is a valve problem, someone must have inspected the engine to determine that.

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If I had this problem as a diy’er my first step would probably be to remove the valve cover to see if the valve really is stuck in the down position. I presume that would be informative, never had a stuck valve, so never had to do a visual check. There are many ways to approach this sort of problem. The most cost-effective might be to simply give up and ask the dealership to replace the engine. Hard to know.

16

Tester

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17

My recommendation? Pull the engine, drop in a 502 big block.

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That would work! Problem solved. … lol …

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LT4, more power and better MPG… :grin:

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The thing everyone’s overlooking is that OP is presumably trying to fix his truck in order to pass an emissions test, and most states will not let you pass with a non-OEM engine and ECU, unless the vehicle is from 1995 or older. If we were talking about a 1990 truck, my response would be “sure, why not”, but this is a 2015. He can’t replace the engine with anything other than identical–new, used, or remanufactured.

1 Like