Commons? Valve Stuck Open On A 2008 5.3?

simmons41 · March 16, 2009

Hello all

I start off by saying what a great site to get info. (newbie)

now i need your help!!!!!!!!!!

2008, 5.3 crew cab, non flex fuel w/ active fuel managment.

This weekend, my truck made a funny pop under neath my feet, just once, and my truck started flashing the stability service light and engine light. Drove to my dealer, luckily only 2 miles away, and left it. Today they call and say the a valve broke and its stuck open.. ( i might add that on cold mornings, first start of the day, she would make one little knock under my feet with in the first 5 seconds, same spot and would never do it again) Now the truck hesitates gaining speed and you can really feel it in the pedal and steering wheel. Truck has 6400 miles and the warranty will cover all damages from what the dealer said. They said they would need to pull the heads and go from there.

so, whith this said, is this common, does this make sense, and should I trade the truck in?

I am one that thinks that once an engine is torn a part, it will never be the same.

Stevens03 · March 16, 2009

Well, its not common that I'm aware of. There's always those which just fail to conform..

Give the dealership a chance and see what happens from there.

Steven

Zembonez · March 16, 2009

Well, its not common that I'm aware of. There's always those which just fail to conform..

Give the dealership a chance and see what happens from there.

Steven

+1

Highly unusual. Possibly something to do with the AFM valve train maybe?

Dealer will fix ya up! Let us know what they find once its done OK?

mkelly · March 16, 2009

I am one that thinks that once an engine is torn a part, it will never be the same.

I have never understood this kind of logic.......................

Schmids5.3l · March 16, 2009

I don't see how a valve sticks open and doesn't get ass packed by the piston, which would more than likely completely grenade the entire engine. I don't see how a valve get's stuck open period, lol. The retainer/lock would have to fail for the spring not to lift it back up & seal the combustion chamber, and in that case the valve would drop into the cylinder and dooms day your engine. Same scenario would happen if the spring broke.

Zembonez · March 16, 2009

I am one that thinks that once an engine is torn a part, it will never be the same.

I have never understood this kind of logic.......................

I would not worry about that. Your engine was built by a human before it was ever installed in the truck and it can be repaired by a good technician. It isn't some sacred object... just an assembly of parts. If done correctly there is nothing to worry about.

I don't see how a valve sticks open and doesn't get ass packed by the piston, which would more than likely completely grenade the entire engine. I don't see how a valve get's stuck open period, lol. The retainer/lock would have to fail for the spring not to lift it back up & seal the combustion chamber, and in that case the valve would drop into the cylinder and dooms day your engine. Same scenario would happen if the spring broke.

It's possible that one of the AFM lifters stuck or broke, causing the valve to remain open. That whole "activate and deactivate" thing with my valvetrain doesn't sound very good long term to me. Too many added possible part failures for me for the little it gains in economy (if any)..

Schmids5.3l · March 16, 2009

I don't see how a valve sticks open and doesn't get ass packed by the piston, which would more than likely completely grenade the entire engine. I don't see how a valve get's stuck open period, lol. The retainer/lock would have to fail for the spring not to lift it back up & seal the combustion chamber, and in that case the valve would drop into the cylinder and dooms day your engine. Same scenario would happen if the spring broke.

It's possible that one of the AFM lifters stuck or broke, causing the valve to remain open. That whole "activate and deactivate" thing with my valvetrain doesn't sound very good long term to me. Too many added possible part failures for me for the little it gains in economy (if any)..

Must have missed the AFM part I don't see it being too beneficial either. Honda's variable valve timing is decent for economy and also for power on demand, but trucks need low end. They could reverse it to have full valve lift at acceleration & in tow mode and low valve lift at cruise. IDK if they could work that out with push rod engines though.

Zembonez · March 16, 2009

Must have missed the AFM part I don't see it being too beneficial either. Honda's variable valve timing is decent for economy and also for power on demand, but trucks need low end. They could reverse it to have full valve lift at acceleration & in tow mode and low valve lift at cruise. IDK if they could work that out with push rod engines though.

I don't know if that is his problem but all of this "messing with stuff that already works fine" stuff spooks me. I say build a good pushrod V8 and leave it the hell alone. If people want better fuel economy, let em go buy a 4 banger.

VR021302 · March 16, 2009

Must have missed the AFM part I don't see it being too beneficial either. Honda's variable valve timing is decent for economy and also for power on demand, but trucks need low end. They could reverse it to have full valve lift at acceleration & in tow mode and low valve lift at cruise. IDK if they could work that out with push rod engines though.

I don't know if that is his problem but all of this "messing with stuff that already works fine" stuff spooks me. I say build a good pushrod V8 and leave it the hell alone. If people want better fuel economy, let em go buy a 4 banger.

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simmons41 · March 16, 2009

Thanks everyone for your comments.

as for the valve clearence, one service guy told me that it was ok to drive, (i have to take it to another dealer since that other dealer can't work on it for a 3 weeks, only 4 mechanics) the other dealer said it depends. Depends? oh well, having it towed on GMC tab. Guess they cover a hundred bucks under this warranty.

as for the engine never the same, seen my dad have fits on his GMC van. Never could get that thing to run right and had to pull the motor three times after the heads we off of it. (this is mainly personal experience) It probably be fine once put back togeter but now i just worried that it will happen again, after the 3year 3k miles i get to flip the bill. NO THANKS!

Draenor · March 16, 2009

as for the valve clearence, one service guy told me that it was ok to drive

I'd get that in writing, if you really have to use the truck in the meantime.

Zembonez · March 16, 2009

Thanks everyone for your comments.

as for the valve clearence, one service guy told me that it was ok to drive, (i have to take it to another dealer since that other dealer can't work on it for a 3 weeks, only 4 mechanics) the other dealer said it depends. Depends? oh well, having it towed on GMC tab. Guess they cover a hundred bucks under this warranty.

as for the engine never the same, seen my dad have fits on his GMC van. Never could get that thing to run right and had to pull the motor three times after the heads we off of it. (this is mainly personal experience) It probably be fine once put back togeter but now i just worried that it will happen again, after the 3year 3k miles i get to flip the bill. NO THANKS!

Several random points here.

If the original tech really has a clue what is wrong with it (which I now doubt) you do not want to drive a truck with a valve stuck open.
It sounds more to me like you may have one of the AFM lifters that is not activating.
If the technician hasn't torn down the engine to repair it, I think he is guessing at this point.
Take the truck (tow it) to another dealer and have them fix it ASAP.
No reliable dealer would have you wait 3 weeks for them to work on it. I've dealt with hundreds of dealerships in my work and never saw one that busy... EVER.
An engine that is properly repaired is EVERY BIT AS GOOD as one that has never been worked on. It is no more likely to fail than any other engine.

Good luck!

silveradobobby · March 16, 2009

I've been seeing the valve springs breaking on the 5.3 due to coil bind due to the AFM system messing up! Its been common in my shop!

And yes valves get stuck open all the time its easy but usuall on older models or in proper engine building or bad parts (guides, valves, springs).

On the 5.3 it has enough room to were the valve wont hit the pistons they have enough room on the 5.3.

minibike132 · March 17, 2009

A problem with the 5.3 AFM lifters causes the valves to be stuck CLOSED not open. It isn't an interference engine so even if it was stuck open there would be no "grenading".

It's a good motor, I had a customer feel the same way as OP and not trust his engine after getting into it. I told him it was silly and I was taking his money but he wouldn't hear it. So I bought it, the truck is a daily driver for the little lady and 30k later there isn't a worry in the world with it.

There is a common issue with the AFM lifters dropping out but after replacement they are fine. I would not drive it though, when they collapse if driven for any amount of time you risk flattening a cam lobe.

simmons41 · March 17, 2009

The first dealership only had four mechanics and one that can work on engines. Had some people in front of me i guess.

if it only got any better....

did you know that GMC only covers 5 days worth of rentals while they work on you car.. told by both dealershipds today. The original dealership i took it to says that he could make a case with GMC that it was going to take longer but not promises to extend it out for 3 weeks once i said that a tow co was coming to pick it up. I WOULD HATE TO GET A BILL AFTER GETTING MY TRUCK BACK FOR TWO WEEKS OF RENTAL. i will never take my truck back to the first dealership but didn't want to drive it 35 miles acting like it was. plus these guys said its ok to drive like it was.

should i have them replace all the lifters if it is the case?

to be continued.........