Cursed Intake Manifold Bolts?

[Kwing]

I got a heck of a WTF situation with my intake manifold bolts. Hoping you folks can help me figure it out and fix it.

A couple years ago, I had an air leak on my '07 Tahoe 5.3, currently at 310k, and it was probably 250k or 260k at the time. I tracked down the leak with a smoke machine, and it wound up being the passenger front intake bolt - which had completely fallen out. The only time I had taken the manifold off to that point was when I replaced the long block at 200k due to my first AFM failure. When I did the engine swap, I replaced all 10 bolts with brand new ones.

After discovering the missing bolt during the air leak episode, I replaced all 10 bolts again, and in so doing discovered all of them were barely finger tight. Mystery solved on how it fell out, right?

Since then, I have had several other repairs that required either removing the manifold or working in close proximity to it. Each and every time, I have found the bolts either loose, or loose with shredded and/or missing seals. Each time, I have replaced all 10 bolts, installing and torquing according to the Haynes manual.

So imagine my surprise when I went to take the manifold off today for another AFM failure, and discovered 5 of the 10 of my 4th or 5th set with shredded and/or missing seals, and all but 2 finger loose.

Yet again, I've ordered 10 replacements, but this is getting REALLY old.

Has anyone else had issues like this with the intake bolts? Any ideas what the bleep is going on? I'd really like for this to be the last set...

 

[OR VietVet]

What torque spec are you using? What gasket manufacturer are you using?

 

[Kwing]

What torque spec are you using? What gasket manufacturer are you using?

IDK? LOL

Seriously though, I have a terrible memory and would never be able to remember the specific torque values for more than a couple days, but I know this, so I crack open the Haynes manual every time for the pattern and values. I know it's a two stage torque, center-out pattern, and I seem to remember the values being fairly low, but not surprisingly so given length of the bolts and the plastic manifold. The manual is on the other side of town with the torn down truck at the moment, so I can't open it to tell you .

As for gaskets, the intake manifold gaskets are Felpros. The bolts come with the seals already on them and have varied in brand. First set was AC Delco from Rock Auto (where I got the longblock). Second set was either from Autozone or O'Reilly's, but I can't remember if they were house-brand or Delco. All the subsequent sets have been from Amazon, because both Autozone and O'Reilly's have quit carrying them. The Amazon bolts proport to be "OEM", and the box does seem to indicate they are (some boxes have shown up with AC Delco labeling, others with "GM Genuine"), but I probably wouldn't bet the farm on authenticity if I had to.

These are they: https://www.amazon.com/GM-Genuine-8...------------&vehicleName=2007+Chevrolet+Tahoe

 

[Charlie Yukon]

I got a heck of a WTF situation with my intake manifold bolts. Hoping you folks can help me figure it out and fix it.

A couple years ago, I had an air leak on my '07 Tahoe 5.3, currently at 310k, and it was probably 250k or 260k at the time. I tracked down the leak with a smoke machine, and it wound up being the passenger front intake bolt - which had completely fallen out. The only time I had taken the manifold off to that point was when I replaced the long block at 200k due to my first AFM failure. When I did the engine swap, I replaced all 10 bolts with brand new ones.

After discovering the missing bolt during the air leak episode, I replaced all 10 bolts again, and in so doing discovered all of them were barely finger tight. Mystery solved on how it fell out, right?

Since then, I have had several other repairs that required either removing the manifold or working in close proximity to it. Each and every time, I have found the bolts either loose, or loose with shredded and/or missing seals. Each time, I have replaced all 10 bolts, installing and torquing according to the Haynes manual.

So imagine my surprise when I went to take the manifold off today for another AFM failure, and discovered 5 of the 10 of my 4th or 5th set with shredded and/or missing seals, and all but 2 finger loose.

Yet again, I've ordered 10 replacements, but this is getting REALLY old.

Has anyone else had issues like this with the intake bolts? Any ideas what the bleep is going on? I'd really like for this to be the last set...

I'd ck it with another torque wrench.

 

[strutaeng]

I can't imagine how the bolt would fall out, given that they thread downward. The bolts have to get pulled up the full length of them, to fall off.

You sure you didn't have any work on that vehicle at some point at a shop? It's more likely that someone tightened the bolts with an impact (would explain the torn seals) and just never reinstalled the missing bolt because they lost it...

 

[swathdiver]

First pass is to 44 inch pounds of torque and second pass is to 89 inch pounds. I've done it enough to remember.

Some fellas torque using foot pounds and wind up destroying the rubber insulation and or ripping the heads off the bolts.

I've only used GM OE parts and have not replaced my bolts even though the insulation is aged.

 

[Kwing]

I'd ck it with another torque wrench.

I can't imagine it being that far off, but I guess anything's possible. The wrench is lightly used, but coming up on 20 years old now.

I can't imagine how the bolt would fall out, given that they thread downward. The bolts have to get pulled up the full length of them, to fall off.

You sure you didn't have any work on that vehicle at some point at a shop? It's more likely that someone tightened the bolts with an impact (would explain the torn seals) and just never reinstalled the missing bolt because they lost it...

I have nothing intelligent to say, LOL. I had the same reaction when I discovered it. Because I'd only taken it off and installed it that one time, I didn't even recognize it was the bolt hole when I found the leak. My only guess is that it had backed out completely, and one of the bounce fests taking my kid to camp tossed it out, although for a 4" bolt that's such a bear to put in, I'm still with you on this one.

The truck has only been to the shop once, for a new ECU. There was one, very regrettable time, when the truck needed a new dipstick tube, exhaust seals, and an oil pressure sender in the worst way, and I had just had surgery, so my monkeys-posing-as-BIL's came over and "helped" me. They broke the heater Y at the firewall, stripped the threads completely out of the valve cover bolts, broke some spark plugs, cut the harness off going into the oil sender, and managed to mangle every connector on the passenger side. But that was AFTER the missing bolt incident and could only explain one of the subsequent episodes, assuming they did mess with the intake bolts.

Regrettably, whatever stupid thing is being done here is being done completely by me, LOL.

First pass is to 44 inch pounds of torque and second pass is to 89 inch pounds. I've done it enough to remember.

Some fellas torque using foot pounds and wind up destroying the rubber insulation and or ripping the heads off the bolts.

I've only used GM OE parts and have not replaced my bolts even though the insulation is aged.

One of the few things I can guarantee is that they have not been torqued to ft-lbs . I only have one torque wrench that can do in-lbs, a little 1/4" drive unit, and it doesn't even have a ft-lbs scale on it. My other torque wrenches bottom out at 20 ft-lbs (240 in-lbs), so they couldn't even be used in a "maybe" moment of desperation. I'd also imagine if that had happened - attempting to torque to 44 ft-lbs and 89 ft-lbs - there would be no threads left in the holes, like what was done to my valve cover bolts... which will finally be getting drilled and threadserted today as a matter of fact, LOL.

 

[mikez71]

Metal fel pros?

I notice you had a previous post where you found all intake manifold bolts missing the grommets..

Also you mentioned the hole missing bolt appeared jagged.

Any chance the grommet sealing surface got chewed up?
Engine vibrations cut up grommet, lessening tension, loosening bolts?

 

[SpareParts]

Im at a loss here. I have R&R many LS intakes. I can not ever remember seeing a grommet on any intake hold down bolt.
What am i missing?

 

[Fless]

Loctite an option?

 

[SpareParts]

I never knew this. I have only ever seen the second pic.

 

[mikez71]

The pictures of his bolts on amazon had loctite.

I'm guessing those earlier mani bolts with grommet, must not quite interface properly with the later manifold? Maybe the flange is different thickness?

 

[Kwing]

Metal fel pros?

I notice you had a previous post where you found all intake manifold bolts missing the grommets..

Also you mentioned the hole missing bolt appeared jagged.

Any chance the grommet sealing surface got chewed up?
Engine vibrations cut up grommet, lessening tension, loosening bolts?

Plastic Fel-Pros. Didn't know they made metal for this intake.

I guess the jagged holes could be chewing it up. Idk how to verify the holes aren't the way they're supposed to be though.

Any suggestions?

 

[Kwing]

Loctite an option?

They come with blue loctite on them. I considered cleaning that off and putting red or pink on there, but it makes me shudder when I think of taking it off next time...

 

[Kwing]

The pictures of his bolts on amazon had loctite.

I'm guessing those earlier mani bolts with grommet, must not quite interface properly with the later manifold? Maybe the flange is different thickness?

Now ya'll got me worried. Every set I've bought has had the grommets, and all of them claimed to be for my truck.

BUT, there are several parts I've had to source for this truck that always bring me to '06 and older models, almost like '07 was a squishy transition year like the GMT100 to GMT400 transition, where trucks rolled over in '88 and the SUVs didn't catch up until '92.

Fudge.

Anyone know for sure if the '07 and up should or should not have the grommets?

 

[SpareParts]

My 07 6.2 does not have the grommet style.

 

[Kwing]

My 07 6.2 does not have the grommet style.

But is the 6.2 the same as the 5.3? That's well beyond my knowledge base...

 

[mikez71]

Well if I go to rockauto, and select an '07 5.3 tahoe, it shows the non-grommet style..

 

[SpareParts]

Wife 2013, 5.3 Avalanche does not have grommets.

 

[Kwing]

Son of a.............

Ok, so two pre-sword-falling questions:

1. How do the flanges seal without the grommets?

2. Anyone know if I can just pop the grommets off and use these? Or anyone maybe have some hanging around they could measure the sleeve length on?