Intake Manifold Torqueing

[Wild one]

My buddy ported his intake manifold on his 6.4 Scatpack a couple weeks ago,and last weekend i helped him reinstall it,and we torqued all the bolts to 108 in-lbs. I told him to plug in the block heater for a couple hours each day,and i'd come back this weekend and we'd recheck the bolts. I went over tonight and we got another full turn on every bolt.The car hasn't moved and was only started twice,once when we first reinstalled the manifold,and i had him start it last night and bring it up to temp,then shut it down, that way it would have one more heat cycle,before retorquing it today.
He used all new gaskets when we put it back on.
Just goes to show how much the bolt torque changes over a week,even if you don't drive them.
All i got to say,is check your intake manifold bolts every time you change oil,and retorque them if they're loose.
It's one of my standard checks ,while the oil is draining,and should be on the list of things to check while doing an oil change in my opinion.

 

[EdGs]

Would threadlocker help any?

 

[HEMIMANN]

All new gaskets is the key term.

Brand new squish to keep retorquing over and over.

Threadlocker does not help. The screws are not backing out - the gasket is taking a compression set. They need a better gasket.

Which reminds me - I need to go change my gear oils!

 

[Wild one]

Would threadlocker help any?

I've used blue thread locker,and they still end up needing retorquing Ed. I don't think it's an issue of the bolts backing off,so much as an issue with gaskets and the manifold itself changing shape.He never drove the car,and it only ran for maybe 20 minutes at most between torquings,with 3 days of about 4 hours of being plugged in on the block heater,so it had about 12 hours of block heater heating,and the 2 heat cycles of being started and brought up to about 185 engine temp,so i don't see that causing a bolt back off issue

 

[EdGs]

All new gaskets is the key term.

Brand new squish to keep retorquing over and over.

Threadlocker does not help. The screws are not backing out - the gasket is taking a compression set. They need a better gasket.

Which reminds me - I need to go change my gear oils!

That makes sense.

But, if that thing happens, why are they not retorqued when the vehicles are built?

 

[Wild one]

All new gaskets is the key term.

Brand new squish to keep retorquing over and over.

Threadlocker does not help. The screws are not backing out - the gasket is taking a compression set. They need a better gasket.

Which reminds me - I need to go change my gear oils!

Even well used O-rings still need retorquing every once inawhile so i don't think it's exactly a new O-ring issue.I agree,they need a redesign on the way the manifold is sealed though,as we never had these issues back in the days of actual intake gaskets

 

[Wild one]

That makes sense.

But, if that thing happens, why are they not retorqued when the vehicles are built?

I'm actually wondering if it's not a manifold issue Ed,and not so much a gasket issue.I'm no engineer,but i wonder how much squish the composite manifolds have once they've been heat cycled.
The early 6.1's used an aluminiun intake manifold,and i've never ran into one of them needing constant retorquing like the composite manifolds require

 

[EdGs]

I never touched my intake bolts until I checked them several months back, and they were all tight.

Weird.

 

[Wild one]

I never touched my intake bolts until I checked them several months back, and they were all tight.

Weird.

Your truck does throw a monkey wrench into the mix,lol. The bolts are loctited from the factory,which makes me wonder if the loctite might be giving you a false sense of torque,as you're about the only one who hasn't reported an issue with intake bolts. Did you check them with a torque wrench,or just by feel.

 

[EdGs]

No, just by feel.

 

[Ken226]

I'm actually wondering if it's not a manifold issue Ed,and not so much a gasket issue.I'm no engineer,but i wonder how much squish the composite manifolds have once they've been heat cycled.
The early 6.1's used an aluminiun intake manifold,and i've never ran into one of them needing constant retorquing like the composite manifolds require

I believe these manifolds are made of glass reenforced Polyamide66 (PA66), A type of nylon. I think it's commonly referred to as Nylon 66.

The glass transition temp of PA66 is around 70-90c, depending on the exact formulation, so you are probably right.

I'm sure it's great for keeping a cool air charge flowing into the heads, but I wouldn't be surprised If a really hot day and higher than normal under hood and engine temps could get parts of the intake up to the glass transition temp.

 

[Wild one]

No, just by feel.

Do you have access to a decent inch-pound torque wrench Ed,as i wonder if you shouldn't check them with a torque wrench

 

[HEMIMANN]

That makes sense.

But, if that thing happens, why are they not retorqued when the vehicles are built?

Let me be simple - if it starts and runs, it ships.

The end.

I have many stories to tell if you'd like.

 

[Wild one]

I believe these manifolds are made of glass reenforced Polyamide66 (PA66), A type of nylon. I think it's commonly referred to as Nylon 66.

The glass transition temp of PA66 is around 70-90c, depending on the exact formulation, so you are probably right.

I'm sure it's great for keeping a cool air charge flowing into the heads, but I wouldn't be surprised If a really hot day and higher than normal under hood and engine temps could get parts of the intake up to the glass transition temp.

I've wondered if it's a manifold issue for a few years now Ken,as i've never ran into a 6.1 intake having issues with maintaining bolt torque

 

[HEMIMANN]

Even well used O-rings still need retorquing every once inawhile so i don't think it's exactly a new O-ring issue.I agree,they need a redesign on the way the manifold is sealed though,as we never had these issues back in the days of actual intake gaskets

Well hell - remember when they first started putting aluminum heads on cast iron blocks and all the head gaskets failed ~ 60,000 miles cause they got torn by the thermal cycling between two very different materials with 3 times differing thermal expansion rates?

Uh huh.

Hence the composite head gasket with steel sheet backing.

 

[EdGs]

I have a cheapie click type I bought from RockAuto.

Im always scared the cheapie wrenches won't work, so I 'test' them at a light torque, then increase it in a couple steps up to the torque I need.

Always worried I won't hear or feel the click when I reach the set torque.....lol.

 

[Wild one]

I have a cheapie click type I bought from RockAuto.

Im always scared the cheapie wrenches won't work, so I 'test' them at a light torque, then increase it in a couple steps up to the torque I need.

Always worried I won't hear or feel the click when I reach the set torque.....lol.

I can relate to that,lol.You can home calbrate a torque wrench.There's a few videos on youtube if you google how to calibrate a torque wrench.

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