Intake manifold gaskets

1998 CHEVROLET 1500

240,000 MILES • 5.7L • V8 • 4WD • AUTOMATIC

PPRINCE72

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58 POSTS
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Hi, my original engine intake gasket failed and trashed the engine at 120,000 miles. My fault was using a little antifreeze.
Picked up used engine and Chevrolet dealer replaced intake with old engine and installed it and ran like new again. Then about 50,000 miles later it started using antifreeze again
Then I replaced the intake gaskets with Fel-Pro Intake Gasket Part # MS90131-2 I was told they were the best to keep manifold from leaking again. Now about 60,000 miles later the same thing.
Runs great Last time I replaced them I checked with straight edge and looked okay. I didn't replace the intake bolts when I did it last and unsure if Chevrolet dealer did.
My question is on the gasket manufacturer, should the bolts be replaced every time, and should I get the intake machined to be safe?

Thanks! PHIL

Jan 2, 2022 at 8:42 PM

JACOBANDNICKOLAS

CERTIFIED EXPERT
110,175 POSTS

Hi,

The bolts don't need to be replaced if they are still in good condition. However, the manufacturer does indicate applying thread lock GM P/N 12345382 to them before reinstalling them.

Additionally, there is a specific torque sequence and torque spec that should be followed.

As far as having the intake machined, if you use a straight edge and there are no variations indicating it's warped, then no to that as well.

Let me know if you have other questions and if this helps.

Take care,

Joe

Jan 2, 2022 at 8:53 PM

KASEKENNY

CERTIFIED EXPERT
18,907 POSTS

I agree with Joe but just want to add that if you are machining any surface then you need to take that into account when you are tightening it back down.

Basically, if you are taking material away on the mating surfaces then you need to account for that in increasing the seat space on the bolt with a washer. This will prevent you from bottoming out the bolt and either damaging something or not getting the proper torque.

Plus, I am attaching the process below on how to replace the intake because there is a torque sequence as Joe mentioned but also some other info that you should be aware of, if you are not.

Thanks

Images (Click to enlarge)

Jan 4, 2022 at 9:52 AM