1998 yukon Mystery p0300 and rough idle still

[OilBurner2003]

I would recommend using New Felpro intake bolts when re-assembling. They come with loctite Pre applied. Using a thread chaser and cleaning up internal threads is a good idea as well.

https://www.amazon.com/Fel-Pro-ES72224-Engine-Intake-Manifold/dp/B0039SOMUE/ref=mp_s_a_1_1?crid=IF24TTJVPWR0&keywords=felpro+72224&qid=1671328656&sprefix=felpro+72224%2Caps%2C147&sr=8-1

I do not have he’s bolts unfortunately. However, I do have locktite.

 

[OilBurner2003]

How does the mating surface on the Lower Intake look around the coolant ports? Mine were Very pitted!

Now that I'm cleaning it, both surfaces are very pitted, it's very hard to clean. I've been scraping for a hour with a plastic blade and I can still feel the rust/rot whatever this is. How did you handle this?

 

[east302]

Got a picture? Heads or manifold?

It’s usually worst at the corner ports.

 

[OilBurner2003]

This is what it still looks like after my attempts, and it’s manifold.

 

[east302]

Going to defer to others on the feasibility of repair, but I’d be real tempted to find another one. It’s been five or six years, but I’ve bought new ones from GM twice. Part #17113201.

How are the head surfaces in comparison?

 

[OilBurner2003]

Going to defer to others on the feasibility of repair, but I’d be real tempted to find another one. It’s been five or six years, but I’ve bought new ones from GM twice. Part #17113201.

How are the head surfaces in comparison?

The heads look fine, barely any rust or anything like that, can only slightly feel it and I haven't been working on it as much as I've been working on the manifold.

Yikes, I really don't want to have to replace that manifold.

 

[east302]

You can try laying the gasket on it, pressing down and seeing how the gaps look. I’ve heard of people using epoxy to fill in minor pitting. It may just be your photo, but it looks like it has points corroded to the point of forming ridges - particularly the lower right corner.

 

[OilBurner2003]

You can try laying the gasket on it, pressing down and seeing how the gaps look. I’ve heard of people using epoxy to fill in minor pitting. It may just be your photo, but it looks like it has points corroded to the point of forming ridges - particularly the lower right corner.

I'll go test it now.

 

[OilBurner2003]

You can try laying the gasket on it, pressing down and seeing how the gaps look. I’ve heard of people using epoxy to fill in minor pitting. It may just be your photo, but it looks like it has points corroded to the point of forming ridges - particularly the lower right corner.

When I press down on the head surface it looks like it lines up really well, little tricky with the manifold. Can't really tell because If I push down it'll seat all the way, I would imagine that with proper torque it would seat nice and flat? Although I could be wrong of course. Any opinion from you folks is appreciated. Both gasket surfaces are brake cleaned and swiped with a plastic blade, It's as good as I'm gonna get it. I am gonna continue this in the morning, too dark now. Might give me enough time to research if this "Pit" Is going to be a issue for me or not.

 

[east302]

It’s not torqued down a ton, so using the gasket you should be able to tell where the gasket lip will hit if you can put some uniform pressure along it. A straight edge on those areas would work as well so I’d just make sure that they’re flat where the gasket seals.

The areas inside the seal area (between the gasket and the ports) wouldn’t worry me and those are usually where they corrode the most. It’s just where that corrosion creeps toward the gasket lip and goes underneath it that would be of more concern.