1998 yukon Mystery p0300 and rough idle still

[OilBurner2003]

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.

Roger, will double check in the morning. Thank you!

 

[YukonGTmaster]

Roger, will double check in the morning. Thank you!

I was in the same boat as you. I have attached the link of my documented adventures. Hope some of it helps you. I found that replacement intakes were not available, that incorporated the stock fuel delivery system. I repaired mine myself, and still holding.

5.7L Vortec Problems

I was having a rough idle, and the Amber engine light would flash (Random misfire) when I started up in the morning. I would cycle the key off for ten seconds, the light would go out and I would drive to work. It was not latching any codes. I had a bad coolant leak as well. Then I started to...

www.tahoeyukonforum.com

 

[OilBurner2003]

I was in the same boat as you. I have attached the link of my documented adventures. Hope some of it helps you. I found that replacement intakes were not available, that incorporated the stock fuel delivery system. I repaired mine myself, and still holding.

5.7L Vortec Problems

I was having a rough idle, and the Amber engine light would flash (Random misfire) when I started up in the morning. I would cycle the key off for ten seconds, the light would go out and I would drive to work. It was not latching any codes. I had a bad coolant leak as well. Then I started to...

www.tahoeyukonforum.com

Well shit... Looks like mine are even a lot worse than yours. Makes sense too. P0300, vacuum leak, This damn intake probably explains all the engine issues I've been tracking down, I have the upgraded spiders in the current intake because I ruled out I had one or more leaky injectors. I would love to take a crack at fixing it, But I don't know the first thing when it come to epoxy/sanding. If I buy a new intake, means I have to take out my upgraded Injectors, Folks have told me from the manual that they really shouldn't be removed, Now I'm in a bind lol. Well, Looks like it's not going on tomorrow! From the symptoms you just told me other than the coolant leak, It's the exact same as mine. I have two options it looks like. Fix the pitting or get a new intake. Time for research! Thank you for your post, it was extremely helpful.

 

[OilBurner2003]

I was in the same boat as you. I have attached the link of my documented adventures. Hope some of it helps you. I found that replacement intakes were not available, that incorporated the stock fuel delivery system. I repaired mine myself, and still holding.

5.7L Vortec Problems

I was having a rough idle, and the Amber engine light would flash (Random misfire) when I started up in the morning. I would cycle the key off for ten seconds, the light would go out and I would drive to work. It was not latching any codes. I had a bad coolant leak as well. Then I started to...

www.tahoeyukonforum.com

Did you follow a step by step guide when fixing your intake, or did you just slap some epoxy on there and smooth it out?

 

[YukonGTmaster]

I have a background in aircraft maintenance, so I followed some "standard practices". I was lucky enough to have access to an industrial hot bath parts washer, then hit the area with a bead blaster. I contemplated Alodine etching the area before epoxy, but decided against it. The main goal was to smooth on the A4 Metalset, as Thin as I could get it, with a razor blade. After the coats set up. I took a flat metal bar and lightly sanded it. I think it came out quite good.

 

[YukonGTmaster]

Did you follow a step by step guide when fixing your intake, or did you just slap some epoxy on there and smooth it out?

Above.

 

[OilBurner2003]

I have a background in aircraft maintenance, so I followed some "standard practices". I was lucky enough to have access to an industrial hot bath parts washer, then hit the area with a bead blaster. I contemplated Alodine etching the area before epoxy, but decided against it. The main goal was to smooth on the A4 Metalset, as Thin as I could get it, with a razor blade. After the coats set up. I took a flat metal bar and lightly sanded it. I think it came out quite good.

That makes a lot more sense looking at it that way. I’ve been calling machine shops all around and it looks like no one does lower intake manifolds with my luck! I saw a video of someone who did their own repair and it didn’t look so hard. Although…It was using JB WELD and sandpaper, I’m not sure I have the skills for such a repair, mostly because I don’t know what to look for. Am considering a new intake at this point!

 

[YukonGTmaster]

That makes a lot more sense looking at it that way. I’ve been calling machine shops all around and it looks like no one does lower intake manifolds with my luck! I saw a video of someone who did their own repair and it didn’t look so hard. Although…It was using JB WELD and sandpaper, I’m not sure I have the skills for such a repair, mostly because I don’t know what to look for. Am considering a new intake at this point!

When I first saw my intake, I thought of scrapping it immediately. Only after trying to source a new one with no luck, did I start planning the repair. The main thing is to blast the area and clean out all the pitting corrosion. If you do attempt the repair take your time, and clean and prep well. I used Methyl Ethyl Keytone on lint free cloth as a final wipe before the Metal Set. Don't get that crap on you skin! Wear gloves! Lol

 

[OilBurner2003]

When I first saw my intake, I thought of scrapping it immediately. Only after trying to source a new one with no luck, did I start planning the repair. The main thing is to blast the area and clean out all the pitting corrosion. If you do attempt the repair take your time, and clean and prep well. I used Methyl Ethyl Keytone on lint free cloth as a final wipe before the Metal Set. Don't get that crap on you skin! Wear gloves! Lol

Looks like I’m gonna take a crack at it, it’s my best shot. Looking on the head, the first coolant port on driver side seems to be slightly rough, gonna figure out a way to clean that up. It’s surface corrosion/rust, the rest of the ports are fine. What a journey this has turned out to be! All I wanted to do was just change gaskets, If it doesn’t work at least I can say I tried. More concerned about that one head coolant port than anything else now.

 

[Fless]

When I first saw my intake, I thought of scrapping it immediately. Only after trying to source a new one with no luck, did I start planning the repair. The main thing is to blast the area and clean out all the pitting corrosion. If you do attempt the repair take your time, and clean and prep well. I used Methyl Ethyl Keytone on lint free cloth as a final wipe before the Metal Set. Don't get that crap on you skin! Wear gloves! Lol

Yes, gloves! Should consider wearing a good respirator when working with MEK, or at least do it outside and upwind.