2000 suburban 5.3 l bad intake gasket?

**markpa** · 01-05-2017

Pretty sure I have this diagnosed as a leaking intake manifold gasket that seals up when warm. Has a lean code on both banks. P0172 and P0174 iirc

Here is a cold start at -5 F with the block heater plugged in. Idle surges for 45 seconds or so when temp is below 10F. After it warms up runs great and runs great on any other start that day.

https://vimeo.com/198207399

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**markpa** · 01-05-2017

Sorry video error on my part. I will grab one tomorrow.

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**markpa** · 01-05-2017

Got the parts already. Will do the knock sensors while I'm in there.

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**Scottydoggs** · 01-05-2017

might want to change the k/s harness while your there too, they get beat up from the heat and can and will break if they want to. if yours has them foam inserts at the front and rear of the manifold toss them in the trash, and then you'll want to rtv the foam covers over the knock sensors to seal them up, the rear one will likely be full of water. the rtv stops that.

like so.

**markpa** · 01-05-2017

Yep saw that on you tube. Picked up a new harness and RTV as well. Thanks for the tips. Hardest part seems to be not breaking any 17 year old plastic parts you have to undo.

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**Scottydoggs** · 01-05-2017

the evap line down the back of the engine is a fun one. other then that its not all that bad, dont loose the fuel line o rings, they are 40 bucks to replace with ones that work. dealer only item. you can use other types but they all seem to leak later on. yes, i lost one, only to find it over a year later in the gravel driveway i was working on.

**markpa** · 01-05-2017

Are those at the main rail disconnect? I planned on leaving the rail on the intake.

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**Scottydoggs** · 01-05-2017

theres a hard fuel line over the top of the manifold, pretty sure it had to come off. i ended up removing it. its been like 4 years since i did the job so all events are foggy at best. i recall all the headaches tho like it was yesterday lol

**Below Average Joe** · 01-05-2017

Did this to my Silverado as well. I removed the fuel rail iirc. There is a special tool you are supposed to use to disconnect the lines for the rail. i cut a sharpie cap in half, the sliced one side down the middle so it can fit over the rail. Press it into the clip and it should come free. Its been a few years as well for me, so all of the steps seem foggy too.

**Scottydoggs** · 01-05-2017

Originally Posted by Below Average Joe

Did this to my Silverado as well. I removed the fuel rail iirc. There is a special tool you are supposed to use to disconnect the lines for the rail. i cut a sharpie cap in half, the sliced one side down the middle so it can fit over the rail. Press it into the clip and it should come free. Its been a few years as well for me, so all of the steps seem foggy too.

the same fuel line quick disconnect tool we use for the gp's works to get the line off the rail.

**Below Average Joe** · 01-05-2017

Sharpie cap was free dollars. I'm cheap.....

**markpa** · 01-05-2017

If I pop the fuel rail off do I lube the o rings with oil or something when reassembling?

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**markpa** · 01-06-2017

Fricken Murphy's law. Threaten to put a wrench to it and it starts fine. -9 F cold start block heater plugged in this am and I do the video right and no surging. Solid idle.
https://vimeo.com/198347543

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**markpa** · 01-19-2017

It was 42 today so I decided to just change the knock sensors and gaskets. Did notice a mouse was constructing a nest in an area where I thought the intake was leaking. Maybe some crap sealed it up. Anyway dove in. Pretty straight forward. Lots of cleaning to do.

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