2001 Duramax LB7 Knocking

[rpaoness]

Looks like I may be attempting feed line replacement. Turbo removal likely requires transmission or cab removal to permit access to the exhaust bolts. Feed line replacement is apparently possible, but might require compressor housing removal. I'll have to do some more reading.

[rpaoness]

"It's possible to get the banjo and oil line out of the lb7 without any turbo removal. The horn, and intake ducting has to come off. Get a crows foot (14 if i remember correctly), universal joint, and like 3 long extensions and I was able to get it out. I'm not saying it was easy but I got it. The remote oil line comes with a plug that has an Allen head so you'll have to snake your hand in with an Allen wrench to plug the hole, its do able but a lot of swearing and hopefully you have skinny arms or call someone who has THIN arms to reach down there. While the horns out (pita it self to remove) swap it out for one that's honed and has 2 slots for the two bottom bolts."

https://www.duramaxforum.com/threads/lb ... to.989381/

[rpaoness]

The "horn" they're talking about is just the turbine intake snout, not the whole compressor housing. I was able to get the intake snout off and get the bolt out with a crows foot like they describe. Found a pinhole in the bottom elbow of the line. Ordered a new Gates line from RockAuto for about $95 shipped. Hopefully it comes in soon.

[rpaoness]

Installation of the line was easier than expected. Went pretty smoothly. Ran the truck for about another 10 minutes looking for leaks, then put the inner fenders and wheels back on. Test drove some. I believe there's an exhaust leak that was exacerbating the noise of the knocking that I now think I need to run down. It sounds like the leak is probably right at the firewall - could be an up-pipe from manifold to turbo or downpipe post turbo. Wish I could see better what's going on.

[rpaoness]

Smoke test this morning confirmed there's some very small leak from the drivers exhaust manifold. I wonder how much of the knock was leak vs. injector. If it was mostly exhaust manifold then I guess I could've deferred injector service for a lot longer. Oh well, c'est la vie...

Ordered a Dorman driver's exhaust manifold from RockAuto with a hardware kit. And I finally ordered rotors/pads for the Jeep WK2 since shipping was the same w/ the manifold as for the rotors/pads and the steering wheel shimmy is making me crazy. I also think I had a wheel weight fall off on my last dirt-road-run in VT, so the Jeep has been extra crappy to roll in lately.

[rpaoness]

I forgot about the early Duramax pinched driver's manifold story. So apparently I will be upgrading to a non-pinched manifold because the Dorman manifolds are a copy of the "updated" design that didn't need extra steering shaft clearance.

[rpaoness]

Found the leak - rust hole right through the manifold. I thoroughly inspected gasket areas and mating with the head for any soot or signs of leak. This was hiding under some very crusty pieces of heatshield.

[kevm14]

Now you get to play Russian Roulette with the manifold bolts.

[rpaoness]

Yes. They have been brutal so far. Torched 2, heated 3 up-pipe bolts and then snapped all three (they thread into the manifold, and are likely Monel or Inconel), but not a big deal because the manifold is junk. One unthreaded from the cylinder head so far. 4 more to go. So cylinder head-to-manifold bolts/studs current score is 2 torched, 1 unthreaded, 1 nut cut/removed from stud, and 4 to go.

I also don't like how crusty the water pump-to-oil-cooler pipe looks so I ordered a new one of those. Not sure if I'll tackle that since it might require water pump removal, but I'd feel better having it under the seat traveling since I can get a water pump locally but not that pipe if I get stuck doing a water pump or pipe replacement somewhere. I'm going to poke at it with a screwdriver once I get the manifold out (lays against the block along the manifold), and if it starts leaking I'll go after the water pump now I guess. And I guess that means new water pump? Sheesh this is never, ever, ever ending.

[kevm14]

But think of how safe you are because of all the salt on the roads.