Lower valve cover leak with new gaskets & Bolts

[KEVINL]

I am in the process of installing twins on my LB7 Yukon XL. I noticed the Lower valve cover leaking it has new Mahle gaskets and bolts from Lincoln Diesel it seems the gasket is not really getting compressed enough to seal. I bought Merchant Auto bolts to see if they were longer and they look exactly the same besides color. My stock bolts are long gone.

I am thinking adding a washer under the bolts to keep The bolt from bottoming out on the unthreaded shank to allow it to compress a little more.

anybody else ran into this and figured out a solution

 

[gmduramax]

Does it have arp studs? I’ve heard they can hit the valve cover not allowing it to seal

 

[KEVINL]

It has Arp head studs but i dont see it interfering with anything

 

[KEVINL]

Unless its interfering under the valve cover

 

[KEVINL]

Here are pics when i bolted heads on i dont see anything that could cause a issue

 

[gmduramax]

If I remember correctly the lower valve cover goes right over the second row from bottom bolts on the sides. Check to make sure it’s not hitting

 

[KEVINL]

I did some research and did see what you are describing but its seems its on LLY,LBZ Lmm

The Lb7 has the return lines above the head bolts so its lower valve cover is different

 

[Chevy1925]

a washer wont help or different bolts. those rubber grommets that are on teh bolt holes have steel sleeves that only allow them to be compressed so much before steel sleeve bottoms out. the rubber around it is what sets preload to the rubber gasket and holds it tight.

it would be a good idea to remove a rubber grommet and thread a bolt in by hand to see when it bottoms out. Then you know for a fact if the bolt is bottoming out before the grommet is compressed or if its another issue.

 

[KEVINL]

I will try that the grommets are not the original GM ones they are Mahle so I don't know if they are constructed the same

 

[Chevy1925]

I will try that the grommets are not the original GM ones they are Mahle so I don't know if they are constructed the same

they should be. its all ive used and my buddy has them in his shop by the case lol.