I am replacing the cylinder head on my 2000 4.0 after one too many overheats. I am seeking knowledge/opinions about whether or not the intake/exhaust bolts have to be replaced. If so, could stainless steel bolts be used? I see no markings to suggest the OEM bolts are hardened nor do I see anything in the FSM.


As always, everyone's help is greatly appreciated!

While I'm not sure about your specific situation, I didn't have the need to replace mine during my 0331 project. They were not rusted in and did not break during removal and installation.

You will need a 14mm box end wrench or socket + extensions to get them out. That and a lot of patience

Thanks for the reply. I have mine out and am well on the path of reassembly. Mine were a little rusty and I used my wire wheel on my bench grinder to clean them up and I was just wondering if replacement was required. Thinking of going stainless steel.

I do not recommend stainless steel for this application. They don't have the strength requirements. Stainless steel fasteners should only be used in non-stress type applications. SAE Grade 8 Bolts should be the choice but others say Grade 5 will do. I used Grade 8.


You can buy kits at the auto parts stores. They do not include the conical washers however.

Yes upon closer inspection I was able to see the 6 radial lines on the bolt head showing that it is a grade 8 bolt. I am surprised that that there is that much stress at this attachment. I suppose that holding both the intake as well as the exhaust is the reason.

just curious - why stainless? if torqued to spec the factory bolts will never give you a problem. every xj i've pulled manifolds off of cooperated. basically once you break the bolt loose it will back out with your fingers. i've worked on several that did this. i know the top of them get to looking bad, but don't let it fool you.

I have always used ARP fasteners on my Chevy engines heads were always studs and their black oxide -8 as heads are removed often and the studs can stay in the block.


I asked ARP rep at a SEMA show about the stainless fasteners as I had planned on going to them that year, they gave me the same advice as Ken just did and a chart of where they were useful on the engine. Wish I could find that damn thing but was lost in several moves ago.

Rust. I am just tired of dealing with rust on every component on which I work. I want to leave it a little better for the next person.