I’m finally getting my 1995 XJS 4.0L back together after installing a complete rebuilt power steering system & new hoses, new oil cooler hoses and a new downpipe w/catalytic converters (with all new gaskets and exhaust nuts). Looking at the service manual, it calls for the four “Manifold to Downpipe” nuts to be torqued to 30-35 Nm. That seems a little excessive to me. I am at 18Nm right now. Do I keep going? As always, your input will be greatly appreciated.

 

I just can’t come up with a single reason to tell you to deviate from the manual. If it says 35Nm, and you’re sure it’s 35Nm, then damn the torpedoes and torque them to 35Nm!

 

By the way, when I did this project, I noted that I tightened them to 30Nm. There’s a reason you’re using single use nuts. (You are using those, right?)

The manifold to the block was tightened to 50Nm!

 

Thanks VEE. Yes on the single use nuts and manifold to engine torque. I was just afraid of twisting off a stud but you make a good point. Thanks again.

 

The crushable gasket ring between the downpipe and the manifold needs to be crushed, so use the factory settings. It can seem a bit hard to do before it gets started on being crushed. Number 2 on this diagram for your car, I think - not being very knowledgeable about 4 litre cars..
https://parts.jaguarlandroverclassic.com/parts/index/part/id/C03.910.91030.91030251.910302514249/brand/jaguar/

 

Took the words outta my mouth...

Just try to turn them down slowly, evenly, straight-ly and in stages... I didn't, now I have to go back - new gaskets. If they are crooked, getting to the spec will "feel" weird, where rather than crushing down the gaskets it'll be a more pinched manifold on down pipe metal on metal STOP...

First time around, I messed up.

 

You mean #3

those are the donuts, or olives. When I did this, I received parts that were the wrong size, I just couldn't get them to fit. Wasted the one-time use nuts trying to make it work, and I ruined them. When I re-ordered new ones, they were different, fit right in, and I was able to torque them down correctly. I had never done work at the exhaust before, so I didn't know how they should fit before getting crushed.

JayJagJay gives excellent advice here as well. Access with your extension sockets while underneath the car, and over the top of the car will be challenging here to be patient, so you may need a second person here.

 

Expect to have to revisit them more than once for a nip up to get the seal.

 

I guess that means I have to go back in there and check. I haven’t ever gone back to mine…

Will update in about a week when I set some time aside to check. (Getting ready to replace both tie rod ends.)