The subject title pretty much says it all. Where can I find step by step instructions for replacing a exhaust manifold gasket on my 90 XJ-S?
Thanks for any help you can give me!
V12?- You may have to take the studs out, or the engine.
Note that the exhaust manifold gaskets were updated somewhere along the line. The later ones have a metal flange around the opening. I wouldn’t accept any replacement gaskets that don’t.
The process is straight-forward: undo 16 nuts, pull manifolds away from engine, clean mating surfaces and reassemble. Undo an additional 4 nuts to separate the manifolds from the first cat to make cleaning the mating surfaces easier.
Now we can talk about reality…
- Steel studs chemically boded into aluminum heads
- Rusted nuts bonded to the other end of the studs
- Is there enough room to maneuver the manifolds after 6 studs are snapped off?
- Do you have a right-angle drill and proper tools to replace the stud holes in the head?
This thread dealt with it better than I can:
You can do those easily - not sure how much space you have around v12 version. Two main methods:
Dewalt DCF894N impact wrench or similar with DWARA120 attachment, hex socket holder and 300mm impact hex extension (milwaukee 305mm). Your rusty nut will go off with thread or without, in pieces. Just spray with Liquid Wrench first
Sulfuric acid (or phosphoric if you’re chicken scared, must do several times), hammer. Whack few times into stud face. Place few drops of acid on nuts or brush in with something narrow. Wait 24hours then spray with Liquid Wrench (not WD40).
Strong suggestion to combine both methods.
To make it right - place piece of glass on the kitchen bench , smear some superglue on it and attach a4/a3 sheet of sand paper 180 grit. Place removed manifolds on the paper and start to dance Macarena until it clears evenly.
Grab grinding wheel or knife sharpener (brand new, block shaped), go under your Jag and do the same with exhaust ports.
Second part wirh grinding is not required/for fanatics only.
Ready to assemble.
If you don’t have a tools required - what you are doing with your pension huh???
There is no room to get the manifolds off the studs, hence take the studs out.
You are AvE, and I claim my £5.
You can remove all four manifolds with studs intact and engine in the car, I’ve done it.
I had the steering rack, starter and downpipes removed.
I did not break any studs, the manifolds come off fine with the studs in place.
Having said that, breaking or damaging studs is a real concern, because if that happens, getting them out of the head is a real problem with the engine in the car.
I held my breath and “went for it” and it all worked out.
Plan for the worst and hope for the best.
FWIW I also removed the “impossible” air pump to air rail pipe at the same time. It took about 47 tries to maneuver it just so, but it finally slid out.