Hi,
I will be swapping out my 2 cracked exhaust manifolds with replacements from a donor car and am looking for advice on how to prep them before installing.
I will be cleaning them down with wire brushes and carb cleaner, as sandblasting is not an option. then maybe painting them.
I have found many High Temp Paint options as well as spraying with Graphite Lubricant spray. Any advice on these would be really helpful.
Also, does painting have any mechanical or protective benefits and should paint them at all or just leave the bare metal?






Crack 1 Front Header

Crack 2 Rear Header

Good Headers from donor car

 

Clean the cylinder head side with sand paper, Clean studs with green or red scrubby. Install new gaskets. Clean flat sides of manifolds with sand paper, If you have a straight edge, Check and see if flat. Clean area where the Olive's will seat with sand paper. Don't bother painting. Torque from center out to 23 to 28 Nm's. Good luck.

Thank you.

Larry Louton

 

Hi Larry,

Thanks for the detailed run through. It all makes good sense.,
I'll make sure I clean up the olive seats as well. I guess with the heat shield there's not much to see if it was painted anyway. So, no benefits gained by painting?
I had no problem getting the replacements out from the top of the engine, so am expecting they go in as easy as the come out.

I didn't see any sealants of any kind taking them off, so I am assuming I shouldn't need any going back in.
please correct me if I'm wrong.

 

To emphasise a point made by Larry, take time to prepare the olives and the mating surfaces to the downpipes. New olives wouldnt be a bad idea. The joint is quite tricky to connect due to restricted access, and will give problems with fuel trims if there are any leaks. Ask me how I know.....!

 

If the replacement manifold sealing faces aren't flat, then get them skimmed, otherwise they will be stressed when they are clamped flat against the cylinder head.

 

No sealants.

Get new olives.

Get new exhaust manifold gaskets.

If you have an EGR, you’ll need a new gasket there too.

Everything is straightforwardly difficult to access and tight, but manageable. I had to combine many socket extensions to access the olives, but certainly doable.

Last recommendation, I had trouble getting some of the double theaded screws out, so you may need some extras. The 13 or so nuts for the exhaust manifold came out great, it was either at the olives or the EGR that I had trouble. I’ll go back and see what I ordered....

 

As the XJRengineer pointed out the manifold has to be very flat with the head surface very clean so as not to crack as you torque down. Ask me how I know... No paint. Torque from the center out.

Larry Louton

 

Read through these:

https://www.jaguarforums.com/forum/x...cement-200933/

https://www.jaguarforums.com/forum/x...nifold-134044/

https://www.jaguarforums.com/forum/x...nifold-134620/

 

Thanks to you all for the advice and pointers.
I have new gaskets and olives ordered
So the plan is

Wire brush and carb cleaner to the manifolds
Sand manifold flat surfaces
I know a man with a straight edge
Sand down pipe flanges (will stuff with a cloth first)
Spray with wd40 a day before extraction
Hope the original manifolds come out ok
Check the nuts look healthy (I'll have 2 used sets to play with)
Scrubby the studs
New manifold, downpipe and egr gaskets
Slow and steady with the downpipe flanges
Reconnect EGR to rear manifold
Torque manifold nuts to to 24-28nm
Tidy up, close the hood and go

Thanks
TBC

 

I think there are some single use nuts you're missing...

I will also assume you have no EGR.

If you reread one of those posts I linked above you'll read that I made a list of what you will need to complete this job:

​​​​​​This is what you'll need:

EBC11330 - Gasket Manifold
EBC2909AA - Gasket Manifold
EAC9388 x2 - Donut Downpipe Gasket (OEM seems to be preferred)
FN110041J x14 - Manifold Locknuts (only needed if you have trouble removing yours, I didn't have any issues)
JZN100024 x4 - Downpipe Locknuts (single use only)
EAC3823 x4 - Downpipe Studs (I believe this was for the EGR)
EBC10827 - EGR Pipe Gasket (obviously not needed if you don't have one)

 

WD40 (Water Displacement 40) is NOT really a penetrating oil. (it is mostly fish oil)

I would recommend a product specifically made to penetrate.
Oil of Wintergreen
PB Blaster
Kroil
Liquid Wrench
et cetera

 

I have very recently obtained a can of Kroil and find it most impressive. I used it on a sieved rotary lawn mower blade that would not loosen with WD 40. Alec G.

 

Well if you’re comparing Kroil with WD40, then being most impressed is completely understandable.

One displaces water, the other is a penetrating oil.

 

Thanks again for all the good advice.

I didn't realize the 4 copper downpipe nuts were single use. I am going to order replacements while I wait on the gaskets.(Although the ones that came out of the donor car were not copper)
Searching for JZN100024 x4

I checked the olives (Flange Seals/Donuts) on the old car and they were stuck tight on the downpipes.
Is there an recommended way to remove these and position the new ones for installation?

Mine does have an EGR, so will install a new pipe gasket

Also am hoping I don't need Kroil, but am keen to get some and see it in action.

 

Seems like everyone wants between $5 and $8 for a single nut (JZN100024) plus shipping.
SNG Barratt and OE Jag parts site only sell them in 10's. I can go an pick up from the local dealer 10 for $30.
Probably doesn't hurt to have some spare copper,

 

Welsh has the nuts for $3;98 each, couldn't find the olives on the welsh site? The olives are like a donut with a asbestos interior. Sharp screwdriver to punch a hole thru and pry over the center of the pipe, not the soft outer pipe which forms the flange. Wear mask, gloves and safety glasses if you have never done this before like those buffoon's missing body parts on You-tube. Remove front O2 sensor's, Mark first so you don't have to remember which one goes to which exhaust.

 

I had to use a dremel to cut one out. Be careful not to cut into the downpipe, but I made a notch, or notches big enough to weaken it so it could be pried out with a screwdriver.

 

Thanks again,
I really appreciate all the good advice. I'm waiting on gaskets and nuts which could be a week or two.
I read a lot more about the graphite spray, there doesn't seem to be any ill effects and the finish looks great, not at all like paint. I decided to take the plunge.
It leaves a coating of graphite, which looks like black cast iron
Thank you Larry for the 'No Paint' advice, but I kind of went with my heart on this one.
Please let me know if I've made a horrible mistake. I did manage to find a local company that can sandblast them

 

They look good! What's the temperature range on the paint? I assume it won't last, but I don't think there's any harm done. The XJS has a metal shield so you can't even see these manifolds...

 

So does the X300.