When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Replacing the exhaust sealing rings at the manifold
Dear friends, I have a slight blow at the rear manifold joint. I intend to replace both of the sealing rings EBC 9388. I have a couple of queries that I would appreciate your valued opinons.
I want to replace the four nuts that clamp to the studs on the manifold. I am not sure if they should be brass, stainless or mild steel. A part number of the correct nut would be great.
Secondly, my heat shield plate is rather scruffy and I intend to spruce it up as I am in the area.
I have managed to remove the two smaller bolts on the left side, but the large 7/8 AF bolt at the rear is siezed solid. I have been soaking with penetrating mixture of acetone/transmission fluid for two days and it still wont budge. I am worried if I try much harder, the bolt would shear and I might swear a little!.
I have resisted the urge to give it some shock with a hammer as the manifold is cast iron I believe. Should I get the blowtorch on it, or just give it a few more days for the fluid to penetrate? Any advice would be much appreciated on this matter also.
Best wishes to all, Danny.
I've never had one of those not come out after soaking for a few days with PB Blaster, bolt C23435 right ? I would try running it ( if possible ) or heat the manifold with the torch until it gets hot then cool just the bolt with ice cubes, freeze spray etc. That should make it break loose. It's not been put in with JB Weld ( metal epoxy ) has it ?
Hope this helps,
I have used stainless steel nuts at the down pipe flanges in both my Jags and no problem. Brass is too lame in my opinion,
For the manifolds-to-head, brass is fine, but for the exhaust pipe flanges I don't like them.
Don't forget to use anti-seize on those 8 nuts.
Removal of the giant bolt is a pain, I ended up using a short socket with a 1/2" ratchet and tapping it with a rubber mallet back and forth until one day it gave.
I say Back and forth because the scottish machinist in youtube says to gently tap it clockwise as if tightening it, then tap it counter clockwise until you break the rusting glue. Takes a while doing this but it works. Just don't rush it.
HINT: WD40 is too weak for this bolt. you need industrial strength penetrating fluid. Blast Off.
I would not mess with any type of fire or torch in there. Worst case just remove the rear manifold and then torch it. It is another pain to remove but....
I sent my manifold shield to Jet-Hot Coatings and they did the Sterling coating (ceramic and silver).
The coating keeps the shield about 40% cooler than before. Highly recommended.
Many thanks Jose for your very good advice, as always. I am most grtateful.
Kindest regards, Danny.
you're welcome Danny.
On reassembly, I suggest you get two stainless steel fender washers, one for the 13mm bolt and one for the giant bolt and place them under the shield, on top of the manifold holes for those bolts.
this will raise the shield about 1/16" away from the manifolds, allowing some air circulation between the shield and manifolds preventing rust accumulation. This has worked great in my car.
You will need to enlarge the hole of the washer for the large bolt, hard to find one that large.
Thank you Jose, I will definitely do that. More sound advice, which is why I really love this forum.
I have not been able to find any stainless steel manifold nuts here in the UK as yet. Do you have a part number or specs that will help me?
Many thanks once more, Danny.
Danny,
I just took an old nut to my local ACE Hardware store and I just gave them the nut and told them I needed 10 nuts in stainless steel. They have Metric and SAE sizers to find out the thread, whether coarse or fine.
I can't recall the size or thread, that was years ago. They even had them chromed but each nut cost a fortune.
However if you can't find them, I will get them for you. Shipping to UK is between $25. and $35. depending on size and weight of package.
Oh Jose, that is so kind an offer, but I am sure I will be OK. Fraser has pointed me in the right direction here in the UK.
Thank you so much.
Regards, Danny.
Jose - I'm thinking of sending my two manifolds to Jet-Hot coatings. Engine temps run fine without A/C running (185-190) but run up to 200-205 when running A/C. Think the ceramic coating will help? Anyone else please feel free to chime in.
Bill,
Jet Hot does headers for hot rods so surely it will help the under hood temp, but I don't know to what extent.
They offer different levels of coatings so I would call and ask them, being that the manifolds are cast iron as opposed to
stainless steel or mild steel as I did to the Y pipe in my car.
they will first blast clean the parts you send them, then they are coated inside and outside.
I did not have the manifolds done because of the expense of the other parts I had done at the time.
I can tell you that the hot floor under the front seats dissapeared, so these ceramic coatings are not snake oil, they do work. Also in my car, I had this done in 1999 and it is still like new, it is long lasting.
If you have your manifolds done, document the before and after, I am still wanting to do my manifolds with their "extreme" coating.
I got a quote from Jet-Hot to do just the manifolds and it was a whopping $600 plus I pay shipping to get it there. I found a company here in Palm City Florida called Power Coating FL and they do ceramic coatings also. I went there yesterday with my XJ6C and saw several samples of their work and I was impressed. Owner is Kris Heveron 772 215-0309. He looked at my car and quoted $150 for both manifolds AND the Y pipe to ceramic coat them inside and out. I pulled them off the car last night and broke one stud on the back one and one stud is in a cracked hole. So I brought it to a machine shop this morning to have them replace both studs, but they can't weld the cast iron. Drat! Guess I'll JB Weld that one and not tighten it as much as the other three nuts for that compression ring. Always something. The machine shop just called and said it's ready so I'm bringing all three parts to Palm City place. They said they could get them done for beginning next week. When I drop them off I'm going to make sure that it's going to be their best job and if not, I'm willing to pay a bit more for the top shelf stuff. I'm only doing this once and I want to see a temperature change! I will keep you all posted with pics and dialog.
Well, I just got a major disappointment when I picked up the rear manifold. They broke off a piece from the manifold when they removed the stud from the cracked hole. And they cracked another hole when removing the broken stud. I now have to go the route of acquiring another good rear manifold. I tried to PM you, but can't figure it out off my phone. Can you PM me and give me the particulars of what you have? Many thanks, Jose.
Hello Jose, just an update. I finally managed to free the giant bolt with lots of patience and a 6 sided 7/8inch socket. Hooray! I noted what you had said about ceramic coating my heat shield, and decided to bite the bullet. I have taken both manifolds and the heat hield for a silver ceramic coating to a local company near me. A rather expensive job however, a total of £414 UKP. I think it is worth it though, my poor old manifolds were very rusty and the shield was scruffy. I have now purchased stainless 3/8 UNF nuts for the clamp along with 5/16 UNF brass nuts for the manifolds, and stainless steel spring washers for both sizes. Also, I have obtained stainless steel washers that are 16mm internal and 34mm external for the giant bolt, so I will do as you suggested and place them underneath and top of the heat shield to assist air flow.
I would value your opinion on reassembly, would you advise using any type of grease to the manifold gaskets? My ceramic coating items will be another two weeks so I will update soon.
Many thanks once more, Danny.
Last edited by DannyRobertHoward; Jun 4, 2020 at 07:40 AM.
Reason: missed location of brass nuts
the ceramic coating lowers the temperature of those parts and the engine compartment as a result.
no grease on gaskets or seals. But anti-seize paste on those two shield bolts and the flange bolts is a good idea. No anti-seize needed on the manifold-to-head nuts either.
post pictures of the manifolds and shield when they are done.
you need to handle those parts very carefully after the coating is on, especially the shield, since any scratches are impossible to remove.
Replacing the exhaust sealing rings at the manifold
