Manifold repair - presumably not sandpaper & BBQ paint...?

(Rob Ward) #1

This past weekend I carelessly showed my Father-in-Law my progressively flaking exhaust manifold and resultant cracking paint above it and told him I needed to get them professionally re-done, at which point he reached into his toolbox for a wrench and started talking about sandpaper and BBQ paint…

“Give me half an hour and I’ll have it done…”

I wrestled the wrench from his hands and gave him a soothing Single Malt to assuage his ardor, but I thought I should actually check with the Brain Trust here that he is indeed, however innocently, leading me astray, particularly since I have subsequently found all sorts of similar ideas on The Internets. (Or wrapping them).

So, sandpaper & BBQ paint or take to a professional shop? And assuming the latter, what am I looking for - exhaust shop, a good “collision” body shop with paint facility?


(Paul Wigton) #2

Sand paper will NOT remove the remaining porcelain: BBQ paint, on clean iron will work, but will need periodic refreshing.

JetHotting is the best, least-expensive method to coat them. Pictures abound in the archives.

If you arduously grind and polish the manifolds, prior to JetHotting, the resultant finish isnt quite as shiny as the porcelain, but WAY more durable.

(David Jones) #3

BBQ paint works well on the manifolds provided the old finish has been removed. Easy to apply, looks good, lasts well, cheap to do and easy to reapply periodically. Not much not to like!

(69 FHC ) #4

I had good success with this from Eastwood. I used the aerosol and baked them in the oven for a couple of hours. After three years the dark black has faded to medium gray in a few spots. It might be time to remove them and recoat.

And speaking of Eastwood I wonder if this product is any good.


(Geo Hahn 1969 Series 2 OTS) #5

I used a wire wheel to strip the old coating off of mine - probably helped that it was very cracked & crazed.

I used some high temp VHT and a gloss clear coat - both of which claimed some rather optimistic figures on heat tolerance.

They looked good when they came out of the oven:

But after a couple of months they looked like BBQ paint to me:

I know one concours entrant who sprays his with a thick coat of WD40 after he gets to the show and they have had a chance to cool. Quite a sight (and stink) when he starts it up to leave.

(Nick Saltarelli) #6

What I did. Like Geo’s experience, the semigloss finish didn’t last long.

Paint cracking above the exhaust manifolds won’t be cured by sanding and recoating the manifolds.

(Len Wheeler) #7

I too used the BBQ paint to get a nice flat finish. Have to do a respray but acceptable finish to me.

(Rob Ward) #8

Thanks everyone. I should add that I am also to going to fit the nice shiny heat shield that arrived in the mail last week, but figured doing the manifold too could only help.

Based on this thread I’m now working with the Jet Hot guys. They have a range of products but as the best & most expensive is still less than $200 I don’t see any reason not to do that.

(ronbros) #9

i still think the Jet Hot is by far the best, V12 has four diffecult to remove exh. manifolds!

had mine done 26yrs ago, still close to perfect!

O -maintainence.

(Ben E) #10

I’ve used Rustoleum BBQ paint on the exhaust collector of a 20,000 hp gas turbine at work, and I’ve been astonished how well it’s holding up.

I sprayed it over clean, smooth stainless steel with no primer, and the exhaust gets run, stuck outside for a few months, then run again…over and over. Two years later, it still looks like new!

On the other hand, I get the headers on one of my cars re-coated with a hi-temp ceramic coating, and it seems to only last 4-5 years. Those headers are hand-fabbed, and represent a TON of man-hours, so it’s worth trying to preserve them.

(Eric) #11

I had these ceramic coated by a local shop that services the offshore oil industry. They haven’t changed at all since installed about a year ago. Basically the Jet Hot process. He also coated (and polished) the rest of the system as I was on a mission to reduce interior heat.

(David Ahlers) #12

+1 on the Rustoleum BBQ. It looks better on the exhaust manifolds than on my Weber.
That’s a grill not a carburetor, btw.

I even dribbled some 15w-50 on them w/o staining. Maybe that’s why my Weber looks so bad - there’s oil, marinade, sauce, and charcoal dust all over it.

Chef Dave

(Les Halls 1968 S1.5 2+2 Atlanta) #13

Make sure they coat the inside as well as the outside, takes care of the heat better, and helps performance a little.

(Rob Ward) #14

Wow, Ok, did a search on the forum and I had no idea that removing the manifolds was such a PITA! Sadly I have nothing like the skill level or resources of many here. I have a friendly local-ish guy that puts bits back on when they fall off, but even if he manages to get the manifold off he doesn’t have the space for the car to sit there for 2 weeks while it gets sent off to get Jet Hot’d.

My initial idea was to fit the heat shield that has been floating around on various threads recently, to which effect I bought one, but then had the additional thought that doing the manifolds as well could only be better.

So here’s my question, if it makes sense: whilst doing both is surely ideal, how do we expect the heat shield and manifold coating to each contribute to the heat reduction? Which has the most effect? If I’m going to do the heat shield anyway would fixing the manifolds take the temp down by another 5%? 50%?

Hot Jet is saying 50% reduction for their stuff, but how much of that would be addressed by the heat shield alone?

Picture of the heat shield attached, stolen from one of the other threads but pretty sure its the same. Also current state of my manifold attached.


(Bob Faster) #15

I dont know about 50%. However, I did go with Jet Hot and after coating them the temps are an average of 50 degrees cooler at each cylinder. this was with the same set of manifolds that looked pretty much, maybe worse, than the ones in your bottom picture.

Bob F

(Paul Wigton) #16

I might have a spare set of manifolds, yours for the shipping, to work on, to keep the car intact till they are JetHotted.

PM me to enquire!

(Clive Wilkinson) #17

I first had my manifolds porcelain coated by a local company who warned me it wouldn’t last because the old processes are no longer allowed. They looked beautiful for a while but then started to crack and flake off. That only cost me $100 and would have probably been ok for a show queen if the car wasn’t used much. I did win a JCNA Championship concours at that time, 99.4 something and the engine compartment had zero deductions.

Next, I had a local Jet Hot competitor do them for a much higher price. They didn’t look as good as the porcelain and didn’t last much longer. So for the rest of the time I owned the car, I just used a VHT spray and made do. If I ever did it again, I’d use Jet Hot. I used them for other manifolds since and was very pleased with their service.

(Rob Ward) #18

Odd that no-one on this thread mentions any challenges with removal, just straight to what to do with them once off. I suppose that’s a result of the subject line - “repair”, not “remove” - but looking at some of these others threads it looks like the chances of stripping all the bolts apart from the ones that break completely off are about 100%.

The hitherto unappreciated importance of the absence of an acetlyne torch in my garage apparently leaves me woefully under-equipped. Something my Wife has been saying for some time.

That, and a wide array of penetrating oils and the critical instructions of what to hit, where to hit it and at what temperature - or not to hit anything upon pain of death.

(Robert Thomas 68 FHC ) #19

Rob, it is just for that reason that I chose to install the stainless heat shield ( the photo above is my car) The challenge of removing the manifolds, from both the head and the exhaust, is not insignificant. When you combine that with both the high cost and iffy outcomes of the various treatments, I thought the shield was a viable option, particularly for a driver

(Paul Wigton) #20

The only telatively-successful way Ive gotten the studs out of the flanges, was with oxy-acetylene.

I’d get the ear red hot (after 10-15 minutes of heating the down section up, too), then attach vice grips to the stud, then “ back’n forthing’ it. At a later stage, I might squirt it with Knock’er Loose.

Slow and steady would almost always be a winning strategery…:stuck_out_tongue_closed_eyes: