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Last year I removed my exhaust manifolds to try and repair the cracks. I'm finally getting around to posting about this but I wish I would have done it sooner so I remembered everything. Hopefully most of it comes back to me as I type this. This is something that can be done mostly by a regular person in their garage. The actual welding or brazing and machine work would need to be done by others if you don't have the equipment.
Here are a few photos of what I was starting with. The cracks are hard to see, even with a hole drilled at the end of it!
Next I ground out the cracks.
I chose to try the brazing method using silicone bronze brazing rod with my tig welder. I first cleaned everything then put it in the oven at 500 degrees for two hours. This is supposed to limit/reduce cracking when brazing/welding as the base metal is already hot so the temp diff isn't as much. However I watched a nice crack form right next to the one I was filling on the first try! See it here.
I kept going knowing I would have to do the process all over again to fill that one. From my research you want to get in and out as fast as you can. They were wrapped in a welding blanket right out of the oven and as soon as I was finished brazing I put them in a huge bin filled half with sand, then covered them in sand and let them slowly cool for a min of 24 hours. Here are a few more pics after brazing and grinding flush.
I had to buy a long shaft carbide burr to get inside and grind down what melted through. I had checked the manifolds for flatness before doing this process and they were NOT flat. After the process they seemed to be just as warped as before. I have a milling machine so I made a fixture to hold them and had to take about 0.030" off to make them flat again.
I finished sandblasting them along with some other parts from that area of the car and painted them with high heat paint.
I bought new donut seals and manifold gaskets along with new proper hardware and 4 new O2 sensors. I torqued everything in place, got the car up to temp, then re-torqued.
Results. After heating it up a few times following both the paint and torque instructions, I removed the heat shield to re-torque the manifold nuts. The rear manifold was perfect, but the forward one had formed another crack. It's small but was somewhat demoralizing.
Up to this point I've owned the car almost 3 years and had only driven it twice. I figured I'd let this new crack enjoy it's life awhile so I could move on to finishing the car and actually drive it. In my other throttle body post I updated today the car is finally out of my shop and I drove it home today!
At some point I'll get that heat shield back off and re-inspect the manifolds. Perhaps I'll try a different technique next time or maybe some jb weld schlock in situ!
A great deal of work involved.
I realize you may be looking to keep your car all original, however you may like to have a look at my solution. Car stalling. Will not hold idle.
Post 30/6/25 has photos of the result.
There's a much simpler solution.....Caterpillar sells an exhaust manifold repair sealant for their tractors....Paint it on and go for a drive = all fixed 😏
Caterpillar part number 2P-2333 is a high-temperature exhaust manifold sealant, not a manifold itself. Its purpose is to prevent exhaust leaks at the slip joints of multi-piece manifolds and cannot fix existing cracks in the manifold's metal. Cracks in an exhaust manifold are typically caused by heat fatigue and require a different repair or replacement.
This is obviously the proper way to fix these but I've fixed quite few of these by simply MIG welding them directly on the car with great results. Simply run car to temp, disconnect the battery and blast the crack at full welder power(Clarke 90EN) through the crack, then let it cool as normal, all manifolds I've fixed this way held well with no cracking or warping.
This is obviously the proper way to fix these but I've fixed quite few of these by simply MIG welding them directly on the car with great results. Simply run car to temp, disconnect the battery and blast the crack at full welder power(Clarke 90EN) through the crack, then let it cool as normal, all manifolds I've fixed this way held well with no cracking or warping.
We are very close and perhaps we can work out a trade if you fancy a drive to Kent Island where my shop is located. I could probably use that jag computer connection you have one day.
I wonder if anybody wants an uncracked set of used US (EGR and Secondary Air ports) exhaust manifolds. Only issue is the one downpipe stud was bent but i've managed it to unscrew. Might need some threads chasing.
I would be interested in them...I come by Philly every now and again. With the holidays coming, it's going to more now and again than ever!
Perfect. I would like that prospect customer to have a look personally that's why i still keep them and don't want to put somewhere for sale remotely and i even can't say what it the fair price (as almost nothing of thislike is offered for now to compare) for it so make your offer.
Since some states have old emissions standards, I'm not sure why, as it all blows into Texas from New Mexico. I guess I have to keep the pipe in the back of the rear manifold and the catalytic converters. What stainless steel options do I have? I have reviewed 100 posts, and they all share the same makeup. I have fixed many, and yet they will eventually crap out again, so I want to fix it and not have to screw with it again.
Exhaust Manifold Repair
