Exhaust Manifold Crack Repair Epoxy

Yup dip. managed to do it again and forgot to pull the hoses off the water jacket manifolds lower rear portion on my V-6 Mercruiser 4.3L Chevy in my boat. I hate the cold. Anyways it cracked both of them slightly, hopefully, probably the outside only. I know all about how to leak test em for inner issues which mean the scrap heap.Anyways I never had cause to weld cast so figure this is the time to give her a whirl. Whats the best EASY method to do this? I have some Nickle 99 laying around from my last dozer headache as well as brazing rod and a torch set.

Would you guys weld or braze it considering it carries almost no pressure and if it leaks a tad it won't be the end of the world as I can get at it on the boat easily for touchups. BTW the risers are only about 1.5 years old and in perfect shape, no rust ect. I hate ice! A pair of these were brought to me last year.

But V8.went to a local pro.was welder for O.M.C. Before it's fall.He advised prep. I removed iron per instructions.He did an awsome O.A. Brass bronze, whatever.these were not little cracks!but he has a good track record. And I know what I am doing with the prepping.$125 or $175 he charged but said not to pre-estimate any more like it.it was a lot of involvement.my customer was happy to pay it, said even used manifolds would have been $450 ish. Drizler, The only good way to repair a mairne exhaust manifold or riser is to replace it, PERIOD. The cracks can be welded sure enough, but you won't believe how much heat these water cooled exhaust parts see.

The frequent heating and cooling cycles will make the repaired cracks open up in a short time. You won't realize that you have a crack until it's too late.

You come back from a hard run and the riser is hot, so the crack is open, you shut it down and head home. Now water is running out of the crack in the riser down through the exhaust manifold and into the closest cylinder with an open exhaust valve, where it will lay until you go to use the boat next week. Next week will come and the boat won't start. You'll think the starter is bad, and spend a half a day cursing with your body bent up like a pretzel trying to replace a starter on the bottom of an engine that they built a boat around, only to find out that the engine is locked up.

I see this scene play out in our shop several time each year. Do yourself a favor and replace the risers and or manifolds. Then take a hammer and break a small piece of the old riser off and drill a hole in it so you can attach it to the ignition key for the boat as a reminder, and it will be the last time you forget to winterize the engine. They arern't cracked all that bad to warrant replacement.They are just barely cracked and probably on the outside only. My others were full of water not just some remaining in the rear and even they held internally.

Thermosteel Exhaust Manifold

It seems they break out rather than in. One of my originals drooled for years harmlessly till I fixed it with a dab of JB Weld.

As for heat, what heat you talking about? Those manifolds ( Mercruiser V-6 ) 1990 are darned near stone cold all the time with a 150F stat. You can hold your hands on them any time. I have seen a lot of them cracked to that extent and repaired lasting for years.

This is just a single drooling crack I am referring to not a complete breakout with spiderwebbing ect like my last fiasco.With that in mind whats the better route? As I said I have both braze and 1/8' NI 99 rods on hand. I do have a #6 propane heater nozzle so keeping a casing hot isn't much of a problem I wouldn't think. I would just change these but they are only 2 years old. As for those new replacement costs someone needs to find the internet. I never never go near a dealer of any sort. My current manifolds only cost around $250 I think.

Still If I can fix em for free what the heck. As for heat, what heat you talking about?

Those manifolds ( Mercruiser V-6 ) 1990 are darned near stone cold all the time with a 150F stat. You can hold your hands on them any timeThe heat ( 1200. F ) would be on the exhaust side of the manifold.For readers not familiar with boat exhaust, take a regular car exhaust manifold and wrap it in a waterjacket. This is done to prevent high temps in the engine compartment.Why not try cast iron tapered plugs? Iron tite in El monte CA was a name I've heard of before, there are probably others. These have been used for years to repair cylinder heads.

One method is to drill on alternating sides of the crack line at 2' intervals. The tapered plugs then squeeze the crack shut. This works fine for water jackets.High pressure areas like the combustion chamber use overlapping plugs on the crack line. Driz, There are many ways to repair the cracks you can see in the risers, but replacement is the only good fix. The stresses that caused the fractures that you can see, also cased fractures that you can't see on the inside of the casting that will open up when heated. It might not leak at first, but it will eventually leak.

We all work hard for a $$ and I hate to tell someone how to spend their hard earned money, but a few hundred for risers beats a few grand for a motor next year. I've been making a living turning wrenches on boats for the last 30 years. 80% of the motor failures that I see can be traced back to a problem with a water cooled exhaust component. It's just not worth the risk of having a problem on the big pond at the worst posible time in the worst posible weather, because that's when it will fail and you can't walk home.

Exhaust Manifold Crack Repair Epoxy Products

Jeff Loughlin's Jeep Manifold Crack Repair Jeff Loughlin's exhaust manifold crack repair - Jeep JK Wrangler How to Fix an Exhaust Manifold Crack With ThermoSteel ByThis was originally posted on. I'm moving it over here so it doesn't get lost in cyberspace.Most of us with the 3.8 engine will eventually have it: a crack in the. Mine cracked on the driversside around 80,000 miles. My passenger side is okay so far, but it's only a matter of time.Anyway, I looked into replacing it, but the dealership wanted $450 to do it. You can buy the part for around $100 and do ityourself, but that's a lot of work, so I went looking for a quick, easy, and cheap solution instead.I read about a product called ThermoSteel on another forum. ThermoSteel is an epoxy-like adhesive, and the manufacturer claimsit can withstand temperatures up to 2500F. They also claim that this stuff is as strong as a hot weld.

I have my doubts aboutthat, but for $8 at AutoZone, I figured it was worth a shot.It's not hard to do. The whole process took me about 20 minutes, and the hardest part was just getting the heat shield off.The bolts are very tight and rusted on, and the rear-most bolt is very hard to get to:The bolts are 10mm, and you'll need a U-joint and a long extension or two to reach the rear one. You might want to spraysome penetrating oil on first and let it sit for a few hours or overnight, because yours are probably rusted on like mine were. Just a note here about tools: buy good ones. Most cheap sets come with a 1/4' drive on the smaller sockets like the 10mm.The 1/4' drive ratchet handle that comes in the set won't be long enough to get the kind of leverage you'll need to getthese bolts out. Do yourself a favor and buy a good set of 1/2' sockets and a good long ratchet handle to go with them.Trust me on this. The skin on your knuckles will thank me later.The other two upper bolts are a little easier to reach.

The lower bolt is tricky too, and there's not much room to work downthere. You'll probably need the universal joint for that one too.The heat shield is in two pieces, and they will come apart after you remove the bottom bolt (which is actually a nut - thebolt is mounted to the engine block). You'll probably want to remove the spark plug wires before you try to take the heatshield off, so they're out of the way.Once you have the heat shield off, you'll see something that looks like this:Now pick up your ThermoSteel and read the directions on the package:The directions are pretty simple: Mix thoroughly, and smear it on. Make sure you mix it very thoroughly, as there willbe a lot of gunk that has settled to the bottom. I used a flathead screwdriver to mix it up. When you're done, it shouldbe about the consistency of toothpaste - if it's thinner than that, keep mixing.Smear it on with a toothbrush (preferably someone else's) or your finger.

The instructions say you can make it up to 1/4 inchthick, so put it on nice and heavy. If your crack is wider than mine (shut up), you might need to pack it down in there or usesome wire mesh to cover it first. Mine was just a hairline crack, so I just smeared it all over the top.Let it cure for five or six hours. The instructions say you should heat the surface gradually after it cures, but you can'treally do that with an exhaust manifold. I just started the engine and let it run for a minute or two, then shut it down andwaited a half hour or so, then started it again. I repeated that three or four times and figured that was good enough.

ThenI reinstalled the heat shield and let it sit overnight before running the engine to full temperature.That's all there is to it. Mine's been holding up well so far. I'll update this if it ever fails, but it looksgood so far.Return to Jeff Loughlin's page.