Is this as bad as it looks?

[Bleemus]

Originally Posted by carlheintz

Yikes! Worse than it looks! I'd be afraid to motor out of the slip... in fact, I'd be afraid to be in the slip. Get that thing outa the water and off the boat!

A wee bit alarmist I would say. You can remove that without sinking or hauling the boat.

[CelestialMelody]

I would pay attention to it. There will be a gasket under the flange to replace. PB Blaster to loosen will help. The most common place for failure is where the cooling water injects and is hidden under asbestos wrap. If it fails you get water pouring into boat as well as exhaust fumes. You can get new one fabricated from black iron or 316 stainless. Good luck

[Sailmonkey]

Originally Posted by Madwand

Attachment 138106

I'm not sure how worried I should be about this corrosion. This is the $100 flange that attaches to my $1500 exhaust manifold on my Universal M25XP engine. Both parts would beed to be replaced to fix it. Surveyor didn't mention it. An elbow attaches to this and goes to another corroded chunk of metal. For all I know, this could have years of life left in it.

just curious why you think the manifold would need replacement?

[SteveSails]

The flange is definitely shot and should be replaced but the exhaust manifold might be OK, maybe a machine shop could clean up the mating surface once you get apart. The exhaust riser and exhaust hose downstream of the flange will also need to be replaced. And don't forget the flange mounting studs, gaskets, hoses and it's a good idea to use new manifold studs when putting it all back together.
Are you paying a mechanic to do everything or is it a DIY project? If you are paying a mechanic then it might be cheaper in the long run to replace parts rather than pay him to 'fix' the old.

Good Luck

[Island Time O25]

Originally Posted by Sailmonkey

just curious why you think the manifold would need replacement?

This joke from a Russian buddy will explain.

A Russian oligarch is showing off his brand new Mercedes Benz S600 to his friends.
-Nikolai, didn't you just bought one last month? What happened to it? Did you smash it? Was it stolen?
-Nyet Ivan, the ashtray got full and it became too smelly to drive.

[Brigadoon]

first I would get those rusty bolts out ASAP. In my recent working with old engines and car suspensions (1957 AC Bristol), I have used PB Blaster plus several days incubation time with good success. Torch heating on the manifold will also help as will light hammer tapping on the bolt head. Work slowly for fear of turning off the bolts. If that happens, it's a job of drilling out the stub and retapping, not fun, but doable. At least it looks like you have good access. After removal, wire wheel the flange, and use loctite rust reformer to clean up. Then rust preventative paint, since the water cooling prevents it from getting too hot.
Finally, when reassembling, use 316 stainless bolts (as from McMaster-Carr). Unless the application needs high tensile strength bolts (e.g., head bolts) anyone who uses standard carbon steel bolts on a boat is an idiot.

It constantly annoys me when I see boat engines using common carbon steel bolts everywhere when the cost savings are in the pennies on an engine costing $ tens of thousands. Carbon steel and salt water don't mix

I agree also that the insulation wrapped on the tailpipe is hiding more rust that will inevitably cause an exhaust system failure. Stainless piping is the only good answer if you need such extensive wrapping

[foufou]

I had an exhaust problem when I bought my boat. even after motoring several minutes to the yard for haul out and survey it went un-noticed. It wasn't until two days later, motoring to my harbor 6 mi away that the problem became apparent. the steel exhaust riser/elbow had a crack that was camouflaged by the insulation wrapped around it. An the insulation held it together. Lucky for me it held until I got to my berth. And luckier still II have a welder friend who welded the new stainless tube I had bent at a muffler shop. but the stainless tube and its welds do not like hot saltwater and exhaust gas much and I suspect its longevity will short lived. What material might be a better choice for the exhaust elbow/riser?

[Cheechako]

As mentioned, investigate and clean it up. I hope those bolts will come out of the manifold for you. If they do, put some anti seize when you reinstall. I used a galvanized elbow and nipple on a Volvo I had, It seemed to last as well as the original piece.

[Brigadoon]

The only stainless to use with salt water is 316 or 316L. Most welders wouldn't have this in stock, so you have to special order. (e.g., McMaster -Carr -- https://www.mcmaster.com/#standard-m...tings/=15id1f6) , but it is well worth it . The welder also has to use 316 welding rod. If the environment includes corrosive liquids, you have to go to nickel alloys, for lots more money

[sanibel sailor]

The wrapping is in all likelihood fiberglass rather than asbestos so you do not need to call in the HazMat team...

[Brigadoon]

For the exhaust tubing also use 316 stainless, welded with 316 rod McMaster-Carr has in stock (e.g., https://www.mcmaster.com/#standard-m...tings/=15id1f6

[scotty c-m]

Originally Posted by Sailmonkey

just curious why you think the manifold would need replacement?

I agree that this should be taken care of. The problem is that this shows a lack of timely maintenance. What other items have been left to slide? For example, how about your heat exchanger? Has the zinc been changed regularly? No way to know... so take it apart and check it. Better to have it fail under inspection, than under way!! Check pretty much everything. Try not to take too much apart; you can do a lot with proper diagnostic skills. The good news is that most of the issues with these sturdy little diesels can be fixed and the engine will give you (hopefully) years of dependable service.

[Horus]

I gues this won't be the only thing on the 'to do' list. This is only the start for a complete and good cleaning job in your engine room, so far I can see on the picture.
Good luck and take your time to make fun with this job. You will be proud when it's finished!

[Brigadoon]

I agree also that the insulation wrapped on the tailpipe is hiding more rust that will inevitably cause an exhaust system failure. Stainless piping is the only good answer if you need such extensive wrapping. For the exhaust tubing also use 316 stainless, welded with 316 rod McMaster-Carr has in stock (e.g., https://www.mcmaster.com/#standard-m...tings/=15id1f6

[JOHNMARDALL]

I've recently worked on a Universal M4-30 with a similar exhaust riser, Before you put a lot of time, effort and money into that engine, give some thought to how old it is and the likely condition of all of the marination products installed on what was an excellent Kubota engine. The chances are that everythingis worn out. A new Beta or Yanmar now will give you reliable trouble free motoring now, or you can buy parts for, and work on, that old engine for a couple of years of non-stop frustration and then buy the new Beta or Yanmar.
Sorry, but that's been my experience.
Good luck
John Mardall
Vetus Maxwell Group