Small Exhaust Leak - What would you do?

We have a cracked manifold on one of our 1975 Perkins 6.354’s and have probably had a small exhaust leak for a long time. We have never smelled it, probably because the air intake is just over a foot away and it simply gets re-circulated. We have smelled exhaust in the cabin only when running directly down wind with the windows open and the wind faster than the boat. It’s very obvious then and we know the smell. We have never smelled exhaust any other time. I go into the engine room right after shut down to turn off some switches and have not noticed anything but the usual diesel smell.

A JB repair lasted 4 days before cracking in the same place. The only immediate fix with replacement parts for these old engines that I have been able to find is a nice upgrade but would come to about 1/4 the current market value of this boat for both engines and also replace the heat exchangers which we recently did. We can neither afford nor justify that investment at our age.

The only welder I have found who is confident he can repair the manifold is in Maine. He did a lot of beautiful work on my sailboat and has fixed many “un-repairable” manifolds and other parts for the Portland fishing fleet. He is certified to weld nuclear power plant piping while underwater so not your usual rod pusher.

The boat is in Savannah and we are back in New York dealing with non boating things for a couple months. Local knowledge doesn’t turn up anyone we would trust to remove the manifold and ship it in our absence. We can only afford to keep this boat if I do most of the work myself anyway.

So: Would it be reasonable to put a couple more CO detectors around the boat, keep an eye on this, and not give up our winter cruising plans? It will be a lot easier to deal with it in the spring when the boat is back north and we can drive the manifold to Maine. These engines run at about a quarter their rated output in cruise and the exhaust is crystal clear. It’s hard to believe they are producing much CO running that lean anyway.

What would you do (on a shoestring)?

There are 2 ways to rejoin broken cast iron. The oldest and most common is brazing with an oxyacetylene flame. The second is stick welding wit a special high nickel rod from Eutecic Castolin. Here’s a link to their website product page; https://www.castolin.com/product/eutectrode-2-44-welding-electrodes

Snoop around for brazing rods and flux- they make those also. Better yet, call their Tech Support- it’s awesome. Note: brazing is more difficult than stick welding.

I’m certain there are a dozen backyard shops around Savanna that can weld that manifold with this stick material.

The stick welding isn’t difficult nor overly technical. I’m not a highly skilled welder and have used the stick to repair a broken bell housing on an old Massey Furgeson tractor 45 yrs ago and it’s still holding!

Just make sure the gasket face of the manifold is rigidly clamped to a robust, flat surface before welding so it doesn’t warp. Weld prep bevel should be 1/4” +/- bevel.

Greetings,
Mr. RL. Perhaps a picture of the site of the crack might generate more "shoestring" ideas. Can you get a clamp in the area? Is there anything you can wedge a patch onto?

I cannot help with any useful info regarding the method of repair or whether replacement is in order. However, I can say this: use extreme caution when it comes to carbon monoxide. As you probably already know, it is colourless, tasteless, and does not smell. It mixes well in air (about the same density), and it is insidious. Most often, it's affects are cumulative, and people being exposed have no idea they are being exposed until it is too late. Larger exposures require medical treatment as CO binds to the blood better than oxygen, or worse (results).

I suggest being very, very careful operating with an exhaust leak. After all, What is your life worth? CO monitors are always a good idea regardless.
Good luck with your dilemma and I hope you can find a "workable" solution, but be safe.

RT Firefly said:

Greetings,
Mr. RL. Perhaps a picture of the site of the crack might generate more "shoestring" ideas. Can you get a clamp in the area? Is there anything you can wedge a patch onto?

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Crack looks big but leak is just a pin hole. Looking for a welder in the Savannah area who is as experienced as the guy I know in Maine.

firehoser75 said:

I suggest being very, very careful operating with an exhaust leak.

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I dealt a lot with the CO issue while managing aircraft. Learned, for example, that standard household detectors are set at a level higher than that which can impair the ability to do complex tasks. Otherwise, they would be going off constantly in cities. We had to get a medical Rx to buy ones with a digital read out and lower alarm settings from a source in Canada. Slight impairment landing a plane is probably a bigger deal than docking a boat.


The two engines are sucking 143 CFM out of the engine room at 1400 cruise RPM. That's a cube of air over 5 feet on a side. Engine room volume is about 500 cubic feet so an air change about every 3 1/2 minutes. Since we smell the highly diluted stuff that comes with the CO when conditions are right to bring it all the way around from the transom, it's hard to believe we wouldn't smell the same stuff coming from a small leak in the engine room. Diesels make much less CO than gas engines anyway.

If we do run the boat before a fix, I'll put one of those CO detectors right in the engine room and report back.

mbevins said:

https://www.cotronics.com/vo/cotr/rm_putties.htm

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Thanks. That might work where the JB High Temp didn't; especially if reinforced with some fiberglass cloth.

From the above postings, I am going to assume there is at least one CO monitor aboard. The idea of adding more reminds me of what I did last year while delivering a twin gas engine houseboat with a known proclivity to spread exhaust gases through the aft sliding glass doors. I first installed a boat CO alarm and after a test run added two more bought at a local hardware store before setting out. At what I considered a fast-ish cruising speed of around ten mph the CO detector with wind from the stbd bow the CO alarm aft near the doors went off followed by the midships one and finally by the boat CO alarm at the helm well forward in the cabin. We immediately opened all the forward doors and windows and slowed to a trot. It was 47F outside, and we were now cold! While the alarms ceased sounding one by one, I taped up all the crevices around the aft doors and cracked open the forward and amidships windows while cranking up the reverse cycle AC to WARM. Thereafter, during the two-week delivery, we would occasionally get the aft CO alarm going off at which point we always slowed the boat and threw open the windows to eventually silence the alarm. When at anchor, we ran the gasoline generator all night with the CO alarms surrounding the bed but never had an alert.

rgano said:

From the above postings, I am going to assume there is at least one CO monitor aboard.

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Two actually. Never gone off and I'm sure this leak has been going on for a while. Going to add another at the helm and one in the engine room itself.

Diesels run at light to moderate load make very little CO. I'm not freaked out with the safety aspect of this, as long as you do have a functioning CO monitor or two.

Kinda looks like a Bowman manifold. Are you sure it is not aluminum?

Ski in NC said:

Kinda looks like a Bowman manifold. Are you sure it is not aluminum?

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Never occurred to me. I believe it was made by Bowman. Aluminum would be good because probably more reliable to weld.


Does anyone know the material? I'm far away from the boat.

And.

The engine in question.

Roger Long said:

Crack looks big but leak is just a pin hole. Looking for a welder in the Savannah area who is as experienced as the guy I know in Maine.

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If it really is a pinhole you can drill it, tap it and insert a fastener.

I would find a replacement manifold.

There has to be something out there. A used manifold would be fine.

From a safety standpoint, folks often overlook that diesel engines produce so little CO that it's almost impossible to find a documented case of CO poisoning from a diesel engine.

Try it sometime... Lots of cases from everything But a diesel engine.

Thats one of the arguments for diesel engines in boats.

If you run with widows open then smaller risk of CO building up. I would not run with windows closed. If you take the risk, then be aware of creeping tunnel vision. If the edges of your vision start going black, you probably have 30 sec or less to get outside the cabin. If you make it, you will have the king of all headaches. If not...

I once had a leak in the turbo housing of a T6.354. Mechanic(ex submariner) was very concerned, especially if we would have children onboard, pending replacement he advised a temporary fix using auto muffler putty and a wrap of auto "muffler bandage" which once wrapped on goes hard with heat. It worked pending the yard manufacturing a new cover for $1K AUD.

Barking Sands said:

If it really is a pinhole you can drill it, tap it and insert a fastener.

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Not a bad idea.....if nothing else, might keep the hole from enlarging.

I would be a bit nervous about the large crack. Has a decent head start on becoming a bigger problem.

Good luck

Peter

Maybe rig up a regular 12v bilge blower.....flex hose over to a small metal hood arrangement at manifold?

Multiple possibilities to reduce leak, multiple possibilities to reduce CO buildup in both inhabited/engine spaces, addition of digital sensors to show buildup in inhabited spaces.


More safeguards possible than a NASA launch.


With Ski that problem probably controllable even without multiple safety layers...but still wise to consider.


Continuing trip with continuous monitoring to a better repair facility would be my approach.

mbevins said:

https://www.cotronics.com/vo/cotr/rm_putties.htm

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wow this adhesive company has it all. very impressive product line.

Is this the typical Perkins raw/salt water cooled manifold?
If it is I would be wary of an impending internal failure/leak.

jleonard said:

Is this the typical Perkins raw/salt water cooled manifold?
If it is I would be wary of an impending internal failure/leak.

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Jay, Would you please explain this in more detail,I'm not understanding. Thanks

Dwk said:

Jay, Would you please explain this in more detail,I'm not understanding. Thanks

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I'm more familiar with the turbocharged version of this engine, and about half the times the manifold leaks externally, the other half internally.
When it leaks internally in the raw water section, the engine will ingest salt water and can take the engine out.
I know of several instances of each from my days where I was involved with the older Mainship 34 Nantuckets. Most of those earlier boats had the T6.354 engine.
That's my experience.

Jay,thanks for the explaination,got it.

I've just learned that this manifold is cast aluminum. That makes repair easier and more reliable. Working on that option now.


Anyone know a good and reliable welder in the Savannah area?

mvweebles said:

Not a bad idea.....if nothing else, might keep the hole from enlarging.

I would be a bit nervous about the large crack. Has a decent head start on becoming a bigger problem.

Good luck

Peter

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I cant tell from the picture where the crack actually is or what kind of access there is. You can actually repair things like this even when there is some length to the crack with the pinning method. If the crack is longer, say 2 inches, but only has a pinhole where leaking, you can drill the ends of the crack which effectively "stop drills" the crack followed by another pin at the pin hole. Of you can pin the entire length.
https://www.freeasestudyguides.com/engine-block-repair.html

However this is NOT the preferred method. But I have seen this method save a Mopar block (cracked water jacket) that remained in use for another racing season. In the end the only true fix is to replace it.

**edit** OP says it aluminum. This temp repair would not be suitable.

Might give mesamarine.com a call.