Leaky bypass valve

[G. Randall]

Hello,
I have an early model raw-water cooled A4. The bypass pipe running from the engine to the exhaust riser has corroded and is spewing water into the bilge. The corrosion is mostly centered on the threads that run into an elbow.
I'm hoping to do a quick fix just to get to the end of the season.
Option one: Slather the corroded section with JB Weld and hope it seals it up till I can remove the whole thing this winter.
Option two: Wrap the corroded section with a layered sleeve of exhaust fabric, epdm and duct tape and hope that it will last the season and be easier to fix the corroded part this winter.
I'm thinking that Option 2 would be simpler and won't leave JB Weld in places I don't want it. But will Option 2 contain the heat and pressure? And can it actually seal the leak?
Any thoughts would be greatly appreciated.
Gary
Ps. I know these types of questions can be difficult without a photo. I'll try to post one after it stops storming.

[Dave Neptune]

First welcome to the MMI Forum.

That is not the best way to fix however I understand the temporary need. There is a product that I think is called "Survival Tape" I have seen it mend many things including radiator hoses. It seems to last a good long time and is easy to work with. You should be able to find it in most marine stores as it was designed for emergency repairs for "cruisers"
Getting the epoxy to stick and then stay will require much cleaning and sanding however it is pretty strong.

The best would be a new crossover which is what I think you are referring to.

Dave Neptune

[Dave Neptune]

Pt II

The tape is called "Rescue Tape" and it is available at Amazon. I checked with a friend who was a distributor for it.

Good Luck
Dave Neptune

[G. Randall]

Got it!
Hamilton Marine in Portland, Maine, stocks it. I'll give it a try and post the results.
Thanks, Dave. Wasn't really crazy about either option.

[Al Schober]

If it's just the cooling water line, you can't get into too much trouble.
I would not use it on the exhaust pipe itself. If the exhaust pipe breaks, you could burn down your boat. Best bet with the exhaust is to replace it before it fails. Black iron pipe should be replaced every 5 years. Stainless will last much longer, no estimate. Examine it while you're in there.
I had an exhaust pipe failure during a delivery. Tow was covered by insurance, but installation of new stainless piping cost the owner over $1K. Yard did a fine job on the fix (Burr Bros) and only delayed us 12 hours - got to see a bit of Marion, MA.

[Dave Neptune]

Second thoughts

I thought you were asking about the bypass where it goes into the exhaust manifold and there the tape would work fine. If you were meaning the hot section water injection point it would be far to hot for the tapes tolerance of 500 degrees. It may hold but only at very low throttle settings.

If it is indeed the hot section do what Al suggested it's not worth endangering you and the crew.

Cobbling a new hot section is a couple days of gathering parts and a few hours to fix properly.

Dave Neptune

[TimBSmith]

Quick fix vs. fix...

You already have some great guidance here. I went through a riser rebuild just after I bought Oasis. I rebuilt the wet exhaust side of things downstream of water lift only to find a leak in my riser the day before my scheduled launch.

I really wanted to get my season started.

Unless there is an emergency, I have found my preference is to slow down and do things right. I enjoy the learning and I enjoy the confidence I develop in myself and my boat.

I delayed my launch a couple weeks. Studied hard. Did a black pipe rebuild. Oasis was telling me she was not ready. I set aside my agenda and listened to her. That is one of the gifts of these motors and the boats they power. They talk to us and we can do something about it without often needing to outsource very much work at all. And the more we do the work, the better listeners we become.

Good luck with repair.

[G. Randall]

I'll definitely take a closer look at things when I can get back on the boat.
I believe the corroded section is part of the temperature control valve and does not get extremely hot.
If I'm wrong and it is a hot section, I will, of course be following your advice and rebuild the entire riser, which is pretty old.

When I do get around to rebuilding it, should I use the black iron pipe you get at Home Depot? Or is there a better source.
And, where would I shop for stainless steel. Not sure I could make it work, but I'm willing to take a look at the possibility.

Thank you, all, for your input.

[TimBSmith]

Black pipe and stainless suppliers...

I bought both black pipe and stainless fittings at Ferguson. They have a walk-in retail shop and despite my concerns they would laugh at my paltry order they were both helpful and gave great advice on laying out the parts, placing them loose then snugging and adjusting in place. Best wishes.

[G. Randall]

The outcome

When all was said and done, I wrapped the corroded section with about 8 feet of Rescue Tape and it is working well so far. I plan to pull the boat out early this year, so I will only have to rely on the patch a couple of times.
I'll be building and installing a new riser this winter with a little bit of help from all the exhaust threads I've discovered in the archives.
The infrared thermometer showed that the corroded section never got more than 90 to 100 degrees, while the riser itself ran up to about 350, so I'm reasonably sure the wrapped section will hold up. The manufacturer rates the tape at 500 degrees F., but I wouldn't want to try it.
Thank you to all who offered advice, especially Dave Neptune, who suggested Rescue Tape would be far better than JB Weld.
The Forum is priceless. Thanks!