Engine Runs Shaking Down- locating exhaust leak

[TimBSmith]

Starting a new thread as I am now tuning and refining the shakedown of my running A4.

The first issue during several 5 minute runs on the hard is that I have noticed an intermittent wisp of exhaust or other smoke which has been elusive to locate. It may be the flange(which was replaced by PO with MMI flange in 2006). It may be at the exhaust pipe joint at the manifold or stack. Elsewhere. Engine compression (100 to 105 cold), temperature (90 to 150 5 minutes infrared multiple locations), oil pressure (40psi), and oil level all good. Exhaust pipe from manifold temp is 300 +-.

Here is the best video I have. I have watched it at .25 speed and 2x speed nothing determinative yet.

https://photos.app.goo.gl/CLZangxGwUoAzpAY8

I will video during run tomorrow from stern of engine with best view possible of piping joint and then flange.

Welcome any diagnostic advice.

Note that I have not dialed in the idle yet, I would appreciate your ears; any thoughts on how the engine sounds as is?

Thank you. Stay well. Tim

[Al Schober]

Engine sounds OK, no cause for alarm.
That smoke does bother me. It shouldn't be doing that.
First thing I'd do is strip off all that wrap so you can see the full hot pipe. The short nipple that's visible looks shaky. Might just be time for new hot pipes. They only last about 5 years.
Replace with black iron, not galvanized. Unless you're feeling flush and want to go stainless.

[TimBSmith]

Evaluating flange and black pipe stack. Researching. Will post back...

Thank you for post. I have been harvesting threads. The amount of material on exhaust leaks and lifter muffler related failure and flooding is epic. Found my prior PO story that led to MMI flange addition, water injector addition, and stack rebuild 2006 (wish he had posted drawings) : ). The stack itself feels very strong and stable. Yet clearly is it out of operating range and due for replacement. Going through unwrapping and will be in water and running at dock for more extensive shakedown under load, dialing in, and evaluating this leak. Steady forward. Stepwise. Stay well, Tim

[TimBSmith]

Inspection of black pipe threads at flange and water injection..

Thanks for guidance...

Before unwrapping ran the engine again to see if I could get around the flange and pipe "L". At 1:02 clearly see exhaust leakage all around threads interface with flange. Best to watch that section at .25 speed if you can.

https://photos.app.goo.gl/uxAdUBzzRFEDeFz46

New finding at water injection intersection. During low idle (more volume) during faster idle (less volume) water leak above water injection site under wrapped piping. :06 to :11 on this video. https://photos.app.goo.gl/Xa4zLgoVbqhowCqd7

This finding is new and subsequent to replacement of wet exhaust hose that was leaking(slow trickle) at stern fiberglass outlet. Same run and diameter of wet exhaust hose. Maybe there is actually more pressure in the muffler system with this replacement hose now evidencing frailty of pipe and water injection intersection?

Time to replace. This is a replace and not repair situation right? Wrap comes off tomorrow. Will research flange and pipe removal/replacement. Keep Moyer flange, get new gasket. Understand I will be going to plumbing supply store have them supply black pipe components to recreate this structure.

Welcome any preventive maintenance I might due during pipe replacement. Manifold stays on I think, just flange and above. Fortunately flange is replacement MMI flange and bolts look good. (Also MMI water injector). Still very leery of manifold injury. Will need to inspect where flange seats. May post pic to ensure seating area is reasonable relative to gasket. Researching, welcome any lessons learned.

Welcome any hazards to steer clear of during removal or special tools or approaches.

Thank you . Stay well. Tim

[TimBSmith]

Progress on diagnosing, removing, replacing exhaust riser....

I have been taking my time researching riser rebuild and removing old riser. I have been very lucky. Marina manager bumped my launch by a day and I have found a cascade of riser issues since October 1.

Here is my folder of photos/videos to date.

https://photos.app.goo.gl/nhceKPQi3hjATfrL8

Here is a 30K foot document I am creating to help me summarized work

https://docs.google.com/document/d/1KQXMCNUr5uQ-JcBouFjk9kXtodfZwLruO7Wgp2IfcBQ/edit?usp=sharing

Forum...your assistance please.

I would like to know your opinion of this flange seat on the manifold. Would you reseat a flange gasket here? If yes, what preparation steps would you take and what seating approach would you use. I am buying new MMI gasket. Salvaging MMI flange. Would use Permatex exhaust copper below flange gasket after cleaning up seating area.
https://photos.app.goo.gl/CQgUyKnhAQ3ynoMC9 (gasket on manifold)
https://photos.app.goo.gl/FX8kZxGjwumxr6qQA (gasket off)
https://photos.app.goo.gl/6pXQ7gyoZA7C8ygD7 (gasket off)

Suggestions for salvaging MMI Flange and MMI Water Injector

https://photos.app.goo.gl/dEvhdcVx7Tm8x7Rk8

https://photos.app.goo.gl/4zusz59LKHfUJgiX6

My plan is to soak these components in something for a day or two before trying to get them to release from the rusty blackpipe. Welcome any suggestions.

Any additional "I wish I had....or remember to..." suggestions for rebuild of riser. Photos/videos of your work? I am comparing stainless and stainless/schedule 80 black pipe hybrid. I like Thatch approach to use Barbeque Rustoleum on black pipe and bake before wrap. Has anyone tried any coating on the inside of black pipe to protect against corrosion? Get beyond 5 year replacement cycle?

I am aware of other long threads in this arena. I favor stainless steel (revisiting exact schedule and type from McMaster-Carr.) I was not persuaded by the mention of anaerobic bacterial risks though not dismissing caution. If I do not go all stainless it seems that stainless at common corrosion points nipples/or street L combined with Schedule 80 black pipe is viable. It seems that a supporting sling for the riser may take loads off the flange and water injection drop/muffler interface.

(I have researched extensively and especially appreciate deep threads here.) To save anyone new if you want a few quality threads.
July 2020

https://www.moyermarineforum.com/forums/showthread.php?t=11570

May 2018
https://www.moyermarineforum.com/for...ad.php?t=10690 (ndutton video https://www.youtube.com/watch?v=0RAseTsprZ4 and drawing, edwardc album https://www.moyermarineforum.com/for...bum.php?u=4020)
February 2016

https://www.moyermarineforum.com/forums/showthread.php?t=9450

March 2015 (Motherload)

https://www.moyermarineforum.com/forums/showthread.php?t=8870

Cooling Deep Dive April 2020
https://www.moyermarineforum.com/for...763#post120763 (Touches on reversing manifold coolant flow and Thatch modification).

Stay well. I will report back once I have a final approach and materials on ready to assemble. Thank you. Tim

[JOHN COOKSON]

Suggestions for salvaging MMI Flange and MMI Water Injector
My plan is to soak these components in something for a day or two before trying to get them to release from the rusty blackpipe. Welcome any suggestions.
Thank you. Tim

I found a shop that was able to work on pipe threaded material. I took the flange and water injector to them and they cleaned them up and also cleaned up the threads. Only charged $35.00 to do this. You might try phoning around.

ex TRUE GRIT

[TimBSmith]

Found a machine shop that has better tooling than me...

Thanks for reply and suggestion.

Machine shop in Allston, MA will remove flange and water injector for reuse and clean-up threads if/as needed. $85. Owner inspected the hot exhaust assembly, assured me he can remove both nondestructively relative to the full assembly. And that he can rework threads if need cleaning up. I will know more tomorrow at pickup. Also exploring stainless riser approach with him. Wish I had a better home shop, hate to miss the learning experience which is part of the journey and enjoyment. Will talk with him about salvage approach when I pickup tomorrow.

Manifold flange seating area. I am planning to clean up and use the manifold seating area. Welcome any opinions on how I can have best chance of success seating flange.

Stay well. Tim

[TimBSmith]

Update on hot section replacement...question regarding doping/tightening pipes

Al, John, others that have replied here or DM. And to the long lineage of thread contributors on exhaust and hot side rebuilds. Regular monitoring of riser hot section and injection point seems important. Touchless temperature checks/inspection and the role of back pressure as a diagnostic tool is interesting, and I will take more time with it when less critical issues are in front of me.

Thank you for assist so far.....Help please...

I have read above and elsewhere no thread dope on pipes, if anything some high temp anti seize...reconfirming this is the best practice. I tested some high temp pipe dope. Strangely all of the thick dope seems to scrape right out of the threads and end up out of the interface all together.

Guidance for tightening pipe assembly... I have read that others here simply snug the pipes hand tight. In other posts the tightening process is not covered. Is there a good rule of thumb?

Technician at the pipe and plumbing supply advised snug by hand then get 180 turn with pipe wrench. When I dry fit, this does not result in the pipe alignment I need. Proposing approach where I snug then turn straight connects then snug and tighten my street L and regular L at flange for the angular alignment I need.

Flange torque requirments? I have seen warnings about using too much force and pulling threads. Thought I read 35lb somewhere but cannot find thread.

Has anyone used 316/316L stainless nipple with the Moyer flange or SS nipple or connector to Moyer water injector? Noticed accelerated galvanic corrosion? seems like all conditions met especially with the flange. I have both.

I am planning to provide some additional surface rust protection using high temperature primer. For those that have used BBQ paint or other surface protection 1) did you prepare the surface of the pipe or just spray, 2) did you notice any smell in the boat after curing? Wife very chemical sensitive. 3) any other pointers? I have high temperature header spray paint and will cure by baking twice at 400F for 30 min.

I have been reviewing many threads...thread list to be compiled.

Progress slow/steady here is where I am now... about to do final fitting and tightening welcome any helpful hints or lessons learned. I will do all tightening then install and fine tune before seating flange.

https://photos.app.goo.gl/xEEeLfoF9gK4ZMkG6

Here is what schedule 80 connector looks like compared to schedule 40 my PO used. The mass and dimensions are dramatically different...

https://photos.app.goo.gl/zhrN3nsmcqxxnbWM6

Here is the before and after of the flange seating area. I learned a great deal about preparing the seating area. I have come to believe that part of the problem was a gasket buildup on the seating area that lead to several high and hot spots. I believe the PO or his technician passed on the opportunity to clean the flange seat where the gasket was fused.

Part of old gasket fused solid to seating area...thanks to ball peen hammer, picking tools, and Dremel wire brush lowest setting/gentle..between actual work and outreach..way..more..time..than I could imagine. Very confident with seating area and manifold material available for seating and operation.
Before

https://photos.app.goo.gl/3X4iRgPYA5eGkYeC6

After

https://photos.app.goo.gl/4XN1jwepzWx3qDYe7

Hot Spot and seating pattern seems to match these high spots. Gasket before removal. Note high spots and sealing trouble areas addressed with liquid gasket.

https://photos.app.goo.gl/totv6jCan5Qk481TA

Grateful. Stay well. Tim



The folks at Metro Pipe in Watertown are outstanding. They have black pipe and stainless.

Here is

[Antibes]

As I understand it, once the black pipe is used any length of time the threaded connections will basically rust to seal. Making pipe sealant unnecessary. The flange and stainless connections might be differant

[trevvahhh]

Hey Tim -

I imagine you already knocked this out, but for whatever its worth I just replaced the hot section and used a bit of hi temp anti-seize after seeing an old thread where Don may have mentioned it. Was hoping it would help get the extra leeway on turns to get the appropriate angles. I was definitely able to bend certain spots almost a full turn past where I stopped hand tight, I was concerned about trying and not making it all the way around

Might be worth considering undertightening the nipple or street that attaches to the flange until you can get the bolts into the manifold, as once it is vertical the bolts are hard to access. I had to over tighten to get more room and bring it back which was unideal in hindsight

Also, I've been waiting for the exhaust seams to button up after install and noticed it wiggling at the flange the other day. So I did a better job securing a supporting wire to the assembly, the original install was just supported by the flange but clearly it can use the support as many other threads point out. Not going to corrode shut while its wiggling.

Anyway, just some thoughts in hindsight, Hope it all goes/went well!

[JOHN COOKSON]

HERE'S A THOUGHT FOR YOUR CONSIDERATION

Hey Tim -
replaced the hot section and used a bit of hi temp anti-seize

Also, I've been waiting for the exhaust seams to button up after install and noticed it wiggling at the flange the other day. Not going to corrode shut while its wiggling.
!

With anti-seize the threads are free to turn because of the engine's vibration unless something is stopping this from happening. Maybe this why the the hot section is wiggling and not sealing.

ex TRUE GRIT

Why did you use anti-seize? Are you planning on taking the hot section apart in the future?

[Peter]

See this post

https://www.moyermarineforum.com/forums/showpost.php?p=4829&postcount=5

"I would definitely NOT recommend Teflon tape or pipe dope for the hot section. I replaced the hot section on each of our three sail boats over the past years and all I ever used was Never-Seize simply as a lubricant to be sure the tapered pipe threaded fittings were tight, and I never had any leakage. Having said that, I do hear of a heat resistant dope that some folks have been using, but I can't recall the brand or where they got it.

Don"

Best,

Peter

[ndutton]

https://www.moyermarineforum.com/forums/showpost.php?p=123504&postcount=8

McMaster-Carr #4586K8

[TimBSmith]

Thank you Antibes, Trev, John, Peter, Neil thank you

Quick update here and continuing my thread here

https://www.moyermarineforum.com/forums/showthread.php?t=11713

Antibes
Yes. Rust to seal is what I read most. Then using some high temp anti seize where you what to get tight as possible. Thread seal. See product Neil uses. Mine goes to 600F the Graphite Paste 750F. I too don't see a downside as long as temp range is covered. I don't know top range for temp yet, like that Neil trusts 750F.

Trev
"Might be worth considering undertightening the nipple or street that attaches to the flange until you can get the bolts into the manifold, as once it is vertical the bolts are hard to access. I had to over tighten to get more room and bring it back which was unideal in hindsight"

Very helpful. I have to tune the stack I built and am contemplating what I can do in place vs. remove to bench. Don't want to wrap until where it needs to be. I will post more on my follow-up thread above. Seems like a real art to getting these together and tight.

John
I used anti seize with the idea that I would recover flange and water injector more easily next time. That said as you will see in my post to the install focused thread, I have a couple of sealing problems and one of them is at the flange nipple joint where there is anti-seize. What you write seems obvious..unless you are newbie trying to make better sense of all this like me.

Peter
Thanks for guidance on anti-seize. I tightened flange with it but could not get angle right max tight. I am continuing the trouble shoot in my other thread above. I think I may be able to tighten the new slightly leaky nipple with everything in place.

Neil
Appreciate this and post in other thread. The thread sealant you are using meets better specs than one I bought. What are max temperatures these risers/hot exhausts see? You have confidence with 750F that is a good enough working rule of thumb for me.

Again thanks to all. Continuing this install and tuning at continuing thread above. Grateful. Stay well. Tim

[ndutton]

Neil
What are max temperatures these risers/hot exhausts see? You have confidence with 750F that is a good enough working rule of thumb for me.

I don't really know. I've never measured my A4 exhaust temps and a quick Google search turned up examples from engines that are much more exotic than ours in terms of compression, octane, turbo charging and load so I don't think they apply to us very well.

The sealant I chose had the highest temp spec I could find as well as specific chemical tolerance. I've run it for a little less than two years now with no issues. I used the sealant as an enhancement. The threaded joints were still made wrench tight. In terms of the total project cost, the addition of sealant was insignificant and as I said elsewhere, I didn't feel there was a downside.