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Let’s play the guessing game untill I dig into it shall we?
Let’s guess what happened lol.
risers are less than a year old manifolds are unknown but I assume old. engine was at 165° and still pumping water at time this happened. was still running well just made this pop and sounded scary lol! only thing that’s changed is rebuilt the carbs since Cig Rendezvous. I’m thinking the discoloration of the riser is when it came off the manifold there and exhaust was shooting out it probably blowing on it? I’ll let yall shotgun your guesses lol! And I will report back ASAP obviously ended my weekend / poker run but luckily ended up in a new 41ft night hawk for the rest of the weekend lol. cheers! https://cimg5.ibsrv.net/gimg/www.off...40e479f08.jpeg |
Wow! Never seen anything like that before! Stress crack or heat or a combination of all.
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Motor mounts moved and/or tails are hitting on the transom cutouts?
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Snapped????
woah .... never seen or heard of such thing ! |
Over torqued V band clamp?
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Judging by the melted paint them things got hot as balls. The flanges aren`t water cooled..
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Originally Posted by ICDEDPPL
(Post 4932603)
Judging by the melted paint them things got hot as balls. The flanges aren`t water cooled..
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More photos
https://cimg4.ibsrv.net/gimg/www.off...f0820518b.jpeg
https://cimg6.ibsrv.net/gimg/www.off...86958e4e0.jpeg https://cimg7.ibsrv.net/gimg/www.off...f08c4a563.jpeg https://cimg8.ibsrv.net/gimg/www.off...9c023f9c6.jpeg https://cimg9.ibsrv.net/gimg/www.off...889f43cfb.jpeg https://cimg1.ibsrv.net/gimg/www.off...4e25f0aa4.jpeg last 2 photos are the manifold flange it’s self. Other side manifold is perfect in appearance wise on same engine. |
That’s crazy!!
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Heat.
As of right now ( I haven’t gotten the manifold off yet ) I see no signs of heat discoloration on my aluminum head on that side. If that means anything to anyone. When this thing blew off / broke I was 5,000 + RPMS at that particular moment for what that’s worth to?
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Originally Posted by thisistank
(Post 4932617)
That’s crazy!!
never seen anything like this in my life |
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Originally Posted by Ryanw10
(Post 4932600)
Over torqued V band clamp?
not completely out of the question question… |
engineering guess…
I beleive those are cast aluminum manifolds. Likely c355, rr350, or something equivalent. Cast aluminum is only good to 375F-400F worst case. my guess is you lost cooling…and cooked the exhaust. as cast aluminum temperatures rise stress creep and cracking is most common failure mode. and the rest is history… |
I'd say age and a fluke combination of several things listed.
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Scoped
Scoped all the cylinders as well looked fine and no
holes in pistons lol and checked compression cold and attempted a leak down all seems to check out perfectly fine. For what it’s worth. |
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I should mention this is dry exhaust with overboard dumps.
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I don't think those plugs look bad at all. More likely a cooling system problem than a lean running problem.
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Did you check water hoses? Maybe a clog? Water impeller starting to come apart and got stuck in that manifold?
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Right
That’s what I’m gonna tear into next I’m suspecting something along those lines
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What does the other manifold look like?
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Originally Posted by CIG3
(Post 4934333)
What does the other manifold look like?
looks perfect no discoloration or anything at all what so ever which I find weird lol! |
Originally Posted by 87CigCafe
(Post 4934334)
looks perfect no discoloration or anything at all what so ever which I find weird lol!
sensors were happy until kaboom. |
Looking at the picture of the manifold the heat centered around the top of the manifold. The paint around the exhaust ports looks of ok which is really strange if you had a cooling (flow) issue. Maybe the V Brand flange cracked and introduced air into the stream causing a lean condition which caused a backfire. Never seen anything like this before and I've seen many fried headers and manifolds from flow problems
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We all know it’s from heat. But what else could cause that much heat and not melt other things?
We have had cast manifolds crack/blow holes in them on OEM CAT manifolds when they are miss firing. The unburned fuel hits the HOT CAT section of the manifold and it explodes. Cracking the cast manifolds. The cracks/hole we see look exactly like this. Wondering if that spot is hot enough to ignite unburned fuel and causing an explosion right there. Making it even hotter and crack/blow up right there. Just a thought from what I’ve seen look like this on other manifolds. |
http://cimg8.ibsrv.net/gimg/www.offs...7aaf794df.jpeg
http://cimg9.ibsrv.net/gimg/www.offs...6ec55f928d.jpg I don't think the stainless riser that is water jacketed would get hot enough to turn a straw color. Likely a water flow feed issue to the port exh man. The exh man had water in the jacket with sufficient flow to pull some heat out and transfer it to the skin of the outer jacket. The low/zero water flow heated up the water fed to the riser, letting the riser heat up to color. The unjacketed portion of the exh man was unable to conduct away, heating up to a point where mounting forces overcame the structural integrity. Late timing would affect both sides. Fueling would likely affect both sides. Was the hose feeding the riser from the exh manifold pinched enough ro limit the flow? |
Tear down
https://cimg1.ibsrv.net/gimg/www.off...d88d5e180.jpeg
https://cimg3.ibsrv.net/gimg/www.off...f3863f506.jpeg https://cimg4.ibsrv.net/gimg/www.off...b36ab58e0.jpeg call me crazy but I find it tremendously easier to work on these engines outside of the boat and I can have them out and accessible in less than a hour anymore lol. so started at the easy part. Impellers. Which where new the season before. They seem perfect. Wear plates look at have some wear but nothing I don’t see being “ not normal “ no debris as of yet blocking anything either. Pulley spins freely and has a spot it grabs for lack of better words which I think that’s when’s engaging the fuel pump? I’ll keep tracing from here. |
Other manifold on same engine
This is the other manifold on the same engine.
https://cimg5.ibsrv.net/gimg/www.off...9eaee9b37.jpeg https://cimg6.ibsrv.net/gimg/www.off...5a203db2e.jpeg |
Oil cooler
Oil cooler is clean and clear
https://cimg6.ibsrv.net/gimg/www.off...7f0a0d69d.jpeg |
I wouldn't call that impeller perfect. I see the surface that rides on the wear plate as a potential issue
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Top
Top of other manifold with the gasket off tells me a bit more I believe on the age of these things….
https://cimg7.ibsrv.net/gimg/www.off...9420f5dab.jpeg |
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Originally Posted by Ryanw10
(Post 4941431)
And what's going on here?
https://cimg8.ibsrv.net/gimg/www.off...3cc3a33711.jpg https://cimg1.ibsrv.net/gimg/www.off...714662e59.jpeg |
That impeller is smoked...you can see the black rubber bits on the center of the plate....doesn't take much for them to start sucking air and you get steam pockets in the water system....also kinda looks like the center of it is "stripped out" for lack of better terms. Was it actually spinning or was the shaft spinning inside the impeller? Could just be the pic but that impeller is def an issue to me anyway, not saying it caused the issue but it is one issue. Possibly was sucking enough air/cavitating in the housing and the water flashed to steam in the header and POP?? Just a thought....
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I
Originally Posted by BBYSTWY
(Post 4941672)
That impeller is smoked...you can see the black rubber bits on the center of the plate....doesn't take much for them to start sucking air and you get steam pockets in the water system....also kinda looks like the center of it is "stripped out" for lack of better terms. Was it actually spinning or was the shaft spinning inside the impeller? Could just be the pic but that impeller is def an issue to me anyway, not saying it caused the issue but it is one issue. Possibly was sucking enough air/cavitating in the housing and the water flashed to steam in the header and POP?? Just a thought....
luckily I think I did make an upgrade with these Hardin marine pumps https://cimg5.ibsrv.net/gimg/www.off...6e3eaa352d.png |
What fuel pump is that? It does not look like a Merc. Or did you strip the paint off of it.
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