Shredded serpentine belt...again

The way a riser gets that hot is when the water flow to it goes to almost zero. You see white "smoke" coming out of the exhaust and the engine noise gets loud. Within a few minutes....the exhaust hoses will melt and ignite along with their fiberglass components.

From what you have said.....you came very close to an exhaust meltdown which could have become catastrophic for you and your family.

I almost lost a dockmate to a very similar situation (42 Express with diesels).....bad impeller lost water flow at cruise...caught the exhaust hoses on fire...opened the hatch to see what was going on....halon deploys....fire continues to burn....he jumps in 45 degree water and watches the boat burn and sink.

Fortunately he was rescued (by a bass fisherman) before he succumbed to hypothermia.

You and your mechanic need to find out why that riser is getting that so hot. It should be within 10 degrees of the other riser. I'm guessing it is related to a undiscovered blockage or raw water pump problem.
 
PlayDate said:
The way a riser gets that hot is when the water flow to it goes to almost zero. You see white "smoke" coming out of the exhaust and the engine noise gets loud. Within a few minutes....the exhaust hoses will melt and ignite along with their fiberglass components.

From what you have said.....you came very close to an exhaust meltdown which could have become catastrophic for you and your family.

I almost lost a dockmate to a very similar situation (42 Express with diesels).....bad impeller lost water flow at cruise...caught the exhaust hoses on fire...opened the hatch to see what was going on....halon deploys....fire continues to burn....he jumps in 45 degree water and watches the boat burn and sink.

Fortunately he was rescued (by a bass fisherman) before he succumbed to hypothermia.

You and your mechanic need to find out why that riser is getting that so hot. It should be within 10 degrees of the other riser. I'm guessing it is related to a undiscovered blockage or raw water pump problem.
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Oh my! Consider myself blessed at this point. Would I be on the right thought path to think the shredded belt could've been the culprit as the raw water pump would've stopped pumping? Thx for your input.
 
That would make sense if the other engine bank had the same damage in the exhaust.

What is troubling me is that you indicate that after the new belt was installed....that one riser continued to be a lot hotter. If it is more than 10-15 degrees....something is wrong.

The easy way to test the system is to have your mechanic swap the riser cooling lines and see if the problem moves to the other riser. It is easy to do with a couple of couplers and short pieces of hose.

If the original hot riser stays hot....there is a blockage in that riser. If the other riser gets hot....you know you have a blockage in raw water supply line.

I just don't want you to spend the money rebuilding the exhaust without making sure it won't happen again.

Part of the reason I shared that story was how quickly things can go wrong. He was 200 yards from shore. In less than 5 minutes (from the engine alarm) his boat was on fire. The reason that the Halon system didn't put the fire out is that when he opened the hatch to see what was wrong....flames came out and burned the electrical wires so he couldn't close it. When the Halon went off.....it just blew out the open hatch and almost gave him another heart attack.
 
PlayDate said:
That would make sense if the other engine bank had the same damage in the exhaust.

What is troubling me is that you indicate that after the new belt was installed....that one riser continued to be a lot hotter. If it is more than 10-15 degrees....something is wrong.

The easy way to test the system is to have your mechanic swap the riser cooling lines and see if the problem moves to the other riser. It is easy to do with a couple of couplers and short pieces of hose.

If the original hot riser stays hot....there is a blockage in that riser. If the other riser gets hot....you know you have a blockage in raw water supply line.

I just don't want you to spend the money rebuilding the exhaust without making sure it won't happen again.

Part of the reason I shared that story was how quickly things can go wrong. He was 200 yards from shore. In less than 5 minutes (from the engine alarm) his boat was on fire. The reason that the Halon system didn't put the fire out is that when he opened the hatch to see what was wrong....flames came out and burned the electrical wires so he couldn't close it. When the Halon went off.....it just blew out the open hatch and almost gave him another heart attack.
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This makes a lot of sense. I will see to it that this test is done. Thank you for your continued advice. Greatly appreciate it.
 
Yes. It is a 3/4" hose that connects the Heat Exchanger to each Riser. They usually are on or near the ends of the Heat Exchanger.

Raw water is pumped up to the heat exchanger and exits the boat via the Risers.
 
PlayDate said:
Yes. It is a 3/4" hose that connects the Heat Exchanger to each Riser. They usually are on or near the ends of the Heat Exchanger.

Raw water is pumped up to the heat exchanger and exits the boat via the Risers.
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All hoses checked and fine. Met with mechanic and it was determined upon further inspection of the raw water exhaust system that the resonator on the "hot" side had been dislodged from the main hose and was stuck in the outboard section exhaust. No other portion further from the exhaust collector had any heat damage nor was compromised.

Additionally, subsequent to the outboard side riser being removed (in order to provide clearance to remove remaining exhaust components positioned after the collector), the riser appeared to have had raw water in it because of its condition on the internal portion. It was explained this was not necessarily due to actual raw water, rather, possibly the vapors containing salinity from the "backed up exhaust" not having had the ability to exit as a result of the resonator blocking a portion of the outlet. There was no "puddling" found in the manifold upon inspection. A sea trial will be performed today to determine if at this time there appears to be any damage to any of the cylinders. I will provide pictures when received. Lastly, a new raw impeller/housing kit was installed.

The positive news is upon operation of the engine in neutral with increased rpms to 2200, all exhaust parts are now within normal temperature ranges. Will be back to you after sea trial.
 
The dislodged resonator could explain the the higher riser temperature on that side. The purpose of the resonator is to break up the exhaust gas pulse which in theory limits water inversion.

In reality....it increases the exhaust gas temperature in the hose which in theory reduces the amount of moisture that can find its way back into the engine.

Good luck with the sea trail.
 
Sea Trial successful. Both engines throttled up to approx 4500 simultaneously. Engine temps approx 165. All good to go. Observed a slight drip from the hose leading from the remote oil filter to oil cooler. Suggested replacement. Question..seems like a job that would take no more than an hour. He's suggesting it's a 2 hr job. Am I missing something? Also, what part number can I look for if you're in the know? Thank you and all others for your assistance and input with this issue. I've certainly learned a lot and am grateful. I'll upload pictures of the affected exhaust parts shortly.
 
It's a one hour job but if they include travel time....that would make it 2. If you have the Mercruiser Serial Number for the engine (if you had a survey done it should be in that report) I can tell you how to look up the part number.

It's a job you can do.

Congrats on sorting out the exhaust issue!
 
PlayDate said:
The dislodged resonator could explain the the higher riser temperature on that side. The purpose of the resonator is to break up the exhaust gas pulse which in theory limits water inversion.

In reality....it increases the exhaust gas temperature in the hose which in theory reduces the amount of moisture that can find its way back into the engine.

Good luck with the sea trail.
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Below is the inside of the compromised elbow aft of the riser and hose. The hose also had blistered and separated on the inside. Hope you can open up the link.

https://drive.google.com/open?id=0Bx9GZSzaXY62ZjNyTmpBMmE1RzhYZnFIWVpHSTQwZXB2UTFR
 
PlayDate said:
It's a one hour job but if they include travel time....that would make it 2. If you have the Mercruiser Serial Number for the engine (if you had a survey done it should be in that report) I can tell you how to look up the part number.

It's a job you can do.

Congrats on sorting out the exhaust issue!
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Thank you! Engines are #OL394911,2. I've found part number 807411, 808017, and 8061784. I'm thinking it may be prudent to change out the whole loop?
 
I would replace both hoses. Sometimes they go for 30 years and other times they leak around the fitting at 5 years. When you release them from the heat exchanger....oil will run out of the hoses for a short bit so be ready for it.
 
PlayDate said:
I would replace both hoses. Sometimes they go for 30 years and other times they leak around the fitting at 5 years. When you release them from the heat exchanger....oil will run out of the hoses for a short bit so be ready for it.
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It appears there are 3 hoses...1) Bracket to Cooler, 2) Cooler to adapter, 3) Adapter to Bracket. Your thoughts? Thx.
 
Yikes those things are expensive.....I just looked them up on Perfprotech.com . I'm going to reverse myself and suggest that you only replace the one that is leaking.
 
Very pricey oil lines. I had minor leaks on two of the couplings on one engine so bought 4 hoses. Did the worst leaking engine myself. Also happened to be the one with the worst access (port side and the lines/cooler are between the engines). It probably took me 2 hours by the time I cleaned up the mess that happens when you take the lines off and oil drips/flows out (really tough to prevent it in a tight bilge like we all have). The next pair will be done in the spring once I have healed all the scrapes and bruises I got doing the first engine.;)
 
Creekwood said:
Very pricey oil lines. I had minor leaks on two of the couplings on one engine so bought 4 hoses. Did the worst leaking engine myself. Also happened to be the one with the worst access (port side and the lines/cooler are between the engines). It probably took me 2 hours by the time I cleaned up the mess that happens when you take the lines off and oil drips/flows out (really tough to prevent it in a tight bilge like we all have). The next pair will be done in the spring once I have healed all the scrapes and bruises I got doing the first engine.;)
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Took a quick look at the lines into and out of the cooler. Looked a bit tight. RE: Scrapes and bruises. My hands hurt just looking at it.
 
msballin said:
Took a quick look at the lines into and out of the cooler. Looked a bit tight. RE: Scrapes and bruises. My hands hurt just looking at it.
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if I come to work on Monday morning without any cuts, scabs, scrapes, or bruises on my hands and arms then I feel I did not have a very good WE on the boat.....:)..

cliff
 
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