Head scratcher here

[Jetlink]

So my summer season I have been chasing an over temp situation on my port exhaust riser and I am really at the end here. I have taken the entire fresh water cooling system apart multiple times, checked for blockages, checked the brand new impeller on the brand new Sherwood raw water pump and all the vanes are intact. I swapped the elbows on the exhaust to see if the riser was bad and my problem migrated to the starboard side when the port riser went over there so I got a new one and placed it on the port manifold. New thermostat, new gaskets all the way around and here is where I stand as of my water run yesterday. On the trailer at idle sucking water out of a bucket the boat can idle for damn near an hour and the temps are the same port to starboard. Water flow out the back fills the buckets equally. Take it out on the lake to have unlimited water and give it some more throttle and the port riser temp shoots up to around 205 degrees while the starboard remains around 110-115 and cool to the touch. Both manifolds themselves are cool to the touch, only the elbow gets hot and then everything downstream from there is hot as well. The whole time the engine is under 160 degrees at the hottest temperature too.

What am I missing? The only thing I can think of trying now is opening that passageway between the manifold and the elbow that is intentionally blocked off by the gasket to in effect get more water to flow through the port side than the starboard side or placing a small restriction in the water line coming out of the starboard side of the thermostat housing to accomplish the same thing.

[Plum Nauti]

Are the plugs identical in both banks? (Brand, gaps, temp etc) What shape are your hoses going to that side? Rubber hoses can and do deteriorate over time. Maybe blockage in the exhaust??

[SquamInboards]

This is very interesting. As you know I had (still have?) a similar problem except mine favors the starboard side I'm pretty sure. I think you read through my thread from a couple years back, with similar results.

I took most of the same steps to you and I reached the same point. I wouldn't open that passage up that you're talking about (whether or not it made it into my thread, I did try that with little to no effect, if not the reverse effect). I went so far as to grind out the passages in the riser where the hose connects up - in my case it has a series of diagonal channels for the water to pass through.

When I reached this point, the techs at the marina where I was working at the time challenged me with, "What problem EXACTLY are you trying to solve?" In my case, I do a lot of extended idling (while underway) and it was burning up my exhaust hoses by getting up in the 250-300 degree range after a long enough time. THAT was the problem I was trying to solve. So my "solution" of installing VHT silicone hoses that could withstand the temps I was seeing was the most reasonable thing I could think of. It may be a band-aid, but it's the 3M 5200 of band-aids. I haven't looked back.

Like you, I did my homework on the engine side of the cooling system. The only thing I hadn't touched was the parts that are under the floor after the risers and hoses, and I was not going to go down that road. I didn't see another option, and I didn't want to literally replace every single part of the cooling system from the intake to the large hoses, inclusive of all hoses, t-stat, RWP, strainer, manifolds, risers, the works. That might have done it, but what if it didn't?! That's probably $1200 worth of parts all together.

So I'll ask you, what problem EXACTLY are you trying to solve? If the mainfold and hoses are ~200 degrees... so what? Annoying though it may be, if it's not causing damage... I'm not sure I'd keep chasing it.

But boy, if you do I'll be listening.

[Jetlink]

Are the plugs identical in both banks? (Brand, gaps, temp etc) What shape are your hoses going to that side? Rubber hoses can and do deteriorate over time. Maybe blockage in the exhaust??

All brand new hoses last year with my complete overhaul of the boat, only thing I didn't touch mechanically speaking was the engine and the trans, the accessories on the engine are new, new belts, new hoses, new wire harness. Same plugs that I have been running for years, same plug wires that I have been running for years. It ran fine end of April when I put it all together after the winter lay up and then it sat for a month before I dropped it in the water and that was when I cooked the port exhaust hose.


So I'll ask you, what problem EXACTLY are you trying to solve? If the mainfold and hoses are ~200 degrees... so what? Annoying though it may be, if it's not causing damage... I'm not sure I'd keep chasing it.

I'm trying to solve the problem that prevents me from being able to use my boat as intended, doing high power/speed runs so I can actually ski behind it. Anything above idle causes the temp to climb drastically on the port elbow and cook the hose and burn a hole in it. At this point in time, I cannot even use the boat for anything other than to keep the trailer or the boat lift from flying away in a breeze. My problem is that my temp doesn't stop climbing with an increase in power and after you get it hot and pull it to idle it takes it 30 minutes to get below 170. As a reference it will go from 115 at idle to 205 in 45 seconds or so and start heating the hose so that I can smell it from the helm. Meanwhile the starboard side is literally ice cold to the touch and I could rest my hand on it and not even think about having to pull my hand. Something is clearly going on because the two sides should only be about 10-20 degree difference between the two and everything port to starboard side is within 10 degrees or less of the other side except for this elbow which is brand new and then everything after it downstream.

[foxriverat]

So my summer season I have been chasing an over temp situation on my port exhaust riser and I am really at the end here. I have taken the entire fresh water cooling system apart multiple times, checked for blockages, checked the brand new impeller on the brand new Sherwood raw water pump and all the vanes are intact. I swapped the elbows on the exhaust to see if the riser was bad and my problem migrated to the starboard side when the port riser went over there so I got a new one and placed it on the port manifold. New thermostat, new gaskets all the way around and here is where I stand as of my water run yesterday. On the trailer at idle sucking water out of a bucket the boat can idle for damn near an hour and the temps are the same port to starboard. Water flow out the back fills the buckets equally. Take it out on the lake to have unlimited water and give it some more throttle and the port riser temp shoots up to around 205 degrees while the starboard remains around 110-115 and cool to the touch. Both manifolds themselves are cool to the touch, only the elbow gets hot and then everything downstream from there is hot as well. The whole time the engine is under 160 degrees at the hottest temperature too.

What am I missing? The only thing I can think of trying now is opening that passageway between the manifold and the elbow that is intentionally blocked off by the gasket to in effect get more water to flow through the port side than the starboard side or placing a small restriction in the water line coming out of the starboard side of the thermostat housing to accomplish the same thing.

I think you threw some of us off when you said "The whole time the engine is under 160 degrees at the hottest temperature too" You never mentioned it was cooking your exhaust hose.

[lively]

What do the plugs look like ? What octane fuel do you run ? Stock heads ? Last time the heads were rebuilt ?


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[leetudor]

Is the riser gasket installed correctly?

[SquamInboards]

I also didn't realize that the temp kept climbing... how hot does it get? I know you're sick of cooking the hose, believe me I've been there.

Now I really want to get to the bottom of this...

[SquamInboards]

You mentioned idling on the trailer, no issue. But then you said you take it on the lake to go above idle and that's when you see the temp climb. Have you run it at higher rpm on the trailer to see if the flow is still even between the exhausts?

[Jetlink]

After digging into it more today, I have come to the conclusion that the muffler I installed brand new last year as part of my rebuild failed or was faulty when I installed it. I'll attach photo proof to show you just how bad it was. The muffler has what sounds like a bad baffle or two that broke free and were allowed to restrict the flow of water and exhaust gas out my port side of the engine. This created back pressure that forced most if not all the water over to the starboard side and thus resulted in the catastrophic failure of my port exhaust hose just after the elbow. Today I cut my "new" floor to remove the port muffler after looking in from the transom and comparing the two sides, there were definite differences between the two sides. After removing the muffler, I ran a seven foot section of exhaust hose from the port exhaust elbow to the old flange and then ran the boat on the trailer with no temp issues. In fact, after removing it, the starboard riser actually had some heat on it as opposed to being ice cold to the touch, the water coming out of the hose is cold enough to cause it to "sweat." So, long story short, I have ordered another muffler and flange, you'll see why in a minute and I am going to redesign my floor so that if I ever have to get these mufflers out again, I can do it without having to take a saw to it again.

And now, time for some carnage...
17674
17675
This flange is from the port side located about seven linear feet aft of the exhaust elbow. The plastic was so hot and molten that it literally blew back and solidified after the engine was shut down after blowing a hole in the hose before the muffler.

[Jetlink]

You mentioned idling on the trailer, no issue. But then you said you take it on the lake to go above idle and that's when you see the temp climb. Have you run it at higher rpm on the trailer to see if the flow is still even between the exhausts?

We have run it at a "high" idle and it climbs a little but nothing that raises any flags. At idle it is about 20-30 degree difference and when you run it on the lake and go to hop on plane the temp shoots up from 130-140 on the port to 205 just getting out of the hole while the starboard side is still ice cold.

[Jetlink]

Is the riser gasket installed correctly?

Indeed it is with the forward most water passageway blocked and the back open, or said another way, the "tab" is aft on the gasket. I have now installed three of them alone this week on that port manifold.

[SquamInboards]

We have run it at a "high" idle and it climbs a little but nothing that raises any flags. At idle it is about 20-30 degree difference and when you run it on the lake and go to hop on plane the temp shoots up from 130-140 on the port to 205 just getting out of the hole while the starboard side is still ice cold.
Hmm. Thanks for the quick reply!. Do you know how hot it will get? I only ask because mine will never get much above 250. Which is nicely inside of the tolerance of VHT silicone hose...

[Jetlink]

Hmm. Thanks for the quick reply!. Do you know how hot it will get? I only ask because mine will never get much above 250. Which is nicely inside of the tolerance of VHT silicone hose...

The answer is, I don't know and that I don't want to find out. I stop and go to idle as soon as I see 200 degrees or so which is basically the boat coming on plane and then I go to idle. I could guess that my elbow temp could get all the way up to and over what it takes to cook an exhaust hose which I do not know the temperature rating on mine. I know it is less than 600-700 degrees or however hot straight exhaust gas is.

[SquamInboards]

The answer is, I don't know and that I don't want to find out. I stop and go to idle as soon as I see 200 degrees or so which is basically the boat coming on plane and then I go to idle. I could guess that my elbow temp could get all the way up to and over what it takes to cook an exhaust hose which I do not know the temperature rating on mine. I know it is less than 600-700 degrees or however hot straight exhaust gas is.
Well, my phone just told me you replied. But it didn't tell me to go back and read the other post you just wrote about your failed muffler! So I'm glad you found a likely cause.

[SquamInboards]

Well, my phone just told me you replied. But it didn't tell me to go back and read the other post you just wrote about your failed muffler! So I'm glad you found a likely cause.
Oh, also I believe the max. rating on regular exhaust hose is 250F. So where mine was hovering in that range it would take a while but eventually damage the hose. But I could use the boat for months sometimes without a problem because my issue only appears at extended idle, not the other way around. In your case, you are probably wise not to have tested its maximum temp.

[Jetlink]

Well, my phone just told me you replied. But it didn't tell me to go back and read the other post you just wrote about your failed muffler! So I'm glad you found a likely cause.

Straight hose on the port side no issues other than my wife would complain about the noise though I don't really see a problem there...but then I remember I have a little boy now and he does not care for loud noises yet.

[SquamInboards]

Straight hose on the port side no issues other than my wife would complain about the noise though I don't really see a problem there...but then I remember I have a little boy now and he does not care for loud noises yet.
Haha, yes my boy is now 4 and just started loving the sound of the boat. My 2 year old isn't there yet. She likes going slowly...

Glad you solved it!

[lively]

How did cutting into your floor feel ? Lol I'm glad it was justified .


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[Jetlink]

How did cutting into your floor feel ? Lol I'm glad it was justified.

:mad: Do you really want to know? I pretty much just ripped that band aid off and went to town, except that I didn't quite remove enough floor to get the muffler out the first time so I had to cut it twice. I am going to go back and clean up that cut, make a similar cut on the starboard side, you know to make them look the same and like I knew what I was doing and then make a new floor piece for the stern area, glass it, carpet and hopefully have it all done by Thursday next week. But yeah, not happy at all about having to cut out a floor that I overbuilt and had zero intention of ever having to take it out again.

[lively]

:mad: Do you really want to know? I pretty much just ripped that band aid off and went to town, except that I didn't quite remove enough floor to get the muffler out the first time so I had to cut it twice. I am going to go back and clean up that cut, make a similar cut on the starboard side, you know to make them look the same and like I knew what I was doing and then make a new floor piece for the stern area, glass it, carpet and hopefully have it all done by Thursday next week. But yeah, not happy at all about having to cut out a floor that I overbuilt and had zero intention of ever having to take it out again.

I will be ok , lol at least you found the issue !


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[Jetlink]

Update: New muffler, flange and exhaust hoses installed on the port side Monday and Tuesday. Yesterday ran the boat and did a water test as well on the lake and the maximum temperature I saw was around 183 degrees on the port exhaust elbow while the starboard was about 25-30 degrees cooler. I even did a few full throttle pulls and the temperature never went above 185 while according to the temperature gauge the engine is running just under 160 degrees after getting to temperature.

So to recap, the boat has a new raw water pump, new impeller on the raw water pump, new thermostat, new gaskets all the way around, new muffler, flange and hoses on the port side only. The port manifold was gone through, cleaned and found clear of obstructions, new elbow sitting on top of the port manifold and I think I have finally stopped chasing my tail on this. Now to find gray carpet to cover the new floor piece I had to make to cover the floor that I had to cut out to get that muffler out.

[NoWake]

Great news! What is your theory on why the port muffler crapped out like that? Factory defect or cold northern weather?

[Jetlink]

Great news! What is your theory on why the port muffler crapped out like that? Factory defect or cold northern weather?

Going with factory defect, if it was cold northern weather I would expect both of them to have failed. Also, when I installed them right before I laid the floor one had a small rattle to it while the other did not. Guess which side the one with the rattle ended up.