Hot exhaust hose
Printed From: CorrectCraftFan.com
Category: Repairs and Maintenance
Forum Name: Engine Repair
Forum Discription: Engine problems and solutions
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=21336
Printed Date: November-24-2024 at 9:05pm
Topic: Hot exhaust hose
Posted By: Jones
Subject: Hot exhaust hose
Date Posted: April-18-2011 at 9:57pm
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I recently replaced all my cooling hoses, thermostat (142), exhaust manifold and riser gaskets on my 97 SN. My engine is running cool at about 150 and my manifolds and risers are cool to the touch but my 3.5" exhaust hose is HOT. I don't recall this being anywhere close to this hot before. Any recommendations? ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Replies:
Posted By: cjnovus
Date Posted: April-19-2011 at 11:07am
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Posted By: 8122pbrainard
Date Posted: April-19-2011 at 11:24am
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Brad,
If the manifolds are running cool and you have water coming out the aft end, then you're ok. The new hose may be transferring more heat due to it's design or you never noticed how hot the original hose got? ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Jones
Date Posted: April-19-2011 at 12:39pm
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Thanks for your input Pete. I definitely would have noticed when I ran it before however. I can't keep my hand on it for more than a few seconds and can tell at this temp it won't be long until the wet hose is shot. I've had some rust issues with this boat so I might remove the manifolds and or risers to check for blockage. It's the only thing I can think of. On another note; although I was pretty careful to put the riser gaskets back on correctly, if I didn't (if I put them on backwards) could this be an effect? ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Posted By: 8122pbrainard
Date Posted: April-19-2011 at 1:05pm
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Brad,
The wrong position of the manifold to riser gasket would reduce water flow. However, what's puzzling is your engine and manifolds/risers are running cool. How about doing the bucket test to see just how much water you are pumping through the engine. ------------- /diaries/details.asp?ID=1622" rel="nofollow - 54 Atom /diaries/details.asp?ID=2179" rel="nofollow - 77 Tique 64 X55 Dunphy Keep it original, Pete < |
Posted By: Jones
Date Posted: April-19-2011 at 1:08pm
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Great idea. I figure I should do that before tearing things apart again. ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Posted By: Bri892001
Date Posted: April-19-2011 at 1:48pm
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Just throwing this out there, not sure if it would make a difference:
Did you make any other, seemingly unrelated changes, such as to the carburetor. I know running leaner can make a motor run hotter, but I would think this would be all throughout, not just the exhaust temp. Timing? The boat is not backfiring at all or anything? |
Posted By: Jones
Date Posted: April-19-2011 at 1:59pm
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I haven't touched anything on the carburator but i can tell from the smell it is actually running a little rich and runs just a little rough at idle. I plan to have it kitted. The timing apears to be good but I'll check it out. Very strange. ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Posted By: eric lavine
Date Posted: April-20-2011 at 9:45am
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for the life of me i cant figure out to this day why on Randy from Ohio's boat did the same thing, I replaced the manifolds and when we ran it a GL the one hose got so hot it started burning ------------- "the things you own will start to own you" |
Posted By: Jones
Date Posted: April-20-2011 at 4:50pm
We checked the water flow on the exhaust side of the riser and it looks good. Called SKIDIM and they think it is the aftermarket riser the PO installed. They have seen this on some PCM engines and recommend the OEM type. This would make a little more sense why the PO had inserted stainless liners inside both wet exhaust hose.  ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Posted By: TRBenj
Date Posted: April-20-2011 at 4:59pm
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I would first take them apart and verify that you put the gaskets on properly. The bottom/aft coolant passage should be blocked off. This forces water up to the top of the riser, and gravity brings it down, keeping the whole thing cool. If you have them on backwards, water will stay on the lower half of the riser and the top will get hot. ------------- |
Posted By: Jones
Date Posted: April-20-2011 at 5:06pm
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I forgot to mention; yes, I checked the gaskets and they were both on correctly. SKIDIM also suggested opening up the blocked passage by cutting a hole in the gasket. They said it might work but I figure it should just be done right the first time. I just have a hard time believing it could be those aftermarket risers. ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Posted By: Jones
Date Posted: May-05-2011 at 2:28pm
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Update: I replaced the risers with PCM and it seems to have done the trick. The port side is a lot hotter than starboard but it's acceptable. The real test will be when I get it in the water. ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Posted By: Greasy Lake
Date Posted: May-05-2011 at 3:32pm
| FWIW, my driver side Riser and exhaust hose gets quite a bit hotter than the passenger side. I plan to pull the riser to see how many shredded impeller parts I can find down there. I pulled the thermostat and found a bunch of nuggets that had been causing high engine temps at low idle. |
Posted By: Jones
Date Posted: July-11-2011 at 2:28pm
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UPDATE: http://www.correctcraftfan.com/forum/forum_posts.asp?TID=21385&PID=283357#283357 - Hull Hugger
Back pressure turned out to be the culprit. ------------- 1979 Ski Nautique (sold) 1997 Ski Nautique 1998 Super Sport Nautique |
Posted By: stepper459
Date Posted: May-18-2012 at 7:27pm
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I found this helpful thread through Google in trying to diagnose a 'hot exhaust hose' in my boat, it's an '89 supra but has a '99 PCM GT-40 from a nautique. Anyway, I was finding my starboard side exhaust hose getting way hotter than the port side at idle (300+ versus 140) but I couldn't find any evidence of obstruction in the system. Water was getting to the manifold fine, and the manifold and riser were clear of debris, and the muffler had no obvious lack of flow issue based on a reverse water flow test. So I took the 3.5" hoses off that connect the riser to the muffler and they looked fine inside, but I switched them and the problem switched sides. The hose has been overheated before when I didn't get the system to prime correctly, and there wasn't sufficient water getting to the manifolds. In fact, one hose had a pinhole leak in it, that would go away when the hose got warm. So I think that the hose was heating up enough to close off the little grooved water passages in the riser where the 3.5" hose goes on. At high RPM it would be ok but at prolonged idle is where the hose would approach 300+ degrees. I'm replacing both hose sections that connect the risers to the muffler and will report here if that DOESN'T solve the problem. Just thought I'd post here to let people know who might be chasing the same type of problem, with no apparent cause. Cheers! I hope you all get out on the water this weekend, it looks beautiful here in New Hampshire... |