melted my muffler!

96 'bu VLX - my impeller went out yesterday, and the uncooled exhaust got hot enough to smoke my Silent Rider muffler. replaced the impeller and water was coming out of a couple places on it, so had to get off the water. $300 and 5 days for a new one. this thing is just a fiberglass tube - has anyone ever repaired a muffler? (i'm decent w/ 'glass) what do the internals of this muffler look like? are there baffles or something else that would be damaged? the boat seemed to run fine except for the water leaks. anything else i should check for damage?

on a related note - when i started smelling the fg fumes, my engine temp was like 220º (not catasrtophic), but the warning buzzer never went off. what temp is the buzzer supposed to trip at? my engine never runs above 160º normally, so why wouldn't it go off around 180º or so?

I had the same thing happen. I just pulled out the muffler and reglassed it and it has worked fine. No more leaks and just as quite as before it happened.

I read somewhere that even though the exhaust hoses look fine, they can be badly damaged on the inside. Might be worth inspecting them at least?

A good lesson for the future: When the exhaust stopped getting cooled, the boat should have gotten a lot louder. If you had shut down right then you would have saved your exhaust system.

As for the water temp alarm: A funny thing about those temperature sensors is that they need to be wet in order to detect the temperature. An engine that overheats with cooling water can give a true indication, where an engine that has suddenly lost all its cooling water may give a false indication.

The alarm will generally use a different temp sensor than the guauge. It is possible that the guage was still getting enough water to work, or just that the surrounding metal actually got that hot (a bad thing!). The alarm sensor may have been in a more "dry" location.

I tossed mine on my old boat and just ran the exhaust tube straight to the mainifold. Never had a problem and it sounded good. 454 Chevy BB.

I had the same thing happen to my boat. One lesson I learned is never, never, never lend your boat to anybody, including family. You're very lucky that there was no engine damage.

Anyway, we did patch up the fiberglass, and it has run fine for five years now.

Now if I could just get my worthless piece of dookie brother-in-law to cough up the dough for the damage he caused to my boat engine, all would be well.

how are you guys getting to your mufflers? are they not under the flooring? i think i have a leaker and have been told that the flooring has to come up to get at 'em.

Salty,
Depends on the boat. My 81 SN simply has a panel that pulls up that gives access to the shaft and mufflers.

Salty- mine's a V, so it's sorta above & behind the motor.

anything specific i should be looking for as far as engine damage? milky oil, leaking heads / manifolds, spun bearings, ??

when i noticed the problem, we had been idling around the dock, and when we started to get up on plane to head out, it started cutting out. noticed the temp right away & shut it down...

thanks all-

Trace,

Milky oil would mean a head gasket or possibly a cracked head or block.

If you spun a bearing the oil will look like it has gold shavings in it. You may have to tear open the oil filter to check for the shavings. Also, with a spun bearing your oil pressure will fall to nothing at idle.

If you can't find anything wrong with what I listed above a leak down test is a good idea. Easy to do and will tell you if the cylinders are not sealing properly.

Hope nothing is wrong.

thanks for all the replies & concern. i think the engine's OK. i would think most likely serious damage from an overheat event would be headgaskets, and the oil isn't milky. any other ideas? David M - what happened to your boat?

seems like it would have to get REALLY hot to spin a bearing, crack a head/block, or score a bore. haven't noticed any new burned paint or hoses or anything, so crossing fingers...

any ideas why it would cut out when you try to accelerate during overheat? detonation?

i don't even want to know if it won't pass a leakdown test, but i may take some compression readings for peace of mind, after i get the muffler fixed.

any ideas on getting the Ø3.5" hoses loose from the muffler? heat gun? (besides cutting them off...) i couldn't push too hard on the muffler itself because it's been weakened by the overheating.

Good reason to keep a spare impeller on the boat along with the right tools. I was also advised by master craft to change the impeller every 100 hrs but i plan to do it every 80 hrs just to be safe. Impellers aren't real expensive....arounf $35. They also said never start the engine out of the water...not even for a second. he says many people do it to blow out the water but not a good idea. the impeller gets hot very fast and it's made out of just rubber.

yeah, i always carry a spare impeller & belt. i replaced mine this spring & never start it dry, so not sure why this one went out. so any ideas on removing the hoses?

I have heard the same as above about starting dry (and would never do it). However, the first time starting for the year - the impeller is bone dry and probably doesn't get water until it works it's way from the intake. I wonder if this causes impellers to fail prematurely. On my old boat during the de-winterization process, I would pour some water and soap down the hose leading to the thermostat (it was off anyway for the winterization). Never had a problem with the impeller...

Trace,
Everything on the engine that wasn't metal had melted. Carbuerator, water hoses, electrical wires, etc. It was all pretty much destroyed. The Nautique dealer where I took it for repair was absolutely amazed that the engine wasn't seized. About three months of missed prime summer time riding and $2000 later, it runs pretty good. Since you didn't have any significant damage I think you're orders of magnitude smarter than my brother-in-law (well, everybody is orders of magnitude smarter than him) who just ignored the fact that the boat wasn't running right and that it was putting out a lot of smoke.

I've always been told that if the impeller is broken up to flush out the engine also. I don't have any details on how. I would suggest fixing everything you have and then having a boat repair shop go over your work and make sure that you put everything back together right. It sure gives a good piece of mind to have their blessing on it. Good luck.

Keith,
I asked the Nautique dealership the question about starting it up in water, but with the line dry. They said that it sucks it in so fast it's just the same as if it were wet to begin with.

well, i got the muffler out this afternoon with a special brew of grunts, crowbar, sweat, 2 screwdrivers, and this long hook tool i have. it really doesn't look too bad - it just kinda collapsed around the outlet tubes. the hoses even ended up looking good. should have it patched & back in by the wknd. FWIW, it looks really restrictive. thanks for the help!

A buddy and I winterized our boats together last year. He would remove the cover to the pump and let the water out and at that time he would inspect the impeller (without removing it) and then put the cover back on.

I always remove the impeller to let the vanes 'stretch out' and then I coat the impeller in vaseline and put in a zip lock bag so I suggested he do the same.

When we pulled his impeller, almost every vane had a big gash missing out of it. You could not tell by just looking at it when it was installed but it was ruined.

Just a suggestion to remove the impeller at least once per season so you can visually inspect it.

I say just replace it once per year. It's cheap insurance.