Fiberglass Exhaust on FIRE!!!!!

I knew my exhausts were in pretty bad shape. They've had little holes in them that I've tried to patch, and they feel weak enough to crush in my hands. Well, this weekend they started smoking A LOT, and it's like they're going to catch on fire... They're obviously due to be replaced, and I plan to do so but I have a few questions about this...

How are they getting so hot, to smoke like that??? Isn't the exhaust going thru them basically smoky water??

Do you think they could smoke that much??? When the smoke is coming out, I'm almost 100% that it's the exhaust, it even smells like burning fiberglass, but if no one's ever had this problem... maybe it's my engine smoking... also my exhaust seems very hot to touch, but not exactly fire hot...

And Finally, what should I replace them with?? Fiberglass again? Or is there a different plastic/rubber product I should buy?? Also, where can I get the best price? They're like 3" tubes that angle up at the engine end... I'm guessing you guys will know what I'm talking about.

Thanks,
kal

check with skidim.com for replacement parts / prices - can't help with any of the other questions

What is your engine temp reading according to your guage? when you say smoke do you mean steam? You should be abel to touch your exhaust risers on your boat for a few seconds...it should not be scolding hot.

my guage reads 150... I'm not sure if it's that accurate. Do you know where the temp guage hooks to the motor? I was thinking of replacing that too. I think it's smoke... but my brother thought it might be steam. It could be either I guess.

If your raw water pump is not pumping enough water then a direct result will be that your exhaust overheats. If you don't shut down immediatly when the water pump fails a common result is the exhaust system failing.

The raw water pump is the pump that is mounted low on the engine and has a hose that runs to the bottom of the boat (possibly via a cooler for the transmission). This is also the pump that is referred to when talking about changing the impeller.

This pump sucks up a fair amount of water from the lake and provides it to the circulation pump for the engine. After it has cooled the engine the water it dumped into the exhaust system to cool and quiet the exhaust.

Prior to the water being added the exhaust system is all cast iron as it has to survive very high temperatures. Once the water has been added the exhaust system is usually made of fiberglass and/or rubber hoses. These work fine as long as there is a flow of water, but once the water flow stops the extreme heat of the exhaust will destroy them very quickly.

I always advise people that the first indication that your water pump has failed is usually that the exhaust gets a lot louder. When you hear this, SHUT DOWN!

Once the exhaust system has been compromised you should replace it. This can be a critical issue for any portion below the water line as if it fails it can open a large hole that will allow water into the boat.

All boats will steam some. How does the boat run? If it is lean it will run very high exhaust temperatures.

that all makes sense. Thanks a lot. Actually I just replaced my impellor and houseing. I don't think they're failing, but I'll check. Also, my mufflers have fairly big holes in them, and when I'm running the boat, it basically fills with water from the mufflers... I think I'm putting the peices together... those holes are probably taking most of the water out of the mufflers thus making the mufflers over heat from lack of h20. Also, would it be a logical assumption that my raw water pump is working, if water is coming out of the mufflers in the bottom of my boat? thanks for the help by the way!

not sure what you mean by lean Peter?

Rich or lean is a condition of the motor. You shoot for a perfect air fuel ratio but we can only get close. A rich running condition means too much fuel, but the internals and exhaust will run cooler. Lean means too little fuel and the internals of the engine and the exhaust will run super hot. Timing can effect it too.

I believe that your boat uses a quadrajet carb, but I may be wrong. So I ask again how does it run? Power output? Does it idle well and launch on a hard acceleration?

I have no idea the fuel ratio, I'd like to find out though. But from your description I'd say that it is lean. It idles very well and is pretty responsive when you accelerate fast. Not sure if I'm answering your question very well, but I'd be interested in anything to cool it down a little, or making it a little more rich...

Then you are probably just fine. If it was lean, on a hard acceleration it would pop back through the carb or start to accelerate (Accelerator pump adds fuel) then fall flat on its face for a couple of seconds, until it catches back up.

We had an interesting problem on our houseboat. No problem at all when idling or at low rpms, but over 1600 rpm the engine would overheat quickly. It quickly turned the exhaust (mixed with cooling water) to steam. That in turn baked the rubber connections in the exhaust fittings to the outdrive. We tried everything and could not find the problem. After weeks of messing with it someone made the suggestion to take off the exhaust manifold. Inside we found that the passages had been restricted with a sand like material. This was at Lake Powell and with the lower water levels some owners had probably sucked up some sand and silt. With low water flow at the higher rpm the water temp rose quickly.

If you have a slight restriction, such as rubber parts from an impeller the temp may only rise too high when under higher throttle. And that smoke could be steam. Just another possibility.

Hi, Im the brother

I would like to know what would cause the coolant hoses to colapse randomly. For a split second or less they will colapse as though they are trying to suck water but they act like they are pluged for a second. is that normal cuz it doesn't seem normal. there was an issue with this boat chewing up an impeller and the parts were sucked into the coolant system. we took all the hoses off and flushed them out. we also took off the thermostat housing and found nothing. could some parts be hidden somewhere causing the problem? and if so where? Also is it possible to do a ram air induction on an inboard boat such as a scoop or air ducts?

Which hoses collapse?

The hose from the raw water pump to the fitting on the bottom of the boat (via the transmission cooler if your boat has one) is the only section of hose that should have any suction on it. This hose should have a spiral wound wire built into it to keep it from collapsing.

Everything else should have a positive pressure on it. One possible execption would be the hose between the raw water pump and the engine circulating pump, but the circulating pump has so little suction that I would not expect it to collapse the hose.