Exhaust temp at aqualift

Hi all brand newby I have krogen 42with perkins m135 I'm worried about exhaust temp at aqua lift muffler it's about three feet from engine but after several hours at any 1800rpm the temp seems to creep up to about 130degrees I think that's a little hot have owned boat over ten years dont remember it getting that hot have already looked at heat exchanger that looks fine my question is what's normal temp at exhaust

Welcome aboard. Have you ever put your hand in the water flowing out of the exhaust? I used to do that once in a while by standing on the swimstep and reaching down to the twin exhausts just to see how warm the water was from my two Lehman 120 naturally aspirated engines. The temp was always cool enough to hold my hand in the stream without discomfort. At 135F you can get a scald injury in 10 seconds of exposure, but I assume that there is a fair amount of heat lost as the water moves to the exit point from the muffler. So if you do elect to touch that water flow, be a bit tentative.

Welcome aboard.

Welcome to the forum!

If you have easy access to the exhaust port, warm the engine up and run it up to 1,800 RPM (out of gear). Hold a 5 gallon bucket under the exhaust and time how long it takes to fill. Calculate gallons per minute and see how it compares to what the manual says.

Ted

The exhaust hose and the lift muffler are rated to handle 200 deg F. So you are in no danger of overheating anything. Having said that 130 sounds a little high. Do the test Ted recommends above and make sure your raw water flow is within spec. You may have a clog somewhere that is limiting flow which will cause the exhaust temp to be warmer.

David

KADEYLADY said:

Hi all brand newby I have krogen 42with perkins m135 I'm worried about exhaust temp at aqua lift muffler it's about three feet from engine but after several hours at any 1800rpm the temp seems to creep up to about 130degrees I think that's a little hot have owned boat over ten years dont remember it getting that hot have already looked at heat exchanger that looks fine my question is what's normal temp at exhaust

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Welcome. Nice boat! Not sure that one can tell the internal condition of the heat exchanger by looking at it. Unless you meant something different? How many hours on engine? Raw water corrosion surrounding the exchanger can cause the efficiency to drop. This may also be your water pump beginning to fail. I believe there are two pumps, raw water and internal coolant. Don't forget to check the pencil zincs as they are an important part of the cooling system.

Welcome! Good luck sorting your cooling system. Since you've had the boat 10 years, do you remember the last time the coolant system and its components were serviced?

Greg.

Think Barnacle Buster flush.

That does sound a bit hot. My Lehman’s water lift mufflers run about 105-110 at a steady 1800 cruise.

Ken

Typical wet exhaust runs about 20-30F above sea temp with engine under a good load. 130F sounds a bit a hot unless you are in super hot sea water.

Depending on the engine size many send more water to the lift muffler than it can handle.

To prevent this a bypass is usually installed with a valve.

Perhaps the valve is not passing enough water to the muffler?