| Author |
Message |
    
Derek Riley
New member
Username: yelirkered
Post Number: 1
Registered: 08-2022
| | Posted on Tuesday, August 16, 2022 - 08:39 pm: | 
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Hello-
I'm the new owner of a 1956 18' Shepherd Utility with a Gray Marine 135 in it. A local shop cleaned up the valves and put on a new head gasket. They also installed a modern water pump. I'm seeing a fair amount of white smoke from the exhaust at full speed (~3000 RPM), and it is pretty loud.
Is it possible that the new water pump is pushing more water into the exhaust causing the steam? No water in oil so far, so I don't think it is a cracked block.
Also, what options do I have for reducing the drone at top speed? The low speed sound is great.
Thanks in advance! |
Thomas Fletcher
New member
Username: tfletche
Post Number: 2
Registered: 08-2022
| | Posted on Saturday, August 20, 2022 - 02:13 pm: |
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Is it steam or is it smoke? If it's steam then your theory might hold. If the water pump is electronic then you can try disabling it (dropping the water flow) for a short period to see what happens to the exhaust.
The second question is probably more about how your exhaust is set up ... not my ball of wax.
Thomas |
Derek Riley
New member
Username: yelirkered
Post Number: 2
Registered: 08-2022
| | Posted on Monday, August 22, 2022 - 06:30 am: |
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Yeah, it could be steam. The water pump is mechanical, but I can test it out of the water and shut off the water flow. Thanks for the idea! |
miro forest
Senior Member
Username: miro
Post Number: 1195
Registered: 11-2001
| | Posted on Monday, August 22, 2022 - 02:25 pm: |
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If you are going full blast, the engine is working hard and there is a lot of heat coming out the exhaust pipe.
The whole idea is that you inject the cooling water from the engine outlet as close to the outlet of the exhaust manifold as possible .This cools the exhaust gases and quietens the "roar" of the engine.
When idling you'll get a nice "burble" sound but at speed it's a roar. There are mufflers available for the mix of gas and water.
Running the engine at 3000 RPM seems a bit excessive to me. If anything, at that speed you want more water , not less to cool those exhaust gases. I hardly ever ran my engine above 2200 RPM when I had the Seabird.
miro |
miro forest
Senior Member
Username: miro
Post Number: 1196
Registered: 11-2001
| | Posted on Monday, August 22, 2022 - 02:32 pm: |
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I think you are running that engine too hard at 3000 RPM - that's wide open throttle.
You'll be getting a lot of hot exhaust gases coming out of the engine and they need to be cooled - that's why you are seeing white steam.
At idle you'll hear the nice burble sound but at full speed it's a roar. About the only thing you can do is add a gas and water muffler - they work sort of..... but not much.
Sheperds are a heavy boat and running the engine that hard isn't good for the life of the engine.
Plus you'll be burning a lot of fuel with very little increase in speed.
miro |
Thomas Fletcher
New member
Username: tfletche
Post Number: 3
Registered: 08-2022
| | Posted on Monday, August 29, 2022 - 10:40 am: |
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Sorry for the late follow up, but when I look at the service manuals for the 109 it's got the max horsepower listed as 109HP at 3400 RPM
Given the idle speed at 500, that's not a huge range so I would have thought that running at 3000 RPM should be just fine. Yes it is the upper end of the range, but it should be sustainable.
I'm asking out of interest because I'm working on a 1961 Dowty Turbojet with a 109 and the engine hasn't run in years (many many years) and so I'm slowly breaking it back in and had it up to 2500 RPM so far with the intent of tuning it all the way up to the max.
Thomas |
