Help with a Mariner 75 issue please.

S

steve the farmer

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Engine has started running slow. Have attempted to book a service but 2/3 week waiting time, so trying to sort issue myself as we need the rib for a club dive on Monday.

Engine is 1996 Mariner 75 auto oiling 2 stroke 3 cylinder carburetor.

Things that we know are correct. 2 stroke oil is topped up and has not been additionally added to the fuel.
We have replaced the plugs and inline fuel filter. the old fuel filter did have black deposits in it, but I could blow through it, so not blocked.

However, with prop in a bin of water and when I start it up I do not get a flow from the tell tail. I have left the engine running until the block was too hot to touch with my hand and still no water from the tell tail.
Question. should the tell tail be running or did I just not leave it long enough for the thermostat to open?
If water should be pumping from tell tail and it is not, I presume its either, faulty stat, impeller or pump?

Any suggestions would be appreciated.
 
I have the same engine (a few years newer maybe) and water comes out of the tell tail pretty much straight away. I would definately be getting the leg off and checking the impeller before running it again. When was it last done? I would also get the prop off and check for fishing line around the shaft and shaft seal. All straight forward to do.
 
wellf100 said:
I have the same engine (a few years newer maybe) and water comes out of the tell tail pretty much straight away. I would definately be getting the leg off and checking the impeller before running it again. When was it last done? I would also get the prop off and check for fishing line around the shaft and shaft seal. All straight forward to do.
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Yes I think that is wise. Thanks
 
wellf100 said:
And when you say slow running do you mean its not revving? Is it like that as soon as you start it?
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It has been a bit intermittent. Last Sunday we had a long run out of Dover Harbour at 4 knots and when we went to open it up it was like it went into a limp mode. although it has no ECG so wont have a limp, its just not getting revs up. We only went out a mile. The engine then rested for an hour and when started again it went ok for 1/4 ml and then lost power and we limped home.
 
Steve, I think you need to put a compression tester on the cylinders. Chances are the middle cylinder has over heated due to the lack of water from the water pump in the leg.

Pete
 
Pete7 said:
Steve, I think you need to put a compression tester on the cylinders. Chances are the middle cylinder has over heated due to the lack of water from the water pump in the leg.

Pete
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Compression test all of them. The top cylinder may be down due to the stat not working and an overheat.
 
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