97 Mercury 40hp 2 stroke leaking water and exhaust.

milkmanslick

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Jun 23, 2019
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97 Mercury 40hp 2 stroke leaking water and exhaust.

I broke the rule and bought this boat wth it not running. The mechanic did a compression test (95 lbs each cyc.) then rebuilt the carbs and and got it started. It starts right up runs pretty good but is leaking water and exhaust from the front of the motor where the upper and lower covers come together around what appers to be a pipe.

He then tells me the motor is junk because of the leak and he has a 75hp 4 sale that would work on my 2001 BT Proteam 165 which is only rated upto 50hp.

My issue is it runs pretty good and he is opposed to tearing it down to showing me what he claim is a cracked block.

I tried to upload a video but it is an MP4 I will try to get pics if helpful.

Any advice on repairing or junking this motor would be appreciated.
 

QBhoy

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Can’t make out the picture. Is it maybe from the tell tale piping ?
Otjer tnan that. Your compression is on the verge of acceptability or maybe lower...if the gauge is accurate.
 

milkmanslick

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Agreed on the compression being lower than I would like bare in mind the boat had been sitting over a year and he did the test with the motor cold. I have read the motor should be at running temps to pull a compression test.

To try to answer the rest... that pipe is just below the top cover on the what I would call front right side about 8 inches below the feul pump.
 

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milkmanslick

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Ok I have now taken the power head off. The seals seem fine still flexible. I am thinking the unit has been worked on not sure about rebuilt but all the cover gaskets are still very soft and flexible.

The leak is coming from a seal where the what I believe is called the lower unit mounts to the transom.

Also the serial number label is 3/4 missing if any one can help identify thos power unit that would be awesome.

My title has it as a 97 mercury 40hp ID # OG555427 ?????
 

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milkmanslick

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Ok here is an update.

0g555427 is my model #

My parts list for this repair is as follows.

Powerhead Gasket 796501
Adaptor Plate Gasket. 385011
Adaptor Plate Seal. 158663
Motor Mount Seal. 96401 need 2
Motor Mount. 923373 need 2

Elbow grease. URLooking@it

Can anyone confirm?
 

ptochman

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Joined
Jul 11, 2010
Messages
6
Ok here is an update.

0g555427 is my model #

My parts list for this repair is as follows.

Powerhead Gasket 796501
Adaptor Plate Gasket. 385011
Adaptor Plate Seal. 158663
Motor Mount Seal. 96401 need 2
Motor Mount. 923373 need 2

Elbow grease. URLooking@it

Can anyone confirm?
How did you make out? I have the same engine and have good compression (120-125) but showing water on #4 spark plug. Thanks Pete
 

airshot

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Jul 22, 2008
Messages
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Any technition that would tell you a 75 hp motor is OK on a boat that is rated for only 50 hp is not worth a grain of salt. Run dont walk, to get away from him !!!
 
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