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| 115 hp Inline 6 - Learning the Hard w... |
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Rob Westbrook
New member
Username: r_westbrook
Post Number: 1
Registered: 08-2009
| | Posted on Thursday, August 13, 2009 - 12:58 am: | 
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Hello Fellas,
I just recently recieved a 115 hp inline 6, early 80's, with the # 1 (top) piston shot. I replaced the impeller ( had 2 cracked fins at the base), along with a new piston and ring for the number 1, all done with a brand new engine gasket set. The piston that came out was a std borre 2.875 piston with 3 rings on it, the piston that I ordered and recieved was a 2 ring piston, I had just assumed that the piston had been improved and been replaced. I got the motor running like a top, ran smooth in the drive way, water coming from the pisser was warm, almost hot, but you could defiantly hold ur hand under it for a while, so I thought all was good. I took the boat out 2 days ago for the first time on the lake and it ran like a champ for about to almost 2 hrs. I know when breaking in a piston, from my understanding is that you play with the throttle alot, up and down, and never keeping it at a constant speed for very long. So I was doing that, after a little while I thought the motor would be nice and warm so I dropped the hammer for maybe 10 seconds and all of a sudden it cut out and lost power. I was able to get it started after playing with it for a bit. I noticed that there was defently a mild knock coming from the top of the block. So I haven't been able to compression test it yet, I am assuming that a the rings where blown.
After some more research I found a site offering 2 and 3 ring pistons for my engines, I know I should have replaced it with what was there , but the online store I ordered from didn't offer a 3 ring piston. Another thing I was thinking in that maybe the thermostat is stuck partially open and not allowing enought water to get to the # 1, I know the impellers perfect since I just put it in. This is my first experiences working on a boat motor, so as the title says, learning the hard way............... Any advice would be great,
Thanks. |
leo a. pierron
Member
Username: andy_from_ar
Post Number: 32
Registered: 01-2009
| | Posted on Thursday, August 13, 2009 - 08:56 pm: |
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Rob Westbrook
New member
Username: r_westbrook
Post Number: 2
Registered: 08-2009
| | Posted on Thursday, August 13, 2009 - 09:35 pm: |
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So I did a compression test today... Good and Bad news, The # 1 which I replaced( with a 2 ring piston in exchange for the 3 ring that was in there) was still good. Now the #2 Piston rings are gone! I am guessing that when the previous owner blew the # 1 by overheating because of a broken impeller, the #2 was heated to a point of brittleness but didn't break becuase the engine was shut off right after the #1 went, therefore Im guess thats why it went, Im thinking that the new piston would have went aswell if cooling was a problem seeing it is highest on the block. Can some tell me if Im making sense, or just spitting out theories. Also FYI the compression was 120-125 psi all across the board expect for the # 2 which wasnt reading at all. Also is okay then to replace the 3 ring piston with the 2 again? Someone help me out here!!!!!!!!! |
jamie campbell
Advanced Member
Username: outboard_doctor
Post Number: 501
Registered: 02-2009
| | Posted on Friday, August 14, 2009 - 01:36 am: |
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Strip the engine down again and replace all the rings and it wont hurt if its two or three rings...check the timing!!!very important and clean the carbies. No harm in checking the impeller again |
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