mercury 140 hp power issue

[rokitman]

Hello all I havent been here for quite some time now but would like to say
thanks for all the great advice thats posted here. Ok now to my question(s)
I very recently purchased a cool retro 1976 chrysler trihull courier 154 . The boat was owned by the same owners for 30 years. They said they purchased the 140hp mercury on it now in 1980. The owner says the boat was out on the lake a while back and after 2000 rpm all of a sudden it bogs out no power left. A mechanic in a small town looked it over and felt the carbs one by one and said it possibly blew a reed valve out . This is my first mercury and have limited outboard experience . My question is what can I do to check for other possible problems that show these symtoms before I have it torn down ? I'm of course hoping its something less serious. Any help or advice is greatly appreciated. I can be reached at rjcard63@hotmail.com if need be.

 

[arboatdoc71968]

Re: mercury 140 hp power issue

You have to have four things to happen at the right time for an engine to run. Compression, Ignition, Fuel, and Exaust. The exaust system almost never fails so that leaves three. Compression and spark are relativly easy to check. Pull the plugs out noting the order that you pull them and visually inspect each one. Look for the odd plug color. The plug(s) that are odd in color usually point to the problem. Chalky grey is a bad color to find so I hope you dont see that one. Reeds on that engine really dont fail that often so I woud look for other more common problems first. Gather a little more info and maybe we can help you out some.

 

[daveswaves]

Re: mercury 140 hp power issue

Hello all I havent been here for quite some time now but would like to say
thanks for all the great advice thats posted here. Ok now to my question(s)
I very recently purchased a cool retro 1976 chrysler trihull courier 154 . The boat was owned by the same owners for 30 years. They said they purchased the 140hp mercury on it now in 1980. The owner says the boat was out on the lake a while back and after 2000 rpm all of a sudden it bogs out no power left. A mechanic in a small town looked it over and felt the carbs one by one and said it possibly blew a reed valve out . This is my first mercury and have limited outboard experience . My question is what can I do to check for other possible problems that show these symtoms before I have it torn down ? I'm of course hoping its something less serious. Any help or advice is greatly appreciated. I can be reached at rjcard63@hotmail.com if need be.

Obviously its hard to second guess what may have happened after 30 years so you are going to have to start with some basics. First in order is a compression check of all 6 cyl, don,t skip no 6, use a compression gauge with a flex hose to get in there. The compression ideally should be 115 plus and all within 10 pounds of each other. Post your numbers, which ones are low or high can help to troubleshoot. This is an ADI engine so there is a good possibility that the stator windings for the high speed are bad. There is a test that you can do to determine this but don,t start throwing money at electrical until you know that all cyl are up to the task.

 

[rokitman]

Re: mercury 140 hp power issue

Thanks arboatdoc71968

I do understand your reply I was going in that direction anyhow just trying to narrow down the issue I'm having for peace of mind I guess I would say. I
have been reading any posts similar to mine to gain more knowledge. I will repost with my findings.

 

[rokitman]

Re: mercury 140 hp power issue

Hello daveswaves.
I do appreciate your response to this and will do the compression test hopefully this weekend. I have read about the high speed stator problem recently I'm not sure of the cost associated with that just yet but If I can revive this motor I'l be happier than a ... well you know. The motor itself looks in really nice shape only used approximately 2 weeks a year and garage kept. Thats it for now I will post my cylinder numbers asap.

Thanks

 

[rokitman]

Re: mercury 140 hp power issue

Hello daveswaves.
I do appreciate your response to this and will do the compression test hopefully this weekend. I have read about the high speed stator problem recently I'm not sure of the cost associated with that just yet but If I can revive this motor I'l be happier than a ... well you know. The motor itself looks in really nice shape only used approximately 2 weeks a year and garage kept. Thats it for now I will post my cylinder numbers asap.

Thanks