Got my 40 HP rebuilt now this...

[fisher]

Some may recall I had a bogging issue with my 40 HP Mercury outboard. I brought it to a marina and they fixed it by rebuilding it - new pistons, impeller, fuel pump, spark plugs, etc... They said my compression was bad on 3 of the cylinders (?) and since they were working on it, they should do all 4 pistons as the other showed sign of wear.

 

I did not know, because they did not mention it to me, but after getting my motor back, I was supposed to break it in (now it makes sense after having been told it) but at the time I was anxious to get the boat back and did not think twice and I took it on a ride on Lake Ontario. After a 10 minute boat ride on the lake, I starting doing some trolling for Salmon (did not catch any by the way).

 

Anyway, after about an hour of trolling, I decided to give it a run to see how it performs (I now know this was not a good idea). After a few minutes at close to top speed, the motor shuts down. I start it up again and after a minute or so at close to top speed again, it shuts down again. I now decide to call the Marina from the lake and ask what is worng. It's then that they tell me that I should not have trolled or tried to run it too hard. I was supposed to break it in slowly (changing speeds once on plane, etc...). When I asked if I did damage to the motor, they replied likely not and that it's probably plugged up somewhere and to bring it in for a clean up (spark plugs, diaphram, etc...). That is where my boat is now....

 

They said that once I get the boat back I would need to break it in by going through 2 tanks of gas at speeds that are varied (not too low or not too high) using a fuel mix that has a higher mix of oil than normal (100 ML of oil per gallon of fuel). After that, I should be good to go.

 

My question to the board is...is my motor going to be okay?

 

Thanks as always for your input.

[Smokey]

Probably going to be ok but they did warn you about it. I had an old 73 rebuilt and it ran better then ever once the break in period was over.

[Kerry]

I might be wrong but my question is does your motor have four cylinders?Most if not all 40's that I know of are only two cylinders.

Kerry

[jwl]

I might be wrong but my question is does your motor have four cylinders?Most if not all 40's that I know of are only two cylinders.

Kerry

 

My 40 Merc is a 3 cylinder...as for the new break in period on your motor Fisher,is you motor oil injected????

 

only asking because I find it funny that different dealerships or marine mechanics tell people different things in regard sto stuff like break in periods. For example, when we got our boat we where told to burn 3 tanks of mixed gas through it, of course running the boat at various speeds ect as per most break in advice,then told on the 3rd tank of gas we should start noticing the oil injection working and see the oil starting to go down in the oil level indicator tube on the motor, once the oil injection was working then we didn't have to run the boat with mixed gas anymore. Motor runs like a champ for the last 5 years and still going strong as ever.

[JohnAB]

For my new 2008 Merc 50 HP 2 stroke, the Merc manual stated to run one tank of mixed fuel thru it as well as the oil injection. Vary speeds etc. Did that and then went about normal boating after that and so far no problems.

[Tybo]

Your engine should be fine.

 

As for motors, I didn't know you had to break them in.

[fisher]

My 40 Merc is a 3 cylinder...as for the new break in period on your motor Fisher,is you motor oil injected????

 

only asking because I find it funny that different dealerships or marine mechanics tell people different things in regard sto stuff like break in periods. For example, when we got our boat we where told to burn 3 tanks of mixed gas through it, of course running the boat at various speeds ect as per most break in advice,then told on the 3rd tank of gas we should start noticing the oil injection working and see the oil starting to go down in the oil level indicator tube on the motor, once the oil injection was working then we didn't have to run the boat with mixed gas anymore. Motor runs like a champ for the last 5 years and still going strong as ever.

 

 

I could be wrong regarding the cylinders...not sure how many I have but pretty sure he said 4 pistons (I have 4 spark plugs if that helps) - Obviously I am not good at mechanical stuff - that's why I brought it to the mechanic (lol).

 

My motor is oil injected...he did not mention anything about the oil injection kicking in later. But wouldn't the injection work right off the bat - how would the motor know if you had mixed oil into the gas?

[Bernie]

Your engine should be fine.

 

As for motors, I didn't know you had to break them in.

 

I gave up on trying to tell people the difference between them a long time ago Paul.

[Bernie]

My motor is oil injected...he did not mention anything about the oil injection kicking in later. But wouldn't the injection work right off the bat - how would the motor know if you had mixed oil into the gas?

 

It's a 4 cylinder engine.

It doesn't "know" the difference. The injector should be working. Just that a richer oil mixture helps to lubricate during break in.

[jwl]

My motor is oil injected...he did not mention anything about the oil injection kicking in later. But wouldn't the injection work right off the bat - how would the motor know if you had mixed oil into the gas?

It's a 4 cylinder engine.

It doesn't "know" the difference. The injector should be working. Just that a richer oil mixture helps to lubricate during break in.

 

I believe that this was just to make sure that the new parts in the motor where well lubed up being new out of the box, and as for the oil injection getting started to work, the mixed gas is just to ensure that when running the boat at different speeds, that it was getting more than enough oil to lube it right up in the first place..the oil injection, really isn't injection so to speak on my motor, there for example is no oil pump that really works to pump oil into the motor, it just feed off suction really so to speak and supply and demand according to how much gas is being fed into the motor at different throttle speeds...the gas gets sucked through the line, and a syphon kind of action pulls the oil in along with it..so for break in, it just seems kind of logical that you need some extra lube in the engine parts from the get go..it would not be doing your motor much good if ya took it for the first run and ir's pretty much dry just have have a couple drops of oil run through it...it's a pretty simple looking set up on mine...you can see how the fuel gets fed into the carbs...the gas goes through the line..through the oil tank feeder...gets sucked out as the gas goes through, feeds the top carb, fills it then feeds the second fills that then fills the bottom carb on it's way through....it's not that the oil injection really kicks in later..it's just a basic supply and demand thing on this set up, half the idea of the break-in is to get the engine well lubed up..it's pretty much just called oil injection, there is no pump that mechanically feeds the engine the oil.

[Bernie]

there is no pump that mechanically feeds the engine the oil.

 

There is a mechanical oil pump on this engine.

[jwl]

I like these kind of posts, everyone can learn alot from eachother in regards to different experiences, different motors ect for example when people start to comparte what they have and experiences and troubleshooting along the way. There is a huge amount off knowledge on this board

[fisher]

I like these kind of posts, everyone can learn alot from eachother in regards to different experiences, different motors ect for example when people start to comparte what they have and experiences and troubleshooting along the way. There is a huge amount off knowledge on this board

 

 

I agree about the knowledge sharing/experiences -

 

So after all that, I think the consensus is that my motor should be okay (despite the fact that it shut off by itself when I brought it close to full throtlle). Phew!

[aplumma]

after you break it in you can bring it to Bernie's Shop to see what the compression is that will tell you if you have scored the cylinder or damaged the rings.

 

 

Art