Give this a listen

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Kerlin

Kerlin

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Mercury m2 240. Been fighting with her last 2 years. Or more. Please listen to the video and assess the sound. Is the knocking normal? I’m grasping at straws here.


Background: won’t plane out on water ( get above 4K rpm)
New parts
Air temp sens
Engine temp
Rev limit
Trigger
Stator tested ok
Cleaned vst filter
New primer filter
New fuel sep filter
New plugs
Spark on all cyl
Good compression on all cyl
TPS tests good
New battery
Volt reg tested in spec
36 psi on fuel reg
New bottle excedrin migraine
New exhaust hoses
 
From the vid... it sounds like there is an abnormal knock. But with that said... my engine is much louder, and "Clanky-er" when it's not in the water. Also... since I don't have a "3D" sound reference... it's hard to tell if that's normal or not. Also... since the system doesn't have a load on it... things like the drive gears can bounce on each other, and echo back though the fiberglass of the hull.

But, visually... your engine seems rough. It's bouncing and torqueing more than most of the Merc's I've seen.

So lets go down your list......

1) Excedrin is a good thing. Just make sure to wash it down with a caffeine drink.
2) When you checked fuel pressure...was that static, or trying to run? (you may find loss of pressure as the engine looses power)
3) I know you said it has new plugs, and has spark. But do this for me... pull the plugs, and lay them in order... and post a pic for me. (With enough detail of the electrodes so I can "Read" them)
4) As with the fuel pressure... did you check spark trying to go? Maybe we are loosing spark up high. To check this... you need a helper, and a couple in-line spark testers.
5) What was the compression numbers?
6) I know you said that the stator was checked... but was there also a visual check? You may want to pop the flywheel off, and make sure nothing is rubbing... and that the magnets in the flywheel are good. (I've seen them separate)

OK.... a few more things that come to mind.

A) Did you verify that the throttle is actually opening all the way? I've seen some engines with a stretched, or miss adjusted cable... and it simply wasn't opening past 60% throttle.
B) Did you verify that the timing is correct, and that the ring is moving freely with the throttle link?

Lets work though some of this... and I'm sure we will get you back up and running.
 
Dr Honda said:
From the vid... it sounds like there is an abnormal knock. But with that said... my engine is much louder, and "Clanky-er" when it's not in the water. Also... since I don't have a "3D" sound reference... it's hard to tell if that's normal or not. Also... since the system doesn't have a load on it... things like the drive gears can bounce on each other, and echo back though the fiberglass of the hull.

But, visually... your engine seems rough. It's bouncing and torqueing more than most of the Merc's I've seen.

So lets go down your list......

1) Excedrin is a good thing. Just make sure to wash it down with a caffeine drink.
2) When you checked fuel pressure...was that static, or trying to run? (you may find loss of pressure as the engine looses power)
3) I know you said it has new plugs, and has spark. But do this for me... pull the plugs, and lay them in order... and post a pic for me. (With enough detail of the electrodes so I can "Read" them)
4) As with the fuel pressure... did you check spark trying to go? Maybe we are loosing spark up high. To check this... you need a helper, and a couple in-line spark testers.
5) What was the compression numbers?
6) I know you said that the stator was checked... but was there also a visual check? You may want to pop the flywheel off, and make sure nothing is rubbing... and that the magnets in the flywheel are good. (I've seen them separate)

OK.... a few more things that come to mind.

A) Did you verify that the throttle is actually opening all the way? I've seen some engines with a stretched, or miss adjusted cable... and it simply wasn't opening past 60% throttle.
B) Did you verify that the timing is correct, and that the ring is moving freely with the throttle link?

Lets work though some of this... and I'm sure we will get you back up and running.
Click to expand...

1: soaked with sweat skipped excedrin and drank beer
2: fuel pressure check was idle out of water. Will take to lake to test under load and and let you know
3,4, will advise after load test
5: compression
1- 100 2- 100
3- 105. 4- 105
5- 100. 6 -100

6 - stator. When I changed the trigger I inspected and tested. Everything was in spec. No chaffing and magnets look good intact. Checked battery voltage at 12 volts then with running at 13-14 volts.

A: throttle opens all the way no issues there

B: timing. I’m completely lost on this topic and don’t know where to begin testing for this.

Now for more news as the day goes on. It seems there is a lot of oil coming from the exhaust. I’ll post a vid shortly. You can see black spots on the ground which I assum is carbon buildup? It seems to get it started now that it’s warm I have to give it some extra push by turning the steering wheel at max to open it up before it fired. Otherwise it just cranks. Once running it will idle around 900 rpm without stalling. If shut off it won’t start again until I hammer the wheel again.
 

Video of knocking seems more pronounced in the jet pump plus excess oil / carbon. Pulled exhaust lines and tanks both seem clear but have light coat of oil.
 
You can also see in the vid more smoke from the right side than the left. Not sure if this is relevant. Just taking note
 
all info is good... but without a load... it's going to smoke, and run funny. Yes... the engine may be physically getting hot... but it's not burning out. (takes a load to really push combustion temps) So... at the moment... I wouldn't read too much into the oil, and smoke. (other than it's good that there is oil)

The timing is something you check with an old-school timing light. There should be some marks on the flywheel, and you hook it to the #1 cyl. I don't remember the idle and full power spec off the top of my head, but if you don't have the manual, I'll look it up for you.

Now onto the bad part....

Your compression numbers are WAY under spec. If those are right... then the engine needs a top-end done. Normally I tell people to verify the gauge they are using... but in this case... with the low idle RPM and that you need to turn the wheel to start... I'm guessing it's right. BUT... a second opinion is always welcome. (With a known good tool) Low spec is 125 psi... and I normally see the 240 engine closer to 135 psi.
 
I wanted to take a look at the plastic spline inside the oil pump that everyone is talking about. Mines metal. Not sure if prev owner replaced it or what. Problem is there was no visible oil on the splines. Should I be concerned. I reinstalled it and bleed the pump. Got steady flow of oil from it so the pump seems to be working okay.
 
If you pulled the pump, you will see the metal drive. The plastic gear is on the crankshaft. To see it... you would have to pull the shaft out, and the bushing. THEN... you would need a bore scope.
 
Ok. So I ordered the lower timing controller box. Fired up instantly. Idling at a steady 1000 rpm instead of a low 900 and struggling to stay running. Would a bad controller cause low compression?
 
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