Merc 120 HP Rebuild parts, where to buy?

[Fordiesel69]

Is there a total kit avail to do a refresh, and if I wanted to go the cheap route, can indiviual parts be purchased? If so where are you guys buying them.

Compression wise, the cylinders are nice a strong. Its got a newer head on it, but it has a nice rattle. I assume wrist pins, piston skirt, or cam / timing component related. If it was piston slap, I would then assume it would have low compression / excess blowby which it doesn;t.

 

[Fordiesel69]

Re: Merc 120 HP Rebuild parts, where to buy?

Nobody??????????

 

[elkhunter338]

Re: Merc 120 HP Rebuild parts, where to buy?

? is the compression good and is the oil pressure good.
Does the engine burn any oil.
My limited expereince with these 4 bangers is they are alittle noisy. I have owned two of these motors.
1. 1971 140 hp, it always developed what I would call valve noise/rattle at a certain rpm. I forgot the rpm, but I do remember it idled nice and at full throttle it sounded good. It sounded like the timing was too advanced. I played with different dist. weights and check timing several times and nothing seemed to change. I ran this motor for probably 200+ hrs, then one day the timing gear broke out of the blue, no warning skipped a gear and about 5 seconds later shut off like you turned the key off.
Long story short I ended up replacing the engine with a brandnew 2007 crate engine with a new dist. and everything.
2. set timing on this new engine per book, engine makes the excact same noise at about the same rpms as the old engine did. I have put 140 hrs on the engine so far and it sounds the same as the day I put it in the boat.

I would check comprssion, oil pressure (30 weight oil is recommended), see if you have metal in the oil filter, check timing to verify it is correct, tune-up and if all checks out good I would run it.

 

[havasuboatman]

Re: Merc 120 HP Rebuild parts, where to buy?

Be sure you rattle isn't coming from the exhayst flapper in the down tube. They can make a lot of noise. Or a simple out of asjustment rocker arm.
It is very improtant to find you problem before you start writing checks to the parts man, or you will start to hate boats faster than normal.
As far as where "we" get our parts, well, I am a factory trained and certified mechanic, I got mine shipped to me directly from Mercruiser to my shop. But then, mine was a Merc dealership shop.

 

[Silvertip]

Re: Merc 120 HP Rebuild parts, where to buy?

Piston slap and compression are not related. Try to isolate where in the engine the noise is coming from. Front, back, top, bottom, under load, at idle what???? Try pulling one plug wire at a time. If piston slap, a wrist pin, or in some cases even a rod will quiet down when the cylinder is not firing. At least you find the cylinder.

 

[Peaceful Pirate]

Re: Merc 120 HP Rebuild parts, where to buy?

Have to second elkhunter?s comments. One thing the 140s, especially the older models (70s/80s), are not noted for is a ?sweet sound? common in some other power plants. Think of it this way, have you ever known of a quiet running tractor? But you can normally count on a tractor to run, and run long and run hard. That trait of reliability and power-for-the-pound is why the 120s/140s were made for so long and why so many of them are still providing their owners some great times on the water.

Spend some time making sure the noise is something wrong, or just the ?sweet? sound of a water tractor!!

 

[Fordiesel69]

Re: Merc 120 HP Rebuild parts, where to buy?

Let me put it to you this way, have you ever listend to the rattle of the old 80's 2.5L GM used in all their lines of cars and trucks, noticed how they all sounded like thrashing machines? Also notice how if you were lucky to find an old lady with only 20k on it how they were quiet? Somthing is inherntly making the noise. I have time over the winter to tear it down and inspect.

It is not a rod becuase i have put 10 hrs on it this month at 4k RPM. If a rod, it would have blown by now.

To me it really sounds like cam, or wrist pin. Stripping it down is a sure way to find out.

I will also post a video here for you guys, but nonetheless I would like to know where I can get parts.

 

[Alumarine]

Re: Merc 120 HP Rebuild parts, where to buy?

I buy engine parts at my local auto parts supplier.

 

[Peaceful Pirate]

Re: Merc 120 HP Rebuild parts, where to buy?

For complete rebuild kits, you might check with marineengine.com.

 

[elkhunter338]

Re: Merc 120 HP Rebuild parts, where to buy?

You might want to call michigan motorzs this is where I bought my new engine in 2007 and dist. They might sell engine rebuild parts.
I would still have to question you on at what rpms does the engine sound bad?
If that thing will run 4k rpms for 10hrs does it still sound the same at the end of the 10 hrs. or does it sound like something is changing.
These motors have a rattle sound to them at certain rpms, my 1971 sounded the same as my 2007 motor. The 2007 was a brand new crate engine now has 140hrs on her.
If you rebuild yours I would replace the timing gear set since mine broke on me out in the ocean. The gear that broke was the plastic/composite cam gear.

 

[zbnutcase]

Re: Merc 120 HP Rebuild parts, where to buy?

NAPA can get 'em. 'nutcase