Mercruiser 140 cylinder wear and timig gears

[kayakoc1]

Boat is 1983.
Mercruiser inline 4, GM 140, SN 6004051

I had the Head reworked 1 season earlier and it ran good, except for a bog (hesitation) on initial throttle up. Next season, I rebuilt the carburetor and it still bogged on inital throttle up, took it to the dealer, who rebuilt carburetor and adjusted valves and it ran good. Next time in the water, the bog was back, so I took it back to the dealer and carburetor was cleaned. During dealer checkout it ran good.
I took it out and it ran good, but during the run, it developed a tick or click (or some type of sound) coming from the engine. I was fairly certain it wasn't some type of valve noise. The head mechanic took it out and thought it might be a piston slapping. I shut it down after this run. This engine has never used oil or even discolored the oil during each season's operation.

I have removed the engine, disassembled and have not noticed any severe looking disorders (severe wear, marks, etc.). I have ( portable drill) honed the cylinders and the only thing that concerns me is a mark on #4 cylinder. I have attached a couple of pics. The plan was to hone the cylinders, go back with new rings, rod bearings and main bearings, however, I'm wondering whether I should take the block to a machine shop and have it honed or bored. The boat is old and not worth that much and I was hoping to do this job on the cheap versus just getting rid of boat with a slight noise in the engine.

In addition, I have found a few chips missing on the gear teeth of the composite/fiber timing gear. (see pic) I'm assuming that this will need replacement. I read in another post to replace both gears, just curious on why. Can the fiber timing gear be pulled and hammered back on without pulling the camshaft? My current puller will not fit the fiber timing gear, does anyone have a suggested tool.

Any comments on using Automotive Parts Store for rings, bearings. I looking for economical pricing. I am also using Mercruiser dealers to price.

Any advice or suggestions will be welcome. I'm somewhat mechanical in nature, however, I'm not an experienced engine mechanic.

Tim

 

[Fishermark]

Re: Mercruiser 140 cylinder wear and timig gears

It it were mine, I would go ahead and take it to a machine shop and have it done right. It shouldn't cost too much more money or time than you already have in it.

You also certainly need to replace the gears - they are pressed on, so the machine shop can do that for you as well.

Good luck.

Oh yeah - welcome aboard!

 

[Fishermark]

Re: Mercruiser 140 cylinder wear and timig gears

Be sure to mark the lifters when you pull the cam - you will need to put them back in the same bore when you put things back together.

The cam is easy to pull out - no reason not to.

 

[mariner1900]

Re: Mercruiser 140 cylinder wear and timig gears

If the engine noise is piston slap, then just honing and re-using the old pistons with new rings will not get rid of the noise. If anything you will be increasing the cylinder/piston clearance with the result the noise will get worse.Looking at the cylinder photo there is a fairly prominent wear ridge not to mention the score. The block needs needs to be bored and over sized pistons fitted. You can change just the fibre cam gear but the best way to replace the gear is to remove the cam, use a press to remove the old gear and fit the new gear.

 

[zbnutcase]

Re: Mercruiser 140 cylinder wear and timig gears

Replace the fiber gear with aluminum one, the auto parts stores at least around here can get parts for these engines.

 

[kayakoc1]

Re: Mercruiser 140 cylinder wear and timig gears

I have contacted the Machine Shop and just have to get it loaded and delivered. I will see what the next step is after he goes through it.
Tim