Question about a 150 Opti

[WorkerBee]

My brother has a 2004 150 Opti.

He has had issues with the belt tensioner a couple of different times now. Of course it only happens when he is in the most remote place he can find.

The first time the tensioner broke it cracked the block where it connects to it. Luckily Mercury supplied a new power head.

This time the spring broke and the block was ok.

He is worried about this recurring problem. If the block is damaged again, it is on his dime.

Does anyone have experience with this issue on these motors? He is starting to wonder if he should start looking for a new rig. His isn't as reliable as he needs it to be.

Anyone have any input?

Thanks,

b

[staylor]

...but it does come up now and then. Some say that the tensioner seizes, others say its because the grease fitting on the tensioner arm was never lubed- it is a bit hard to see. The third theory is that the main air compressor is ready to seize and it's internal crank and piston assembly is jamming now and then putting a shock load into the system. Merc claims the third theory is "bull stuff" and failed compressors come only from over-revs or poor winter storage. Most Merc techs suggest putting 4 drops of Merc DFI oil down the compressor air intake tube when the motor is winterized to prevent the compressor bearings from rusting- and this isn't in your owners manual!

Magically, Merc re-designed the compressor last year and the new design provides a much stronger crankshaft for the compressor. Don't rush out to buy one, since they are very expensive.

I have a 2002 Opti 150, well lubed, never over-revved, and I've had no troubles. I do know some racers who claim that it takes only one over-rev on an Opti compressor to begin the failure process.

You have several options, including just replacing the spring, replacing the entire tensioner mechanism, or paying a Merc Tech to tear down the compressor and inspect for bearing scoring/galling on the compressor crankshaft.

If your brother bought the motor new, then he should know if its ever been over-revved- and in a pinch the Merc tech can run the motor on his computer and tell you the number of over-revs. If he bought it used, then at this point I would consider trading it in. Sadly, the days of being able to beat the snot out of two cycle motors and prop them over the factory rev limit are long gone....and to think I used to prop my modified 1950s Merc race motors to 2000 rpm or so over the factory limit and run them like that for years. We used to "mock" the OMC owners because some of the OMC V-6s had a resonance that came in if you ran your 5000-6000 rpm motor too many times into the 6400 to 6700 rpm range- causing the flywheel to come off when the crank snout snapped.
Doug

[WorkerBee]

Thank you for the info. He did buy it used. It was a demo that was only a year old when he got it. He goes pretty easy on it but who knows about how the demo was used before he got it. My advice to him was to at least consider getting rid of it. I know his second power head is really down on power compared to the first one. I'll pass along the info.

My brother and dad are both in NW Ontario this week. Been a tough week. The tensioner for my brother and my dad took out his lower unit. The dealer in Kenora got them both fixed up today though. My bro was a fairly cheap fix. Pops got dinged for about $5200. Luckily they had his lower unit in stock. He can sort it out with the insurance company when he gets home.

Makes me glad I had to work this week! My boat is safe and sound in the garage.

[TomP.]

Another issue with the compressor is they are water cooled and the filter can become plugged and cause the pump to overheat causing pump and mounting failures.

[DRICH]

Do you have picture of where you have to lube the compressor at? I have a new 06 that i bought last year and want to take good care of it. Also how do you put the oil down the intake? Thanks

[staylor]

On my 2002 I pull the kill switch, then pull the cowl, then remove the top air box that houses the air filter, covers the flywheel and has the air intake horns molded/cast into it. This just lifts off its mounting grommets and you will have a couple of hoses/pipes that have to be gently pulled out of their grommets in the airbox. One of the tubes/pipes that go into this housing at the rear comes off the belt driven air compressor- this is a metal tube around 5/8 inch diameter that goes into a sealing grommet on the air box. This is the compressor air intake. Take a teaspoon with oil on it and dribble 4-5 drops or so down the pipe. Only a few drops is needed- more can cause compressor damage. While the airbox is off I also lube the pesky little zerk fitting under the tension idler pulley, and lube the splines on the starter Bendix drive and the starter gear teeth. I then make double sure the kill switch is pulled- then with gloves on- turn the flywheel slowly thru 1 revolution. I put a little grease on the mounting grommets and tube connections on the box, then put the air box back on making sure in front throttle body intake, all hose and tube connections, and the box mounting pins are all engaged. Double check this last step! When the cowl is back on don't forget to set the kill switch back to "run".
Doug