What's the story on "an oil injected Merc can't sit more than a few months"

[Ron V]

This topic has come up a few times and I'd like to hear from someone who actually knows. A number of people have mentioned that the EFI motors should not sit for more than a few months, or the plastic oil gear will disintegrate when the motor is put back in service.

What are the differences in the oiling systems on the EFI motors compared to the carb motors like mine? I thought the plastic gear everyone talks about is actually on the crank, and that the (worm?) gear that goes to the pump is metal? I really don't know anything else about how it works. Will the plastic gear on the crank disintegrate after it sits even if the rest has been disconnected?

Does the type of oil used before storage have anything to do with it?

Would like to know if this is a concern for me since my motor will have sat from August to April by the time I get the boat back together. The motor was flooded with fogging oil while it was run out of gas, per the owner's manual. I plan on keeping the injection hooked up for now, but I don't want trouble especially since there is no alarm for oil flow.

The factory test runs these things, puts them in a box, and they sit for however long....can't understand why this gear problem would happen when the customer puts it away for a much shorter period of time.

[Dean Dorsey]

I guess I'm another that doesn't know but can say that my 98 promax gets run hard and put away at the end of the season with min winterizing and have not had a problem. I do not drain oil tank nor unhook and bleed off what is in the line and pump. DD

[M.CHAPMAN]

Ron and Dean,
Sometimes when the motors are put into storage with out having stabilized fuel ran through them varnish from fuel going bad can collect on the driven gear(steel). The end of this gear rotates in a bushing inside the block, the bushing supports the end of the gear shaft. If varnish collects enough on the gear shaft and inside the bushing it can cause it to stick and when the crank turns it can strip the plastic gear on the crankshaft. I have seen it happen many times. It is not guaranteed that it will happen but it can. When I have a motor come in for service that has been sitting up for a while it's a standard practice to remove the 2 mounting bolts from the oil pump and remove the pump, then slide out the driven (steel) gear and clean it and make sure there is no varnish on it. It only takes about 5 minutes or so to perform this simple check. Anyone can check it and know. Better to check it than to start it up and take the risk of the gear stripping. If you run a good stabilizer in your fuel before putting it up for storage the odds are better it won't happen. This applies to the carb motors as well as the EFI. Just my experience with them.
-Michael

[Raceman]

I have a '98 Sportjet (175 V6 carb) with 8 hrs on it from new. I am the original owner. It's been through stages of sitting in the garage for a couple of years at the time and it destroyed the gear and scuffed a piston. When it stuck I was turning about 3500 RPM and pulled the kill switch the minute the horn beeped, but it stuck anyway. I've had two neighbors with the same system on bassboats (both lazer injected) that sit around that lost the gear. One of em lost 1 cyl and the other lost all 6. I didn't see any signs of shellac on any of the three.

I love Mercs, and have been a devoted/fanatical customer for over 30 years, but that system is absolute JUNK and should have been recalled and fixed. Unless you want to buy or build a powerhead, if it's the type with plastic gear on the crank the system should be removed and the fuel premixed in my opinion.

[Reese]

Are you talking specifically about "sportjets" or the merc oiling systems in general.

Don't forget the thousands of happy 225 PM customers that haven't felt the need to change out the system.

[The Big Al]

All Mercury oil injection mechanical systems have the plastic gear on the crank shaft.
This is a constant problem when engines sit.

Synthetic oils have helped, but if it does not run often it will become part of this problem.

Take some premix oil and gas put it in a small jar, seal it up and look at it in 6 mouths.

Also take a little amount of oil just enough to cover the bottom of the jar and watch it for 6 months. (Not sealed)

Do not move or shake it up during this time.

Al

[Reese]

So what exactly happens to the plastic gear when it "sits" for long periods of time? Last year we fired up an older 150 that had been "sitting around" for almost two years...no winterizing, no special anything. It's running today without a problem.

Again...what about all dem Pro Max 225's. They sure don't seem to have a problem.

[riverrunner114]

So what exactly happens to the plastic gear when it "sits" for long periods of time? Last year we fired up an older 150 that had been "sitting around" for almost two years...no winterizing, no special anything. It's running today without a problem.

Again...what about all dem Pro Max 225's. They sure don't seem to have a problem.

did you "read" m chapmans post? here I will help...

If varnish collects enough on the gear shaft and inside the bushing it can cause it to stick and when the crank turns it can strip the plastic gear on the crankshaft. I have seen it happen many times. It is not guaranteed that it will happen but it can. When I have a motor come in for service that has been sitting up for a while it's a standard practice to remove the 2 mounting bolts from the oil pump and remove the pump, then slide out the driven (steel) gear and clean it and make sure there is no varnish on it. It only takes about 5 minutes or so to perform this simple check. Anyone can check it and know. Better to check it than to start it up and take the risk of the gear stripping.

I like the part about "its not guaranteed that it will happen but it can"

And thats a very good practice MC. I would have to agree, the oil injection is junk. as soon as your warrenty is up, trash it.

And Al, not all the gears are plastic. I have a few cranks in my shop that have metalic gears on them, **** metal, but still metal. Regardless the material of the gear, the system is junk and should be treated as such.

in my opinion, john

[Ron V]

OK, thanks for the replies, I guess that makes sense. This must explain why you hear stories from commercial boats that have 3000 hours on the system with no problems and that sort of thing. Worst thing for any mechanical thing is for it to just sit. But nobody has yet explained why the factory manages to get away with it. Sure, they probably used stabilized fuel for the test run, but stabilizer goes bad after a year anyway and causes even more problems.

I ran the gas out of mine, but did not use stabilizer since I wasn't sure how long it would sit. I drained the carbs (wasn't even necessary, about 1 drop ran out of each one). Was using Premium Plus oil. I'd prefer to keep the injection hooked up because the motor gets run half throttle a lot and the motor is rich as hell to begin with. Yamaha was 40 years ahead of this system with their Autolube that they had 40 years ago. Gee, all metal gears that inject the oil behind the carburetors so there is no delay in the mixture change, who would've thought.

I'll pull the gear in the spring and check it before starting it up. Maybe if the spirit moves me I'll can the system completely.

[Reese]

Sounds like a sound solution looking for a problem to solve.

[M.CHAPMAN]

I suppose if you took the ratio of Mercs produced that have had no failures to the ones that have. the ratio may favor the ones that have not. I agree it's not the best system designed and I personally do not run oil injection on any of my motors. It's not my place to tell a customer what he should run or not. I can merely offer my advice and experience and let them make up there own mind. Not all of the gears are plastic as riverunner said. The plastic ones are the most troublesome. Some prefer to keep the injection for convenience and that is their right. I simply reccomend that if you are running the injection to do as much preventive maintenence as you can with it. The one question I do ask when someone wants to know if it's better to run the injection or not is which method can guarantee you that your motor is getting oil to it? There's only one answer to it........................
-Michael

[Reese]

Michael:

I appreciate where your are coming from.

Let's just say that sometimes these things get blown (no pun intended) way out of hand. I think it's fair to say that the vast majority of folks never have oil injection problem with their outboards. The proof is when there is a problem like in the case of the the early VROs? everyone knows about it.

You think mercury's has a bad design....but I guess if that were anywhere close to being true you would have a bunch of folks jumping up and down screaming their heads off......and that obviously not the case.

[M.CHAPMAN]

Over the years of going to Merc schools I have asked the question repeatedly as to why they used a "plastic" gear on the 2.0/2.4/2.5 powerheads. They simply stated that is was "easier" from a manufacturing standpoint to machine the cranks to accept the 2 piece gear and put the void in the block casting where the driven gear rides than to re-design the block and crank combo. I guess that's why the later model 3.0 blocks were different, they started from scratch with those. Who knows, like I stated the overall failure amounts versus the amounts that have not must have been enough positives to keep them satisfied. I guess they have more faith in the material than some do, afterall they removed the rotational sensor from the warning system starting in 2000' as I recall. I think the latest version of the electronic oil delivery incorporated in the Optimax line is a better step as far as reliability.

I have serviced and rebuilt many Yamaha powerheads in the last 10 years and have hardly seen any failures due to oil injection. For the most part there system is a good one in my opinion. I still look at it the old school way and know that when I pre-mix it's getting oil.
-Michael

[150aintenuff]

ron aslong as you ran the motor out of fuel you should be fine... its when fuel sits in the motor it has time to varnish... our merc on our fussin boat is an 89 and olly the silinders fogged each winter fuel ran out of motor EVERY time it is done being used for the day.. and never an oil related problem one..

[David]

You know you have oil if you put it in yourself. My family members use my boat and I trust the oil injection more than I trust them. I've had my XR4 since 1993 and the powerheads never been apart. In the fall it gets fuel stabilizer, fog, and then fresh lower unit oil.