Is there a home remedy to flush gearcase before changing lube ...

[bobgritz]

I'm changing gearcase 'oil' and wanted to do a simple flush first. I haven't done it in about 2 years and it's way overdue (has that mock-burnt smell) and rather than simply change the oil I wondered if there was a home remedy flush anyone uses, for instance, something basic like kerosene?

 

[oldcatamount]

Re: Is there a home remedy to flush gearcase before changing lube ...

Pump through a couple cups of "sacrificial" lower unit oil. Catch it in a can and pump it through again. Unless you have a magnetic drain screw, take a "pick up" magnet and stick it in the drain hole.That'll let you look for tiny shavings of metal.

 

[eavega]

Re: Is there a home remedy to flush gearcase before changing lube ...

I had a LU that a previous owner had pumped full of the wrong oil. I cleaned it out by filling it with Kerosene and running it briefly. That was the suggestion given to me way back when. It definitely cleaned out the LU...

Rgds

 

[hotshot123]

Re: Is there a home remedy to flush gearcase before changing lube ...

I had a LU that a previous owner had pumped full of the wrong oil. I cleaned it out by filling it with Kerosene and running it briefly. That was the suggestion given to me way back when. It definitely cleaned out the LU...

Rgds

i did the same thing but i used deisel fuel. it seemed to work ok

 

[jere1972]

Re: Is there a home remedy to flush gearcase before changing lube ...

Agree with Hotshot123, was told by a OMC Mech of 40+ years use diesel fuel, drain your oil, fill gear case with Diesel run it for 2-3 min, and drain, I would never but anything in the gear case that was ignitable, diesel is combustable the gear case can't pressurize it enough to combust

 

[Jlawsen]

Re: Is there a home remedy to flush gearcase before changing lube ...

1. Drain the existing lube.
2. Replace lower drain plug.
3. Fill with paint thinner (home depot brand is fine).
4. Let stand for 1 hour.
5. Remove lower drain plug.
6. Let drain for 1 hour.
7. Tilt the engine up and down a few times to get any remaining fluid out.
8. Refill from the bottom until fluid comes out the top.
9. Replace the upper plug.
10. Remove the filler from the lower plug.
11. Allow about 1 oz of lube to flow out.
12. Replace lower plug.
13. Clean up and go boating.

 

[boobie]

Re: Is there a home remedy to flush gearcase before changing lube ...

I used the Kerosene trick years ago and it worked real good.

 

[Chris1956]

Re: Is there a home remedy to flush gearcase before changing lube ...

I cannot imagine it is a good idea to run the motor on anything other than the proper gearoil. Gearoil is also cheap enough to use as a flush, if you really need to. I would just refill it and move on to something else.....unless there are clumps of old gear oil or something.

 

[Jlawsen]

Re: Is there a home remedy to flush gearcase before changing lube ...

I cannot imagine it is a good idea to run the motor on anything other than the proper gearoil. Gearoil is also cheap enough to use as a flush, if you really need to. I would just refill it and move on to something else.....unless there are clumps of old gear oil or something.

The paint thinner, kerosene or diesel fuel trick has been around for years. Its a sure fire way to find a seal that's ready to let loose before it does and ruins your gearcase. If the seals are in normal condition, they won't leak and none of these oil rich solvents will harm them.

 

[Tim Frank]

Re: Is there a home remedy to flush gearcase before changing lube ...

If there were a really good "cleaner" it would be mentioned in your owner's manual or OEM Repair Manual.
Best way to clean the gear case is to drain and refill with the correct lube, run the engine for 1/4 hour, then drain and refill again.

 

[BoatDrinksQ5]

Re: Is there a home remedy to flush gearcase before changing lube ...

yeah if it looked like black shiny oatmeal...maybe....

otherwise don't sweat it...pump a little lube in through the upper vent and let it pour out bottom.

2yrs is nothing! MANY MANY MANY folks run for years and years (often until death)! before a 'tune-up' - haha

 

[bobgritz]

Re: Is there a home remedy to flush gearcase before changing lube ...

Thanks for all the great ideas and comments.

After reading all the 'gearcase cleaning strategies' I have to conclude that a quick flush with a solvent is the best solution. Other engine components (such as the carb, rings and valves) need to be cleaned, de-carboned, or de-greased periodically and we use specialized sprays, liquids and solvents to do the trick. We wouldn't run fresh anti-freeze through a radiator to clean out sediment or rust and I feel that this same logic should be applied to the gearcase.

The whole point is to remove any sludge, fines and unwanted residues in the gearcase and it seems perfectly sensible that a quick rinse might be the best solution. I think a 20 or 30 second running with any of the straight 'solvents' is a sound idea. For those more skeptical souls, perhaps a 50/50 mix of fresh gear lube combined with your choice of the above-mentioned additives might me more paletable.

With respect to "2 years is nothing". In my case, 2 years is a lot, I am a commercial clammer and we go out 365 days a year (God willing) with shut downs for rain closures, red tide, etc. Our outings are relatively short, high speed, trips to the flats but the last thing we need is to have an engine/transmission breakdown when the temperature is zero and the winds are blowing at 30 mph (talk about Dirty Jobs ... next time you groan about a 5 second dash to your car in a downpour or blizzard, think about us clammers who'll be out there for the next 5 hours ... I'm just saying!). In all fairness, when it's 70 degrees, sunny and there's a gentle breeze, there's no better place on earth and we wouldn't trade our job for any other and know how lucky we are (it's all relative).

Eat more clams guys ... fried, steamed or in a chowder ... there's nothin' bettah!

 

[Tim Frank]

Re: Is there a home remedy to flush gearcase before changing lube ...

After reading all the 'gearcase cleaning strategies' I have to conclude that a quick flush with a solvent is the best solution. Other engine components (such as the carb, rings and valves) need to be cleaned, de-carboned, or de-greased periodically and we use specialized sprays, liquids and solvents to do the trick. We wouldn't run fresh anti-freeze through a radiator to clean out sediment or rust and I feel that this same logic should be applied to the gearcase.

I don't think that is a valid comparison.
The other systems are either dismantled and reassembled after cleaning (carb) or the cleaner is burnt off or is flushed through very well as part of the system operation (cooling system flush) and the solvent.
Running varsol, or some other solvent in the gearcase will as likely as not carry small particles into the wrong places where it won't come out, AND remove the lubrication from shaft/bushing/bearing interfaces.

You aren't taking the gear case apart to clean it, so you'll never get all the solvent out....and Martha Stewart would not say " That's a good thing."

 

[archcycle]

Re: Is there a home remedy to flush gearcase before changing lube ...

It ought to be a closed and sealed stainless steel system so sludge and grime buildup like in a carb shouldn't be an issue and corrosion like in a radiator shouldn't be an issue and the inside of it doesn't have anything like the reservoir or other hiding places you'd find in an automotive transmission. Considering the seals don't last forever then it already gets cleaned every so often. Not like cleaning it would hurt anything, but I just don't see why one would in the absence of a clear reason like the oil coming out like oatmeal which, to me, would say there was some other problem that refilling the oil wouldn't have solved anyway.

 

[robert graham]

Re: Is there a home remedy to flush gearcase before changing lube ...

How about just pump in a quart of some cheap, off-brand detergent motor-oil, run the motor, shift gears back and forth a few times, then drain.....maybe better than Kerosene or similar solvent.

 

[Tim Frank]

Re: Is there a home remedy to flush gearcase before changing lube ...

How about just pump in a quart of some cheap, off-brand detergent motor-oil, run the motor, shift gears back and forth a few times, then drain.....maybe better than Kerosene or similar solvent.

....or cheap off-brand GEAR OIL....you know, the stuff that the owner's manual suggests for the gearcase....

 

[bobgritz]

Re: Is there a home remedy to flush gearcase before changing lube ...

CONCLUSION:

Like I said in first post, my oil had that "mock-burnt smell". That doesn't mean that it's actually burned but that's just the traditional odor of well travelled and tired gear lube. With that in mind, and because gear lube is sticky-sticky stuff, I simply wanted advice relative to removing as much of that crap as possible! Half of the contributors seem to be leery of introducing any foreign fluids into the gearcase therefore, let's look at it from a slightly different angle.

What if the gearcase was totally disassembled. Hopefully nobody would advise 'washing' all the parts in a bath of clean gear lube. If you had the gearcase assembly sitting on your workbench and wanted to give it a thorough scrubbing you'd break it down, toss it in the washtank, and add a good solvent. As you re-assembeled it, you'd slather each part with a coating of fresh gear lube.

For what it's worth, here's what I ended up doing.

Since I didn't have the luxury of time, I had to work within the parameters of a closed gearcase. Since I wanted my stinky lube out, I drained it ... filled it with diesel oil ... ran it in forward then in reverse for about 10 seconds each ... drained it ... filled it with fresh gear lube ... ran it for one outing (about 10 minutes out and 10 minutes back) ... drained it ... filled it with fresh gear lube. Less than 15 bucks of diesel and lube. Done!

Thanks to all for the input. There's no right or wrong system so choose the pattern that makes most sense. I happen to like the pattern I came up with but if my lower end blanks-the-bed before 2 more years are up, I'll report it here (and in another post as what not-to-do). I'm here to learn and hopefully pass along some good and bad experiences along the way. Happy boating!

 

[markheb]

Re: Is there a home remedy to flush gearcase before changing lube ...

What did the gear lube look like when you drained it after your 10 + 10 minute outing??? Was there any metal, discoloration, smell, etc.? Was thinking of doing the same with mine but wondering if the diesel fuel got all of the corrosion out.

 

[bobgritz]

Re: Is there a home remedy to flush gearcase before changing lube ...

I hated to toss it ... there was no grit and it looked (and smelled) like new. But, for the extra work of the 'rinse' plus the cost of a tube of lube, I felt that the lower end was worth the additional few bucks and well worth the peace of mind.

Perhaps if the gearcase oil didn't have such a strong burnt odor at the outset I may not have gone through the extra work. But, in this instance, it seemed to need special attention.