Lower Unit - gear fluid trouble - need advice

[ifish4tuna]

A little advice please - especially if you had this problem and have cured it.

1999 Yam 250HP Saltwater Series

Every spring before launch, I have changed gear fluid.

This year while draining into a funnel and into a plastic 1 gallon bucket, I noticed my port engine was draining very slowly, and the fluid coming out was grey. It was a verrrrrry slow drain. Not a drip, more like a trickle. In years past I never really paid attn to how fast or slow it came out, nor did I pay attn to whether all of it came out. I usually just wait for it to slow to a trickle/drip before refilling. Maybe this year I was more attentive.

In addition, the propeller does not spin as freely as the starboard side.

After letting it drain for well over an hour. I attempted to squeeze fresh gear oil in from the top. The oil did not immediately drain through the bottom hole. I was really squeezing the bottle hard....Then I inserted through the bottom. Results not much better. All the while spinning the prop. Fluid was coming out of the top as well as bottom. A sure sign of blockage.

I attempted heating the bulb of the lower unit to see if that would help any. It was only marginal.

So clearly there has been some coagulation of the gear fluid.

So what to do next? What is the best thing to add to break down the bad oil prior to filling up? And should I run the engine to try and break it down with what ever I put in there? Should I just try flushing repetitively / running with lower gear oil, or something more emulsifying?

Thanks in advance, Ed

 

[Megabyte]

Sounds like you had a seal or gasket go bad which let water into the gear case causing what is known as a "milkshake".
Yours sounds to be a bit more than what can be fixed by simply replacing the fluid.
I'm thinking you need to drop the lower unit and see what it looks like inside, and then inspect all of the seals and gaskets.

Edit:
On my 1997 OX66, I discovered that the upper and lower oil plugs are not interchangeable.
If you swap them inadvertently, you can get water intrusion. Ask me how I know this...

Not certain about your 1999, but it might be something to look at.

 

[Bryan 2530]

What color is the oil??

I have never heard anything remotely like that, and I have plenty of experience with lower units from various makes and models.

Is the excessive metal on the magnet?? or water as Megabyte suggested. A pic of the oil might help.

 

[gw204]

I think the first thing I would do is leave it open for a week or so and see how much additional oil drains out. Then I might try one of the following (I don't know if these would cause any harm or not, so use at your own risk):

1. ATF
2. Marvel Mysery Oil
3. Kerosene
4. Diesel Engine Oil (like Shell Rotella)

All of these can/have been used to clean sludge from engines. The first three are generally run in low concentrations w/ engine oil (idle only) and the diesel oil already has lots of cleaning additives, so any of them should work and I doubt they will attack the seals. So maybe you could just put some in from the bottom, some in from the top, or both, let it sit and turn the prop. You might even go so far as to take the plugs out, disable the ignition, put the engine in gear and turn the prop by hand so you get the driveshaft spinning as well. See if that frees it up any or allows you to get out any of the goop. Do it several times. If you get to spin normally, I would grab yourself enough cheap gear lube to do several changes in order to flush all remnants of the cleaning solution out. Go through those in your driveway only running on the hose and then put in the good stuff before you put a load on it. New gaskets on the drain/fill screws for the final change of course.

It doesn't sound like a water pentration issue to me. Since you let it sit over the winter, I tend to think the water would have separated from the oil and you would clearly be able to see the difference.

That's what I would try before having a mechanic tear it down. None of those fluids will hurt the internals. The only things that may be at risk are the seals, which a mechanic would have to replace anyway.

You could also try putting some brake cleaner in from the top hole. Squirt it out of the can into a container you can pour out of. Pouring it as opposed to squirting it in should help prevent it from splashing onto things you don't want it on. Tilt the motor up slighly to try and keep it from getting to the prop shaft seal and see what happens. Last resort though as that will damage/shorten the lifespan of seals if it gets on them. Minimize the amount of spinning you do on the prop because that WILL wash the gears clean of all lube.

 

[ifish4tuna]

Thanks for the advice. Will report back after the weekend.

It was definitely not swapped plugs. The magnetic one was on bottom, but that one did not have the plastic washer on it, so that may be the source of the leak. There was a very minor metal dust on the plug tip. More so than the starboard engine which was almost clean.

Ed

 

[gw204]

Thanks for the advice. Will report back after the weekend.

It was definitely not swapped plugs. The magnetic one was on bottom, but that one did not have the plastic washer on it, so that may be the source of the leak. There was a very minor metal dust on the plug tip. More so than the starboard engine which was almost clean.

Ed

You sure it didn't have a washer? Sometimes they get stuck to the housing. If it really was missing, then I guess I was wrong because you'll definitely have water in the lube.

I wouldn't worry about the slight difference in dust on the plugs. From what I have been told, counter rotating lower units are a bit harder on internals than standard rotation.

 

[Megabyte]

It was definitely not swapped plugs. The magnetic one was on bottom

Interesting.
Both of my drain plugs have magnets.

 

[DaleH]

Sounds like a seal could be bad. I'd refill form the BOTTOM hole uising the pump system until full. Then I would put it in water and idle around at headway speed only, no > 1200 RPMs for 15-mins or more, then bring home and drain and re-fill again. Also use PREMIUM or Ultra-based synthetic L/U gear oil, as they will protect even when compromised upo to 25% with saltwater. Make SURE you have gaskets or O-Rings on those drain & fill screws.

Then check bi-weekly. If you have an issue, you'll need the L/U torn down and pressure checked anyway, so this method here (above) only costs you some time and oil.

 

[ifish4tuna]

Guys - Thanks..I really appreciate the feedback thus far.

Unfortunately she's a big girl (30' grady CC) So it will require me to have the marina put it in, once I get the LU cleaned out. Once in the water, it's in until the fall unless I pay extra to yank it.

In York Harbor, we do have spot where i can ground it on some telephone poles along side the town dock. The lobster guys have set this up. A few years ago I changed both water pumps in between the tides there. That's a hell-story for another day. But it will give me a chance to inspect for water leaks. If bad I can take the LU off there for overhaul.

Fun stuff.

Ed

 

[ifish4tuna]

OK - where do I begin? With my conclusion or the advice I need????

Here's the short/long of it :

Filled with fresh gear oil
Run for 15 minutes at ~1200 RPM - 15 mins
Drain
Repeated 4 times


Each time the oil got cleaner and cleaner. You would actualy think it was as good as what went in after the 4th flush, however, as it was draining into the funnel I poured some in from an open container to compare...still somewhat milky (only by comparison).

I am convinced I know how the water got in there. My local marina (shameless plug - York Harbor Marina - Merc/Honda/Whaler dealer), let me borrow their pressure tester - Nice guys - much appreciated.

My manual says to pump to 14.2lbs of pressure and see if it holds for 30 sec. Do not over pressure to avoid blown seals. Anyway it was only after I took the prop off while under pressure that I could see it weaping some milkly fluid along the props shaft. Could not hold more than 8lbs of pressure. So my thought is that the unit heats up from exhaust from the engine and possibly gear motion. On the cool down it is likely sucking the water back in through the compromised seal.

Oddly the port engine was only holding 8lbs also, but no weaping at the shaft, and the fluid on that one is perfect....perhaps a leak around the shift rod or the water pump...

Anyway, I stopped by Baert in Danvers on saturday (before my discoveries on sunday) on my way to a HS graduation, talked to the boys there, they recommeded checking for fishing line around that shaft seal which is what made me take it off to inspect under pressure.

I need to call them on monday to determine how to replace the seals. From the image http://www.boats.net/parts/search/Y...URX/LOWER CASING DRIVE 3 L225 250/parts.html#
it shows the seals (#15 in the link) being on the outside of the gear case housing, but I wasn't comfortable clawing at the seal to dig it out. I clealy don't have the tools to remove the housing. I have a steering wheel puller that worked on my 30hp omc, but will not fit the 250 Yam. It's possible I might need O-Rings #1 & #2 and #16 needle bearing also.

So I'll get a price from the boys at Baert and see what it will cost to drop the unit and bring to them for repair or if it makes more sense to buy the various specialized tools and do my self. Seems like a lot of tools.

Lastly - I was never aware there is a grease nipple on the outside housing of the gear case next to the prop shaft.

Son-of-a-bitch....I wonder if that was possibly the cause of the worn seal.

Attached pic shows the seal. You can see it's a bit jagged. Probably from fishing line.


So - now my question - anyone replace shaft seals before? Big job or does it need to go to the shop? I have torn down a 30hp gear case so I'm not a complete rookie. Do I need to pull the housing to do that needle bear & seal? Or am I better of tearing it down for inspection anyway?

 

[ifish4tuna]

So no mechanic on duty today at Baert, so need to call tomorrow. I also called Port Harbor Marine in Portland. The guy I talked to there said they have a 50/50 success in pulling the housing. When it doesn't work, it usually means the housing gets cracked. So some additional searching on this topic show it doesn't seem like many people try this on their own. Perhaps due to the tools involved. In any case I found this guys post on another forum and have reached out to him for some more info...

I just finished doing mine on my 250 hpdis. I could not get the housing out after trying spray,heat, and even a little banging. I then measured new seals width and put a piece of tape on drill bit. I drilled a pilot hole on each side of shaft then run a screw in each hole being very careful to not go too deep. After alot of patience and persistence I managed to get both out. Be sure to have some Pvc pipe that fits over shaft to beat new seals in properly. Mine is fine and I would not hesitate to do it again.

 

[DaleH]

To me, that guy was foolish (not saying he is a fool, mind you). Think about it ... whatever caused those seals to fail "could have" caused damage in other ways that you won't know about, if you aren't looking for it and/or don't have the eperiece to diagnose, or right tools to correct.

Were the bearing carriers compromised? You can't tell by looking at them. Is the propshaft bent? You can't tell and even if you were successful at getting the runout without removing it (I have done so myself) ... do you know what the OEM specs are? (I have various OEM service manuals on hand). Believe me, I'm an avid DIY'r, but IMHO there's somethings that are best left for the professionals.

Case in point, I once fooled around with a V6 motor for many days over a few frustrating weeks, but just could not get top RPMs. Tried every test in the OEM service manual .. spent $100 on the diagnostic tools, but finally admited defeat and brought it to my local OB guru for that specific make motor. Taking it out for the diagnostic test run, he ID'd the problem by ear (and experience), confirmed it in 20-minnutes or less back at the shop ... and charged $40 for the correct part and 2-hours total labor, which included the haul & short tow to his shop, the repair, and then dropping me back into the water. $$ dayum well spent I say! FWIW, the 'problem' wasn't even mentioned or discussed in the OEM service manual and yet he knew the resolution in seconds.

Sometimes you just can't beat experience ...

 

[ifish4tuna]

Yeah -point taken. Will be calling BM tomorrow.

 

[sparky]

To me, that guy was foolish (not saying he is a fool, mind you). Think about it ... whatever caused those seals to fail "could have" caused damage in other ways that you won't know about, if you aren't looking for it and/or don't have the eperiece to diagnose, or right tools to correct.

Were the bearing carriers compromised? You can't tell by looking at them. Is the propshaft bent? You can't tell and even if you were successful at getting the runout without removing it (I have done so myself) ... do you know what the OEM specs are? (I have various OEM service manuals on hand). Believe me, I'm an avid DIY'r, but IMHO there's somethings that are best left for the professionals.

Case in point, I once fooled around with a V6 motor for many days over a few frustrating weeks, but just could not get top RPMs. Tried every test in the OEM service manual .. spent $100 on the diagnostic tools, but finally admited defeat and brought it to my local OB guru for that specific make motor. Taking it out for the diagnostic test run, he ID'd the problem by ear (and experience), confirmed it in 20-minnutes or less back at the shop ... and charged $40 for the correct part and 2-hours total labor, which included the haul & short tow to his shop, the repair, and then dropping me back into the water. $$ dayum well spent I say! FWIW, the 'problem' wasn't even mentioned or discussed in the OEM service manual and yet he knew the resolution in seconds.

Sometimes you just can't beat experience ...

What motor, and what was the problem? Can't tease us like that.

 

[DaleH]

Sometimes you just can't beat experience ...

What motor, and what was the problem? Can't tease us like that.

New to me V6 OMC 225hp ... wouldn't turn full RPMs even though linkages and all electrical systems checked out (bought stuff to test stator, timer base, and all 6 plugs at once) ... brought to Paul @ Ipswich OB in Ipswich, MA ... he took it for a run, took off the air silencer and said "Oh, she's running rich, I bet the wrong year manifold ports (plastic parts) were installed ..."

Yup, fixed ... just by experience.

 

[ifish4tuna]

Brought it into BM.
Bearings Shot.
Broken gear(s)

The result of sitting in salted water over the winter. Bearing couldn't handle it during the flushing process. A few times while running it I noticed it sputter. Likely the result of eating gears.

Replacing the lower unit - it's only money. I'd have spent it in gas by now anway....

Guidance for the future:
- Change the fluid in the fall. Don't let the gears sit in salt water.
- If you notice in the fall. Don't run the engine like I did to flush it. Just have it inspected and bearings, seals, etc replaced...

Better on land than sea...