Sportmaster oil fill level practices?

**nelson edens** · 01-04-2021, 03:55 PM

has anyone ever done an expansion kit for a 2.5 sportmaster or CLE? I have seen an external one that uses the top vent plug, but that is external and could get ripped off.

**Capt.Insane-o** · 01-04-2021, 04:52 PM

Pretty hard to rip them off. I have built several using the gear lube monitor bottle from a gen2/Bravo. I have a reliable person online to make up the fitting for the vent plug soon and will have the hose/fitting kits. You supply the bottle which are easily found on ebay. The low oil sensor can be wired into the alarm easily as well.

The seal carriers on the 3 liters was about as piss poor of a design for a high performance gearcase as it comes.

**Markus** · 01-05-2021, 02:02 PM

Originally Posted by nelson edens

has anyone ever done an expansion kit for a 2.5 sportmaster or CLE? I have seen an external one that uses the top vent plug, but that is external and could get ripped off.

no need for one

**nelson edens** · 01-05-2021, 06:17 PM

that's what I thought. Only problem I had was overfilling and blowing out the seals. Learned the hard way.

**Markus** · 01-07-2021, 08:04 AM

You must be running higher and hotter than most folks...

As far as i know, as opposed to the 3 liter sm, the problem is not widespread enough for someone to develop a fix.

__PRESENT

**nelson edens** · 01-07-2021, 03:49 PM

I think my problem was that I changed the oil on a day that was 35 degrees and filled it all the way up. The first warm day (70 degrees) it must have expanded and blew the propshaft seal out.

**CI STV** · 01-08-2021, 06:20 AM

Is there any reason why you couldn’t use one of the canister kits for the Champ/S3000 L/U on a Sportmaster or CLE?

https://www.crowleymarine.com/mercur...cfm?mdl=BKPWKW

**XstreamVking** · 01-08-2021, 07:41 AM

To me it's the same theory as running a deep pan on your tranny or engine. More capacity and better cooling and lubrication. The big plus is the system makes it almost impossible to blow out the seals. We do all kind of mods, why not this? It's a win,win.

**Turborr** · 01-08-2021, 08:20 AM

If you have the mad efi billet seals, you don't really need the vent kit right?

**Sleek Jr** · 02-06-2021, 03:21 PM

Originally Posted by powerabout

what happens all depends on the conditions under which the box operates.
very high and hot water or very little coming down its going to get very hot blow the oil out then pull the water in when it cools

This makes sense. Mine was filled to the vent by factory Merc dealer by previous owner. It never pushed the seals out, but started leaking out the top seals, I think shifter seal or both.
Draining, I found it had water. So must have pushed out oil when hot, then when cool, sucked in water.

Boat is a 23 ft mod V tunnel, sport boat mostly used for weekend recreation (40-50 mph), with occasional warm water top speed run, so that could explain it.

**Sleek Jr** · 02-06-2021, 03:34 PM

Gentlemen, thank you all for your helpful responses. It seems the answer still varies depending on individual experience. This is a summary of answers:

1. Flll till it comes out the top hole, then drain and ounce or two. This will be much more than the manual 28oz. spec, about 34-36 oz. I put a full 32 oz bottle, plus extra, still nothing out of the top.
2. Fill the factory manual spec amount, seems to be 28 oz.
3. Install an expansion kit.

I guess the final choice is up to the owner or shop. I find it interesting that it was a major Merc dealer/shop in Minnesota, that seemed very experienced (the tech/installer of the engine raced for Mercury), and they filled it till coming out the top hole and quickly plugged it. In fact, after I got the boat, well before it started leaking, I pulled the top vent plug (unit cold, level, and sitting for weeks), and lots of oil came out.

I think I'll go with some expansion space for now.... I note one guy on here said he filled to 28 oz, and no problems.

**Sleek Jr** · 02-06-2021, 05:34 PM

UPDATE, NEW INFO: After putting 32 oz in, I decided to continue to measure and fill till it came out the vent hole. Total capacity: 44 ounces!! L.U. leveled, 62 degree day, completely drained and flushed before fill.

That's a lot more, 16 oz more, almost 60% more than the 28 oz. capacity in manual. Is this normal, or do I have some kind of "special" lower unit? (2007 3.2L 300XS Sportmaster)

If I had used the old "fill it till it comes out the vent" method, that means 44 oz. Seems over filled, but 28 oz seems under filled. What do you guys think?

Anyone else here actually measured their capacity?

**DewRonInc** · 02-06-2021, 07:18 PM

I have switched to mercury racing gear lube, todd said i would have zero problems and i havent......

**Sleek Jr** · 02-06-2021, 07:26 PM

Originally Posted by Captin Hazlewood

On a 3 liter sportmaster, fill from the bottom until it comes out of the top then drain off about an ounce. It will take more than a quart. Maybe 34-36 ounces. I have done it this way for years and have never pushed out a seal much less burned up any bearings.

I just filled mine, and it took 44 oz., until it just barely comes out the vent hole. I would have to drain 8 to 10 oz. to get to the 34-36 you recommend, and drain 16 oz. to get to the 28oz factory spec!

**Sleek Jr** · 02-06-2021, 07:33 PM

Question: If we bought a brand new 300XS with a Sportmaster and drained it, how many ounces would we measure? It would seem the factory would put in the ideal amount to ensure longevity and avoid warranty claims. (?)

When I bought the seal kit, and asked how much oil I need to buy, the local Merc dealer looked it up and said fill capacity is 28oz. so sold me just a quart.
Weeks later after installing, I wanted to confirm the fill capacity, so called them back, and a different guy said "fill till it comes out the vent hole" (which is 44 oz.).
Both of them were parts counter guys, not service techs. Said to call back on weekday and as service dept.