Oil Leak or Oil Injection not working? 1998 Sportster 1800

[mattbraafhart]

I noticed my 98 Sportster rotax 720's was leaking more oil than usual out the drain plug, after further investigation, the starboard engine has a large pool of oil on the rear engine mount which is dripping into the hull and out the drain eventually. I've also noticed that I haven't used as much oil this year as I typically do. Two questions then, how do I know the injection system is working properly? Is this a leaky hose or something worse? What should I check?

Thank you!

 

[Seadoobuddy]

HI, I would install a new grommet on the bottom of the oil tank, but also check to see if that tanks is a 2 piece tank. If so check to see if you have tiny cracks around the seam some place. Same thing happened to me and I replaced it with a 1 piece tank. If you have tiny cracks then it would only leak if over 1/2 full or tilted to be 1/2 full in one spot or another.

If you have not replace the tiny tygon oil line from pump to carbs then I would replace those too..esp if your are still painted white. Get yellow or clear so you can see oil going through the lines…..most ACE hardware or a mower shop will carry that line. 3/32 in size.

 

[mattbraafhart]

I'm not sure what you mean by double tanks, looks like just one to me, also not sure about white lines, mine are not white? Here are some pics the first one is where the majority of the oil was, under the engine pooling on the engine mounting bracket, I've wiped it all off so it's not there now.

 

[Seadoobuddy]

OK IN PIC #5 IT LOOKS LIKE YOU have a 1 piece tank…..I mean the top & bottom are glued together with a big fat seam for a 2 piece.
See below….

the first 2 are pics of the 2 piece oil tank….notice the brown spots….those are hairline cracks which leaked my oil out a couple times
…..……

The next 2 are the new small oil lines from oil pump to carbs….OEM lines were painted white.
…...

 

[mattbraafhart]

Ah, I see, thank you for that explanation.

In your two bottom pics, is that what I will see if I take off the carb air intake big black thing? It's down under that? Do I need to remove carb also?

Thank you!

 

[Luv2Camp]

Check the oil line that goes to both side of the block for the rotary valve bath. You could have a crack at the clamp or the clamp loose. I had a large puddle under my engine mount this year and when I put my hand under the engine and felt that line, the oil was leaking at the clamp.

 

[Waterluvr]

Cosign on the suggestion Camp made for the connection/clamp at the engine for the Rave bath lines, or you may have a slow leak up at the grommet that's making it's way down the tubing and dripping off. I clean the tubing up good below the grommet in the tank and wrap a couple clean paper towels around that area and wire tie that in place.

You'll know in a day or three if that grommet is leaking by doing that.

 

[Upallnight]

Could be the cranks seals is leaking. You will need to perform a pressure test of the crankcase to determine this.

 

[mattbraafhart]

Are there any good diagrams/images out there of how to get to this area so I can see those hoses? looks like I have to remove the carb to see down here?

 

[alexd51]

Are there any good diagrams/images out there of how to get to this area so I can see those hoses? looks like I have to remove the carb to see down here?

The area is not where the carbs are at !!!!
First use a mirror and make sure that is were your leak is because the only easy way to work in there will be removing the exhaust and you will need to replace the exhaust gasket after you take that out .
This is were you will be looking at.



Your boat might be slightly different from mine but you get the idea were you will be working at.


Good Luck

 

[alexd51]

Actually looking at the pics from your motor you don't need to remove the exhaust , is different from mine and from the looks of it out of the way a bit.

 

[mattbraafhart]

Ok, so I cleaned up all the oil and put the boat away for winter, just opened up the engine compartment yesterday and there is about half a quart of oil under both engine blocks and in the hull, so I'm pretty sure it's a line or clamp as others have stated but before I get in there and start breaking my ribs leaning over the engine compartment upside down I want to get a good idea of what I'm looking for and what I'm going to be working on.

Are there any good manual's or diagrams or videos of the rotax 720 oil system, oil flow, etc... I've been searching the internet but have not had good luck with an all inclusive reference to the 720 oil system.

Thank you!

 

[Waterluvr]

90/10 odds on the oil tank grommet leaking and your rotary valve oil supply and return lines are tracing the oil down the lines and into the bilge.

Start over with a thorough cleaning, Castrol super clean sprayed on the oil lines and all over the bilge followed by a low pressure wash will strip away all the oil film and follow my previous suggestion of wrapping the lines just below the oil tank in heavy paper shop towels and cable tying in place. Let it sit for two days, you should see the paper towels wetting out from the leak and everything else below it still clean and dry.

The supply and vent return connections where the lines connect to the lower cases rarely leak as their is no real pressure on either of those lines.

The shop manual will show you anything you want or need to see on the connection or routing of those lines.

 

[mattbraafhart]

Update on this thread:

It was the bottom oil tank gromet/line where it was leaking down the lines and underneath the engines. After cleaning up all the oil and wrapping a rag around that line, no more oil leaking. I must have bumped it loose when I did the winterization.

 

[robing]

You need a new boat. Just kidding. Mine leaks out of vent when it's hot outside. Little tube on top of tank zip tied up about six inches. So I got in the habit of keeping oil tank cap loose and tighten at the lake before boating.