90TLRC low oil sensor leaking at cap

[fastback4]

My 07 90TLRC started a first time in 2 years, a slow messy oil leak at the end of the fishing season here in KY. It appears to be coming from under the cap, where the low oil sensor is located on the oil reservoir and down the neck spreading down the oil reservoir bottle and into the sump area. Maybe a ounce of oil, more or less. I have removed the reserve tank to cleanup the oil properly and took some pictures of the sensor and tank minus the zip tie that I had to cut. Other than what's showing are there any missing seals I should be aware of?
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[boscoe99]

There are no missing seals. The cap is the seal. Over time it loses its grip and oil may weep/seep from the tank.

Some will use a couple of zip ties around the perimeter of the oil cap to try and make a better seal. You may have to replace the cap/oil level gauge assembly.

[scofflaw]

Got me the same issue on this new to me txrz. Thinking it was the rubber cap, I put on the cap that was was on my previous blown motor, which never leaked a drop and results were the same. I don't see any defect on the plastic tank neck...will give the zip tie idea a try

[99yam40]

Is this leaking while tilted or is the tank overfilling?

Just to let you know you need to keep track of the foam strainer/seal at the bottom when pulling and replacing the float assembly in that tank . from what I have read it can cause major problems if not put back in place to filter the oil going into the oil pump/motor if something plugs things up.
new one may be a good idea

[boscoe99]

Good point about the seal. Make sure it does not fall off the oil level gauge assembly when the assembly is lifted and/or removed from the oil tank. Highlighted in yellow in the illustration shown below.

If there any orientation markings on the tank and the oil level gauge assembly make sure they are aligned when reinstalling the gauge assembly. Which has switches in it.

[scofflaw]

Mine leaks when tilted, like it may be slightly overfilling. Rarely do I tilt, so no big deal. Arrows aligned

[99yam40]

never mind on the tilting as I see this is one that is not filled from remote tank and the float assembly sits below the oil level

[fastback4]

I've had this motor for 2 years and I did not see or loose a foam seal ( item 42) when disassembling. Motor runs great and spark plugs look normal. I would think a foam seal would disintergrate when mixed with 2 cycle oil. I have it re-assembled now and will report the results to the leak or no leak situation

[boscoe99]

I've had this motor for 2 years and I did not see or loose a foam seal ( item 42) when disassembling. Motor runs great and spark plugs look normal. I would think a foam seal would disintergrate when mixed with 2 cycle oil. I have it re-assembled now and will report the results to the leak or no leak situation

The oil leakage now might be the least of concerns.

The seal is designed to live its life in the oil supply. Its purpose is to force oil to flow through the strainer and not bypass the strainer at the nipple.

Need to find the seal. They sometimes are dislodged when the gauge is being removed and it can wind up at the bottom of the oil tank. Nothing good comes from it not being where it is supposed to be. In worst case it can starve the engine of oil.

Fair warning!

[fastback4]

I will disassemble the low oil sender unit and filter assembly and install the $2.00 seal and get it done right. Thanks for the demonstration.

[rodbolt17]

not the first v4 or v6 two stroke I ever saw blown due to either debris entering the oil pipe when the strainer was removed OR the seal being shoved down the oil pipe on reassembly.
ALWAYS tilt the motor and drain the tank via the water trap BEFORE removing the screen.

ALWAYS retrieve and replace with new the foam seal.

[99yam40]

the scary part is where did the other one go to.
if it went down in the hole the float/screen plugs into things can get bad

[fastback4]

Bought the foam seal today and installed. I cleaned up the rough edges on the oil reservoir neck top and perhaps this may reduce the oil leaking from the low oil sensor cap. I am the second owner of this matching 2007 19ft. G3 and 90 TLRC. I decided to also replace the drain line that comes from the bottom of the oil tank and re-enters at the top of the tank. This line is very hard and dark looking. Item 27
m97kp4.jpg

[throrope]

Rodbolt's guidance is always ****.

On our 90 hp TLRD the oil tank seal is not at the cap, but on the sensor below the cap. Apparently over time the seal shrunk and left me with a puddle of fresh oil in the cowl every trip. I wrapped yellow fuel grade thread tape around the sensor at the seal and haven't had issue since. A search on this site will reveal other's similar experience and photos of my wrap.

[boscoe99]

A 90 two stroke oil injection model actually uses two caps. One cap that is removed to add oil. The sensor assembly uses a "cap" to try and prevent oil leakage. Because the sensor assembly is under positive oil pressure it is more prone to leakage. That and because rubber loses some of its elasticity over time and the cap does not grip the flange of the oil tank as it should.