Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

[Ian Kicker]

Changing the gearcase oil for on my 2003 motor.
After allowing the gearcase oil to drain for 24 hours I tried to refill the gearcase accoring to the instructions - i.e., forcing the oil in the lower hole by squeezing the tube of oil. But the oil would not go in. On checking the upper plug opening I observed a lot of white flaky material. I removed as much as I could with a small wire and, eventually, I tried my drill with a small bit. I was able to blow some stuff out but the hole is still plugged. I tried some WD40, but it just sat there and did not penetrate. The only way I could get oil into the gearcase was by turning the motor upside down and dripping it in the lower hole. Incidentally, nothing came out the upper hole even though both plugs were out and, since the motor was upside down, it was the one closer to the ground.

Questions:
1) What is the junk inside the upper plug hole and how do I get it out? How do I know when its all out?
2) What does it mean that there's junk in there? The old oil was not milky, so I don't think this is salt.
3) If this is the result of some sort of galvanic corrosion process, how do I stop it (the anode looked not too bad - is all clean and shiny now)?
4) Could whatever have caused the blockage have done some more serious damage to my gear box?
5) Is it OK to use the motor now? -The gearcase is full (albeit by flipping the motor upside down and dripping the oil in the lower hole) and the two plugs are secure. Also, is it really full since it is not possible to do a oil level reading at the top oil plug?
6) Could my digging around in the upper plug hole and the WD40 have made the situation worse?

 

[Sea Rider]

Re: Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

So you have managed to remove both plugs, right ? How much W-40 did you squirt in, depending on the quantity, better remove new added oil, don't know the mix of gear oil + W 40 what could do to gears ? Try blowing compressed air from lower plug up, see what comes out upper plug, once obstruction is completely removed, squirt some new oil on upper plug and let drain through lower plug, just to remove excess of W-40, debris, whatever particles still inside. Could white flaky material be gear metal limays ? Place a magnet and see if attracted ?

Happy Boating

 

[pvanv]

Re: Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

The only way to definitively know the LU is full is by the upper hole. No idea what stuff might be blocking it. Since drained fluid looked OK, LU is probably OK. Would continue efforts to clear that upper hole, then refill as usual.

 

[Sea Rider]

Re: Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

You have this motor from brand new or it's a second hand motor as to guess what might white flakes be or last owner could have done ? Could it be salt flakes ?

Happy Boating

 

[Ian Kicker]

Re: Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

Thanks for the helpful comments. You guys are great.
Here's some additional information you asked for:
1) Yes, both plugs were easily removed. There is no evidence of corrosion or leakage around the plugs or washers.
2) The total amount of WD40 that could possibly have entered the gear case (assuming it leaked pass the blockage) is probably one quarter of one teaspoonful (about 1Ml).
3) Its too late to use a magnet to help determine if the flakes are metal. I used a straw to blow away the small bits that came out using the wire probe and drill bit. They certaily did not look like metal - more like chewed up paper.
4) I don't have access to compressed air.
5) The motor was purchased new in 2005 (model NS 3.5 B2) and was serviced professionally for the first time in 2009. This is the only other time the gear case oil has been changed. The motor is used once a month in the winter months and twice a week in the summer months. In recent years, each time the engine it used used it runs for a total of 20 minutes. The motor probably has a total of 10 to 20 hours on it. (My boat is a sailboat and I use the motor to/from the harbour only.)

It seems to me that the gear case is now full of new lubricant based on the following - (A) it seemed that the full capacity of old oil drained out (about 250 Ml) which might indicate that the blockage is isolated to the immediate region of the top plug and, (B) the oil level is now full based on observation through the lower drain hole plug when the motor is angled so that the drain hole is the highest point in the gear case.

Would it make sense to use to use the motor a few times and then re-check and/or professionally repair the blockage? I don't want to risk damaging a perfectly good gear case. I need to use the motor for a regatta next week.

 

[pvanv]

Re: Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

No guarantee that you're full; however, if you need it for a regatta, you don't have much choice. Just make sure that you are as full as you can be. A slight overfill would only cause a little extra internal pressure, and if the pressure is high enough, it might leak out of a seal until the pressure comes down to normal. Not a catastrophic event.

You can pull out the prop shaft housing and then get compressed air to the upper plug hole, so that any debris can be pushed through the vent hole, into the LU housing, and then removed through the prop shaft housing opening. Assuming that the LU was drained/refilled before (by the shop), it's possible that some debris, such as a fiber washer, etc., got accidentally inserted in the upper hole before the plug was reinstalled. Then installing the plug squashed it into a "cork" that is your blockage.

 

[Sea Rider]

Re: Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

When you removed upper and lower oil plugs, did both had their round gaskets with them ? Sometimes one of them o both stays sticked to lower tail.

Happy Boating

 

[Ian Kicker]

Re: Nissan 3.5 HP 2 stroke - upper oil plug hole plugged and can't pump new oil in

Thanks for your advice, everyone. Here's the update: I hung the motor upside down for 24 hours with both plugs closed and the gear case full of new oil. Then, with the motor still upside down, I opened the 'lower hole' and then the 'upper' hole (now the one closest to the earth). Some really thick, sludgy, black, goop ozzed out of the formerly blocked hole. With a wire I was able to coax some more out - but there was no proper flow as such. I closed both plugs after topping up the gear case with oil through the 'lower hole' with the motor still upside down. I let the motor sit upright for 24 hours and then ran it (on the boat). It ran for 15 minutes just fine with no evidence of leakage or abnormal noise. We didn't end up racing last weekend due to a sever weather warning. I'll tackle this again early in the spring and take it into a shop if the problem persists. Still curious to know what the root of the problem is, though.