SIP Medusa 950

Generally speaking I find SIP products to be pretty good, but this one has just needed a bit of fettling in spite of only very occasional use over the several years I've owned it.

 

The problem was a slight fuel leak where the fuel shut-off valve screws into the base of the fuel tank. As the generator runs off two stroke (and my two stroke oil happens to be dyed red) I did notice the early signs and intended to investigate further, putting a cloth under it to catch the occasional drip.

 

As is always the case with these things, it took time for me to get around to it (i.e. I didn't) and went into the garage one day to see a large pool of fuel/oil mix all over the workbench and dripping on the floor and the leak was far worse. Further investigation revealed the die-cast nut securing the seal/valve to the base of the tank was cracked, and I reckon must have been since manufacture.

 

On closer inspection, there were three other hairline cracks up the nut, and I found I could easily break the nut in half once I'd removed it (see photo below). Not good - especially considering it is a special flanged nut with a recess in the base to compress a rubber seal to the base of the tank and around the threads of the valve.  

 

I suppose I could have hunted around for a replacement but I'm not that happy at how weak this item seemed to be in the first place, and the sealing design doesn't seem that good either - i.e. there seems a possibility of fuel seeping down the threads.

 

So repair has been effected using a combination of Loctite 577 thread sealer (petrol resistent and quite expensive) a stainless steel M10 x 1.25mm nut, and a fibre washer. Note the nut is a metric FINE nut - standard metric is a wider thread pitch of 1.5mm. Cost of parts around £10 on ebay.   

 

In reality, this probably isn't peculiar to SIP since what appears to be the same unit (apart from different colour petrol tanks and slightly different ratings), is sold under a number of brand names: