Mariner 5hp 2 stroke - Fuel tap leak that stopped - Why?

Mark-1

Mark-1

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Filled up my Mariner 5hp and ran it in a wheelie bin ready for the new season. It's been standing completely empty of fuel for 18 months.

Fuel tap was fine in off position but dripped badly in on ('internal tank' ) position.

I ran it a bit later after changing the plug and noticed the leak had stopped. Gave it a good clean with a cloth and there's no doubt it's stopped leaking - from quite a fast drip to no trace. (Cowl was off so I could see all round the fuel tap.)

It's not a problem - the taps are commonly available - but I'm curious. I understand back in the day cork seals would dry out, shrink and leak until they swelled up in use again but surely a more modern engine has rubber seals. Why would a leak start and then stop?
 
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The rubber seal could get displaced, maybe dragged out of place due to sticking when dry, then settle back into place and work OK.
Some of these taps rely on a spring pushing a plate onto a shaped rubber seal. If things don't move smoothly, it might not seal.
A bit of dirt can have the same effect, holding the plate away from the seal.
 
LadyInBed said:
Sounds to me like the tap seal just needed some lubrication.
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*Seems* that way to me too, pretty much as lw395 suggests.

anoccasionalyachtsman said:
You didn't overfill a little and its way out of the cowling was down the outside of the tap?
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I was filling from a 1ltr sigg flask with the cowl off, I can't see how I could spill any without noticing - I checked the tank for spillage in my hunt for the source of the drip. I can't 100pc rule it out but it seems very unlikely.
 
29th March 2020

I started my Mariner 5hp 2-stroke today. I had wanted to run it in the big plastic trunk I used back in November, but that had developed a leak, so I borrowed SWMBO's kitchen bin instead. Dangerous territory.

I had the foresight to borrow a bin-liner too, so the black sludge which the engine spits out would grease-up the bag, not the bin, and it wouldn't be stinking up the kitchen till Christmas.

The guttering taped to the back of the outboard was because I thought the drain squirts out diagonally, and would have missed the bin.

The bubble-wrap under the the engine was because I had twice brained myself, getting up from close examination of the leg.


Close observers may note that a) the bin was roped to the frame so it couldn't move, and b) the engine leg was also wired to the frame for the same reason (it doesn't lock down like it should in reverse). Nevertheless, I was worried because the inside of the bin isn't much longer or wider than the prop, so I didn't dare put the engine in gear or the prop would have destroyed the bin.

But does it do the engine any harm to flush only in neutral?

The smallness of the bin had another effect - the water warmed up quite quickly! I had put only 200ml (about a third of a pint) of mixed fuel in the tank, but it ran and ran, for a good twenty minutes. How hot is too hot, for a two-stroke's cooling water?
 
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Its also quite normal to run the engine in a tub with the propellor taken off, rather than have water spraying everywhere, especially on small engines without neutral. If you notice any steam coming from the tell tale then its overheating.
 
Thanks. The water coming out of the telltale wasn't even as hot as I like to wash my hands in. It was getting warm, but only because the whole bin-full was.
 
VicS said:
Perhaps the tank is now empty ... or you've forgotten that you shut the vent. ;)
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In the good old days this was normal with fuel cocks on antique cars, motorcycles lawnmowers and outboards. It was due to the fact that the seal on the cock was a cork ring and when out of use it dried and shrunk. One petrol was put in it swelled again. Maybe some modern materials react the same?
 
dancrane said:
29th March 2020

I started my Mariner 5hp 2-stroke today. I had wanted to run it in the big plastic trunk I used back in November, but that had developed a leak, so I borrowed SWMBO's kitchen bin instead. Dangerous territory.

I had the foresight to borrow a bin-liner too, so the black sludge which the engine spits out would grease-up the bag, not the bin, and it wouldn't be stinking up the kitchen till Christmas.

The guttering taped to the back of the outboard was because I thought the drain squirts out diagonally, and would have missed the bin.

The bubble-wrap under the the engine was because I had twice brained myself, getting up from close examination of the leg.


Close observers may note that a) the bin was roped to the frame so it couldn't move, and b) the engine leg was also wired to the frame for the same reason (it doesn't lock down like it should in reverse). Nevertheless, I was worried because the inside of the bin isn't much longer or wider than the prop, so I didn't dare put the engine in gear or the prop would have destroyed the bin.

But does it do the engine any harm to flush only in neutral?

The smallness of the bin had another effect - the water warmed up quite quickly! I had put only 200ml (about a third of a pint) of mixed fuel in the tank, but it ran and ran, for a good twenty minutes. How hot is too hot, for a two-stroke's cooling water?
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First of all ... REMOVE THE PROP !!!!!

Second ... if the water is warm but not hot - you are OK ...

Third - neutral or not makes no difference to cooling water as its cooling the engine - not the shaft.
 
anoccasionalyachtsman said:
1. Why REMOVE THE PROP off if it's in neutral?
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Ever have a mind in neutral moment when you think its a good idea to just do something ... forgetting where you are ? If not then you are a perfect person ...

And if you care to google test running an Outboard ... you will often see the recc'd Prop Off comment ... mainly because of start and go small engines - but good practice for all.

Its same when we test model airplanes ... prop off ... one stupid moment can spoil your whole day ...
 
You'd have to be a special sort of stupid to get tangled up with a prop when it's in a bucket of water. The reason you might take one off a clutchless motor is because there isn't a better way to empty said bucket.

Out of interest, how d'you do a full power test on an ic engine in a model aircraft with no prop?
 
anoccasionalyachtsman said:
You'd have to be a special sort of stupid to get tangled up with a prop when it's in a bucket of water. The reason you might take one off a clutchless motor is because there isn't a better way to empty said bucket.
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As I said - EVERYONE has moments .... except those that are perfect and never make mistake ...

Out of interest, how d'you do a full power test on an ic engine in a model aircraft with no prop?
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That is one time of course you have prop on and make sure you are BEHIND the model etc. but we do other tests as well as just power tests ...

Most models today are electric and they can start up if stick is moved and you don't have Throttle Stop enabled etc. They don't need starting routine as an IC does ...
 
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