[Al Posts: 880 Status: Offline WWW]

Battery isolator switch ordered along with heavy duty tin coated solid brass battery terminals and new 170 amp (25mmsq) battery cables.

[Ronnie L Posts: 507 Status: Offline]

The battery isolation switch you fitted to Kermit is still there and working.
Every aircraft I have had dealings with have had a battery isolator switch.
They just need to be good quality……..like everything that works for a long time.

[John Robertson Posts: 5130 Status: Offline WWW]

Everything will fail/wear out eventually.  Battery terminals get bent back and forth every time you remove then and we know what happens to metal when you do that often enough!   Battery terminals should be solid brass rather than the brass plated metal-of-unknown-origin most seem to be.   Don't connect the cable using the crush screws - fit a proper high current sealed ring terminal and use the connector post clamp bolt to connect to the terminal.


Using switches is convenient BUT they need installed properly for the environment they are used in.  I've used "normal" key type isolators for years without issue but that was after a significant learning curve!  The switch has to be mounted so that the drain hole in the rear case is downwards, the cable connections and the rear case joints need waterproofed (PU40 etc.) AND lastly, the keyhole in the front needs to be covered when the key is removed (they aren't waterproof despite what the manufacturer may say!).   I also use the single screw type battery post isolators when access is easy - they also seem to be reliable (see above regarding cable connections and material.

[Nick Flint Posts: 4862 Status: Offline]

I totally agree with isolating the battery when not in use for a while.
Totally.
However ive tried many isolation types over many years on hovercraft / boats / motorhomes.
ALL eventually FAIL no matter what is done, after a deteriorating period of unreliability.


We ALL know- due to starting / cranking amperages- current demands are high which result in failure to "sufficiently" pass HIGH current to starter motor.
Sit on a silent loch side and listen to the deathly silence when you activate a starter switch (that worked 10 minutes ago.)
Feel the blood drain from your eyes whilst you contemplate a push start on your intransigent hovercraft. Sense the wife's questioning looks without having to look at her.


N0000oooo


Simply undo one 13 mm nut and remove the +ve clamp.
Advantages---
1 Costs are ZERO £0-00p.
2 This method of connection /disconnection simply cannot go wrong. All hovercrafters are well adapted to loosen nuts.
3 Makes you check the terminal occasionally (wipe over with nocrode smear) - Other smearing agents are available (baby vaseline- no vat!)
4 Whilst you're there- glance across the engine area, checking for nesting fauna or areas of known disquiet etc
------------------------------------------------
I challenge anyone to either-
A) Disagree with 1,2,3,4. with reasons
B) Suggest ANY isolation/ connection means, that will not (or can be proven) to NOT deteriorate with salt/sand/vibration.
C) Find any resolution (that cannot go wrong) that costs less than £0-00p


In modern parlance- what is there NOT to like?
------------------------------------------------
Have a nice day!

[Al Posts: 880 Status: Offline WWW]

Looking promising with the starting issues.  The past couple of weeks we've had 9" of snow covering the Marlin and now over the past few days we've had two named storms with a lot of rain thrown in for good measure.  This afternoon I thought lets see if the Marlin will start, pleased to say it started instantly 


Next job will be to add an isolator switch, I'll probably need to replace the battery cable to the starter motor  so I can get the isolator switch in a position that's not going to be in the way or cause discomfort to my legs. 

[Al Posts: 880 Status: Offline WWW]

Staring problem sorted "I hope"


I wasn't happy with where the air filter was mounted (very close to the floor) so relocated it to sit on top of the engine cover. 
Where the air filter was mounted I have now mounted a fuel filter/water separator in the hope that will help keep water out of the carburettor.


I removed the inlet manifold and carburettor so I could check inside the carb and also make sure that the carb solenoid pin had been removed.  The carb had a fair bit of water in the float bowl, so I blew the carb out using compressed air.


I removed both coils and cleaned up the metalwork on them, gave them a few coats of PCB lacquer, used a Sikaflex type sealer on the earth tabs as per the marinizing guide on this site, I also used sealer inside the rubber plug caps where the HT leads go.  Once the coils were refitted I then smeared the coils with corrosion block waterproof grease.


I also replaced both spark plugs with new ones.


While I was feeling motivated I also replaced the oil filter and replaced the old oil with 5W/30 grade fully synthetic oil.

[Nick Flint Posts: 4862 Status: Offline]

Just one thought ref fuel primer bulbs. In MY experience Ive found they denature in modern (E5/E10) fuel EXCEPT when you buy BRANDED ones such as Genuine MERCURY / Johnson items which lasted many years. Cheapo Ebay lookalikes lasted a few -----weeks and went solid!
All my H/C have run with water separators for the last 35 years. I can't remember being troubled by this (ever) but that's probably due to my poor memory!

[Al Posts: 880 Status: Offline WWW]

I drained most of the fuel out of the tank, & refitted manifold & carb.  As there is still a little more fuel to get out of the built in tank I used a 5ltr fuel can with some 75:1 2 stroke mix in it & dropped the fuel line direct from the fuel pump in to the fuel can.  I gave a quick squirt of easy start into the carb & engine fired straight into life.  I let it run for about 10 minutes and it ran as it should.  Initially it sounded a bit sluggish, but once I fitted the air filter back on it ran & revved as it should.


I let the hover sit for a couple of hours then tried starting again and it started immediately, so looks like I have sorted the poor starting issue.



I've ordered new fuel pipe, fuel priming bulb & a hose tail to fit in to the water separator that I shall be fitting.  Hopefully by the end of next week, hover will be ready for another test flight  [size=78%]  [/size]

[Steve Holland Posts: 1582 Status: Offline]

We used Sta-bil at the mower shop, it seemed to work quite well, I assume they make it suitable for current ethanol containing petrol.

[Nick Flint Posts: 4862 Status: Offline]

We've all been hit by the water in the fuel scenario.
As we know- E10 petrol is hygroscopic, and it absorbs water readily - its a mute point that is this GOOD - so it absorbs a small amount of water / condensation in the tank or is it a BAD thing because it absorbs too much water INTO the petrol. We get into miscible fluid arguments but ive personally seen all manner of mulsch inside aluminium carbs turning into frog spawn or waxy deposits  inside.
I sometimes wonder how engines run at all?
I hear of additives for winter lay ups, but have no experience of such. Has anyone used them to report back here?
Im sure we all "know" we should drain all fuel perhaps from all areas and or store inside and or use our craft every week, but Autumn just nullifies my best plans and I keep warm instead.
On one positive note - THIS is the very last time I store outside as today my craft was covered in 6 inches of dead wet leaves and I shall NO DOUBT pay the price soon in Spring as I reverse all the damage done because I simply didn't get around to putting it under cover.   

[Al Posts: 880 Status: Offline WWW]

Before the rain came today I thought I would have another look at the Marlin.  First job was to take off the rocker covers and check valve clearances, just in case one of the tappet adjusters had come loose.  Tappet clearances were 0.008" so they are OK.


Next job was remove the carburettor and check inside.  Carbs on these engines can be a pain to take off, so I took off the whole inlet manifold with carb still attached simple job doing it that way 


While I had the carb off, I removed the fuel shut off solenoid to check the the pin had been cut off "which it had".


Once on the bench I removed the float bowl from the carburettor & I was greeted with lots of water in the float bowl.  There was also water in the inlet manifold "which could be from condensation".  I used compressed air to blow out all the water from the carb & manifold. 


Rain stopped play, so unable to refit the manifold today.  Next job is to pump out the fuel from the petrol tank to check that it's not full of water.

[Steve Holland Posts: 1582 Status: Offline]

There must be quite a bit of water in there as E5/E10 will absorb quite a bit before the water then becomes visible.
Cranking with some flammable spray should get it to at least kick over if it has compression.

[Steve Holland Posts: 1582 Status: Offline]

Apologies for late reply nick, those coils were from ali Express.

[Al Posts: 880 Status: Offline WWW]

I had a thought this afternoon    while removing a fuel pump from a EFI Triumph motorbike I'm playing with at the moment.  Inside the tank, there was some petrol, but also below the petrol was a significant amount of water. "the bike has been stood idol for two years".  I'm thinking that even though the petrol I dipped the cardboard in lit OK, the engine probably picks up the fuel from the bottom of the tank, which could be mainly if not all water, which in turn would probably clog the carb jets, as water has a thicker density compared to petrol, which would probably stop engine firing even with easy start, as it won't be getting the required oxygen to cause the ignition of the fuel.


This could explain why the last time I tried starting it, it wouldn't fire or start for about 45 minutes of trying.


I think my next job is to drain the fuel tank & strip & clean the carburettor.   Then fit a fuel/water separator fuel filter.

[Nick Flint Posts: 4862 Status: Offline]

It's a mite confusing here. I understand the engine HAS been working? ie bought and tried and RAN?
As you will know the anti over run solenoid sealing off prong (bottom of float chamber) is perhaps best cut off to allow fuel to do its thing.
IF the prong is still present (remove the solenoid with a spanner) check its action when energised.
Im sure you already know this? My craft is set up with a blanking special thread plug and thus craft  is lighter by the solenoid and associated wire and - more reliable, as this line of imperfection is sidelined!
A tiny  squirt of 4* into the inlets or cylinder should also indicate a tendency to fire.
Also worth noting that sparks are less enthusiastic under cylinder cranking pressures as opposed to 1 BAR pressure, and then there's the old-----------
put new plugs in!
I guess you may also be correct with "coil rob" when too much wattage is expended by the starter motor to allow a sufficiently energetic spark with watts left (pun intended!)
A properly charged battery is a super place to start, especially when cold conditions lower the battery power anyway.
You could warm the float chamber with a delicate and warm area of your manhood to raise the fuel vapour pressure (and unfortunately named "FLASH POINT")
Have you tried a "bump start"- wife to push OBS!
Just trying to help here Al.
Merry Christmas