Mikuni mx60

[Karma Dreams]

As the weather has turned rather chilly in the evening, decided to turn on the C/H for a while, but not working!! Called hubby to investigate and although we could hear the units usual noise,nothing was happening. On closer inspection 'white smoke' was coming from the unit itself, so decided to turn everything off and leave alone.

Anyone know anything about these units on this forum, or is there anyone we can call on for help/service etc in the Fradley area? We dont use the C/H much, but its nice to know it works if needed. So any help much appreciated.

[Robbo]

As the weather has turned rather chilly in the evening, decided to turn on the C/H for a while, but not working!! Called hubby to investigate and although we could hear the units usual noise,nothing was happening. On closer inspection 'white smoke' was coming from the unit itself, so decided to turn everything off and leave alone.

Anyone know anything about these units on this forum, or is there anyone we can call on for help/service etc in the Fradley area? We dont use the C/H much, but its nice to know it works if needed. So any help much appreciated.

 

White smoke will be water (I presume you mean from the exhaust outlet?), if you've not had a few goes at trying to start it retry for a bit the white smoke should clear as it sounds like condensation especially as you've not used it for a while.

 

If it's coming from the unit, inside the boat - check the exhaust connections.

[Karma Dreams]

White smoke will be water (I presume you mean from the exhaust outlet?), if you've not had a few goes at trying to start it retry for a bit the white smoke should clear as it sounds like condensation especially as you've not used it for a while.

 

If it's coming from the unit, inside the boat - check the exhaust connections.

Hi Robbo. Just asked hubby and he said white smoke was coming from the unit 'inside' and no, not from the exhaust. There was no roaring from the burner like you usually hear when it is working!! Weird. Maybe as you say, not been used for a while (which it hasnt) which is why now its not working.

[Albion]

White smoke will be water (I presume you mean from the exhaust outlet?), if you've not had a few goes at trying to start it retry for a bit the white smoke should clear as it sounds like condensation especially as you've not used it for a while.

 

If it's coming from the unit, inside the boat - check the exhaust connections.

 

I'm afraid I disagree. White smoke in this instance is likely to be the result of incomplete combustion. The fuel has been injected and heated but not completely ignited. Under those circumstances you get fairly dense white smoke drifting lazily away from the exhaust. From memory the MX60 should give flashing fault codes but I haven't any details here at the moment. Forum member NMEA specialises in this type of heater IIRC so he may be better placed to advise if you can supply more details about precisely what is happening or any flashing codes.

Roger

[Karma Dreams]

I'm afraid I disagree. White smoke in this instance is likely to be the result of incomplete combustion. The fuel has been injected and heated but not completely ignited. Under those circumstances you get fairly dense white smoke drifting lazily away from the exhaust. From memory the MX60 should give flashing fault codes but I haven't any details here at the moment. Forum member NMEA specialises in this type of heater IIRC so he may be better placed to advise if you can supply more details about precisely what is happening or any flashing codes.

Roger

Sounds like you are on the right track Roger.. your description of 'white smoke drifting lazily away' is the way hubby described it to me... like a ciggy drifting up is what he said lol... as to the 'flashing codes' etc. our manual on this heater mentions about these codes as well.. but dont think either of us have seen any lights on it to make a comment! Would be handy as might give us a clue as to what is wrong with it... ho hum

[Robbo]

If you have manual, there's a trouble shooting guide and start up sequence which will tell you what's wrong (cough). I used to get the smoke as well, so check the exhaust connections to make sure there's no leaks.

[Fred_Smith]

I used to have one of these some years back and had the same problem, as I recall when you turn it on some deisel is injected into the combustion chamber and the heater plug ignites it then the air motor should start (the wirring noise, then the pump starts, the clicking noise) but what happens is the air motor has failed so after the plug ignites the deisel it shuts down the unit but you are left with the whispy white smoke. An air motor will cost about £500, sorry expensive but its the same with them all eberspacher etc. As a tip dont leave the unit unused for too long as the damp gets into the air motor and corrodes it hence it fails

[nicknorman]

It could possibly just be insufficient battery voltage. I would try it again with the engine running. The glow plug takes a lot of current during startup and if the batteries are low or the cabling sub-optimal, the glowplug can get insufficiently hot to light the fuel.

[boots]

No experience with mikuni, but could there be any blockages in the fuel? (had similar problem with a webasto, issue was a small blockage - some fuel was getting through, so it looked like it was working, but turned out not to be enough to ignite properly)

[Albion]

Sounds like you are on the right track Roger.. your description of 'white smoke drifting lazily away' is the way hubby described it to me... like a ciggy drifting up is what he said lol... as to the 'flashing codes' etc. our manual on this heater mentions about these codes as well.. but dont think either of us have seen any lights on it to make a comment! Would be handy as might give us a clue as to what is wrong with it... ho hum

I have found my operator's manual now and, bl&&dy typical, it doesn't seem to mention the fault codes. There is however a fault finding (trouble shooting) table on page 15 which I recommend you work through. There is also a good set of instructions with block diagrams for the operating sequence that you should expect to see if everything is OK and another for a fault situation. Be careful about diagnosing a faulty air motor as it is easy to get this wrong and buy a new motor only to find that you've made the wrong (and expensive) diagnosis. I did just that on an MX40 that I owned so that's how I know. It is difficult to even try to make a sensible diagnosis without a much more detailed description of the full sequence of events before ignition failure. One question though: Do you hear the air fan running doing its 'post purge' 180 second cleansing of the combustion chamber fume after the unit has failed to ignite? If you do then it doesn't sound as though there is much wrong with the air motor.

Roger

Edited June 3, 2012 by Albion

[GUMPY]

Provided the white smoke is coming from the exhaust and not from the unit itself inside the boat then there is not much wrong.

The white smoke is caused by unburnt fuel left from start-up, when I have had this I disconnect the fuel solenoid to prevent any more fuel getting into the combustion chamber and then try and start the unit 3 or 4 times. The unit wont start as there is no fuel but it will clear, then reconnect the solenoid and it should start, it will smoke for a bit just ignore it and it will go clear.

 

This often happens if the unit is not used on a regular basis, mine will do it when I next start it as it has been off for a while as we have been away. I just ignore the smoke and it will clear

[Karma Dreams]

I have found my operator's manual now and, bl&&dy typical, it doesn't seem to mention the fault codes. There is however a fault finding (trouble shooting) table on page 15 which I recommend you work through. There is also a good set of instructions with block diagrams for the operating sequence that you should expect to see if everything is OK and another for a fault situation. Be careful about diagnosing a faulty air motor as it is easy to get this wrong and buy a new motor only to find that you've made the wrong (and expensive) diagnosis. I did just that on an MX40 that I owned so that's how I know. It is difficult to even try to make a sensible diagnosis without a much more detailed description of the full sequence of events before ignition failure. One question though: Do you hear the air fan running doing its 'post purge' 180 second cleansing of the combustion chamber fume after the unit has failed to ignite? If you do then it doesn't sound as though there is much wrong with the air motor.

Roger

Just tried to fire it up again, 'no joy' but engine bay filled with 'white smoke' which as you say think is just unburnt diesel. When you turn it on... you get the 'clicking noise', also a whooshing noise as well (is this the air fan you mentioned on the posts?).. Batteries all ok and charged so not insufficient power here either... Hubby waited a while to begin with when he tried unit again, and at first we both thought, great seems to be working.. until we saw the white smoke that is... what a bugger.. as said, maybe due to insufficient use (through winter)as anything on boats left for a while seem to be pain in the 'arris' when not used for a while as we all know on here. Might have to get someone near to us to have a look at it more closely and see what prob is... Cos dont know enough about this to start taking apart! By way.. I was wrong with the unit it is a MX40 not 60... oopps sorry excuse a lady's ignorance

[Albion]

Just tried to fire it up again, 'no joy' but engine bay filled with 'white smoke' which as you say think is just unburnt diesel. When you turn it on... you get the 'clicking noise', also a whooshing noise as well (is this the air fan you mentioned on the posts?).. Batteries all ok and charged so not insufficient power here either... Hubby waited a while to begin with when he tried unit again, and at first we both thought, great seems to be working.. until we saw the white smoke that is... what a bugger.. as said, maybe due to insufficient use (through winter)as anything on boats left for a while seem to be pain in the 'arris' when not used for a while as we all know on here. Might have to get someone near to us to have a look at it more closely and see what prob is... Cos dont know enough about this to start taking apart! By way.. I was wrong with the unit it is a MX40 not 60... oopps sorry excuse a lady's ignorance

OK, as it is an MX 40 then my guess is that the heater plug has developed some inter-turn shorting of carbon (but not enough to stop it heating up by blowing the main fuse). This, if it is the case, is usually caused by the heater plug holder getting its two air holes plugged with carbon which causes the injected fuel to dribble down the lower side of the heater plug holder and cause the aforementioned inter-turn winding carbon linking. Bear in mind it is so difficult to diagnose over the web. You need to remove the heater plug to check for the inter-turn carbon and to remove the heater plug holder and check the two angles holes for carbon blockage. You should also have the necessary gaskets etc available for reassembly in an ideal world.

Roger

[Karma Dreams]

OK, as it is an MX 40 then my guess is that the heater plug has developed some inter-turn shorting of carbon (but not enough to stop it heating up by blowing the main fuse). This, if it is the case, is usually caused by the heater plug holder getting its two air holes plugged with carbon which causes the injected fuel to dribble down the lower side of the heater plug holder and cause the aforementioned inter-turn winding carbon linking. Bear in mind it is so difficult to diagnose over the web. You need to remove the heater plug to check for the inter-turn carbon and to remove the heater plug holder and check the two angles holes for carbon blockage. You should also have the necessary gaskets etc available for reassembly in an ideal world.

Roger

Tks for that info Roger, much appreciated. We follow what you are saying - and makes sense to have a look, or get someone to remove and find if this is the fault with it. Guess need to get the spares anyway in advance of this happening, then hopefully will be back in action again

[Albion]

Tks for that info Roger, much appreciated. We follow what you are saying - and makes sense to have a look, or get someone to remove and find if this is the fault with it. Guess need to get the spares anyway in advance of this happening, then hopefully will be back in action again

If you look at this diagram MX40 you can see the glow plug and the glow plug holder shown (part no 5). I recommend removing both of them and checking the glow plug for carbon build up between the heater wire coils shown wound round the ceramic nose. If this is present it is usually a sign that the air swirl holes in the glow plug holder (part no 5) are blocked. They are difficult to see if they do happen to be blocked but are situated in the shouldered part of the holder that fits down into the body of the heater. The swirl holes are angled and not 90degs to the shoulder surface so you will have to clear them gently with a small drill bit used between the fingers. The gasket and tip sealing washer that I recommend you change when you remove the glow plug holder are parts 7 and 33. If you don't feel confident doing this then get a professional in.

Roger

PS Make sure you note where the insulating washers go when you remove the wire connections from the top of the glow plug because they insulate the positive and negative wires and prevent you blowing the main fuse every time.

PPS It's worth having a spare glow plug anyway as it can be difficult to remove the inter-turn carbon without damaging the coiled element.

Edited June 3, 2012 by Albion

[Colin Smith]

As the weather has turned rather chilly in the evening, decided to turn on the C/H for a while, but not working!! Called hubby to investigate and although we could hear the units usual noise,nothing was happening. On closer inspection 'white smoke' was coming from the unit itself, so decided to turn everything off and leave alone.

Anyone know anything about these units on this forum, or is there anyone we can call on for help/service etc in the Fradley area? We dont use the C/H much, but its nice to know it works if needed. So any help much appreciated.

 

 

Could be the flame sensor? Though it should turn itself off if that is the case.I'd take out and clean the flame sensor and the glow plug, then re-boot the system before trying to start it again.

 

Colin