Mikuni issue in newly acquired boat

[Doorman]

I was referring to all boat users not just a narrow band, even 60 foot seagoing boat builders where they are really suited seem unaware, the lowest power is 16kw which would be fine even for a large wide beam or small barge whose owners generally also seem unaware. Most wide beams need around 10 to 12 kw for a live aboard comfort when the calculations are done properly which means a thermo 90 or equivalent Eber evaporator at the low end with all the attendant drawbacks, a pressure jet will maintain a heat level and cycle without problems, with greater reliability, lower cost and longer life span, it will also heat a large calorifier quickly for the morning shower. So,yes there is a place for them but they need to be correctly specified.

 

They do appear to be better suited as designated boilers and not over priced duel purpose pre-heater come boat boilers, where as Nick says, their main advantage is their compact size. Up until your previous post, I've never heard the term 'evaporator' used in conjunction with the usual forced air boilers such as Mikuni etc.,

[Doorman]

Contrary to my previous comments regarding the quality of Mikuni admin staff, I telephoned The company yesterday to politely enquire whether my order of two combustion chamber gaskets had been dispatched yet, only to be informed in a rather curt manner that there was no stock availability until next week and that nothing had been received from Mikuni headquarters in Japan since last August.

 

Accepting the chaps explanation, I then tried to acquire the gaskets from a third party supplier online, only to discover that they were low on stock too. As an interim solution, I ordered an in stock service kit which contains the said gasket but at a higher price, along with the £3.50 postal charge for something that weighs a few grams.

 

Arriving home later that day, there on the doormat lay the inevitable Jiffy bag with my two gaskets from Mkuni! Pretty poor service from their admin staff on this occasion.

 

The reason for requiring the gasket will be explained in another thread, once I've corrected what was described to me as an inherent fault in the design of the heater by the charming man at Mikuni.

Edited November 23, 2013 by Doorman

[chilligibbon]

Back again! After all the great advice Mikuni has been running well since bleeding the system. However! After returning to the boat tonight after a week or so away the unit has blown the main 30amp fuse on start up.

I have taken the blown fuse out and it appeared quite damp in the holder, don't have a spare on board so it will be tomorrow now before I get to try a dry fuse.

Could the damp be the cause of it blowing in the first place?

[NMEA]

Unlikely that damp would cause it, main fuse blowing is a classic sign of a duff plug (nine out of then times I attend such an event it's the plug) fortunately most Miki owners cary a spare plug on board as they are so cheap, if you don't and you need one then get two. On another note I always replace the fuse holders with in line blade rubber waterproof ones that have an LED to indicate they are blown on all new installs now and a good smear of silicone grease to boot.

[chilligibbon]

Unlikely that damp would cause it, main fuse blowing is a classic sign of a duff plug (nine out of then times I attend such an event it's the plug) fortunately most Miki owners cary a spare plug on board as they are so cheap, if you don't and you need one then get two. On another note I always replace the fuse holders with in line blade rubber waterproof ones that have an LED to indicate they are blown on all new installs now and a good smear of silicone grease to boot.

Hi NMEA, I haven't seen a spare plug so will get online tonight and order a couple just in case, can you recommend any online suppliers?

[nicknorman]

Damp in the actual fuse holder? I wouldn't have thought so. Anyway, get a few fuses and try replacing one and see what happens. Maybe the fuse was just a bit old and tired, current does get close to 30A on startup especially if the system voltage is up around 14v.

 

It might be worth having a quick look at the glowplug - a 2 minute job - and check that the spiral element is not touching itself on adjacent turns. If it is, possibly this creates a partial short circuit increasing the current demand thus potentially blowing the fuse. In any case, keeping the glowplug clear of carbon deposits will prolong its life.

 

 

ETA

Got distracted then x-posted with NMEA but we think the same thing. You can get glowplugs from ebay a little cheaper than from Mikuni I think, like this one:

http://www.ebay.co.uk/itm/EBERSPACHER-GLOW-PLUG-ORIGINAL-EQUIPMENT-QUALITY-D1L-D3L-D5W-MIKUNI-FREEPOST-/181073046300?pt=UK_CarsParts_Vehicles_BoatEquipment_Accessories_SM&hash=item2a28cb6b1c

Edited December 2, 2013 by nicknorman

[NMEA]

Damp in the actual fuse holder? I wouldn't have thought so. Anyway, get a few fuses and try replacing one and see what happens. Maybe the fuse was just a bit old and tired, current does get close to 30A on startup especially if the system voltage is up around 14v.

 

 

Not so, in fact the reverse is true, a given wattage glow plug (of anything else too) draws more amps the lower the voltage not the higher the voltage, and A Miki ? Beru type draws 18a, @ 11.5v nowhere near 30 unless damaged, then it blows the plug.

A quick point, I get called out to fuses blowing after owners have fitted a plug and they then think it's something else, in fact they have not fitted it correctly and the seperating insulator washer is in the wrong place or missing, take careful note of the two conductor and washer positions when you remove the plug.

Edited December 2, 2013 by NMEA

[nicknorman]

Not so, in fact the reverse is true, a given wattage glow plug draws more amps the lower the voltage, and A Miki ? Beru type draws 18a, @ 11.5v nowhere near 30 unless damaged, then it blows the plug.

Wow that's a slightly scary comment! Does the Mikuni controller in some way regulate the current sent to the glowplug? I would doubt it, because that would require some power electronics with significant heat dissipating ability. And it then wouldn't blow the fuse if some of the turns were shorting.

 

If the Mikuni just puts the supply across the glowplug then what you say is wrong. It is not a fixed-wattage glowplug. If the voltage goes from say 11.5 to 14, the current will increase. Not quite in proportion to the voltage because at the higher temperature the resistance will increase slightly, but the current will certainly increase. To your 18A you have to add the pump and air motor current, totalling maybe 22A at 11.5v. At 14v that is likely to become around 26A.

 

The MX 60 has some sort of voltage regulation for the supply to cater for high voltage, the MX40 doesn't (although I believe it can be added).

[chilligibbon]

I'm now thinking that gather a few fuses, order new glow plug, check and clean existing glow plug while waiting for new one. Fire up and see what happens.

 

Just out of curiosity, our unit I believe is close on 13 years old and maybe if troubles continue it may be worth investing in a new unit. any idea on a cost supplied and fitted?

[NMEA]

I'm now thinking that gather a few fuses, order new glow plug, check and clean existing glow plug while waiting for new one. Fire up and see what happens.

 

Just out of curiosity, our unit I believe is close on 13 years old and maybe if troubles continue it may be worth investing in a new unit. any idea on a cost supplied and fitted?

When I replace them I replace the whole lot, even exhaust, fuel pump and cabling, I think the last one I did came to about £1450 job done but I don't know what is charged in your area.

[chilligibbon]

When I replace them I replace the whole lot, even exhaust, fuel pump and cabling, I think the last one I did came to about £1450 job done but I don't know what is charged in your area.

Ouch! Glow plug is now out and looking a bit mucky so think we may persevere with this one for a little while longer before declaring it dead!

[nicknorman]

Try to get the carbon deposits off the glowplug windings. These lead to local overheating and thinning of the element, which eventually fractures. But gently, the windings are not that strong and rather brittle. And as I said before, make sure adjacent windings aren't touching.

Edited December 2, 2013 by nicknorman

[chilligibbon]

And the saga continues! Put new glow plug and fuse in Mikuni. Unit tried to power up, and then tried again a second time.

 

I started to get a little smoke coming out of what appears to be a small electrical connection on the cover on the left of the body that the plug screws into.

 

Had a little panic this point and turned everything off!

 

Is this normal or do I need to do something else now?

[NMEA]

Can you either post a photo of the "smoking" componet or give the description by looking it up on the spares diagram on the Mikuni UK site, obviously electrical items should not smoke (smoke generators apart) but your description is a little vague and you seem unsure that it is even an electrical connection. Diagnossis or even pointers are reaaly a stab in the dark without knowing precisely where and what the smoke eminates from. Were you getting a little smoke from the exhaust?

[PaddingtonBear]

I think you are pretty brave to admit owning a Hu****, work of the devil good job the Sage of Tring is otherwise occupied.

[chilligibbon]

Can you either post a photo of the "smoking" componet or give the description by looking it up on the spares diagram on the Mikuni UK site, obviously electrical items should not smoke (smoke generators apart) but your description is a little vague and you seem unsure that it is even an electrical connection. Diagnossis or even pointers are reaaly a stab in the dark without knowing precisely where and what the smoke eminates from. Were you getting a little smoke from the exhaust?

Hi NMEA I have done a bit more investigating and believe the wire looks like it is connected to the flame sensor? I have what appears to be a spare gasket for his end of the unit also.

Does this help?

[NMEA]

Pull the rubber boot back so the dog can see the rabbit and try again, see if it is actually electrical smoke (I suspect not as it would blow a fuse if there was a short causing burned insulation) or if the sensor is not tight or the centre has cracked allowing smoke to come out, you should not have to strip deep enough to require the air motor cover gasket though.

Edited December 6, 2013 by NMEA

[chilligibbon]

Not sure how to add pic but taken out flame sensor and it appears the casing is cracked and some is still left in the cover thus allowing smoke out I guess?

 

I have taken pic if you know how to add?

[NMEA]

That souns pretty conclusive, you may have to remove the cover after all and remove any detrioitous from the casing before replacing with a new sensor which is just over £30 + post.

[chilligibbon]

I'll strip it out in the morning then and get one on order. Is there anything else that may be needed at the same time if I am going to strip the cover off?

[NMEA]

Assuming you are right about the gasket you have then the only thing is possibly the spring clip that holds it in if its a bit weak, but I would strip it first so you can order anything else, things sometimes break on dissasembly

Edited December 6, 2013 by NMEA

[chilligibbon]

Assuming you are right about the gasket you have then the only thing is possibly the spring clip that holds it in if its a bit weak, but I would strip it first so you can order anything else, things sometimes break on dissasembly:angry2:

Thanks, will keep fingers crossed for no more breakages and will keep you posted!

[chilligibbon]

I am now seriously thinking about replacing the whole unit.............

 

New glow plug fitted and then discovered on start up that flame sensor casing was cracked causing a smoke leak.

 

Today replaced flame sensor and fitted new gasket to main body and air motor. On start up the box of tricks is now telling me that the air motor is burned out!

 

Checked 7.5 amp fuse and this is good, pump worked when only changed glow plug. One thing is leading to another. Should I continue to persevere with the current unit?????

[NMEA]

Changing the air motor is a bit of a pain as in every case you should then set up the burn ratio, something even the most experienced DIYer is not able to do as they do not have the required kit. Might be best to throw in the towel and sell it on EBay, I have a good used air motor if you want to persevere but you could just be heading for more aggro and I certainly wouldn't buy a new air motor.

Edited December 14, 2013 by NMEA

[Biggles]

I have an unused glow plug for A Mikuni. Open to reasonable offers.