Flushing and Refilling/Bleeding Rads

[canal_man]

Hey guys, I'm in the middle of trying to get my Mikuni back in action for winter and need to refill the rad system (was drained for winter by previous owner about 2 years ago). I have access to inlet and outlet pipes and the header tank etc...

I was assuming just a garden hose into the header tank, and adding antifreeze, but that's where my knowledge would end and you know what they say about assuming! 

How do I go about:
1. Flushing and refilling the system (I know how to bleed the rads here)?
2. What additives should I be using?
3. Any tips? 

[BEngo]

Fill the system by filling the header tank and opening the bleed valves one at a time until water appears, progressively working away from the tank. run any pump and check each valve again and again after about an hour's running.

Flush the system by filling it with water, running any pump for an hour or so then immediately emptying it out again.  You can use a central heating cleaner- follow the instructions on that.  Check it is suitable for the metals in your system.  For a really good flush remove the rads one at a time and hose them out internally to shift the black sludge that may have built up at the bottom.

You only need to add 35-50% antifreeze.  That will protect against low temperatures and contains a corrosion inhibitor which will last for 2-5 years depending on type and your system.   Ideally you would make up the antifreeze mix so that it is properly mixed before tipping it into the header tank.  Do not add neat antifreeze then top up with water as it will take ages (weeks or months) to mix properly and inevitably the expensive bits will be full of water not neat antifreeze due to the workings of the Law of Sod.

Save some mixed antifreeze for topping up.

N

[Jen-in-Wellies]

And check that the drain point has been closed before adding the fresh.

Jen

Edited November 28, 2017 by Jen-in-Wellies

[Sea Dog]

^^^^ Mostly what BEngo said above. However, the antifreeze concentration should be kept as low as possible for most efficient heat transfer as water is better at that than the antifreeze is. Usually (iirc) 25% ethylene glycol based antifreeze will protect your system down to about -12c and 33% down to about -18c (check the label on the brand you choose) whilst still giving good heat transfer and effective corrosion inhibition, so no need to go stronger.  Do pre mix as suggested, as adding neat antifreeze and water separately can introduce stratification which will also prevent proper heat circulation.  Also for this reason, as BEngo says, keep some of the mix for topping up, although I've never needed to add to mine once air from the initial fill has been properly bled.

19 minutes ago, Jen-in-Wellies said:

And check that the drain point has been closed before adding the fresh.

Jen

Did you find that out the hard way, Jen? 

Easy done! 

[philjw]

Worth checking that the expansion of the water/ antifreeze mix doesn't overtop the header tank as the system heats up on first use.

[Jen-in-Wellies]

12 minutes ago, Sea Dog said:

.

Did you find that out the hard way, Jen? 

Easy done! 

Not with a boat, but with a car, yes.

[Sea Dog]

1 minute ago, Jen-in-Wellies said:

Not with a boat, but with a car, yes.

Soggy socks beats antifreeze in your bilge!

[canal_man]

Thanks guys, that covers most of my worries. Good advice on the surprise expansion and adding the correct amount of anti-freeze and keeping the drain point in check!

I need to add in a valve and a T for draining/filling --> flush --> fill up with the new mixture, then I can see if she'll fire back to life...  

Wish me luck, sounds like I'll need it!

[nicknorman]

There is a bleed screw on the mikuni itself, best bleed from this at the end to remove any airlocks.

[canal_man]

On 28/11/2017 at 19:27, nicknorman said:

There is a bleed screw on the mikuni itself, best bleed from this at the end to remove any airlocks.

Hey @nicknorman I had a look for that bleed screw last night on the unit and couldn't see it (Mikuni MX40), can't find a manual or any docs for it either. Where abouts is the screw do you know?

[canal_man]

Update on the progress:
Got the blown fuses replaced and a new air-motor installed (brushes gone), turned it on, it fired up. Lots of smoke/steam but sounded alright! Little did I know I had accidentally run it dry... overheated shut down and the water pump fuse blown. Replaced the fuse, filled with water (definitely this time). No she won't fire again.

Pumps kick in, air motor and fuel pump clicking, glow plug pulling 30 Amps but no fire.

Next on my list is to make sure it has Diesel and replace the glow plug... Anyone know how to bleed the Diesel side, can't find any info online? is it necessary to bleed or will the pump do it's thing? 

Edited November 30, 2017 by canal_man

[nicknorman]

30 minutes ago, canal_man said:

Hey @nicknorman I had a look for that bleed screw last night on the unit and couldn't see it (Mikuni MX40), can't find a manual or any docs for it either. Where abouts is the screw do you know?

Not on the boat at the moment and I think there is some variation, but you can undo the temperature sensor - the nut thing with a wire coming out of it to the right of the glowplug in this pic (ignore the red arrows), air then water should come out.

 

24 minutes ago, canal_man said:

Update on the progress:
Got the blown fuses replaced and a new air-motor installed (brushes gone), turned it on, it fired up. Lots of smoke/steam but sounded alright! Little did I know I had accidentally run it dry... overheated shut down and the water pump fuse blown. Replaced the fuse, filled with water (definitely this time). No she won't fire again.

Pumps kick in, air motor and fuel pump clicking, glow plug pulling 30 Amps but no fire.

Next on my list is to make sure it has Diesel and replace the glow plug... Anyone know how to bleed the Diesel side, can't find any info online? is it necessary to bleed or will the pump do it's thing? 

Have a look outside at the exhaust. If there is no white smoke, there is no diesel getting in. Make sure the fuel tap is turned on! Make sure you have enough diesel in the tank, the take-off point for diesel heater is normally well above the bottom to ensure the diesel heater can’t drain the fuel tank completely. You could simply be low on diesel!

if you are running the thing repeatedly trying to get it to fire - which you will have to do if it’s run out of diesel - best to do it not on shore power as I found that I blew the glowplug after a few attempts with the system voltage up at 14.4v from the shore charger.

As far as I’m aware, the only way to get fuel through is to have several goes at lighting it.

Edited November 30, 2017 by nicknorman

[canal_man]

1 hour ago, nicknorman said:

Not on the boat at the moment and I think there is some variation, but you can undo the temperature sensor - the nut thing with a wire coming out of it to the right of the glowplug in this pic (ignore the red arrows), air then water should come out.

 

Have a look outside at the exhaust. If there is no white smoke, there is no diesel getting in. Make sure the fuel tap is turned on! Make sure you have enough diesel in the tank, the take-off point for diesel heater is normally well above the bottom to ensure the diesel heater can’t drain the fuel tank completely. You could simply be low on diesel!

if you are running the thing repeatedly trying to get it to fire - which you will have to do if it’s run out of diesel - best to do it not on shore power as I found that I blew the glowplug after a few attempts with the system voltage up at 14.4v from the shore charger.

As far as I’m aware, the only way to get fuel through is to have several goes at lighting it.

Great info @nicknorman , I'll give it a bleed at that sensor to be sure I have the air out. I think most likely I have run out of diesel, and the only reason she fired once was the remaining diesel in the line. Dipped the tank yesterday after 6 lighting attempts, and I'm running low... off to buy diesel now. Ordered a glow plug and boss gasket from Mikuni too to be sure. 

I'll update here if I make any progress... here's hoping.

Edit: Also I'll switch off shore power when running again, good advice there.

Edited November 30, 2017 by canal_man

[Sea Dog]

3 hours ago, canal_man said:

 I think most likely I have run out of diesel, and the only reason she fired once was the remaining diesel in the line. Dipped the tank yesterday after 6 lighting attempts, and I'm running low... off to buy diesel now. 

Sounds likely - the fuel take off for your diesel heater should be above that for the engine so that your heater can't burn the last of your available fuel and leave you stranded without engine power.

[canal_man]

Update on the progress:

The reason it wasn't firing was that I was low on Diesel :/. I filled up and shes firing again!

I found the bleed valve, it's to the right of the glow plug inline with the outlet. I have spent the last few days trying to bleed the system and at this point I am 200% sure there is no air in there.

New problem: Fires up fine, circulation pump runs, then the unit overheats (9 led flashes). The water is near boiling in the unit after it overheats.  I have even bled the system as it's running (ensuring header tank is full as I go) but nothing, still overheats. I have ensured there are no blockages by forcing water both ways through the system with a hose, it ran clear by the end. It looks like water will flow freely no problem.

At this point I am almost sure the pump is not doing it's job so I removed the pump and tested it. The pump moves water but not much and with little to no pressure and will not even prime the 1cm of the inlet.

Has anyone heard of a circulation pump doing this before? I don't want to spend on a new pump without knowing for sure, it's hard to tell if it's that with nothing to compare.

I looked at the vanes on the pump and they did look worn but I have no idea if that would even matter. I'll try get a picture tomorrow.

So if anyone has any more ideas I'll give them a try!

 

 

Edited December 2, 2017 by canal_man

[canal_man]

Rang Mikuni there, they recommend a new water pump confirming my fears. Ordered one (£132!) so fingers crossed it gets me over this last hurdle.