Coolant in Nanni 2.14 engine

[iamtjc]

I have a 13 year old Nanni 2.14 diesel in my Hunter 272 that has 386 hours on the clock.
I just replaced the coolant as part of the engine service.
The drain plug is quite inaccessible and was suspiciously fully coated with the blue paint they spray on new engines.
After I got it out it was all gleaming brass - no paint. That made me wonder if it had ever seen a spanner in which case the coolant might never have been changed.

I flushed the system with clean soft water as well as I could given that access is restricted and you can only pour a little in at a time or it overflows.
I also removed the expansion tank and cleaned out the 1cm of thick sludge at the botttom of it.

I then refilled the system with 50/50 antifreeze / soft water mix. However it only took 1.3 litres plus another 0.5 litres in the expansion tank.
The manual says it should take 2.7 litres (no mention of whether that includes the expansion tank or not).
On running the engine, all seemed well, though it wasn't for long enough to get hot.
The coolant level didn't drop which I would have expected it too if there had been air in the system.

So my question is what is filling 1/3 of my cooling system?
My fear is that it is sludge that didn't drain out .
Any thoughts on how I can flush it more vigorously (or other suggestions).

Thanks

 

[footsoldier]

If the engine was not showing signs of over-heating previously, I would not worry overmuch. Many car engines never have their coolant changed over their entire lifetime.

However, you now have a timely warning that it is possible that the system is sludged up. The normal first point of remedy is to poke and prod with suitable probes as far as you can and then to reverse-flush it with a hosepipe. Given the usual constraints aboard a boat, that can prove challenging and will require some ingenuity.

 

[RogerJolly]

Post appears just as I was thinking I need to change my coolant !

Been looking in https://nannienergy.com/downloads/m.../Manuel N2.10-N2.14-N3.21 ENG - 970316081.pdf

Says to open the vent plugs before filling....

 

[ChromeDome]

Make you run it until the thermostat opens before judging whether the cooling system is properly filled

 

[MikeCC]

My older Nanni has two drains, one on header and another low down on block. Did you open both?

 

[iamtjc]

Many thanks to those who replied - here is an update.

I had a moment of feeling foolish reading Roger's post saying "open the vent plugs". Why didn't I think of that?

On return to the boat though it transpired that due to the tilt of the engine the filler is above the heat exchanger vent, so only coolant came out.
The other vent plug in the loop to the thermostat was impossible to shift since it screws into a part only supported by rubber hoses and I couldn't get any torque on it.
Disconnecting one of the hoses had the same effect, but only a little air vented.

A call to A R Peachment (the Nanni distributor) confirmed that there is a drain plug on a little elbow on the starboard side of the engine block underneath the tube for the dipstick.
Pretty hard to get to on my installation but removing the air intake box at least allowed me to see it.

After draining from both locations, I was able to refill with 1.7 litres of coolant. An improvement, but I think/hope Chromedome is right that you won't fill it with all 2.7 litres until you get the thermostat open.
I didn't have time for that yesterday, so I'll update after next week.