Halfords OAT (red) coolant ok in 2GM20F?

[wipe_out]

Looking to flush the cooling system.. Looks like previous owner just had water in the cooling system which is horrible and brown.. I want to flush the system with fresh water and then replace the coolant.. Popped into Halfords and they have the blue silicate and the red OAT versions.. Is the longer life OAT suitable?

 

[lw395]

AIUI, OAT antifreeze should not be used if you have brass or copper bits in the system.
Which I think you do!

 

[VicS]

Looking to flush the cooling system.. Looks like previous owner just had water in the cooling system which is horrible and brown.. I want to flush the system with fresh water and then replace the coolant.. Popped into Halfords and they have the blue silicate and the red OAT versions.. Is the longer life OAT suitable?

Check with the manuals, which can be downloaded fom https://www.barrus.co.uk/divisions/marine/diesel/yanmar-marine/manual-downloads/
( They will be under the 1GM headings)
Unless an OAT or long life type is specified use the conventional low silicate type . (Blue or green usually)
( ive had a quick scan through and cannot see OAT mentioned )

Unless your water supply is soft and low in dissolved solids dilute with distilled water, or ( more simply ) buy it ready diluted

In view of the current state of the cooling system it would be wise to check for any heat exchanger leaks which could lead to sea water contaminating the fresh water coolant.
Also check the injection point into the exhaust is not restricted because this will increase the pressure in the seawater side of the HE and exaggerate the effect of any HE leaks

 

[wipe_out]

Thanks.. I didn't realise the OAT would cause and issue with copper and brass..

I had planned on getting the "ready to use" one but I guess it will be the blue one going in.. Whole exhaust manifold has been replaced, old one was very much at the end of it's life..

Manual seems to suggest only having the anti freeze in over the winter and then draining it out and replacing with water and a rust inhibitor.. I presume there is a rust inhibitor in the ready to use coolant so leaving it in all year is ok?

 

[black mercury]

Yes leave it in all year round. You may find, even though you have flushed the system, that the coolant may turn a rusty brown colour after a few hours use. The coolant has a cleaning effect, so if the engine has only been run on water it is hard to remove all traces of the brown stuff. Don't worry, but you may need to flush again at the end of the season.

 

[VicS]

Thanks.. I didn't realise the OAT would cause and issue with copper and brass..

I had planned on getting the "ready to use" one but I guess it will be the blue one going in.. Whole exhaust manifold has been replaced, old one was very much at the end of it's life..

Manual seems to suggest only having the anti freeze in over the winter and then draining it out and replacing with water and a rust inhibitor.. I presume there is a rust inhibitor in the ready to use coolant so leaving it in all year is ok?

Yes but change it regularly. No longer than every 2 years.

( even the OAT should be changed regularly in boat engines because of the risk of contamination with salt water)