half a pint of coolant every time

stuartwineberg

stuartwineberg

Well-Known Member
Joined
24 Oct 2007
Messages
1,814
Location
Romsey, Hants
Visit site
every time I go out there is about half a pint of coolant in the side of the bilge. A fore and aft stringer separates it from the main bilge so I know it isn't coming from the head and I don't think it can come directly from the header tank. However the set up on the Yanmar is that there is a pressure release pipe under the filler cap leading up to a small plastic tank and I think the idea is that excess coolant goes into this and then sucks back when everything cools. However the Plastic tank is always empty. Can't work it out. could the 12 year old filler cap be tired and releasing pressure too soon? I'm tempted to replace it anyway and see. Ideas welcomed as always
 
Are you having to replace the lost coolant ?

I had a similar issue last year - tuned out to be a perforated heat exchanger. The seawater pressure was obviously higher than the fresh, so although I was finding coloured coolant in the bilge, I wasn't losing anything. In the end I worked it out by measuring the level below the filler, and when I noticed it rise there was only one place it could have come from.
 
I had the same issue with our Yanmar. I was filling to the mid point (min/max) and would find after a run 'blown' coolant as when it expanded it clearly blew.

I eventually filled to just the minimum level and kept a close eye on the temperature - no issues. Checked the header tank after the engine switched off coolant level almost to max. Coolant cooled down and ended at min level.

Never had an issue since.

Clearly it might not be this if all has been fine before.
 
stuartwineberg said:
Thanks all for the advice and comments. James I knew it was you before I saw the boat name - just by the dazzling reflection off the highly polished gel coat!
Click to expand...

well I knew it was you because you didn't have your aft cockpit cover on!

BTW, doesn't a Hardy look smart on the water!


excuse thread drift.... but you will see my point, Our dog, a very smart Scottish Terrier, loves to see a fellow Scottie, but I think in her 4 years she has been on Gods earth she has seen just 3.... Just thinking about it, that is about the same amount of Hardy Mariners as Seabird has see during our 4 years with her!

Barney-20040908.jpg



but, its it nice having a rare boat!

anyway, back onto the Coolant issue...... haven't got a clue, but don't worry, its a yanmar 230..... bullet proof! (fingers and toes crossed!)
 
superheat6k said:
Are you having to replace the lost coolant ?

I had a similar issue last year - tuned out to be a perforated heat exchanger. The seawater pressure was obviously higher than the fresh, so although I was finding coloured coolant in the bilge, I wasn't losing anything. In the end I worked it out by measuring the level below the filler, and when I noticed it rise there was only one place it could have come from.
Click to expand...


That's not good. The system is meant to be set up so as in the event of a cooler failure, the fresh water is a higher pressure than the sea water so as the fresh should migrate to sea. The only time what you describe should be able to happen is if your leaving the sea cocks open with the engine off. That way when the temperature and pressure drop the natural head of the sea water would cause the migration of sea to fresh. But thats why we shut the sea cocks when stopped.
 
nigelmercier said:
I had the same problem, replaced pressure cap and all OK.
Click to expand...


That is definitely my next move - I'm going to strip out the overflow and expansion tank (little plastic bottle actually)as well to make sure the pipe isn't blocked because I think what is supposed to happen is the coolant expands, overflows into the header and sucks back when it cools and I think that process is blocked somewhere. Nasty and expensive seawater in the coolant stuff can wait till after I've tried the simple answers but thanks to all again for advice
 
Firefly625 said:
well I knew it was you because you didn't have your aft cockpit cover on!

BTW, doesn't a Hardy look smart on the water!


excuse thread drift.... but you will see my point, Our dog, a very smart Scottish Terrier, loves to see a fellow Scottie, but I think in her 4 years she has been on Gods earth she has seen just 3.... Just thinking about it, that is about the same amount of Hardy Mariners as Seabird has see during our 4 years with her!

Barney-20040908.jpg



but, its it nice having a rare boat!

anyway, back onto the Coolant issue...... haven't got a clue, but don't worry, its a yanmar 230..... bullet proof! (fingers and toes crossed!)
Click to expand...

Our hound is an ageing chocolate lab who still leaps in and out on the dock but has a healthy respect for deep water so we are happy to let her sniff the air as we come up the river. We still wouldn't put the covers on although I have to admit to having had to dry out the cushions a couple of times when things went choppier than I expected. All in all a much more practical boat than the 36 and a lot cheaper to run so far.
 
cryan said:
That's not good. The system is meant to be set up so as in the event of a cooler failure, the fresh water is a higher pressure than the sea water so as the fresh should migrate to sea. The only time what you describe should be able to happen is if your leaving the sea cocks open with the engine off. That way when the temperature and pressure drop the natural head of the sea water would cause the migration of sea to fresh. But thats why we shut the sea cocks when stopped.
Click to expand...
It was entering when running, and the seawater wasn't going to flow uphill - the header / expansion tank is almost 2' above the water level. Anyway once shut down there is negligible resistance to any residual pressure via the open exhaust cooling injection elbow. Whereas the freshwater partial pressure would remain until the engine cooled. Having seawater in the freshwater system was not causing an immediate problem, and the problem manifest itself before any corrosion could set in. Anyway the freshwater pressure would never exceed say 1/2 bar, yet with the resistance of the various coolers I would not be surprised to see the seawater pump put out a good deal more that this. It was certainly enough to just lift the pressure cap, as the water was trickling down the overflow tube connected to the pressure cap mounting. It was not immediately obvious as the end if the drain tube was concealed. I have now extended these into the shower sump, with upturns at the ends so any coolant in these pipes will be plain to see.

The problem was a pin holed plate heat exchanger where seawater crud build up had found a weak spot in the plates. The cure was an expensive plate heat exchanger element, which was unique to the TAMD60C engine - I was Volvo Pentad that day.
 
You must log in or register to reply here.

Share this page

Top