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Gareth E

Loss of coolant

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My engine (Vetus) has started losing coolant. It only does this when the engine is running. The coolant ends up in the tray under the engine and it's quite significant, around 1/2 litre in an hour. Just now, after a 1 hour cruise I checked the obvious things: hoses and connectors were dry. No moisture apparent around the thermostat housing gasket or the bolts there. Feeling around as best I could everything felt dry. I used a torch and mirror to have a look at the far end of the engine, again everything seemed fine.

Any ideas what might be going on here?

Thanks.

 

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Has this coincided with you doing anything different? For example, have you recently topped up the coolant?

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Yes, several things. I re installed the engine after a rebuild. I didn't do a hose up properly so it lost a lot of coolant. Fixed that and topped up. Then the bleed bolt on the skin tank was leaking so I refitted it with grease. Then I noticed a weep from one of the bolts that holds the thermostat housing on. Despite trying several different washers I couldn't get it to seal. Heath Robinson came into play: I used a rubber washer and that seemed to have a achieved a seal. Topped up once again.

I should add: I had 4 litres or so of coolant left after installing the engine. The only container I had was an old oil bottle which I washed out as best I could with white spirit. There was a trace of residue floating on top of the coolant. I do hope that a trace of oil in coolant couldn't cause damage to a gasket or something?   

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7 minutes ago, Gareth E said:

Yes, several things. I re installed the engine after a rebuild. I didn't do a hose up properly so it lost a lot of coolant. Fixed that and topped up. Then the bleed bolt on the skin tank was leaking so I refitted it with grease. Then I noticed a weep from one of the bolts that holds the thermostat housing on. Despite trying several different washers I couldn't get it to seal. Heath Robinson came into play: I used a rubber washer and that seemed to have a achieved a seal. Topped up once again.

I should add: I had 4 litres or so of coolant left after installing the engine. The only container I had was an old oil bottle which I washed out as best I could with white spirit. There was a trace of residue floating on top of the coolant. I do hope that a trace of oil in coolant couldn't cause damage to a gasket or something?   

Unlikely.

What level do you top the coolant up to and is a remote expansion tank involved?

How many times have you tried bleeding the skin tank AND manipulating hoses so any air trapped in them can flow into the skin tank or engine-header tank?

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13 minutes ago, Gareth E said:

I do hope that a trace of oil in coolant couldn't cause damage to a gasket or something?   

I done think so, my first car was a Riley Elf (an original mini with a boot).

I lent it to my grandad, who, never having come across a car with a transverse engine before,  checked the oil, found it a bit low and promptly poured a pint of engine oil into the radiator!

He did several miles in it before telling me he had topped up the oil. I found it was still on the minimum mark,  so I queried if he had put any in. He showed me where he had filled it (the radiator).

I drained the coolant and refilled it with new, and the engine never suffered any gasket issues.

 

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9 minutes ago, Tony Brooks said:

Unlikely.

What level do you top the coolant up to and is a remote expansion tank involved?

How many times have you tried bleeding the skin tank AND manipulating hoses so any air trapped in them can flow into the skin tank or engine-header tank?

There is an expansion tank, I fill it to the 'max' level, which is around one third full. It's not leaking through the top of the expansion tank that would only happen if I topped it up much higher.  

I think the fact that all this coolant ends up under the engine leads me towards a leak rather than air in the system.

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Right that makes some sense but the typical marine exhaust manifold has a water jacket that used to serve (and still does on heat  exchanger boats) as the header tank. To this end a pressure cap was used on the manifold. If you have a remote tank then either you need a higher pressure cap on the manifold, and with very good seals, so the cap[ on the expansion tank is  lifted first.

If the expansion tank is connected to the manifold filler neck by a thinish hose then the cap[ on the manifold must have a rubber seal under the cap itself, not just where the pressure valve seats. An ordinary pressure cap will not make a good seal so coolant will be blown out of the manifold cap. In this case as long as there is an pressure cap on the remote expansion tank you do not need a pressure cap on the manifold, just a cap to seal at the top of the manifold filler neck.

Coolant leaking from the manifold filler cap will usually end up in the engine drip tray.

Air trapped in the system will expand a lot more than the coolant so something wrong with the manifold filler would allow coolant to leak out there.

Once you are sure the leak is not coming from the manifold filler the next thing to do is to get up close and personal a hot running engine using torch and mirror to inspect the whole lot for leaks although they may be difficult to spot when hot so I would tend to try to use a cooling system pressure tester on a cold, stationary engine.

Take special care to inspect the front of the engine below the water pump pulley. Old water pumps can leak and seal at various times in the engine running cycle. Look for water drips, water stains or antifreeze stains down the front of the engine. Horribly inconsistent things once they start to leak.

Then there are the core plugs to inspect on the engine.

 

 

  • Greenie 1

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On my Vetus, the expansion tank needs to be nearly empty when cold, otherwise it will push out excess when hot.

The expansion tanks have nothing to do with the engine - mine is a Renault!  So you can ignore any Min/Max levels.  When the engine is cold, the level should be about a centimeter below the bottom of the filler on top of the exhaust manifold.  Try the header tank with just a little water, then check that the bottle is filling up when the engine gets hot.

 

Cross-posted with Tony's.  Also, try spreading paper under the engine when cold, then run the engine. The paper getting wet might make it easier to identify where water is leaking from.

Edited by dor

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59 minutes ago, cuthound said:

I done think so, my first car was a Riley Elf (an original mini with a boot).

I lent it to my grandad, who, never having come across a car with a transverse engine before,  checked the oil, found it a bit low and promptly poured a pint of engine oil into the radiator!

He did several miles in it before telling me he had topped up the oil. I found it was still on the minimum mark,  so I queried if he had put any in. He showed me where he had filled it (the radiator).

I drained the coolant and refilled it with new, and the engine never suffered any gasket issues.

 

PICT0012.JPG.e5174b5f3dd828c3beecbb2dcb336443.JPG

BMC never sold many 'Elves'; Rileys were always a niche market, you paid a lot more for a bit of luxury. The front end was a bit prettier than the standard mini

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12 minutes ago, OldGoat said:

PICT0012.JPG.e5174b5f3dd828c3beecbb2dcb336443.JPG

BMC never sold many 'Elves'; Rileys were always a niche market, you paid a lot more for a bit of luxury. The front end was a bit prettier than the standard mini

Thanks for looking up the photo OldGoat. Brought back many happy memories.

Last one I saw in the flesh was at the Black Prince hire base at Acton Bridge on the T&M, back in 1995, where the proprieter,  Phil Dowling, had restored one for his wife. He also had a Jag Mark 10 and a Rolls Royce Silver Shadow. Nice guy.

Edited to change the autowrong induced "popriveter" back to what I rote, "proprieter". Mind you I'm sure Phil was pretty handy with a pop riveter. :lol:

Edited by cuthound

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K Seal might be an option?

My BMC 1800 has alway lost a little water over several days boating. More recently it began to loose enough water when worked hard to the point where it was overheating heating after 2hrs. Replaced filler cap, not loosing water there, checked thermostate,  working ok, and can't find any obvious leaks through pipes. 

I put a bottle of K Seal in with the water and it seems to have done the trick. 

 

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Thanks for the replies. I've had a thought; I'm wondering whether the coolant might be leaking from the thermostat housing gasket. I placed a rubber washer on one of the bolts to stop it weeping, the connection feels 'squishy'. Could someone please confirm, if this were the case, might I have the symptoms I'm having? That is, coolant only leaking when the engine is running. I was wondering if, when the engine reaches the temperature that makes the thermostat kick in, this might expose the gasket to coolant, whereas the area is dry at lower engine temps? Hope that makes sense, I don't really understand these things...   

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Is it one of those engines where the thermostat can be installed upside down (following the rebuild?  That way there is no easy way for the coolant to expand so it forces itself through a gap that isn't a gap under normal operating temperatures and pressures.

 

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Quite common for thermostat housings to leak, they tend to warp especially if alumunium, whether 2 or 3 bolt fixing, warped between the bolt holes.  If there's no locating spigot underneath it it can be re-surfaced and made nice and flat again quite simply. Remove it, place a sheet of fine emery or production paper will do on a mirror glass. Give a rub or two of the housing flat face down on it and inspect, don't rock it, keep it flat down as you rub. You will probably see that its shiny around the bolt holes where they have made contact with the emery but the rest is still untouched. Keep rubbing and inspecting until its contacting and shiny all over. Refit with new gasket. Don't overtighten.

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End caps of heat exchangers can leak a bit, mine does and it drips onto the back of the engine and finally drips off the front of the gearbox, not a place where you would expect a drip of coolant.

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2 hours ago, Tony Brooks said:

Yes, but not for the resaon you think. When its hot its under pressure so it will tend to leak more.

I once had a Moggie 1000 that used to stall when stationary in traffic, took ages to find the cause. It was a tiny pinhole in the top hose, when stationary it squirted a very thin jet of coolant onto the distributor king lead stalling it which caused pressure to drop and the jet to stop and so no visible trace when lifting the bonnet to investigate. When moving air turbulence deflected the jet + it only did it with bonnet down! Pure luck that I idly squeezed the top hose and spotted it.  

Edited by nb Innisfree

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That is why I like cooling system pressure testers. You can get the system up to around 20PSI or more and that shows such leaks when cold.

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I've re fitted the thermostat housing, topped up the coolant, now need to test it. I'm not planning to go anywhere for a week or so, thought I'd run the engine this evening to give it a go. Any thoughts how long the engine might need to get up to working temperature, fastish tick over with no load? 

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14 minutes ago, Gareth E said:

I've re fitted the thermostat housing, topped up the coolant, now need to test it. I'm not planning to go anywhere for a week or so, thought I'd run the engine this evening to give it a go. Any thoughts how long the engine might need to get up to working temperature, fastish tick over with no load? 

Feel the hoses to and from the skin tank. When they’re both hot it’s up to temp. 

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2 hours ago, WotEver said:

Feel the hoses to and from the skin tank. When they’re both hot it’s up to temp. 

Thanks, I'll do that. Just so I understand; is that because the thermostat has kicked in and starts pumping water round? The hoses will be completely cold before this happens?

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5 minutes ago, Gareth E said:

Thanks, I'll do that. Just so I understand; is that because the thermostat has kicked in and starts pumping water round? The hoses will be completely cold before this happens?

Yes :)

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