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I've just had somebody in to do some work on my boat which included changing the antifreeze which had been in about 3 years. I expected him to completely drain off the old stuff and replace with new, but he only removed about 5 litres before topping it up with the new.

Is this normal and is it okay? Because I was under the impression that the old antifreeze having lost it's anti-corrosion properties would just be treated as water and that providing the percentage tester showed that the mix was correct then that would be alright. But somebody has told me that the old antifreeze could actually cause damage irrespective of the readings on the tester.

Which is correct please?

 

 

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Just now, Grassman said:

 

I've just had somebody in to do some work on my boat which included changing the antifreeze which had been in about 3 years. I expected him to completely drain off the old stuff and replace with new, but he only removed about 5 litres before topping it up with the new.

Is this normal and is it okay? Because I was under the impression that the old antifreeze having lost it's anti-corrosion properties would just be treated as water and that providing the percentage tester showed that the mix was correct then that would be alright. But somebody has told me that the old antifreeze could actually cause damage irrespective of the readings on the tester.

Which is correct please?

 

 

It is easy for any of us to slate peoples work which I would not do as I havnt seen exactly what was done or your boat. However if I were to change all my antifreeze or pay to have it done it would include draining and filling engine and cooling tanks etc.

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Opinions vary, but the anti-freeze properties don't change, only the anti-corrosion properties, and these steadily degrade over time. In the absence of leaks, antifreeze chemicals such as ethylene glycol or propylene glycol can retain their basic properties indefinitely. Corrosion inhibitors are gradually used up, and must be replenished from time to time but for simplicity, most automotive manufacturers recommend periodic complete replacement of engine coolant, which renews the corrosion inhibitors and removes accumulated contaminants. However, you can perfectly well top up with a corrosion inhibitor and leave the antifreeze in place.

Any idea how much coolant your system holds in total (they all vary)? 

If yer man took 5 litres out you have at least some additional corrosion inhibitor, and some of the crap may have gone.

Edited by Machpoint005
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If he drained 5Litres off and replaced it with 5Litres of neat undiluted antifreeze it is probably now way over strength.  Beware leaks and head gasket trouble.

Edited by bizzard
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As said above, the antifreeze bit never wears out and this is was the antifreeze tester measures. There are also lots of additives, mostly corrosion inhibitors bit also possibly seal lubricants and even anti-cavitation additive. The corrosion inhibitors do wear out which can be tested if you really want. I believe this results in the antifreeze becoming more acidic. Draining and replacing the whole lot is best, but draining half at more frequent intervals is probably a good second best. Some people like farmers with big machines that use a lot of antifreeze will sometimes just top up with concentrated additive from time to time.

......................Dave

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14 minutes ago, Machpoint005 said:

Opinions vary, but the anti-freeze properties don't change, only the anti-corrosion properties, and these steadily degrade over time. In the absence of leaks, antifreeze chemicals such as ethylene glycol or propylene glycol can retain their basic properties indefinitely. Corrosion inhibitors are gradually used up, and must be replenished from time to time but for simplicity, most automotive manufacturers recommend periodic complete replacement of engine coolant, which renews the corrosion inhibitors and removes accumulated contaminants. However, you can perfectly well top up with a corrosion inhibitor and leave the antifreeze in place.

Any idea how much coolant your system holds in total (they all vary)? 

If yer man took 5 litres out you have at least some additional corrosion inhibitor, and some of the crap may have gone.

I think it holds around 18 -20 litres'

So does this mean that although the meter readings will show the percentage mix being what it should be, the anti-corrosion properties of the whole mix will not be as good as if he had completely replaced the old stuff, and therefore probably not as effecient?

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1 minute ago, Grassman said:

I think it holds around 18 -20 litres'

So does this mean that although the meter readings will show the percentage mix being what it should be, the anti-corrosion properties of the whole mix will not be as good as if he had completely replaced the old stuff, and therefore probably not as effecient?

I would think this is the case but the anti-corrosion might still be adequate. I believe it starts off with lots and this slowly depletes till it becomes inadequate so as long as some is replaced its probably good enough, but don't quote me on that. Its a very complicated bit of chemistry, there is some interesting stuff on the www.

...........Dave

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Personally, I drain off and flush a couple of times every couple of years. it is amazing how much sludge comes out. It was left longer than this at one time, and to drain out both the Bowman and the block required clearing through the drainholes. If the amount of sludge does build, then obviously the cooling in those areas is compromised.

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You can assess whether the anti-corrosion additives are still effective by putting a sample of antifreeze drained from you engine in a jar and adding a few nails, bits of aluminium,  and bits of copper to the jar. 

If these begin to corrode then the corrosion inhibitors in the antifreeze are no longer fully effective. 

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The stronger the antifreeze concentration, the less effective the coolant becomes at taking away heat. There's a balance to strike, and simply keeping adding antifreeze will tip that balance. I'd be surprised if the manual for your engine says anything other than drain, flush and refill with something between 25% and 50% antifreeze to water mix.

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When you drain the engine do you just flush through by gravity, by putting a hose pipe in the filler, or do you run the engine to  pump the water through?

 

also if leaks occur due to over strength antifreeze in the system, will they stop when the correct strength is subsequently used or are the gaskets permanently affected?

Edited by swift1894
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Antifreeze needs to be added at the same concentration as what's already in the system. . If it's not it won't mix evenly with the rest.  On my boat I drain the whole lot, engine and skin tank and then refill with premixed 50% solution. I mix it in a 20 litre plastic container . I then have reserves at the same strength to top up if needed before next change, usually 2 years. I do the same with the radiators & pipework on the eberspacher system too.

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1 minute ago, boatbodger said:

Antifreeze needs to be added at the same concentration as what's already in the system. . If it's not it won't mix evenly with the rest.  On my boat I drain the whole lot, engine and skin tank and then refill with premixed 50% solution. I mix it in a 20 litre plastic container . I then have reserves at the same strength to top up if needed before next change, usually 2 years. I do the same with the radiators & pipework on the eberspacher system too.

Yes it will: once the engine is started it will soon get mixed, but as a result the concentration of the combined coolant will be different from what you think it is. 

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1 hour ago, Machpoint005 said:

Yes it will: once the engine is started it will soon get mixed, but as a result the concentration of the combined coolant will be different from what you think it is. 

There is a theory that because antifreeze and water have different densities that if added separately there can be a sort of stratification effect and they never mix.

I suspect this might just happen in some heating systems where the flow is quite gentle, but I reckon in an engine it would soon get mixed.

.............Dave

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Antifreeze is very searching. It can leak and seep out of place where water or the recommended mix didn't.  In extreme cases of too much in the mix it can penetrate between cylinder head gaskets and cause lots of expensive trouble.    I remember years ago, a customer who was a lorry driver filled his E93A engined Ford Prefect  with neat Bluecol, I think he'd nicked it from his firm as Bluecol antifreeze was very expensive in the early 1960's.  Apart from the engine overheating ''Thermo- siphon cooling on those'', it had leaked out from literally everywhere, hoses, gaskets ect and seeped between the head gasket nearly ruining the engine. The whole car inside and out was a horrid sticky mess.

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British Railways Cartage did not use antifreeze in their delivery vans, trucks and Scammel 3 wheeler tractors until well into the 1960's. In the winter all drivers had to drain their rads and engine blocks after use and refill them with water before use as well as checking the oil and batteries.

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1 minute ago, bizzard said:

British Railways Cartage did not use antifreeze in their delivery vans, trucks and Scammel 3 wheeler tractors until well into the 1960's. In the winter all drivers had to drain their rads and engine blocks after use and refill them with water before use as well as checking the oil and batteries.

Rebuilt a six Cylinder Jaguar Engine for a friend.the Cylinder head Studs went through the Water Jacket in the Block.

He wondered why they were badly corroded I explained that it was lack of Antifreeze  in the coolant,so no corrosion Inhibitor.

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1 minute ago, cereal tiller said:

Rebuilt a six Cylinder Jaguar Engine for a friend.the Cylinder head Studs went through the Water Jacket in the Block.

He wondered why they were badly corroded I explained that it was lack of Antifreeze  in the coolant,so no corrosion Inhibitor.

Yes and those engines had a thin sheet steel head gasket. The old all cast iron engines seemed fairly happy without antifreeze. I reckon Brittsh Railways would have worked out the economics of it, the cost of antifreeze and the likelyhood of having gallons of it stolen against any engine damage.

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1 hour ago, bizzard said:

British Railways Cartage did not use antifreeze in their delivery vans, trucks and Scammel 3 wheeler tractors until well into the 1960's. In the winter all drivers had to drain their rads and engine blocks after use and refill them with water before use as well as checking the oil and batteries.

We use to do that with the tractors on the farm, Drop the coolant when you put it away

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2 hours ago, dmr said:

There is a theory that because antifreeze and water have different densities that if added separately there can be a sort of stratification effect and they never mix.

I suspect this might just happen in some heating systems where the flow is quite gentle, but I reckon in an engine it would soon get mixed.

.............Dave

Very true for central heating. hot going into the bottom right of the rad and hot coming out of the bottom left but the rest of the rad cold. I drained and refilled well mixed.

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23 hours ago, bizzard said:

British Railways Cartage did not use antifreeze in their delivery vans, trucks and Scammel 3 wheeler tractors until well into the 1960's. In the winter all drivers had to drain their rads and engine blocks after use and refill them with water before use as well as checking the oil and batteries.

Auld guy I drink with used to work for Midland Red and tells me that they never used anti-freeze in their busses because they were never switched off for long enough to cool down. 

 

When Midland Red were taken over the new management gave orders to put anti-freeze in and it all turned out to be a bit of a disaster, with burst hoses, blown head-gaskets, you name it it failed! 

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17 minutes ago, mattlad said:

Auld guy I drink with used to work for Midland Red and tells me that they never used anti-freeze in their busses because they were never switched off for long enough to cool down. 

 

When Midland Red were taken over the new management gave orders to put anti-freeze in and it all turned out to be a bit of a disaster, with burst hoses, blown head-gaskets, you name it it failed! 

Before the 70 mph speed limit was introduced many express long distance coaches and buses were built specially or re engined for high speed. The likes of Midland Red, Ribble and others were belting up and down motorways at 100mph. The rivalry for the traffic was fierce.  I had an uncle who drove coaches for Grey Green at the time and he happened to overtake a Ribble double decker doing 105 mph. The Ribble driver reported him ''snitch'' and my uncle was on the carpet with Grey Green over it. The boss of Grey Green said to my uncle ''When you see another Ribble bus in front of you''Bloody well do it again''.

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4 minutes ago, bizzard said:

Before the 70 mph speed limit was introduced many express long distance coaches and buses were built specially or re engined for high speed. The likes of Midland Red, Ribble and others were belting up and down motorways at 100mph. The rivalry for the traffic was fierce.  I had an uncle who drove coaches for Grey Green at the time and he happened to overtake a Ribble double decker doing 105 mph. The Ribble driver reported him ''snitch'' and my uncle was on the carpet with Grey Green over it. The boss of Grey Green said to my uncle ''When you see another Ribble bus in front of you''Bloody well do it again''.

Grey-Green Coaches! That takes me back...

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3 minutes ago, Machpoint005 said:

Grey-Green Coaches! That takes me back...

Yes a good old company. Most of those old high speed coaches and buses used the very powerful Bristol engines as The National coaches do today, so I believe, but are now heavily governed to 70mph I expect.

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