Author Topic: Foam in radiator.  (Read 1202 times)

mgb789

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Foam in radiator.
« on: October 22, 2019, 03:26:11 PM »
Hi,  After draining cooling system I slowly refilled with antifreeze. I loosely replaced the cap and started the engine, with
 heater on. After about 5 minutes I checked and topped the level up. Ran the engine again for 5 minutes took top off rad, there was white foam.  Freaked me out!  No problems before replacing antifreeze.  Any thoughts would be welcome.  Should I drain and flush with hose pipe?  Thank you.

culzean

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Re: Foam in radiator.
« Reply #1 on: October 22, 2019, 04:40:04 PM »
Which coolant did you use,  the OEM fill for decades now has been long life OAT / HOAT (organic acid technology or more recently hybrid organic acid technology ) which is why it now lasts 10 years instead of 2 years.  Maybe a previous owner used stop leak or some other chemical that has reacted with new coolant.  It is the corrosion inhibitors that get worn out, not so much the ethylene Glycol ( anti-freeze ) part ( the OAT refers to the inhibitors,  the anti freeze is still Glycol,  which is colourless ). 

The foam may just have been trapped air that had been compressed by being heated up bubbling out ( like taking the top off a aerated drink bottle ) - it is dangerous to remove rad cap when engine is warm as compressed air and hot coolant can cause it to erupt out of the filler cap hole.

one of the many 'coolant' threads on this forum
https://clubjazz.org/forum/index.php?topic=9163.msg48651#msg48651

This is the ready mixed coolant I have used in the past - it is already mixed to 50% with distilled water,  which is the ideal ratio,  do not use a silicate based one in modern engines. 
https://www.halfords.com/motoring/engine-oils-fluids/antifreeze/halfords-oat-ready-mixed-antifreeze-5-litres

Don't be fooled by the different colours of coolant - they are all Glycol based and the colour is added to show up any leaks better. I know silicate based ones designed for older engines can cause problems in newer systems, mainly because they are abrasive and can cause premature wear on water pump impeller and seals - the OAT ones are much better and where silicate ones have to be changed every two years ( the silicate starts to cause problems ) the aftermarket OAT based ones are good for 5 or more.
« Last Edit: October 22, 2019, 04:56:05 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

mgb789

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Re: Foam in radiator.
« Reply #2 on: October 22, 2019, 04:53:59 PM »
Thank you for your reply culzeal.  I've no idea what type of antifreeze was in the car.  The one I 'tried' to use was a ready mixed one called Prestone coolant/antifreeze. It says suitable for all cars.  The foam was pure white. I checked the oil and it was clean.

mgb789

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Re: Foam in radiator.
« Reply #3 on: October 22, 2019, 05:24:41 PM »
Thank you for the information. Prestone contains ethanediol, I've no idea if that's good or bad. Perhaps I should buy the OAT one you linked to culzeal, and use that after flushing with the hose. The reason I mentioned the oil was because the postman stopped on my drive for a chat, he said it could be a blown head gasket!  He's a nice postman but I'm unsure of his mechanic credentials!  Thank you.

culzean

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Re: Foam in radiator.
« Reply #4 on: October 22, 2019, 06:30:46 PM »
Oil actually is hard to foam and works against it ( pouring oil on troubled waters ). The thing with blown head gasket you would have noticed coolant level dropping and water in the oil, which turns it to the consistency of mayonnaise ....

Ethanedoil is a fancy name for ethylene glycol...

Your postman may not be a mechanic, he is a man of letters though.....
« Last Edit: October 23, 2019, 04:42:05 PM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

mgb789

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Re: Foam in radiator.
« Reply #5 on: October 22, 2019, 07:57:59 PM »
Thank you for taking the time to share your knowledge culzean.  I'll give it a thorough rinse then try again.  My apologies for misspelling your name earlier.

mgb789

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Re: Foam in radiator.
« Reply #6 on: October 23, 2019, 10:58:32 AM »
" -- he is a man of letters though." :)

ColinS

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Re: Foam in radiator.
« Reply #7 on: October 23, 2019, 04:45:36 PM »
" -- he is a man of letters though." :)
Let's stamp on this right now :)

culzean

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Re: Foam in radiator.
« Reply #8 on: October 23, 2019, 05:08:46 PM »
By passing an opinion on your car your postman was working outside his envelope, but to be frank(ed) he was only trying to help, he probably feels it is part and parcel of his job to assist.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

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