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Bi-metal engines & coolants

Started by thysonsacclaim, 06 February 2011, 12:58 AM

calvin streeting

you guys are making me paranoid..... i reakon i am going to get wet at some point this year when i dump, flush, and fill

WGB

Quote from: calvin streeting on 07 February 2011, 08:48 AM
you guys are making me paranoid..... i reakon i am going to get wet at some point this year when i dump, flush, and fill

I thought we were talking about cooling systems not an enema ;D

Bill

thysonsacclaim

QuoteI thought we were talking about cooling systems not an enema

Haha!  :D


As per colors, yes they are mostly just dyes. It's only there to differentiate it if you grab the wrong one. Doesn't mean all blues etc are equal to each other, so color alone shouldn't be used. Just check the labels and see what it says.


Just don't put salt water in  ;D

MB_Mike

Awesome post! It really makes the whole ''use the right coolant' argument pretty ominous.
1987 Home market 560 SEL

thysonsacclaim

Just remember this, too: we all say it is important to change coolant fluid regularly, but why?

Well for one thing, coolant isn't going to last forever. It will last a while, but there are very few chemicals which can be heated and cooled and heated and cooled and not break down. It will degrade over time, I can guarantee you that.


The last reason, if you're not using deionized or distilled water is this:

Now what happens if you're using cruddy, hard water? Well, look at it this way: say you have 2 litres of water in a pot which has 5% dissolved substances. Okay so down the road you get down to 1.5 litres since some has evaporated, so you add .5 L to get the pot filled up to 2 L again. You do this over and over and you are increasing the amount of dissolved ions in the water.

After a while, water cannot hold anymore substances, just like you can only dissolve so much salt into water. After that, the minerals will precipitate out of the water and be in solid form, floating around and becoming sediment.

You run the car it heats up, these sediments move around. When you turn it off, it cools, they fall to the bottom. When in contact with the metal, some of them attach to it and voila! you have build up (combined with the electrolysis effect).




oscar

Here's a curly one I can't find the answer for.  Why don't they use oil as a coolant?
Separate from the sump, I reckon it would remain stable for a long time due to no combustion biproducts nor be subjected to sheer and pressures from contact surfaces, plus it should transfer heat ok and more importantly I presume it wouldn't react with metals?
1973 350SE, my first & fave

TJ 450

Good question oscar. I'm pretty sure thermal efficiency is the answer, but perhaps someone could elaborate?

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Big_Richard

already looked into this in the past, TJ is spot on.

otherwise its use would have been phased out decades ago.

Big_Richard

I wonder

would oil versus water reach 100c from room temperature at the same time ?


oscar

Quote from: Major Tom 6.9 on 09 February 2011, 06:43 AM
I wonder

would oil versus water reach 100c from room temperature at the same time ?

A quick bit of googling and wikkiing says that the advantages of water is that it's thermal conductivity is 4 times that of oil, plus oil is thicker and needs more energy to circulate.  I would've thought that apart from the advantages of being non corrosive that oil could carry more heat, well above the 100degC of water or 135 with additives.  But it must take too long for the heat transfer to occur.  Still, oils aint oils and you'd think a low vicosity suitable oil with good heat transfer charcteristics could be developed for the conditions of an engine's cooling system.  Though as a guess conventional water based coolants are probably far cheaper.
1973 350SE, my first & fave

calvin streeting

I heard some moden cars use a gell as a coolant.

TJ 450

If it takes longer to heat up, it will also take longer to cool down and I think therin lies the issue.

The cooling system relies on quick heat exchange. 8)

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

Big_Richard

i bet various liquids have been used in vehicle cooling systems over the years in emergency situations.

such as beer, soft drinks, urine or even sea water..  ::)

oscar

Only Bear Grylls would use urine.
1973 350SE, my first & fave

Big_Richard

Bear Grylls is a fraud - if you like that kind of thing, watch survivor man - not that its made anymore but atleast he's for real and dosent sleep in hotels between shooting days.  8)

Still entertaining though i suppose.