Author Topic: Engine Coolant needed ..?  (Read 1435 times)

Annastesia

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Engine Coolant needed ..?
« on: July 17, 2022, 01:41:37 PM »
Hello,

I've just checked my coolant levels and my radiator is FULL and my reservoir is between MIN and MAX - about an inch above MIN.

I bought the car a few months ago so I haven't put any coolant in it before.

Would anyone see these levels as ok and to continue as normal? Or would anyone feel the need to top up the reservoir to MAX?

Someone told me that if I put coolant into MAX (with radiator full) this could cause spillage, so I thought I'd ask on here as I usually get really good answers  :)

It's just reassurance really that the car is alright.

embee

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Re: Engine Coolant needed ..?
« Reply #1 on: July 17, 2022, 01:57:13 PM »
Probably not an issue.

To be sure, check the level when the engine is cold (mark the level if you wish, put a piece of masking tape on the bottle) and then check it again when it is hot. You would usually expect the hot level to be higher than the cold level, the bottle is to allow for expansion of coolant within the engine closed system, it gets pushed past the radiator cap valve into the bottle when hot and then gets drawn back into the engine system when it cools down again, it is designed to change level like this.
If the hot and cold levels are comfortably within the max/min markings it's fine.
Check that the system is not losing any coolant, i.e. the levels are not gradually going down over time. This is probably the most significant thing, you don't want any leaks. Under normal circumstances the system will not lose any significant coolant (there may be a very minor drop over time as it contains 50% water and some inevitably can evaporate, but that should be absolutely minimal and negligible, it should be stable for a year or more).

If it needs just a tiny amount you can add deionised water, or clean rainwater is good as it has essentially no hard salts content, the dilution will be of no concern (it might end up 49/51 instead of 50/50, but that's fine). If it needs more than a cupful or two then use mixed coolant. Anything added to the make-up bottle will end up getting mixed with the system coolant after a few hot/cold cycles.

Obviously NEVER remove the radiator cap when hot!!
« Last Edit: July 17, 2022, 02:00:05 PM by embee »

Jocko

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Re: Engine Coolant needed ..?
« Reply #2 on: July 17, 2022, 04:06:19 PM »
Mine has sat midway between the marks since I bought the car - six years ago. I only ever check it cold.

jazzaro

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Re: Engine Coolant needed ..?
« Reply #3 on: July 17, 2022, 06:16:44 PM »
Hello,

I've just checked my coolant levels and my radiator is FULL and my reservoir is between MIN and MAX - about an inch above MIN.

I bought the car a few months ago so I haven't put any coolant in it before.

Would anyone see these levels as ok and to continue as normal? Or would anyone feel the need to top up the reservoir to MAX?

Someone told me that if I put coolant into MAX (with radiator full) this could cause spillage, so I thought I'd ask on here as I usually get really good answers  :)

It's just reassurance really that the car is alright.
I had the same doubt some years ago, the coolant level was close to the MIN. So I bought a liter of Honda coolant and I filled the reservoir to the MAX. After a couple of days the level was again close to the MIN, and it's still on that mark.

Glosrich

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Re: Engine Coolant needed ..?
« Reply #4 on: July 18, 2022, 06:14:55 PM »
They do find their natural level, as long as the level doesn't drop it's ok.
You can add a little water, as the antifreeze is very strong, so it won't dilute it that much.

SuperCNJ

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Re: Engine Coolant needed ..?
« Reply #5 on: July 20, 2022, 07:17:17 PM »
I've never had to add coolant in all the Hondas I've owned over the past few decades. They just don't seem to consume any coolant at all - unless there is a leak somewhere.

My BMW on the other hand does, and I've had to top that up every now and then.

If your engine temperature stays in the normal range, it's probably ok. Obviously, if you're concerned, have it looked at and perhaps changed at your next service.

Lord Voltermore

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Re: Engine Coolant needed ..?
« Reply #6 on: July 21, 2022, 07:40:27 AM »
Cars shouldnt 'consume'  coolant, apart from maybe a very small amount over a very long period  -which shouldnt be apparent if the coolant is changed at the recommended periods.  If it loses a significant amount there are two possibilities
1) There is a leak somewhere.  Could be radiator, faulty pressure cap, damaged rubber pipes, leaking 'water' pump,  head gasket,   etc. etc  The leak should be fixed, not simply topped up.

2) As others have found  the level may drop  a short time after  filling the system then settle down.    Although the header bottle may have a  max and minimum line  it doesnt mean it must always be on the max line  ,or that you need to constantly top up to maximum.    The cooling system  has its own 'happy medium'  where it has  just the right quantity of coolant to fill all the pipes and run at an ideal pressure. This level  should be somewhere between max and min.      If you fill to max  it might actually be too much coolant, causing excess pressure in the system. The system will vent this excess coolant ,through its pressure cap until it falls to the ideal  level and then remain  constant.    Its easy to mistake this drop  as a leak  ,and keep topping it up to max, only for it to be vented out again in a never ending cycle. 
The same can also happen when filling the system if  you get air locks in the pipes.  After a few miles the air will bubble out  to be replaced by a similar volume of coolant, so the level drops.  (on some cars air locks can be difficult to eliminate and cause cooling problems. )   

Of course you should check the coolant level from time to time to ensure its not leaking more than normal ,ie dropping below the minimum line.  But if the level remains constant at a level somewhere between max and min ,its fine. 

Probably going beyond the question here, but if you do top up use the correct type of coolant for the car. Typically there are two types , OAT (usually red)  and others that are usually blue/green. Dont mix them  .      It also comes in two basic formats , 100% antifreeze  which will need diluting or as 'coolant'  which is typically ready diluted to 50%.
The car takes coolant.     Dont top up the system  with water  , except in an emergency,  in which case you will be need to drain  and replace the coolant anyway, as part of the repairs.

Couple of other tips,which may help some.   Dont try and plug coolant leaks with 'rad weld' type products, unless its literally a case of keeping an end of life car  out of the scrap yard for a few more months  - and you are prepared to take the consequences and possible dangers of a seized engine miles from anywhere or on the motorway.
Some products still use quite crude ingredients.  (Back in the old days Mustard powder was often used,  it dried solid as it leaked out  - its works quite well  :P  )  These products wont work for some leaks, or might work too well, clogging the radiator etc.   

The source of a slow leak  may not be obvious as wetness or steam.  Steam is actually invisible  (its the slightly cooler water vapour you can see)  and the coolant may dry as soon as it emerges.  A slow leak may reveal itself as whitish staining.   
  Trust a dog to guard your house  , but not your sandwich

jazzaro

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Re: Engine Coolant needed ..?
« Reply #7 on: July 21, 2022, 09:25:47 AM »
Jazz has a motorbike-type cooling system, the reservoire is not pressured while other standard cars use systems with a pressured reservoire on the top of the engine bay: Jazz's reservoire is under the cylinder heads, as you can easily check.
The fan switch is no more put on the radiator as in old engines: fan is operated by the engine ecu, setting it on or off and often in low or high speed depending from the liquid temperature, the car speed and A/C cooling requests.
The radiator cap is a double flow valve that keeps in pressure the circuit (engine, pump, radiator) with no air or vapour in it. If pressure exceeds a preset value, the cap valve will slightly open sending liquid and vapour towards the reservoire: that's why the reservoir level is usually close or over the MAX when the engine is hot. In this condition, the level can completely fill the reservoire that isn't ermetically closed, so the exceeding  liquid can overflow from it and fall over the ground.
When the engine cools down, the pressure decreases and the circuit can go in vacuum, with the pressure under the atmospheric level. In this case the cap valve will open and suct liquid  from the reservoire to refill the radiator: always check that the hose end in the reservoire stays close to the bottom (and the level at cold engine is at least over the MIN), because the hose end must be always wet and under the liquid level, it must suct liquid and never air.
In my case, I saw the cold level was close to the MIN so I topped the liquid to the MAX: probably the first time I used the car, the level overflowed the reservoire cap because at the next check the level was again at the MIN, and it's still there after more than three years.
Pay attention to use original Honda liquid to refill the level or small amounts of deionized water (once or twice,then re-add pure liquid): Honda type2 is a Phosphated Organic Additive liquid (P-OAT), silicate borate, ammine and nitrite free, this to preserve pump blades and aluminum parts (radiator and the whole engine), so do not add other kind of liquids, you may create precipitates: NEVER fill or adjust level with tap water, there are too many salts in it. And remember that the colour of the liquid DOES NOT relates to its composition as commonly intended, so check liquid specs and composition before adding or completely changing it: this can be used in Hondas https://www.mpmoil.co.uk/products/86000CLP/coolant-low-phosphate-37%C2%B0c-ready-to-use if the Type2 is too expensive or hard to find. 
Last tip: the liquid must be changed every 5-6 years, additives lose their chemical properties and the liquid can become corrosive for alluminum parts (the whole circuit in our Jazz). So do not leave the same liquid for the whole car life, one of the cause of head gasket failure for Fiat Fire engines is the corrosion due to unproper cooling liquid, frequently tap water.
« Last Edit: July 21, 2022, 12:16:34 PM by jazzaro »

embee

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Re: Engine Coolant needed ..?
« Reply #8 on: July 21, 2022, 10:34:20 AM »
Jazzaro is spot on above, other than perhaps describing it as a "motorbike" type cooling system (but I'm being pedantic here). Yes, bikes usually use a cold bottle system but so do a lot of cars.

Vehicles typically use one of two system types, commonly referred to as a "hot bottle" or a "cold bottle". The cold bottle system is as he described very well, the expansion/contraction of the "closed" part of the system is accommodated by allowing coolant out through a high pressure one way valve in the cap (typically +1 Bar more or less) into a catch bottle, and it then gets drawn back in when the engine cools through a low pressure one way valve (reverse) to ensure the closed system remains full with coolant. The cold bottle is vented to atmosphere and runs at no pressure, and does not have a through-flow of coolant. The area round the rad cap is designed to collect any gas generated within the closed system to vent it out into the cold bottle and thus to atmosphere.

A "Hot bottle" system (often used by Ford/VW etc) has a reservoir (usually a plastic sphere type) within the "closed" system which has a pressure cap on it and is designed with a closed air volume above the coolant which accommodates the expansion by compressing. If you top that right up it will eject coolant when heated and then draw air back in to give the desired compression volume. Hot bottles are generally designed to be at the highest point of the system (often at the bulkhead) and have a continuous bleed flow through them to collect any gas (e.g. from head gasket leakage or from corrosion products etc), this gas then forms part of the expansion volume and gets ejected when it next heats and the pressure rises. Usually the coolant level will remain within limits.

There are pros and cons with both systems, but both work well if designed correctly. Cold bottle systems are generally less fussy in my experience (from a design point of view, you need to get the volumes right) but that's just my view. One advantage of the cold bottle is that it can be mounted in different places, as long as the dip (vent) tube goes below the coolant level and there's enough coolant in the bottle it will work.

100% agree with the comments regarding corrosion protection and additive types, that's what determines the life of the coolant.

jazzaro

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Re: Engine Coolant needed ..?
« Reply #9 on: July 21, 2022, 12:00:54 PM »
Jazzaro is spot on above, other than perhaps describing it as a "motorbike" type cooling system (but I'm being pedantic here). Yes, bikes usually use a cold bottle system but so do a lot of cars.


To be honest, Hondas and Toyotas are the only car brands I've seen with a cold bottle circuit, all Fiat, VW, Ford, Renault, Mercedes and PSA hoods I've opened had hot bottle system, even Rovers with the infamous K engine.  This can mean I've opened only hoods with hot bottles, not "all car engines have hot bottles"  :D
Which ones I've lost?
In Italy we do not know these systems as "hot" or "cold" bottle, anyway the meaning is the same, correct.
« Last Edit: July 21, 2022, 01:02:46 PM by jazzaro »

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