Loss of coolant expansion tank still full

Rob S
Which vehicles have an electric water pump? Interested to know of one.

RMD
Various Later model BMW have electric water pumps,ie E90 325i, X5 etc etc

Thanks Rob. Haven't looked into a BMW. I wonder how reliable they are.

Thanks for the replies , just read Robs so I forgot to mention 2001 troopy Natural diesel 227,000 km never missed a beat before this will now read the rest ,thanks

RMD
Yes probably not as reliable as a belt driven pump they will give you a warning, like leakage or noisy bearing, when they are about to die.
Electric ones just usually stop no warning, they usualy only get around 160k klm out them, if I owned one I would carry a spare in the boot!
Mine has a belt driven pump, but has a small electric pump for the heating system,
Have to make sure you turn on the heater fan to operate the pump to circulate the coolant when doing a flush.

Thanks Pete oil is fine

Thanks RMD, as far as I can tell the exp tank isn't working at all the hose is good and the cap looks good? I will change the cap Toyota only want $22 so I will start there. This all started with me flushing and changing the coolant and money right now is tight so I am not paying a Mechanic when I should be able to nut it out with a little help from my friends !!

Wayne.
Did you at any time remove the hose from the Overflow bottle filler and also it's vent pipe? Often if they have been removed the hoses may be inadvertantly refitted to the wrong pipes of the bottle.
If so that usually pushes coolant out the overflow bottle and that amount is lost each time the engine heats.
"Full" has been mentioned by a couple of people and an overflow bottle is never "FULL". Normal use is not below LOW when cold and not above the upper level indicator when hot, but never full. Just clarifying the terms used.

Athol
Do you mean the air will enter during the cool down period and rather than draw fluid from the Overflow bottle through the caps one way valve, it ingests air through the water pump seal although it is under a positive system head pressure while cooling down?

Never seen that happen.

Great name Athol, what you have said makes good sense and I have been underneath today checking under the pump , I can't see a leak but You have a point. Here's comes a good whinge on a company. 2 years ago I took my car in for a timing belt replacement to the mechanics the previous owner used Robson Brothers in Welshpool.I said I wanted a full change eg, new pulleys and pump and what ever it needed , money wasn't the issue, the manager rang 1 hr or so after I left and said the belt was fine I replied I want it changed and he tried to talk me out of it . Ever heard of a mechanic knocking back work, So I got annoyed and said just do it and forgot about the pump and everything else . I have wondered if it will bite me down the track and maybe it has . So now maybe I know where to start from and it has never gone over 3/4 temp even under full load up hills so thanks and !?&;:.?! Robson bros of Welshpool WA

RMD

Yes, air can enter via the water pump seal as there is a low pressure caused via the radiator cap seals. There IS vacuum required to lift the return valve in the radiator cap and this vacuum can be enough for air to pass the water pump seal if it is close to leaking water, or if the spring that holds pressure on the seal is weak or broken.

Have seen it on several occasions. Can be very hard to detect.
Regards
Athol

IF and only IF the water pump seal did ingest air, the resulting relative water displacement will only be equivalent to the coolant volume change when hot or cold. ie, air above water in radiator. When engine runs the water gets hot so increases involume and the air is forced into the overflow bottle as bubbles and lost out the vent. No change in Oflow level register.
The radiator will be full while running hot. IF air has again replaced the cooling water volume, the system will find and equilibrium of level (as in old times with no bottles) and the engine won't overheat as no fluid loss is actually occurring much at all.
In that case the overflow bottle will remain at the same level hot or cold.
Now, is the pump really leaking air into the system?

I have had the radiator on my KIA nearly empty due to a leaking heater coupling that only leaked when the system was cold.

Now considering the coolant system was full initially and it is fully if I check it normally, when the cooling system heats up it forces the hot expanded coolant out of the radiator into the reservoir. As the system cooled down air was drawn in from the leaky coupling and also coolant dripped out.

Eventually the radiator was empty and the reservoir full, I can't see why simialr couldn't happen with a water pump seal?

I did everything You suggested Ron except use Toyota coolant and I don't believe Toyota hold the key to quality coolant, maybe I am wrong , so long as I sort it !

Ron
In what way is Toyota metallurgy any different to other engines?
I agree their coolant is good.
I used normal green coolant in my HJ61 Land cruiser for 25 years and it didn't corrode anything. Inside of system was still very good, almost unmarked at that 25 years. Sold with all original parts, hoses and water fittings.

I can't see the coolant as an issue in this case. Seeing Wayne has changed it a few times previously with no problems.
The type of coolant doesn't cause fluid loss or sealing issues which weren't there before the change.

I may well be wrong but I thought that you couldn't differentiate coolant just based on colour. If you mix different coolants it can form a viscous gel that won't pump easily. It may be possible that when you drained the original coolant some may have remained in the system. When you refilled with the new coolant it may have formed a gel and you are not getting good flow.

I am offering this as a possible problem, but more to get comments back to improve my own knowledge.

RMD - "in what way is Toyota metallurgy any different to any other engines?"

In the iron, alumimium, and magnesium alloys they utilise, as well as the range of thermoplastics, rubber and gasket and seal materials.

The range of new alloys in use in modern engines, is ever-increasing. Toyota are at the forefront of the newest metallurgy techniques, as regards engine alloys - from the basic iron alloys, right through to magnesium and aluminium alloys, that now contain a staggering array of additives.

Toyota use aluminium and magnesium alloys that contain varying levels of iron, copper, zirconium, silicon, manganese, nickel, zinc, and even ceramics and strengthening fibres such as silicon carbide and alumina-boria.

Varying alloying elements added to to the light alloys, affect the corrosion resistance of those alloys - sometimes improving the corrosion resistance, and sometimes worsening it.
Manganese is added to aluminium and magnesium alloys to improve corrosion protection. Magnesium suffers the worst from galvanic corrosion (dissimilar metals reaction corrosion).

Coolants have to be compatible with iron components, aluminium radiators and heater cores, alloy blocks and heads, magnesium-alloy engine components, gaskets and seals of varying material construction, thermoplastics used in piping, thermostat housings and radiator tanks, and a multitude of hoses and piping.

Toyota Long-Life coolant contains 934ml/L ethylene glycol plus a range of corrosion-controlling additives known as OAT's (Organic Acid Technology).

Those OAT's are proprietary (commercially secret) to Toyota, but are known to be sebacate, plus silicates, plus phosphate compounds, plus other proprietary protective ingredients, in small amounts.

The latest Toyota coolant is known as a H-OAT (Hybrid Organic Acid Technology - because it has phosphates added, and silicates reduced or eliminated).

The phosphate compounds in Toyota coolant generate a rapid coating on exposed aluminium and magnesium components, which can become exposed to air, when air enters the cooling system.

Light alloy components in engines and cooling systems can rapidly corrode when exposed to air at high temperatures, such as those found in hot engines.

There was a legal kerfuffle in the U.S. when an additive known as 2-EHA (2-ethylhexanoic acid) in Dex-Cool coolant, was found to be a plasticiser (a product that softens plastics and rubber).
Toyota coolant does not contain 2-EHA and as such, there is no possibility of plastics or rubber softening in engine components, when using it.

Toyota do extensive, long-term testing on their specific engine metallurgy, and many of the ingredients in those Toyota metals (and plastics) are known only to them, due to proprietary design and engineering.

For any company making aftermarket coolants, they would have to know the precise levels of each additive to Toyota metals and alloys, and the precise composition of every component in Toyotas engines, that is in contact with hot coolant.

I don't believe that is possible, and I believe that all aftermarket coolant manufacturers merely use a basic ethylene glycol content in their coolants, and throw in a few known additives - on the basis of a "one-size-fits-all" approach - and that they believe this then provides adequate cooling system and engine component protection on a general basis.

However, generalising in this manner, when each manufacturer uses different, and often company-specific alloys and metallurgy, is highly unsatisfactory, in my view.
I have personal experience of using "alternative" coolants in Toyotas, with resultant cooling system corrosion issues.

All of the above is just my .02c worth, based on over 50 years of very extensive ownership and experience of a substantial range of engines, equipment, machines and vehicles, and long experience with a wide range of corrosion issues in cooling systems.

My experience goes right back to early days of soluble oil being the only cooling system additive to prevent corrosion. My, how things have changed.

Cheers, Ron.

Ron
I agree the metals have changed a lot in newer vehicles.
I just recently changed a sump gasket in a car and the sump bolts were single use aluminium, as the engine block is a magnesium alloy, and steel bolts just corrode. Not only have to buy the sump gasket but a set of oem aluminium bolts which aren't that cheap.
Cheers Rob

I have talked to many radiatorshop.
By far they all say the toyotas running the toyota coolant is the cleanest when it comes to a strip down and re clean the cores.
Also for many high performance v8 of any kind
The toyota stuff is by far the choice
Very reasonably priced coolant.
Even at retail

Whilst I do agree that the EGR Cooler can, and is, a source of coolant leakage in the modern vehicles it will not be the case in this vehicle, being a 2001 model and about 10 years before the advent of cooled EGR systems.

I have thanks Barnray, but why am I losing fluid?

Stuck open or closed? A stuck closed thermostat will cause overheat and the resulting water will expel into the overflow reservoir.

Yeah, but when the block cools it *should* suck coolant back into the block.

If the water is getting out somewhere in that can also serve as a leak path for air to get back in, then as the coolant warms, pushes water into the expansion tank as well as out the leak, but after the pressure drop on cooling doesn't occur due to the leak the water doesn't suck back into the block.

A stuck thermostat may have caused the system to blow out somewhere, but wouldn't cause the symptoms described.

You might need to bleed the system to get heat around the thermostat.

No you won't.
All decent thermostats either don't completely seal all the flow, ie leak some through, or have bleed holes to eliminate airlocks. You can only bleed the system if a bleed port is provided.

Thanks Pete , because I am aware of the problem I will not cook the motor ? Eventually I will sort it out , might take time but with everyone's input I will get there ! I am not a novice 59 yr old and driven Toyotas since the late 70s , moving to Wyalkatchem next Monday for good I will have all the time in the world to fix it . Everyone who comments I listen and when I fix it I will post the solution for all of us , because it is a bit unusual!

If the problems wasn't present before the coolant change then something you have done has altered the situation.

With any vehicle problem, always ask who touched it last and what did they do.
Usually narrows the search items considerably.

Hi Swampy, in my experience with HZ radiators is they never run hot if the fins are clean, mostly it's a blocked condenser and for the record I don't have air con it's an ex NSW police troopy