Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

[Ahbengdriver]

Hope someone can chip in please. Thx in advance.

To cut the story short, today, one of my 335's cooling system's hose had burst/broke, spilling coolant and car is currently almost un-drivable unless I keep topping up with water to keep the car engine cool. There is some amount of coolant/water remaining but the warning indicator is still showing low coolant level(yellow light).

Could it be due to this? Recently, a workshop over topped up my coolant, way way above the max level than is required. When I opened the coolant reserviour cap, the internal floating stick indicator literally pop upwards to the max if you know what I mean. Someone(not car expert but a technician) said it could be too much steam pressure inside the cooling system due to too much coolant/water and the hoses were under super high pressure when heated up, and the weakest hose just gave way. Is this a possible reason, or its just a normal wear and tear issue as the hoses age.

 

[cccc]

Re: Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

I'm no expert but i believe the main cause of this issue of yours is caused by the over filling of coolant which resulted in the cooling system being over pressured.

 

[eacsjb]

Re: Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

There is an vent hole on the spare tank cap...should not be over pressure unless the spare tank cap faulty...

 

[Red_Bean_Bun]

Expert Advice needed-Negligently overfilled coolant system causing hose to bu...

Don't think the overfilling would cause the problem unless your coolant cap spoilt. It's a pressure cap with a release mechanism.

Get a WS to use a refractometer to test the level of ethylene glycol. If the level of EG is below the a certain level the the BP of the water would not be raised sufficiently high enough to avoid the change state ..... Then you will have steam which like what your mech friend described would happen.

 

[Blitzer]

Re: Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

There are a few immediate, and under-lying issues in this respect:

First, the cooling, being a sealed system, is designed to pressurize as heat builds up. Pressure builds up to just under 2bar, after which the cap then vents excess pressure at 2bar.

The expansion tank structure requires some airspace in order for the system to pressurize correctly. Since the coolant mixture expands when it heats up, but is not 'compressible', it is the airspace in the expansion tank that allows for this expansion of the coolant. There's no "overflow tank" like in many cars with a non-pressurized cooling system - the system is closed and sealed.

If the expansion tank is overfilled such that there is no airspace, the expanding fluid will either cause the cap to vent (spraying coolant out the cap and hence your nice artistic mess), OR if the system is old, it may cause your old and weak expansion tank/hoses to burst. Thorough inspect the expansion tank to check if it has cracked.

On a more general note, regular checks on all coolant hoses should also be done, All hoses that are bloated must be changed immediately. BMW engines run very hot, and bloated hoses deteriorate very quickly. the same goes for hoses with 'weathered' end connectors.

Last and perhaps most importantly if the state of thr coolant in your car, What type of coolant you use, the concentration of the balance (refractometer readings will tell), the coolant/water ratio and whether tap or distilled water was used all contribute to the pressure build up dynamics. It is typical of many workshops to just shove the water hose to fill up - a HUGE No-No as this leads to coolant de-generation, increased acidity, sludge build-up and internal rust.

Your coolant system extends beyond the radiator, it includes the water channels around the engine block and gearbox providing the much needed heat dissipation that your hot running system needs - what more a turbo charged engine.

Hence, burst radiator hoses can be a precursor to a more fundemental thing: the need to have your whole coolant system checked (pressure-tested), fully system-flushed to clear clogs and arrest rust before more major issues arise.

 

[Red_Bean_Bun]

Re: Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

Not trying to be pedantic but 2 bar is quite high for pressure venting - that's almost 30 psi (tyre pressure level). Usually 15 plus psi is enough to pressure test the hoses would reveal weaknesses in the system. IIRC the pressure cap should be just over 1 bar.
Just some thoughts in case someone decides to test at 2 bar .... Things might really break ...

 

[Slow_poke_driver]

Re: Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

You guys are talking about the same thing.

One guy is saying 1 bar above atmospheric.

Another guy is saying 2 bar above 0 absolute.

 

[Slow_poke_driver]

Re: Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

And I could be wrong...but bmw are mainstream bread and butter cars that any ah gong ah ma will buy. Surely the coolant system was designed to be idiot proof...i.e. catering to conditions such as an old grandpa overfilling the coolant...no? Totally no vent any where?

 

[cccc]

Re: Expert Advice needed-Negligently overfilled coolant system causing hose to burst?

BMW recommended for qualified mechanics to service your vehicle. How to design a system that is totally idiot proof?