Cooling System overpressurising

[Moci]

My engine oil is ok, I don't have emulsion on it for now. Will check tomorrow with mechanic for sure.

I suspect on thermostat because inlet hose is hot but outlet hose cold but I am concerned because I have changed whole cooland and flush system 6 months ago and I see now that fluid is very dirty.

Checked now but definitely no water in engine oil. Cooling fluid looks like this on pictures.

[erad]

I tend to agree with an earlier posting about mixing coolants. This model should use green or blue coolant and it should never go this colour. My guess is that someone has used the wrong coolant and you have a gel blockage in the radiator core, and probably a few other places eg heater cores and maybe even parts of the engine as well.

[Dicko1]

I tend to agree with an earlier posting about mixing coolants. This model should use green or blue coolant and it should never go this colour. My guess is that someone has used the wrong coolant and you have a gel blockage in the radiator core, and probably a few other places eg heater cores and maybe even parts of the engine as well.

I reckon your right. I,ve never seen coolant this colour..Time to flush out motor and refill.

[Moci]

Hmmm... So weird because I have had 3 Pajeros since 2012 years and all of them had "Red" coolant fluid. Maybe European models have different type of fluid.

Will try to flush it and also a new thermostat to see what will happend

[old Jack]

I suspect on thermostat because inlet hose is hot but outlet hose cold

Which hoses are you referring too?

The inlet/outlet hose to engine or the radiator, normally people refer to the top or bottom hose to save confusion.

Here is a diagram of the coolant flow direction.
Most people think that the thermostat directly is upstream of the radiator and release water directly into the radiator top hose. The thermostat is actually downstream of the bottom radiator hose and controls the flow of cooled coolant from the radiator.

http://faq.out-club.ru/download/pajero_iv/maintenance/Service_Manual_2008_2013/img/14/AK602436AB00ENG.pdf

OJ.

[David45]

That's interesting because it's not what I expected. I've always seen the thermostat at the top of the engine releasing coolant to the top hose. Never expected to see any other configuration where it's controlling flow from the bottom hose. Thanks for pointing that out.

[BruceandBobbi]

https://www.carparts.com/classroom/coolingsystem.htm


Circulation
The coolant follows a path that takes it from the water pump, through passages inside the engine block where it collects the heat produced by the cylinders. It then flows up to the cylinder head (or heads in a V type engine) where it collects more heat from the combustion chambers. It then flows out past the thermostat (if the thermostat is opened to allow the fluid to pass), through the upper radiator hose and into the radiator. The coolant flows through the thin flattened tubes that make up the core of the radiator and is cooled by the air flow through the radiator. From there, it flows out of the radiator, through the lower radiator hose and back to the water pump. By this time, the coolant is cooled off and ready to collect more heat from the engine.

[old Jack]

As previously posted the 4m41 diesel engine has a different coolant flow;

http://faq.out-club.ru/download/pajero_iv/maintenance/Service_Manual_2008_2013/img/14/AK602436AB00ENG.pdf

OJ.

[BruceandBobbi]

Thanks OJ. Do you know why MM do it that way. Is there any advantage/disadvantage flowing either way?

[old Jack]

Thanks OJ. Do you know why MM do it that way. Is there any advantage/disadvantage flowing either way?

I do not know the reason but I think it will depend on the design of the engine and where the water pump and thermostat are located on the engine relative to the radiator outlets.
Have a look ar these water passage diagrams for the 4 engine options fitted to the Challenger, note; there is a significant difference between diesel and petrol engines.

http://faq.out-club.ru/download/pajero_sport_2008/maintenance/Service_Manual_2009_2011/2011/index_M2.htm

The Gen3/4 with the 4M4 series engine all seem to have a down flow radiator with a top and bottom tank where as the Challenger has a cross flow radiator with side mounted tanks. Normally the choice of radiator is dictated by the size and shape of the area available for the radiator, and not based on cooling efficiencies.

OJ.

[Moci]

We opened engine and head was cracked...

System was only overpressurising but no mixed oil and coolant.

I will update here when it's everything done.

[Moci]

Sorry for dobule post.

Head sorted out, new gasket, new water pump, new thermostat.
For now everything is working fine. Will test it these days.

I am a bit disappointed because i was thinking that 3.2 did engines are unbreakable but stuff happens. Car is at 270.000km and I am very slow driver (driving to about 2000-2200rpm). Maybe first owner wasn't driving that slow and maybe he was "angry" driver and because of that head cracked but I am hoping that I won't have any trouble with engine.

Cheers

[erad]

Pleased to hear that you have solved the cooling problem. The mode of driving does not normally cause a cylinder head to crack. Probably the engine was overheated because of blockages in the cooling system. Hopefully the water passages in your system are clear now and will stay that way.

[Moci]

I was very confused because I had done full detailed cooling "super" flush about 6 months ago, and still this happend.

I also forgot to say, head was cracked at 2 places.