Help overheating problem

[JackCollo]

Hey guys I urgently need to find the source of the problem my patrol has developed. So basically since MELBOURNE has been quite hot over the last few days I’ve been careful on coolant temperatures but everyday it has been hot it has had problems.
So what happens is that normal driving around is fine and traffic is fine but as soon as I power the car off the water spews out all over the place and I have repeatedly bled the system and topped the water up. This only happens after the car has been switched off not while operating. Can you guys help me please
Regards jack


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[the evil twin]

Could be one or more of quite a few things...
First thing I would do is get a pressure test done and also replace the Rad Cap
Did you try burping the system?
Slight nose up, cap off, run the engine for a couple of minutes

When you switch off you get a very significant heat spike so it can be low pressure in the coolant system or air pockets

Do the easy/cheap things first and work from there

[JackCollo]

It’s not coming out of the radiator cap it comes out of the 2 overflow bottle the one underneath the main one


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[AB]

Hey Jack, make sure the overflow bottle cap is on the right way too Rossco had exact issue and it was overflow bottle cap was on wrong way so hot coolant goes into overflow bottle and cant come back to radiator so pisses out of overflow.

[JackCollo]

Hey Jack, make sure the overflow bottle cap is on the right way too Rossco had exact issue and it was overflow bottle cap was on wrong way so hot coolant goes into overflow bottle and cant come back to radiator so pisses out of overflow.

After I switch it off I can watch the water level rising then the bubble come in and it spills about 1-2 litres out


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[PeeBee]

I am wondering if its not simply a heat sink effect. The system copes when it is being cooled by circulation and cooling via the radiator, then when you stop the motor the water is exposed to the hot block and the liquid boils, hence releasing the air from the system and by default blowing the water out in front of the bubble.

[JackCollo]

I am wondering if its not simply a heat sink effect. The system copes when it is being cooled by circulation and cooling via the radiator, then when you stop the motor the water is exposed to the hot block and the liquid boils, hence releasing the air from the system and by default blowing the water out in front of the bubble.

Yeah it would appear that way but the odd thing is that the car doesn’t heat up at all while driving


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[MB]

As ET kindly suggested Jack mate it could hopefully be as simple as a dodgey radiator cap. It has happened to me before, 1-2 litres out of the overflow bottle only upon arrival at home.
Fingers crossed for you mate, best of luck!


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[PeeBee]

Yeah it would appear that way but the odd thing is that the car doesn’t heat up at all while driving


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The airflow is stripping the heat away when you are pumping it thru the radiator, when stopped it sits there and percolates.

[JackCollo]

Fingers crossed indeed
So which way is the cap supposed to go. To be honest I didn’t know they had a right and wrong way

I might do a full radiator flush ASAP


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[PeeBee]

Fingers crossed indeed
So which way is the cap supposed to go. To be honest I didn’t know they had a right and wrong way

I might do a full radiator flush ASAP


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I would say this is only relevant if you have been dicking around with the cap recently. If not then its something else.

[JackCollo]

I would say this is only relevant if you have been dicking around with the cap recently. If not then its something else.

Yeah I have because I checked the level in the radiator so the cap was removed


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[PeeBee]

@AB, whats the correct orientation of the overflow cap - is there an in and out which suggests a check valve of some description? If this has not chan ged, then pointing toward the radiator cap?

[AB]

I'm not sure about zd30's mate but the td42 overflow which surely is similar to that is long side down on inlet side and short side on external.

Liquid goes in, long side sucks back into radiator, short side exerts coolant if bottle is full.


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[JackCollo]

@AB, whats the correct orientation of the overflow cap - is there an in and out which suggests a check valve of some description? If this has not chan ged, then pointing toward the radiator cap?

I have no idea to be honest


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[AB]

http://www.nissanpatrol.com.au/forums/images/imported/2017/11/189.jpg

I'm too lazy to take off brace.

Long side left, when cool, sucks back into system.


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[JackCollo]

I’ll take a picture of mine when I get the chance but I really wanna get this sorted out.
Is it worth pulling the radiator out and power washing it?



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[PeeBee]

Do the easy stuff first, check as above. The first question needs to be 'what has changed?". Is it simply the weather and the radiator is suffering because the condition is down, hence its getting hotter, or have you done something to change the heat transfer? New set of radiator blocking lights, bug screen over the front of the grill, blocking flow, radiator level simply down and you didn't notice and then it started to run hot? Is the coolant at the end of its life/ This 'hot snap' has hardly been severe. Do you have a collapsed hose?

[FNqGu04]

Hey Guys
I have a ZD30 the orientation for the rad caps is the pressure cap goes on the overflow bottle near the guard
n the normal cap goes on the radiator . Hope that helps

Craig

[Rossco]

Hey Jack, make sure the overflow bottle cap is on the right way too Rossco had exact issue and it was overflow bottle cap was on wrong way so hot coolant goes into overflow bottle and cant come back to radiator so pisses out of overflow.Yeah was ready to do a head gasket on the thing. Would have been a bugger to do that and have it do the same thing afterwards. Always love a cheap fix. . .

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[the evil twin]

It’s not coming out of the radiator cap it comes out of the 2 overflow bottle the one underneath the main one


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Yeah, I understand that... but you need to consider the pressure cap is there to increase the boiling point of the coolant.
If the pressure cap is knackered the coolant boils at a lower temp
It is OK while driving as the coolant circulates so is constantly getting colder coolant from the Rad
If the pressure is low then when you stop the coolant now 'trapped' in the engine boils and blows by.

Your symptoms are very indicative of a dodgy cap.
It may turn out to be something else but as prev mentioned do the easy/cheap things first

If it is blocked Rad fins etc then the issue tends to be overheating when under load not after being turned off