Radiator cap blowing

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serieslandy65
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Location: Victoria, Australia

Radiator cap blowing

Post by serieslandy65 »

Hi,

I have a mini moke fitted with the 998 A+ engine. I think the radiator is the original, so for a standard 998. I haven't found anything that says the radiator is different for an A+. I have fitted a 15lbs cap to the radiator and it still blows by a little to a certain level in the radiator. I put a 50/50 mix of nulon green in and fill just to the bottom of the cap seal. It blows past this and puts a little in the header tank. After driving for 3 days the radiator hasn't blown the cap again. Have I just put too much coolant in and its finding its level or is there something else I am missing?

Cheers

Rory
Nigel(no top)Sykes
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Re: Radiator cap blowing

Post by Nigel(no top)Sykes »

Have you got a pressure cap on the radiator or the expansion tank?
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serieslandy65
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Re: Radiator cap blowing

Post by serieslandy65 »

Nigel(no top)Sykes wrote: Fri Aug 16, 2019 4:59 Have you got a pressure cap on the radiator or the expansion tank?
Hi Nigel,

15psi on the radiator. The expansion tank just has a non pressure cap on, I think the original.

Cheers

Rory
Willie_B
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Re: Radiator cap blowing

Post by Willie_B »

The radiator is seeking the level it likes best. Mine likes about 1/2" above the tubes. Any more it blows it out.

I thought in a system with a catch tank the pressure cap went on the tank and a plain cap on the radiator.
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grantourer
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Re: Radiator cap blowing

Post by grantourer »

My Aussie has a plain cap on the radiator and a pressure cap on the catch tank, and the Portuguese is the same
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1981 Aussie Moke
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Nigel(no top)Sykes
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Re: Radiator cap blowing

Post by Nigel(no top)Sykes »

As I was going to say....the pressure cap goes on the expansion tank and the radiator gets a plain(sealing) cap. If you look inside the expansion tank with a torch you will see there is a tab that shows the fill level for the tank.
Also, don’t forget...the pipe from the radiator overflow to the expansion tank must be well fastened on as it is subject to the same pressure as the rest of the system
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serieslandy65
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Re: Radiator cap blowing

Post by serieslandy65 »

Ah well you learn something new everyday. I had just left it the way I bought the car which hadn't been driven since an engine rebuild so no one would have had the same problems. My other car (an old land rover) doesn't have an expansion tank so I couldn't refer to that. So swap the caps around and fill the expansion tank with coolant to the tab? Thanks ever so much.

Rory
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serieslandy65
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Re: Radiator cap blowing

Post by serieslandy65 »

Here is a pic of my expansion tank:
expansiontank.jpg
Would the square stamped into it be the fill level? In between the top and bottom of it? I have had a look inside and can't see any tabs in there or spot welds on the outside.

Cheers

Rory
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Doug G
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Re: Radiator cap blowing

Post by Doug G »

I posted another thread query on the best/recommended insulation that should be used to avoid damage to bonnet pain by this sort of problem.
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