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Which Radiator Cap? Recovery Vs Non-Recovery


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#1 nzjb

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Posted 04 February 2020 - 09:08 AM

Hi all,

I have a 1980 998,

I have a problem where the coolant isn't returning from my expansion tank back into the radiator, leaving my radiator low and coolant spitting out of the small hole in the cap of my expansion tank as it overflows. First i thought I should replace the radiator cap, but im wondering whether i need a recovery or non-recovery type cap with my expansion tank. Thanks

#2 timmy850

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Posted 04 February 2020 - 09:46 AM

So:

The stock setup is non-return. Any extra that goes out of the cap isn't really needed, and it leaves some air in the system when it cools down. Anything that goes out (into a bottle) won't return

 

A recovery style cap has a valve in the cap that sucks fluid back into the radiator when the system cools down. One bonus is it keeps the radiator topped up and reduces the possibility of corrosion in the system. 

 

I added the recovery cap and tank to mine and it works great

Attached File  38781427585_71e7ab2746_b.jpg   57.74K   5 downloads

Attached File  38781426635_47bf1897b8_b.jpg   78.52K   2 downloads

 

The stock ones had a level indicator inside the neck, its a couple of cm down

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Edited by timmy850, 04 February 2020 - 09:52 AM.


#3 nicklouse

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Posted 04 February 2020 - 11:03 AM

Hi all,

I have a 1980 998,

I have a problem where the coolant isn't returning from my expansion tank back into the radiator, leaving my radiator low and coolant spitting out of the small hole in the cap of my expansion tank as it overflows. First i thought I should replace the radiator cap, but im wondering whether i need a recovery or non-recovery type cap with my expansion tank. Thanks

it really depends on what you set up is. is it designed for recovery? I am not aware of the Aus builds. pictures?



#4 Ethel

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Posted 04 February 2020 - 02:21 PM

Not original on an 1980 Min, at least not in the UK.

 

Where's the overflow tank mounted? Can't see it developing much suction before the rad hoses collapse.

 

Silly question - the hose end is submerged?



#5 timmy850

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Posted 04 February 2020 - 08:36 PM

There are a couple of different coolant tanks and they all work differently:

 

Stock: overflow goes into the pipe and onto the ground - nothing goes back in. Standard cap

 

Overflow tank: overflow goes into a tank - nothing goes back in. Standard cap

 

Recovery tank: overflow goes into a tank. (The pipe goes to the bottom of the tank to ensure it's always got coolant in it). When cold the coolant returns to the radiator, the tank can be mounted above or below the radiator (this actually works really well). Recovery cap

 

Expansion tank: the tank is part of the pressurised system (used on later cars, Morris 1100). It needs to be the highest part of the system, the radiator has a blank cap (e.g. GRC126) and the expansion tank has the pressure rated radiator cap. Any overflow coolant comes out of the expansion tank






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