Oil cooler reinstate

Hi all - help

I am replacing clutch and damaged the metal coolant pipe. This has led me to notice that my oil cooler is missing. I am trying to source all new coolant hoses and pipe but this means I need to also fit an oil cooler.  
Can I just buy an oil cooler and fit it between the filter and the housing.  Do I need a new housing too?  I have nearly found all the hose and metal pipe now but the oil cooler is worrying me 

Cheers

Jez 😁 85 cabriolet gti dx 

What year and model. Not all cars came with them as OEM.

90-93 Cabriolets didn't.
my 81 Diesel didn't, which it probably would of blown out with the PSI that they rock.

Hi. Thanks for getting back to me.  It is an 85 gti cabriolet   I have ordered a mk2 cooler. Does it just clamp between the oil filter and housing??

I have ordered all the pipes to convert back based upon a diagram of the cooling system off here. 

This might also explain why the heater is so weak too 😁

Clutch now fitted with new pushrod and seal as it was full of oil.  Also new thrust bearing, still waiting for the green cap 😁

The heater is weak, because you probably need to flush and black flush the heater matrix until it runs clear.

The other issue that causes a heater to be weak it the heater valve isn't fully opening, and or it is bad.  Don't bother with the 12 dollar one that is the replacement.  

I strongly suggest that you use the 944 Porsche Heater valve as it is a Vane type, that resembles the original ones that they first used and were very reliable.

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