On my westy it took me a long time to realise the central tube had rotted inside the cross members and had massive leaks in there but they were out of sight. When I finally unwrapped the central tube there was only a small piece of it left, the rest was rust flakes stuck to the insulating jacket. I had a photo at one time but it's lost now, only about 5% of it was still steel. Sorting that out made a big difference as did sorting the door seals. It all adds up doesn't it.
Has anyone had a blockage in the system? Mine is nowhere as good as it was but I have no obvious reason for this that I can see.
mine had multiple wasps nests and mouse nests in the bottom tube but i guess that was from when it was parked up in the US for so long.. if yours worked well previously it's probably got a leak somewhere, might no be visible (upper side of the h/exchanger at the rear rusted through on my old set) or maybe your cables have stretched so the elbows are not closing properly?
Heat exchangers still original and in good nick. When I changed my crank oil seal I sealed everything really well at the engine and replaced the missing tin flaps in the fan housing (type 4). Also cable tied the exchangers fully open. Rats nest hunt begins.
Do genuine heat exchangers, or ones that work as well, ever come up for sale? I think mine are JK replicas or similar, whatever they don't seem to exchange a lot of heat - I have wired the elbows open and sorted out some leaks, but I am getting warm breath in the cab at best, even with the auxiliary blower on. My air cooled 911 gets toasty really quick, however the engine isn't 10 feet away, plus the heat exchangers must be made of platinum for what they cost, but that's 'Porsche tax' for you.
i've bought genuine good condition used ones off the samba. they were expensive to ship, but even so they cost me less than buying some new repros. Cleaned them up and re-painted and they are ready to fit when i get around to it.
