Originally Posted by Burgundymog
Lorne that makes complete sense. My system although on a +4 is identical to your diagram, thank you.

[BLUSH!!!] Well...for the last decade+, I am being told it works. Cheap fix. Not doing anything inevitably has the resultant condensation produced rust out the system. My apologies to you for missing linking to the article on gomog for so long. gomog is merely the result of idle intellectual exercise, like others doodle or do crossword puzzles.

By the way, I stumbled across a cable operated shutoff and bypass (rather than a solenoid) that should also work. (I didn't investigate it much) https://s-pautomotive.com/product/heater-core-bypass-control-valve/ Using a mechanical switch requires more driver awareness but eliminates the wiring I explained.

Now we need George or Davew to explain how the Roadster's cooling system functions. Schematic below. I am most interested in their thoughts and theories. I have yet to come to any conclusions on my own..though I would ask you all note the angling of the stock plastic radiator for a future discussion.

Originally Posted by Paul F
The T piece shown is plastic and is common to all trads of the era (My 4/4, +4 and Roadster).

Hi Paul,

Return pieces have been used since the 1970s, merely higher quality ones then than now. I use one to this day. Image below. For some reason, they were left off when the MMC switched to Hotwire systems. Shutoffs were still used I believe, but no bypass. That leaves those cars with uncirculating coolant in the hoses to and from the cabin heater to become EXTREMELY hot as it runs (until GEMS) through the super hot valley under the intake/plenum. But without the bypass and circulation, you can imagine how hot that coolant got!! For 1984-2000 they changed the hoses to metal pipes in that section! IIRC, (without consulting gomog) with GEMS they ran hoses around the top of the engine outside the convenient passage through the valley. Kinda sloppy. But it confirms that LR or the MMC was aware of the problem they had created but they had forgotten the bypass solution. frown2 There is a consequent of buying out contracts of the older more experienced workers and replacing them with government subsidized "apprentices". That happened everywhere in the developed world.

gmg

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ROADSTER COOLING SYSTEM SCHEMATIC

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