Hercu Posted March 22, 2016 Share Posted March 22, 2016 With all the advice and brain storming of why my Disco 300 TDi would overheat I came across a very sensible mod. That is to close the by-pass hole in the radiator. (The so called tropical mod) If the plastic (should be brass) bleeding plug on top of the radiator is removed and looking down there is a +/- 20 mm hole which will allow water to run straight through. Surely with the older radiator like mine it will be the case due to silting up of the cores. Water always takes the easy route ! That means there will be minimum cooling of water and not to mention oil...? The intercooler next to that will also be affected...? Ok all good and well but how do I close that hole through a 25 mm hole ???? I am 500 Km from the closest Engineering or Radiator works... Is there a way to do it myself....Will prattley steel glue last ????? I might be able to screw something in there...from the top !! Quote Link to comment Share on other sites More sharing options...
Nigelw Posted March 22, 2016 Share Posted March 22, 2016 Never heard of this mod? Over heating says airlock, head gasket, blocked radiator (internally or externally). Quote Link to comment Share on other sites More sharing options...
Hercu Posted March 23, 2016 Author Share Posted March 23, 2016 Nigelw...Yes something new for me as well but totally sense... For us in the tropical southern hemisphere with ambient temps seldom below 10ᵒ C we need more flow through the cores. The ambient can get as high as 48ᵒ C Quote Link to comment Share on other sites More sharing options...
hangover Posted March 23, 2016 Share Posted March 23, 2016 Never heard of this mod? Over heating says airlock, head gasket, blocked radiator (internally or externally). Its not something that is required up north but down here its a common mod, usually done when the tanks are removed from the core so they can be rodded out (manual cleaning of the individual tubes ). Quote Link to comment Share on other sites More sharing options...
Boydie Posted March 24, 2016 Share Posted March 24, 2016 I live in a very hot climate, Australia where in the deserts I experience ambient temperatures of up to 45*C and I've never heard of this "modification". The "by-pass" hole is there to allow any air in the system to by-pass the cores and rise to the top of the radiator. To fill the coolant correctly: Have the car on level ground. Remove the radiator and thermostat plugs. Fill the reservoir until coolant flows out of the top of the radiator, you will notice that this equates to the header tank coolant level being at the correct level. Fit the header tank cap and radiator plug. Pour coolant into the thermostat plug at the same time gently squeezing the return hose to discharge any remaining air bubbles. Refit the thermostat plug, start the engine. Quote Link to comment Share on other sites More sharing options...
Hercu Posted March 29, 2016 Author Share Posted March 29, 2016 I live in a very hot climate, Australia where in the deserts I experience ambient temperatures of up to 45*C and I've never heard of this "modification". The "by-pass" hole is there to allow any air in the system to by-pass the cores and rise to the top of the radiator. Again yes !!! it makes sense !! Quote Link to comment Share on other sites More sharing options...
hangover Posted April 7, 2016 Share Posted April 7, 2016 Almost everyone i know running a TDI has this mod done when getting the rad rodded. This breather hole allows coolant to bypass the cores and not pass thru thus not exchanging heat. Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted April 7, 2016 Share Posted April 7, 2016 I'd just add another row Quote Link to comment Share on other sites More sharing options...
Boydie Posted April 7, 2016 Share Posted April 7, 2016 I agree with the Hobbit, the standard radiator core is, from memory, a 3 row 1/4" matrix, I had mine replaced with a 4 row 1/2" matrix effectively increasing the water volume in the radiator by some 40% (you need the original copper headers to have this done). The breather hole is there for a reason, remove or blank it off and you WILL have an air lock in the radiator ! Quote Link to comment Share on other sites More sharing options...
Daan Posted April 8, 2016 Share Posted April 8, 2016 Does anyone have pictures of the tropical mod? Daan Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted April 8, 2016 Share Posted April 8, 2016 Some while back I did some work for the BGS in the Danakil. Nice people. After a chat with a chap called Ken Slavin, we had the radiators on the 200tdi 110's increased by 1 core - just an extra 1/4" matrix and a later transparent header tank The 110's were well loaded and worked hard. Our daily average temperature in the Danakil was 122 degrees F. That's 50 degrees centigrade. Although the trip from Djibouti was a fair bit cooler We never had any cooling issues Now the 200 is obviously a better engine - we all know and accept that. It also has a massive water jacket so that helps. I've never heard of this Tropical mod and would guess at it being a bodge. Land Rover may be capable of some of the most stupid designs ever but they weren't stupid when it came to just how good a standard vehicle is in extreme conditions If I was young Hercu, I would get everything back to standard and check it was working right. I would look for head issues as well Quote Link to comment Share on other sites More sharing options...
Snagger Posted April 8, 2016 Share Posted April 8, 2016 The 200 rad doesn't have a baffle plate and two passes through the core, as I understand it, because the outlet is on the opposite end from the inlet. On the 300 rad, they're both on the same side. That also means the oil cooler is sitting in fully cooled water on the side of the rad, rather than semi cooled as per the 300, so that may be a factor too. Quote Link to comment Share on other sites More sharing options...
honitonhobbit Posted April 8, 2016 Share Posted April 8, 2016 Just better all round really Quote Link to comment Share on other sites More sharing options...
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