Andy Lowe Posted January 2 Report Posted January 2 Hello All. Can't find the original thread, however it may not have been on this forum. Thought I would share my modified cooling system arrangement with anyone interested. I know the subject has been covered extensively but on following all advice and finding my TR4 system fully serviceable, it still got very hot under certain conditions, so I decided to modify it using a generic modern radiator mounted at the front of the car and with a header tank and two stage electric cooling fans. I can report that it never goes anywhere above the middle of the temp dial in all operating conditions and the stage 1 fan only comes on after a a good run and then coming to a standstill for more that a minute or so. The 2nd stage fan has never come on. I appreciate that those who like to keep their vehicles as original will not be at all impressed and I understand that completely. Hope this is of use to someone. Kind regards..... Andy Quote
BlueTR3A-5EKT Posted January 31 Report Posted January 31 On 1/2/2026 at 2:02 PM, Andy Lowe said: Hello All. Can't find the original thread, however it may not have been on this forum. Thought I would share my modified cooling system arrangement with anyone interested. I know the subject has been covered extensively but on following all advice and finding my TR4 system fully serviceable, it still got very hot under certain conditions, so I decided to modify it using a generic modern radiator mounted at the front of the car and with a header tank and two stage electric cooling fans. I can report that it never goes anywhere above the middle of the temp dial in all operating conditions and the stage 1 fan only comes on after a a good run and then coming to a standstill for more that a minute or so. The 2nd stage fan has never come on. I appreciate that those who like to keep their vehicles as original will not be at all impressed and I understand that completely. Hope this is of use to someone. Kind regards..... Andy Which thermostat design/type is fitted? Was the bore of the bypass hose restricted if a WaxStat type thermostat was installed? Quote
roy53 Posted January 31 Report Posted January 31 33 minutes ago, Andy Moltu said: What was the generic modern rad? Yes that would be of interest Quote
Robin Macmillan Posted January 31 Report Posted January 31 I have a 1963 TR4 LHD reimported but not as yet UK registered. I hope to take it to SW France where it can get very warm. Details of your modification would be a great thing for le to think about Robin Quote
Z320 Posted February 1 Report Posted February 1 Hi Andy, there is a mistake in the Hydra you installed. But - it’s great for me to see your design works anyway! You lucky guy, that mistake very likely safes you from a brakedown by a 2nd mistake! Who sees them? Ciao, Marco Quote
BlueTR3A-5EKT Posted February 1 Report Posted February 1 3 hours ago, Z320 said: Hi Andy, there is a mistake in the Hydra you installed. But - it’s great for me to see your design works anyway! You lucky guy, that mistake very likely safes you from a brakedown by a 2nd mistake! Who sees them? Ciao, Marco I have looked and can only make a comment on two things. Thermostat housing painted BMC green….might change the legendary reliability of a TR! Curious about the nut that holds the narrow belt aluminium water pump pulley on, without the usual very thick washer. That being a wide faced nut has probably reduced the need of the very thick washer. This full width cross flow type radiator fitment is/was common with racers. I think it was some Opel Vauxhall the radiator came from. Quote
Z320 Posted February 1 Report Posted February 1 34 minutes ago, BlueTR3A-5EKT said: Curious about the nut that holds the narrow belt aluminium water pump pulley on, without the usual very thick washer. That being a wide faced nut has probably reduced the need of the very thick washer. A good idea! Quote
Z320 Posted February 1 Report Posted February 1 (edited) Hi Andy, can you please give me some inforamtion: - do you know how much coolant you filled in? - voulume of your expansion bottle? 1.5 liter? https://www.obpltd.com/product-page/1-5-litre-alloy-header-tank-with-sight-tube-vertical/ - level in the expansion bottle when cold? On the clear PVC tube it looks pretty full... - pressure of your rad cap? Ciao, Marco Edited February 1 by Z320 Quote
Z320 Posted February 3 Report Posted February 3 Andy, you have no interest about how to make it better? Quote
Drewmotty Posted February 4 Report Posted February 4 I’d be interested in how to make it better. Quote
Z320 Posted February 4 Report Posted February 4 (edited) Hi all, all my poinion, please come to your own conclusion. Up until the mid 1980-ies most radiators have been the "container style" like on our TRs. They have the radiator cap on top and air in the rad / hoses. Some guys want to vent the air out and hope for better cooling,, but it is needed to be compressed by the expanding coolant to limit the raise of preassure. More air --> less high is the pressure. The air is no problem for the cooling system, the coolant pump keeps it in the flow. From the mid 1980-ies all prodcers swapped to radiators the "pipe style", most likely because they are much cheeper. The radiator cap moved on a container (difficult to fix it on the rad) on a level higher than the rad. It is said all air (still needed) has to be there. Therefore container it is connected with a small hose "to the top" (high speed flow) of the rad and with a wider hose to the "bottom" (low speed hose). A constant small flow of coolant through the container is needed and responsable to collect the air there. All "OK" with the Andy's setup, but the small tube is not connected to the hightest point and all air higher than the arrow stays in the top rad hose and thermostat housing. And there is no pressure there to drive a flow to bleed bubbles out, and 10 mm for this hose could be too wide (better 6or 8 mm). BUT, that's great: against the saying, all air has to be in the container on this rads, and this pretty sure is not the case on Andy‘s setup --> THE COOLING SYSTEM WORKS and Andy is very pleased! I expected nothing else, because the pump is the same and keeps the air in the flow. To get the air in the container the only correct place on our 4 cylinders is on top of the thermostat housing and in front of the thermostat. The resistance of the thermostat powers the flow to the container and this seperates the air. Therefore the housing bust be drilled and tapped on top, even sidewards not works 100%. Guess why I know. My hose is 6 mm diameter inside. Why am I sure Andy has the air still in the system? Air is needed in the system, to my calculation about 0.5 liters (13 PSI rad cap), better / with 7 PSI more, to get a closed system. 1st: in the clear PVC hose of the container I can only see coolant, above the hose is not enough space for 0.5 liter air ("no" air). So the main air must be still in the top rad hose and thermostst housing, and in the flow when the pump is spinning. 2nd: if Andy's setup would have a constant bleeding flow (this is the reason for the 2 hoses) the container must become hot, that's OK. And the clear PVC hose would get soft and flip off from the pipes under preassure. Rule: NO clear PVC hoses in a cooling system! Because it did not fail I'm sure there is no bleeding flow. Good luck for Andy, the PVC hose is the 2nd mistake but it did not fail. Andy now could modify his setup to collect all air in the container (half full) but I'm sure he will not really notice an improvement. BTW to get the hose on the top and in front of the thermostat is difficult in the 6 cylinders (not my challenge). Ciao, Marco Edited February 5 by Z320 Quote
Bfg Posted February 5 Report Posted February 5 (edited) Thank you Marco, I'd never thought about the need for air in the coolant system before. I'd just never even considered it. Of course it makes sense ..now that you mention it ..as it serves as a air-spring, whereas the water/antifreeze mix is not (it's hydraulic. Without the compression / air-spring the water/antifreeze mix would push out of the radiator cap immediately the engine started to warm, ie., very much sooner and much more fluid transfer to the header tank. Andy is clear in saying he's using his auxiliary tank as a radiator 'header' tank. I'm not sure that he's attempting to bleed the system of air. That header tank has three pipes to/from it, aside from the fluid-level-indicator clear plastic pipe, but I cannot fathom where those into the side of tank go to /come from, and/or whether there's a separate expansion tank.? I'm not keen on electric fans, although I do see their advantage ..should a vehicle be stuck in slow traffic conditions a lot, which is when the mechanical fan is not turning as fast. I'm also an advocate for a tidy engine bay, without pipes and cables running all over the place. Each to their own. I'm sure Andy is well enough pleased that his approach has achieved the desired improvements over standard. ..and I'm glad to read his thread and to see the replies. There are of course many who don't have an issue with the standard TR4 / 4A set up. Equally there's a list of proven ways to improve engine cooling. Swapping to a deeper aluminium radiator core is nowadays first choice for many. And of course fitting a finned engine-oil sump. Racers very often used to add an oil cooler and cut extractor grilles through the side wings (TR4 works racers) or or press louvres through the bonnet ..in the low pressure area in front of the windscreen. For my Citroen, I simply added an extractor flap under the car. More recently waterless-coolant has its advocates. Some are easier than others.. On Katie I simply fitted the much improved mechanical fan (contoured plastic blades) off a TR6. It's a easy swap and a straight fit. I also removed the card cowling in front of the radiator and replaced it with a simple air-dam to just one side of the radiator, which allowed cool air flow to the carburettors and around the exhaust manifold side of the engine. Edited Saturday at 04:43 PM by Bfg Quote
Z320 Posted Saturday at 09:12 AM Report Posted Saturday at 09:12 AM (edited) Hi Pete, my job is being a civil engineer for house heating and cooling generally is no mystery for me, but anyway car engine cooling is different from house heating system. I started investigations years ago after I've been told to much bonfire stories, not matching together. Conclusion #1: the water pump in a car is a MONSTER, the system has no height and the flow is not divided. On this point a car's coolant pump keeps the air in the flow and is completely different from house heating systems. Conclusion #2: Air is needed in the system, like you discripe "as a spring", until the mid 1980-ies in the rad and hoses, later in a separate container. Without air the pressure raises very fast and blows coolant out. Without air it is not possible to get a locked cooling system (sadly the TR6 manual explains how to use the locked system as an opened one….) Conclusion #3: I fitted a automatic bleeding and return system and a number of thermometers. This allows me to drive any time I want with air in the flow or air seperated in a container. And the thermomenets show me - it makes no difference at all. That's difffernt from a house heating system with its toy pump and divided flow. How does my bleeding system work? Knowing the pump in a car keeps the air in the flow I fitted a translucent bottle from a Peugeot next the rad and BELOW the max level. Not on top, this is boring and allows no experiments. Of cause this is not practical for common customes, only my pleasure to get knowledge. With the pick up in the thermostat housing and the fast flow hose in a small dimension all air is there very fast (via a tap). Next photo is with all air still in the thermostat housing and top rad hose, the bottle is dark (full with coolant). On the next photo the air collected in the bottle after 10 or 15 minutes driving. With all air in the Peugeot bottle I let the engine run, close the tap and all air stays there as long as I keep the tap locked. This way I drove last summer (all air always trapped there). But trapped or not, it makes no difference with the temperatures. So what in my opinion is an improvement? Conclusion #4: Fit a fan blade with curved wings, mine is from a BMW 1602. Like on a wing of a plane it produces low pressure on top (front) of the wing to such air and high pressure behind to push air. The original TR2-4A fan (only flat bended aluminium) is a extremely uneffective construction. Conlusion #5: Fit a shroud around the fan blade, this is MOST efficient when cooling is needed - at low speed traffic. On the right side you see the wide return hose from the Peugeot bottle to the rad. Now it is real great so see on Petes set up: also with a past 1980-ies rad cooling works lovely with the air in the flow, fan blades with curved wings and a shroud around the fan blade. For my own I need no different rad (specially not aluminium), no expansion bottle on top, and no hose Hydra under the bonnet. Ciao, Marco Edited Saturday at 10:27 AM by Z320 Quote
Bfg Posted Saturday at 05:13 PM Report Posted Saturday at 05:13 PM 7 hours ago, Z320 said: But trapped or not, it makes no difference with the temperatures. Thanks Marco. Interesting to read that the closed cooling system offered no significant improvement over the standard. I note your disregard for the standard water pump. Perhaps you would instead prefer to replace it with and electric water pump, as is being offered in Australia ? I've heard favourable reports, but I have some anxious about its reliability. Certainly, if I'd experienced overheating issues - then I would next have fitted a cowl around Katie's TR6 7-blade fan ...but of course I would have moulded that to include / draw air through all four corners of the radiator core ! My Daimler v8 has such a cowl (above) and I believe it improves efficiently and also helps contain fan noise. I'm thinking this would be easily adaptable for use on a TR, I still don't like the standard TR cowl around the front of the radiator, but that's as much to do with my encouraging cool / fresh air to feed the carburettors. Pete Quote
Z320 Posted Saturday at 05:31 PM Report Posted Saturday at 05:31 PM (edited) Best explanation about „ducts“ I know. If there would be space between the ventilator and radiator, I would have made a „square to round“ duct…..that’s somebody else challenge now. But my cake pan offers benefit enought and with the winged BMW ventilator it is the contemporary improvement from the 70-ies and 80-ies for a classic car, not electric stuff Edited Saturday at 05:54 PM by Z320 Quote
Z320 Posted Saturday at 06:28 PM Report Posted Saturday at 06:28 PM (edited) 1 hour ago, Bfg said: Thanks Marco. Interesting to read that the closed cooling system offered no significant improvement over the standard. Pete Sorry Pete, I NEVER stated that, please! The closed cooling system is the way to go to keep oxygen out of the system. All TR2-4 have a closed cooling system. An the TR6 too, if enough air is in the rad and the overlow bottle empty! I know TR6 owners driving that way. What I state is, I can not notice by my experimenta a benefit of a fully bleeded system (without air in the cooling flow). Ciao, Marco Edited Saturday at 06:29 PM by Z320 Quote
Bfg Posted Saturday at 08:52 PM Report Posted Saturday at 08:52 PM 2 hours ago, Z320 said: Sorry Pete, I NEVER stated that, please! The closed cooling system is the way to go to keep oxygen out of the system. All TR2-4 have a closed cooling system. An the TR6 too, if enough air is in the rad and the overlow bottle empty! I know TR6 owners driving that way. What I state is, I can not notice by my experimenta a benefit of a fully bleeded system (without air in the cooling flow). Ciao, Marco I stand corrected Marco Thank you. Excellent Video. I've never heard the various factors combined like this before. I shall watch more of this man's presentations. Cheers, Pete. Quote
Z320 Posted Saturday at 09:13 PM Report Posted Saturday at 09:13 PM I remember a video but cant find it: a propeller spinning, pulling on a weight, but can‘t move it. On a slight a duct is moved closer and finally the propeller is the duct - and can pull the weight. On a car the propeller can’t pull a weight better, it sucks air better. Quote
Schnippel Posted Tuesday at 09:41 AM Report Posted Tuesday at 09:41 AM On 7.2.2026 at 19:28, Z320 said: Tut mir leid, Pete. Das habe ich NIEMALS behauptet! Ein geschlossenes Kühlsystem ist die beste Methode, um Sauerstoff aus dem System fernzuhalten. Alle TR2-4 haben ein geschlossenes Kühlsystem. Auch der TR6, vorausgesetzt, genügend Luft befindet sich im Kühler und der Ausgleichsbehälter ist leer! Ich kenne TR6-Besitzer, die so fahren. Ich kann mit meinen Experimenten keinen Vorteil eines vollständig entlüfteten Systems (ohne Luft im Kühlkreislauf) feststellen. Ciao, Marco Hello, I'm getting angry! Why? First, a forum in Germany is flooded with these completely wrong recommendations, and now here. In Germany, attempts were made to explain this to him objectively. Ineffective! A TR/Spitfire engine with an expansion tank next to the radiator must not have any air in the radiator, and certainly not in the area of the thermostat. The expansion tank, with the hard plastic pipe extending to the bottom, is half to three-quarters full of water. This man either can't or won't intellectually understand how the cooling system on a Triumph with an expansion tank works! Beautiful tests with digital displays are worthless. Why? No full throttle, no high RPMs! I've had several TRs on my dyno where I hadn't ensured beforehand that the system was correctly filled and bled. It doesn't take long before the air is forced into the engine block by the water pump at high RPMs! ... This has catastrophic consequences for the cooling system. There's a steam surge into the cooling system! That's not funny at all! Best Regards Ralf Quote
Z320 Posted Tuesday at 07:28 PM Report Posted Tuesday at 07:28 PM 9 hours ago, Schnippel said: Hello, I'm getting angry! Why? First, a forum in Germany is flooded with these completely wrong recommendations, and now here. In Germany, attempts were made to explain this to him objectively. Ineffective! A TR/Spitfire engine with an expansion tank next to the radiator must not have any air in the radiator, and certainly not in the area of the thermostat. The expansion tank, with the hard plastic pipe extending to the bottom, is half to three-quarters full of water. This man either can't or won't intellectually understand how the cooling system on a Triumph with an expansion tank works! Beautiful tests with digital displays are worthless. Why? No full throttle, no high RPMs! I've had several TRs on my dyno where I hadn't ensured beforehand that the system was correctly filled and bled. It doesn't take long before the air is forced into the engine block by the water pump at high RPMs! ... This has catastrophic consequences for the cooling system. There's a steam surge into the cooling system! That's not funny at all! Best Regards Ralf Hi Ralf, I expected your appearance earlier 😂 Quote
Z320 Posted 2 hours ago Report Posted 2 hours ago On 2/10/2026 at 10:41 AM, Schnippel said: Hello, I'm getting angry! Why? First, a forum in Germany is flooded with these completely wrong recommendations, and now here. In Germany, attempts were made to explain this to him objectively. Ineffective! A TR/Spitfire engine with an expansion tank next to the radiator must not have any air in the radiator, and certainly not in the area of the thermostat. The expansion tank, with the hard plastic pipe extending to the bottom, is half to three-quarters full of water. This man either can't or won't intellectually understand how the cooling system on a Triumph with an expansion tank works! Beautiful tests with digital displays are worthless. Why? No full throttle, no high RPMs! I've had several TRs on my dyno where I hadn't ensured beforehand that the system was correctly filled and bled. It doesn't take long before the air is forced into the engine block by the water pump at high RPMs! ... This has catastrophic consequences for the cooling system. There's a steam surge into the cooling system! That's not funny at all! Best Regards Ralf Come on Ralf, joking aside! Tell us more, please. Your explanation is a bit angry and "foggy". Very sure we can learn from each other, I give it a try again.... Where is the air in the cooling system on the running engine, if the system is not fully bleeded? Do you think a TR6 cooling system maintained to the workshop manual is fully bleeded? Does the engine in your opinion has heat problems, if not FULLY bleeded? OK, sorry, you blasted several customer engines on you dyno in your workshop because you did not bleed them correctly? What "catastrophic" happend with the cooling system? What damage was on the engine? How do you determine a steam surge in the engine? What rad cap was fitted (7 PSI, 13 PSI)? Ciao, Marco Quote
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