peejay4A Posted May 30, 2018 Report Share Posted May 30, 2018 (edited) Andy's right although strictly the original type was a sleeved thermostat, with a bellows because that was how they all were until the wax stat was born. Edited May 31, 2018 by peejay4A Quote Link to post Share on other sites
Z320 Posted May 31, 2018 Report Share Posted May 31, 2018 The bellows thermostat with skirt is a different story on the TR2-3A forum, I will continue writing there about my experience with different thermostats and water pump housings. Quote Link to post Share on other sites
DaveR Posted May 31, 2018 Report Share Posted May 31, 2018 The present thermostats lack the air bleed hole which can cause a build up of air. It's easy to drill a hole and then fit the hole clearing device from an old thermostat. Dave Quote Link to post Share on other sites
Z320 Posted May 31, 2018 Report Share Posted May 31, 2018 Sorry me, wax thermostats without "hole device" have a "bend" on the "valve plate", they are not 100% close for water flow, there is no need to do anything, they are also marked with tho nite "up", please take a closer look. Quote Link to post Share on other sites
stuart Posted May 31, 2018 Report Share Posted May 31, 2018 Just a thought - has it got the original bellows stat or a modern one? Fitting a modern one isn't a problem so long as you restrict the bi-pass hose. The bi-pass hose allows water to circulate around the engine when the thermostat is closed. When the stat opens the bellows occludes the bi-pass so the water goes through the rad (to get cooled) Without the bellows the flow to the bi-pass remains unrestricted so hot water then returns directly to the engine without being cooled. The trick is to restrict the bi-pass hose so only a limited flow goes through it. (or use a bellows stat) If you are overheating it is unlikely the radiator is the cause which if in good nick is going to have ample cooling capacity whether it's alloy or not! Again fitting a header tank won't improve cooling as such it just maintains the fluid level. Not applicable from TR4 on as they were fitted with a different size bypass so will run perfectly well with a normal thermostat and as stated do need a small breather hole to the top. Stuart. Quote Link to post Share on other sites
Andy Moltu Posted May 31, 2018 Report Share Posted May 31, 2018 Indeed Stuart - for some reason I thought I was in the 4/4A forum. so ignore bellows and bi-pass! The stat should have a hole (usually with a jiggle pin in) to allow air to bleed when filling. The fact that the top of the rad is just below the top of the engine isn't a major issue. If a 6 is overheating then something is wrong and alterations to the plumbing of the cooling system are not the right solution. Quote Link to post Share on other sites
Z320 Posted May 31, 2018 Report Share Posted May 31, 2018 (edited) Stuart, thank you for that post. I will report as soon I have some time free for that. Edited June 1, 2018 by Z320 Quote Link to post Share on other sites
Z320 Posted June 9, 2018 Report Share Posted June 9, 2018 (edited) Hi, this is the story. I own my TR4A since 2009, it came with a 74°C wax thermostat (realized that 2015), no overflow bottle and no cooling problems at all. The overflow bottle I added 2010, but with enough air in the radiator I never needed it. I’ve been often told about air trapped in the thermostat housing and radiator hose, because they are higher than the radiator cap. I did not worry that because I know there MUST be air in the system to be compressed by the expanding coolant. In 2013 I fitted a clear PVC hose between the thermostat housing and radiator and found the standard water pump what I expected – not a toy but a MONSTER. It is located under the water line and smashes coolant into the engine, cylinder head and the radiator. The air plays no rule at all, already on idle revs it’s mixed under and pumped with the coolant. I show this video on Youtube since 2015, but I think it’s often been misunderstood. So I currently modified its comment. https://youtu.be/7Zw4Mj1JbVM With the thermostat closed the mix of coolant and air runs the bypass. This video is from 2017. Do not drive with PVC hoses, they don’t like heat and pressure! You see that on the end of the video. https://youtu.be/QilvpzpuDCo If you look at both videos you maybe ask yourself about the sense of the air bleed valve in the thermostat? I do not know what it’s for. In 2017 I’ve been told the first time about the bellows thermostat with skirt, the “modern” wax thermostat (which is not real modern today) and needed limitations of the bypass flow. I found a wax thermostat 74°C fitted on my TR4A and not limitation on the bypass, bought a 71°C bellows with skirt and was total disappointed, see here, post 49. https://www.tr-register.co.uk/forums/index.php?/topic/39676-thermostat/page-3 I decided to have a closer look on the cooling system and wanted to fit an expansion bottle (not an overflow bottle) in the closed coolant system – as on modern cars, where the radiator is a different construction and out of reach under plastic and sheet steel. That works like this: divide a minimum of coolant (and air), guide it fast through a tight hose to the expansion bottle, slow it down there to get the air out and guide only coolant back to the system by a wide hose. My idea was: the water pump can pump coolant-air mixture through the radiator – so it can pump the air anywhere – and the expansion bottle can be set anywhere! Set lower than the radiator cap the air will rise up again to the thermostat housing when I switch off the engine. So I can use the original radiator cap as usual and the expansion bottle is “hidden”. Expacting this, I did it that way and it works lovely. After driving a short distance, about 5 – 15 miles (depends on revs and temperature), all the air is collected in the lower set expansion bottle, compressed to about 0,7 liter. When I stop the engine all the air is back to the thermostat housing after about 20 seconds. If I close a 1/8” ball valve in the upper hose I go on driving with all the air back in the circuit. By the installed thermometers I realize no difference at all in cooling by driving with air bleeded in the expansion bottle or with all air in the water circuit. Believe it or not. Ciao Marco Edited June 9, 2018 by Z320 Quote Link to post Share on other sites
Waldi Posted June 9, 2018 Report Share Posted June 9, 2018 Hi Marco, Thanks for sharing, niice testing you did. Waldi Quote Link to post Share on other sites
Rem18 Posted June 9, 2018 Report Share Posted June 9, 2018 Well done...I believe it. Years of hard driving in the Alps in Italy in my 5, no electric fan and just standard cooling except for an oil cooler(as I like the idea of cooler oil) and no overheating whatsoever although in traffic it goes from 1/3 to 2/3 on temp gauge. I even by accident drove her through town traffic without water in the radiator and although temp shot up no damage was done I think thanks to oil rad. IMHO people who have problems have them because their car doesnt not have an efficient system. How else can you explain it. For interesting for me would be to find a way to stop heat coming in through the floor as after a hard days driving I am dying!! Quote Link to post Share on other sites
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