Bainzy Posted March 22, 2012 Share Posted March 22, 2012 From 1975 the standard thermostat for a Spitfire 1500 was 88 degrees C. I assumed my car had an 82c, so went to change it this evening to an 88. I was quite surprised to find an 88c one there already, made in West Germany (that makes it fairly old!).The car has an electric fan, full width radiator and a fan switch that cuts in at 90c and turns the fan off at 83c. The gauge sits at just under half way, and takes a while to climb up enough to turn the fan on (at a little under 3/4). The fan turns off quite quickly once in use as the temperature falls straight away once it's on.That all points towards having an 82c thermostat, but I've tested this 88c one and it works fine, opening slightly before temp at 85c and opening fully by 88c.Is there some sort of overcooling issue here then? Or should the thermostat only start to open at 88c?Whats even more amazing is that the thermostat was installed upside down, yet still keeps the car cooler than I expected, not hotter. Link to comment Share on other sites More sharing options...
Clive Posted March 22, 2012 Share Posted March 22, 2012 I would be VERY hesitant to rely on the temp gauge for any level of accuracy. By swapping gauges and senders I can get a reading from about 1/4 to 3/4, they are not calibrated to any degree of accuracy.However, I would use an 82, I believe they were the summer fitment, the idea was that you changed to an 88 over the winter. In reality, I have always run an 82 all year.Just having the thermostat fully open 5 degrees before the fan kicks in seems a bit of a small figure, OK this time of year but in the summer??However, if you are happy with it I would leave well alone. The old thermostat will no doubt give excellent service for many many years to come. Not so certain of your new one. Link to comment Share on other sites More sharing options...
ferny Posted March 22, 2012 Share Posted March 22, 2012 As Clive says, the gauge is just an indicator so I wouldn't rely on that. However, it sounds like your system is working great. The fan is coming on (so you know roughly where 90 is on your gauge) and going off quickly - so the rad is clear. If it were on all the time then I'd worry.I used to happily run a 92 thermostat all year. Link to comment Share on other sites More sharing options...
piman Posted March 22, 2012 Share Posted March 22, 2012 Hello Bainzy, "Or should the thermostat only start to open at 88c?"Yes that is correct and the spread until fully open is about 8 degrees, so fully open at about 96 degrees.Alec Link to comment Share on other sites More sharing options...
Bainzy Posted March 22, 2012 Author Share Posted March 22, 2012 Thanks for the input guys, started the car up today with a new 88c thermostat, absolutely no leaks despite using a rubbish thin card gasket. Looks like adding Loctite 5922 between each side is well worth doing, as it's done the job nicely (despite being an old tube and turning a bit rubbery).The gauge now sits where I would've expected it to for an 88c stat, so this confirms what Alec said, and shows the old one must have been opening earlier due to age/wear. Normal running temp has changed from 2mm under halfway, to 2-3mm over halfway. The electric fan never came on despite the switch for it being 2 degrees C higher than the stat rating, so the cooling system is obviously working exceptionally. The car warmed up noticeably quicker too. I think this may be also because the jiggle pin now works right - the way the old one was installed upside down, it would've been open during warmup because the thicker end of the jiggle pin was being pushed away from the stat, not pushed up into the stat's hole. From what I can gather, it's supposed to be pushed shut by the force of water pumping at startup so water doesn't circulate.I also managed to get the car to lean off a bit and still run smoothly, which will have benefits for fuel economy! Every little helps. Link to comment Share on other sites More sharing options...
2009poolesparky Posted March 22, 2012 Share Posted March 22, 2012 what is the purpose of the little jiggle pin? is it to stop any air locks? Link to comment Share on other sites More sharing options...
Bainzy Posted March 22, 2012 Author Share Posted March 22, 2012 As far as I know, yeh. Probably makes bleeding the system redundant, though I still always do it when refilling coolant just in case. Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 22, 2012 Share Posted March 22, 2012 the jiggle pin is purely to allow air escape, many stats on continous bleed cooling will not have one.the stat will continuously open an close (modulate) as cool coolant is returned back from the rad this process is continuous it doesnt just open and stay there , it will open close every few seconds , if you look down the filler you should see the ebb and flow across the top of the rad core . intrigued as to how it ever worked if it was fitted upside down, how would the hot water be detected ?? pete Link to comment Share on other sites More sharing options...
Bainzy Posted March 23, 2012 Author Share Posted March 23, 2012 Im guessing it was because it had a jiggle pin, which in the upside down position would allow water to flow around the thermostat and heat the wax? Or it wasnt seated perfectly, allowing a small amount of water to flow?Whatever the reason the fact that it still worked is pretty funny. ;D Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 23, 2012 Share Posted March 23, 2012 Ah you mean the jiggle pin was inverted , not the stat, thats more like it, the hole is just to bleed a little , its too small to have any effect on the overall operation of the cooling systemyou could remove the jiggler and it wont make any measureable difference, it may add some effect if the bypass tube under the manifold or its circuit has a block/restriction .Pete Link to comment Share on other sites More sharing options...
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