Clive Posted April 30, 2018 Report Share Posted April 30, 2018 I want to add a fan switch to the bottom hose of the Lady wife's spitfire. Not interested in the kenlowe type adjustable ones for s few reasons and past experiences, nut I intend using a hose adaptor and modern type switch. However, I need to know what temp the water flowing out the rad is likely to be. The thermostat is an 82, though 88 is the recommended winter one (but nobody changes them. OK, maybe a few people) so a sender in the top would be simple, maybe 92-95 on. But it is hard/impossible to find much data about temps leaving the rad. Anybody got any clues? I would guess, purely a guess, that temp drops about 10 degrees (at normal running etc) Anybody got any info? I may just experiment with some of the lower temp fan switches I have here, once I find them in the depths of the garage, but clues would help. Ta Link to comment Share on other sites More sharing options...
JohnD Posted April 30, 2018 Report Share Posted April 30, 2018 Clive, When you say you don't want a Kenlowe adjustable one, do you not want any adjustment at all? Most fan thermostats are adjustable, and with good reason. Once the coolant thermostat opens, the engine temp depends on the heat it generates and the hea that the radiator can dispose of. That depends on air flow through the matrix, a functin of road speed or fan speed (or on/off) So mnay variables that some adjustability is desirable, so that you cabn set the fan to come on at an appropriate level. Guessing and fitting a fixed temperature switch - if that it what you intend - would be just that, gueswork. JOhn Link to comment Share on other sites More sharing options...
Clive Posted April 30, 2018 Author Report Share Posted April 30, 2018 John, I want to fit a modern type one, no capillary tubes sticking through hoses etc. So yes, fixed, like oem rather than the aftermarket type. Really I am more interested in what the water temp is coming out the rad, sadly the IR thermometer I could borrow is tricky to access at the moment, and I thought somebody on here may know.....or at least have some general data. Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 30, 2018 Report Share Posted April 30, 2018 in old school the outlet was 20c lower than the input , you dont want to keep poking cold water into a hot block . 1 1 Link to comment Share on other sites More sharing options...
Clive Posted April 30, 2018 Author Report Share Posted April 30, 2018 Cheers Pete. I was thinking 10c but that isn't a lot. I will try a mid 80s switch, off at 80 and see how it goes. Link to comment Share on other sites More sharing options...
rogerguzzi Posted April 30, 2018 Report Share Posted April 30, 2018 Hello Clive I have a Intermotor 50101 fitted in the bottom of the radiator it is a dual contact type because I fitted 2 fans The range is 83-79 / 88-83 deg C I tried a 50091 88-83 / 92-87 and the engine was far to hot! I find with this the the fan cuts in when the radiator is nice and hot and temperature gauge it just above mid way and checking with the cheap infra red thermometer radiator top is about 85 ish degs The second fan never cuts in I just sometimes turn it on when stuck in traffic in Spain and it is 25 deg + outside This list will help you choose Part No. Temp °C 50100 82-68 50101 84-79/88-83 50250 86-76 50012 86-77 50090 86-81 50120 88-79 50091 88-83 / 92-87 50296 88-79/110-102 50271 88-83 50217 88-83/92-87 50240 90-80 50113 92-82/95-80 50170 92-87 50215 92-87/97-92 50011 93-88 50102 93-88/97-92 50035 95-85/102-92 50130 95-86 50030 95-90 50092 95-90/100-95 50104 97-92 50103 97-92/101-96 50214 97-92/102-97 50190 100-95 50198 100-95/110-105 50000 103-98 50191 120-115 Roger ps I have it wired so the fan in front of the ITB,s and exhaust comes on first the reasoning is that it help cool the exhaust etc as 83 is a lot lower the the exhaust temperature! Link to comment Share on other sites More sharing options...
JohnD Posted April 30, 2018 Report Share Posted April 30, 2018 Lots of these about, Clive, not just this example page from eBay: https://www.ebay.co.uk/i/222698715960?chn=ps&adgroupid=43920634520&rlsatarget=pla-359427365517&abcId=1063846&adtype=pla&merchantid=113115306&poi=&googleloc=1006854&device=c&campaignid=797602469&crdt=0 JOhn Link to comment Share on other sites More sharing options...
dave.vitesse Posted April 30, 2018 Report Share Posted April 30, 2018 Clive, Moss and TR Revington have adaptor for the down pipe. And I would guess do some of the other classic car parts suppliers. These will take the standard screw in sensor switch. But as the current rating of the sensor switch is to low you will need a relay to switch the fan(s). Dave Link to comment Share on other sites More sharing options...
Clive Posted April 30, 2018 Author Report Share Posted April 30, 2018 Roger, that is just what I needed to hear. Something that switches on at 83-85 will do the trick nicely by the sounds of it. Dave, the existing wiring is all there, so pretty easy once the new rad arrives. The existing rad appears to have tubes made from fag-paper thick copper, and has literally blown a hole in a couple, I have lost faith in it and a new one is on the way. The existing setup has a sender hole in the top tank, but I don't like it as it appears too high and a fair chance it could be above the water sometimes. Bottom hose seems a better idea and means it can all be fitted with no more off the road time. John, I am making something similar if I cant find the one I have, but with a std M22 thread. Those ebay ones are as cheap as chips, just a fair wait. But I want to get it all done this Saturday, Gill wants to actually get a chance to drive the car, it has been a long slog to get it ship-shape and now almost there! 1 Link to comment Share on other sites More sharing options...
JohnD Posted April 30, 2018 Report Share Posted April 30, 2018 Clive, if you want something doing properly,....... Butif you wnat it quickly, they have it in stock: https://www.carbuildersolutions.com/uk/aluminium-modular-inline-housing-32mm also for 38mm hose, al;reda taped for M22 sensor. John Link to comment Share on other sites More sharing options...
Clive Posted April 30, 2018 Author Report Share Posted April 30, 2018 John, I have all the bits to make one up, and somewhere I have, or had, one already made. Not seen it in a few years though, might need to have a rummage. I have ordered the same sensor as Roger uses, picked one up for a mere £7.50 as the selection I have are all 90degree plus. Hopefully everything will be here by the weekend, and I will even get the heater working (somebody has fitted the 2 heater hoses to the T at the end of the under manifold pipe, no other connections there at all. No surprise no water flows!!total dead end) Guess it will get an oil change, and as it is suposed to be a 120bhp 1300 (roller rockers, the lot) it ought to have a decent oil.....Millers CSS 20 60 could find its way in. Link to comment Share on other sites More sharing options...
rogerguzzi Posted April 30, 2018 Report Share Posted April 30, 2018 Hello All I think the only place they should be fitted is in the bottom of the radiator or bottom hose as you want the whole radiator hot ish to aid efficiency but just cool enough from bottom to stop engine over heating. That,s how all modern seem to be! Roger Link to comment Share on other sites More sharing options...
Anglefire Posted April 30, 2018 Report Share Posted April 30, 2018 Umm. As a controls engineer, I would say the sensor should be in the top - as you are trying to maintain the temperature of the engine and not the temperature of the water off the radiator. If you maintain the water temperature you are not taking into account the engine load - a constant 75 (say) back to the block may result in a off block temperature under half load conditions of 90 - but full load could be 95. By using the off block temperature, you are reacting to the engine load a lot faster. However, the thermostat will also effect things so in effect that is controlling the off temperature by altering the water volume through the rad - but once above a certain temperature does nothing. Link to comment Share on other sites More sharing options...
Guest Posted April 30, 2018 Report Share Posted April 30, 2018 Hello Mark. I've looked at this scenario over & over again and read varying info numerous times from informed sources, yours included. My Vitesse has an inline temp sensor unit in the top hose and the Alpine has the temp sensor mounted at the bottom of the rad - both operate a single fan. Both work perfectly when demand or override is required and both cut out when the temp has been reduced to the acceptable level. As such I cannot say if one set-up is more efficient than the other as both do exactly and deliver what I want - which is heat reduction asap. Both systems remain on if required after the engine has been turned off. For years I was always in the "sensor bottom hose" brigade as that seemed to be the most logical placement. I think these days it is a case of where the fitting fits best and as such you are in either one camp or the other. If it works and does the required job - that is good enough for me. Clive - I have a spare aluminium inline unit if required and can bring on Wednesday ?? Regards. Richard. Link to comment Share on other sites More sharing options...
Anglefire Posted May 1, 2018 Report Share Posted May 1, 2018 Richard, yes it will work - it will just take a little longer to react as the water has to go through the rad before the change in temperature is registered. And that time might be quite small. And it may well be that due to the differential band of the switches that it ultimately doesn't matter - theoretically at least, the differential in the switch located in the bottom hose can be smaller than the one in the top hose - but that also probably doesn't matter either! The only issue I have in the bottom hose location is that you are controlling the temperature back to the block and not the temperature of the engine. I say issue - bit of a strong word - question mark - but ultimately the switch goes where ever it fits best. Link to comment Share on other sites More sharing options...
Clive Posted May 1, 2018 Author Report Share Posted May 1, 2018 I "think" theoretically the top is best, but an added sensor of the Triumph rad just looks too high to me. And as there are so many variables it did come down to ease of fitment, there being no room in the top hose, and at teh bottom it WILL always be in water. I guess temp changes in the block are not fast, so as long as the bottom sensor is correctly chosen, all will be well. Richard, it would be handy if the spare hose adaptor is available, in case anything happens to my cunning plan! I shall be there, hopefully with a hot-off-the-press MoT on the yellow spit, if not the Toledo.... Turned into a useful technical discussion! 1 Link to comment Share on other sites More sharing options...
rogerguzzi Posted May 1, 2018 Report Share Posted May 1, 2018 Hello All I will throw my hat in the ring first! I do not disagree with Mark as he is cleverer than me in this area, But I still think the bottom /outlet is the best place as long as the thermostat is the correct range(lower) The way I see it if the system is clean and and pump is good the mechanical thermostat controls the engine temperature as long as the water entering the bottom is lower! We are talking about a big cast iron lump not a modern Aluminium lump with not much water in it! I converted to a full width radiator and the sensor is in the bottom tank opposite end to the outlet which if you look at the vertical tubes is under the inlet so one assumes hot water taking the path of least resistance will get here first! We have been to Spain twice and Italy once and I can honestly say the fan does not cut in while on the move (25/30 deg C) and even when sitting in traffic it cuts in and out and second one has never come on on its own I often sit in traffic and can hear all the moderns fans running! It was cold water thermal shock which I am lead to believe was the problem with the MGF (ie radiator in the front and engine in the back) so it tended to get very cold water entering a very hot engine as the hoses are long so all though the thermostat opened ok the water was to cold. Roger ps if the sensor is at the top it would turn the fan on based on top tank temperature(unless much higher) and the bottom would be stone cold! not good for a engine or thermal efficiency plus we need to get the oil up to temperature as well! as this knackers engines. just my two penth! Link to comment Share on other sites More sharing options...
Anglefire Posted May 1, 2018 Report Share Posted May 1, 2018 To be fair Roger, I'm probably overthinking it - given, as you say, that the thermostat is the primary cooling control, the fans are merely a secondary help, then bottom hose is probably suitable. As for moderns running the fans a lot, that may well be due to the air con demand rather than engine cooling requirements - the Disco I had had a viscous fan with effectively an electrical supply (heater I think) that could be turned on (Modulated actually) to tighten the viscous element to make the fan draw more air through and that was largely controlled by the AC system. Link to comment Share on other sites More sharing options...
rogerguzzi Posted May 1, 2018 Report Share Posted May 1, 2018 22 minutes ago, Anglefire said: To be fair Roger, I'm probably overthinking it - given, as you say, that the thermostat is the primary cooling control, the fans are merely a secondary help, then bottom hose is probably suitable. Hello Mark That is the problem with ALL engineers etc (been there done it and got the T shirt many times!) Roger 1 Link to comment Share on other sites More sharing options...
NonMember Posted May 1, 2018 Report Share Posted May 1, 2018 1 hour ago, rogerguzzi said: Hello Mark That is the problem with ALL engineers etc (been there done it and got the T shirt many times!) Roger Well, indeed. And being an engineer myself (motorsport software but with a road car background) I have over-thought it enough to arrive at the opposite conclusion from Mark Like he said in his last post, the primary control of the engine temperature is by the thermostat, which works well if the "actuator" it's using has a consistent efficacy. Since it uses the bottom hose water as its "actuator", the efficacy depends on the bottom hose temperature, so the role of the fan is to maintain that at a good level. Hence the thermoswitch should be in the bottom hose. Most modern cars actually use the temperature of the coolant in the engine but that's just for cost reasons. The ECU needs to know that temperature for Very Important Stuff (relating to emissions) and a fan driver in the ECU is a lot cheaper than a second sensor. Link to comment Share on other sites More sharing options...
dougbgt6 Posted May 1, 2018 Report Share Posted May 1, 2018 I thought the primary, initial purpose of the thermostat was to get the engine up to temperature as quickly as possible, thereafter it maintains that temperature, hopefully, between certain limits. If the thermostat is in the bottom hose there's a great deal more water to get hot before the thermostat actuates. With the thermostat closed the pump is pushing water around the block and head but the radiator water is static so what temperature is the head going to reach before the bottom of the radiator gets hot?!! I'm a great believer in leaving things, most of the time, how Triumph designed them. Doug Link to comment Share on other sites More sharing options...
Guest Posted May 1, 2018 Report Share Posted May 1, 2018 Doug. I think there is some confusion about thermostats and thermal switches. The thread is looking at the pros and cons of a thermal switch in the top or bottom hose; with the current mechanical thermostat position is agreed. That is how I am reading it at the moment. Congrats on your AO posting, by the way !! Regards. Richard. Link to comment Share on other sites More sharing options...
dougbgt6 Posted May 1, 2018 Report Share Posted May 1, 2018 Richard, OK I'm confused, as normal I'll get my coat. Thanks! Doug Link to comment Share on other sites More sharing options...
Guest Posted May 1, 2018 Report Share Posted May 1, 2018 Not confused, Doug, you are just thinking outside the box - a hidden talent held by few !! Regards. Richard. Link to comment Share on other sites More sharing options...
rogerguzzi Posted May 1, 2018 Report Share Posted May 1, 2018 1 hour ago, dougbgt6 said: I thought the primary, initial purpose of the thermostat was to get the engine up to temperature as quickly as possible, thereafter it maintains that temperature, hopefully, between certain limits. If the thermostat is in the bottom hose there's a great deal more water to get hot before the thermostat actuates. With the thermostat closed the pump is pushing water around the block and head but the radiator water is static so what temperature is the head going to reach before the bottom of the radiator gets hot?!! I'm a great believer in leaving things, most of the time, how Triumph designed them. Doug Hello Doug It is the fan thermostat that is in the bottom hose the rest is as Triumph designed it. I just saves a few BHP and cools the radiator when needed(Traffic) Roger 1 Link to comment Share on other sites More sharing options...
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