Bowie69 Posted January 19, 2012 Share Posted January 19, 2012 I'm not on about motor manufacturers..... The x-eng switch is specifically designed to go in the bottom hose. Sigh Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 19, 2012 Share Posted January 19, 2012 I'm not on about motor manufactures..... The x-eng switch is specifically designed to go in the bottom hose. Sigh Here you go! Quote Link to comment Share on other sites More sharing options...
Challo Posted January 19, 2012 Share Posted January 19, 2012 Wow it's like 'play your cards right' with Bruce Forsyth! Top, middle or bottom? Lovin it. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 19, 2012 Share Posted January 19, 2012 Thanks Ross Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 19, 2012 Share Posted January 19, 2012 Thanks Ross You obviously haven't followed the instructions if you are still able to type Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted January 19, 2012 Share Posted January 19, 2012 Surely it would be the bottom hose as the fan should only cut in if the rad is not capable of cooling the water enough by air through flow without forced assistance. This is pretty much it actually, imagine having a bloomin HUGE rad, say 3 times the capacity, there would be no need to run the fans just because coolant temps coming out of the engine were at 95C (where for efficiency manufacturers like to operate at or above nowadays) if the outlet from the radiator is down at 60C -the radiator is more than capable of cooling this by itself, with no fan assistance. If a radiator is smaller (like most vehicles) and the temperature at the outlet of the radiator is approaching the running temperature of the engine, this is when the fan needs to switch on. Basing the switching temp on the outlet of the engine is actually assuming the radiator will not cool the water sufficiently by itself, which it may.... From X-Eng's site: 'The thermostatic switch insert we supply is designed to switch one fan on at 88 degrees C and off at 83 and the other on at 92 and off at 87 which is about right for most vehicles.' So as you can see, the switch is rated to realitvely low temperatures, 92 is only just above the running temperature of the engine, but would probably equate to an engine outlet temp of around 105C or so. 88 is the normal stat opening temperature of most LR products (more modern coilers at least) so if you fitted it in the top hose the moment your stat opens your fan would start running -not good! Anyways, I hope all is clear now Ross - sorry, last post I promise you s3ndy -good luck with your project Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted January 19, 2012 Share Posted January 19, 2012 I think I might have started this fight. Top hose or bottom hose entirely depends on how well your thermostat does at controlling your engine temperature. Imagine, just for a moment, the enormous radiator mentioned in the post above - something with an infinite cooling capacity. You'll always have cold water going back into your engine. How does your engine stay warm in this case? Your thermostat. By varying the flow into the radiator, the 'stat varys the amount of cold water entering the engine, and hence keeps the engine at the correct running temperature. They are not open/closed. They are variable. Now consider that you have a smaller radiator - you'll need something on it to ensure that it is cooling as it should. This is the temperature switch in the bottom hose. The thermostat is still controlling the engine temperature, but the fans are ensuring that the thermostat has a constant supply of cold water with which to cool it. My case is a little special - I have a radiator that's too small for an engine that will produce a lot of heat. While running, the thermostat is almost always fully open. So I need a faster response to rapid rises in temperature - hence why I have my switch in the top hose. With my new engine (diesel) I'll be fitting it in the bottom hose. I see this a lot with the large marine diesels that I work with. The engine temperature is controlled by recirculating hot water from the engine outlet to the engine inlet via a 3 way valve - the quantity of which is dependent on a temperature sensor in the engine outlet (and a whole load of other factors too...but let's not go there). Cooling water is supplied at constant temperature from the coolers - driven by another control system to ensure that the returning cold water is always at 30 (ish) degrees. High load means more flow to the coolers and less recirculation. In fact, several engines are operated from one set of coolers like this. This is analogous to our thermostat and fan - and I hope you can see how the control systems on both the engine (thermostat) and radiator (fan switch) work together to stabilise the engine temperature, and why it's almost always correct to have the switch in the bottom hose. Quote Link to comment Share on other sites More sharing options...
p76rangie Posted January 19, 2012 Share Posted January 19, 2012 You only need the fans at a temp above when the thermostat is fully open. So any discussion about the thermostat and position of the fan switch is largely irrelevant. The people above appear to believe that a motor generates the same amount of heat whether it is at idle or pulling 4 ton up a hill. Any logic will tell you that this is not true. So if the coolant is going into the engine at idle at 85C it will come out only slightly hotter. If I am pulling 4 ton up a hill the coolant will come out a lot hotter. So if you have your fans switching on based on the temp the coolant is going into the motor the fans will switch on when the top of the motor is quite cool at idle when you don't need them on and may not switch on when the thing is under heavy load when you need the motor's temp under control. It is the top end of the motor (heads, etc) that are more prone to issues with heat. Too much heat in the top also affects fuel economy, power, etc. This is why all your temp sensors are in the top of the motor. Having the temp sensor in the bottom radiator hose will not, and cannot, control the temp in the top end of your engine as well as one place near the coolant outlet of the engine. But then again every car manufacturer in the world could be wrong and you guys could be right. Quote Link to comment Share on other sites More sharing options...
sussex-landy Posted January 19, 2012 Share Posted January 19, 2012 I have the same setup but pulled the probe out of teh top hose in the end as i couldnt stop it dripping which was annoying even with two tight jubilee clips. Any tips on safe sealant to stop this and does it need to set first. Quote Link to comment Share on other sites More sharing options...
SPendrey Posted January 19, 2012 Share Posted January 19, 2012 I had this problem when installing mine, and found that Vallance All-Weather Sealant (now EvoStick I think?) plastered over the radiator inlet bunched up nicely as I pushed the hose on. This created a good seal, and will peel off if I need to do any work. Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted January 19, 2012 Share Posted January 19, 2012 You only need the fans at a temp above when the thermostat is fully open. So any discussion about the thermostat and position of the fan switch is largely irrelevant. Having the temp sensor in the bottom radiator hose will not, and cannot, control the temp in the top end of your engine as well as one place near the coolant outlet of the engine. But then again every car manufacturer in the world could be wrong and you guys could be right. Not true. Imagine a perfectly working radiator with a 70 mph breeze going through it. Engine working hard, 'stat fully open. Cold water will be coming out the bottom of the radiator, fans off, everything in control. Good. Now imagine the same engine doing the same amount of work with the 'stat fully open - in a mud caked radiator, in an offroader stuck in a bog. Radiator will be doing nothing = hot water out the bottom of the radiator. Fans come on to aid the radiator in cooling the water. I think you are missing the point here - the fan switch does not control your engine temperature. The thermostat does. And I think you'll find that the fan switches in most cars are actually in the bottom hose or return to the engine. On the BMW rad I'm using, the original fan switch is in the cold side of the rad. The temperature sender(s) is in the top hose yes - but this doesn't (always) control the fans. Quote Link to comment Share on other sites More sharing options...
Tanuki Posted January 19, 2012 Share Posted January 19, 2012 Look at pretty much any vehicle with an electric fan as standard: the sensor is in the outlet-side of the radiator. Same goes for the big half-Megawatt Rolls-Royce turbodiesels I work with professionally. Forget how hot the water is when it comes out of the heads - provided the radiator's cooling it adequately [to maintain a bulk-coolant/overall block-temperature around 90-95 Centigrade] you're doing just fine. Same goes for oil temperature: on the big diesels we look for an oil temp between 95 and 150 Centigrade. A hot engine is an efficient and long-lived engine. I'm talking here of engines which run for months at 85% of their rated-horsepower. And we even do on-the-fly oil-changes on them at this load without shutting them down . . Must admit though, when we crash-start them from cold and hit them with 70% load within 5 seconds I get a little bit nervous. Never had one fail - if it does we get a free replacement - that's the sort of product-confidence I like. --Tanuki. " The last Tormentor General was one Thomas Bainbridge, appointed to the post by Oliver Cromwell in 1642. With his creative punishments he played a major part in the Massacre of Drogheda in 1649 but on the restoration of the Monarchy in 1661 Bainbridge was arrested, found guilty of high treason, and executed by being lowered head-first into a barrel of toads". Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 19, 2012 Share Posted January 19, 2012 I like the idea of on the fly oil changes! How do you do that without killing them? What do you use the engines for? Quote Link to comment Share on other sites More sharing options...
Tanuki Posted January 19, 2012 Share Posted January 19, 2012 I like the idea of on the fly oil changes! How do you do that without killing them? What do you use the engines for? The big RR diesels are used for generators in locations where the 'local' power just can't be trusted. Oil-changes are arranged by taking a sample of the oil every week and sending it to the testing-lab; within a couple of days they analyse it and tell us what the level of metallic contamination/reserves of the various protecting-agents in the oil are. They keep a history and can forward-project the time to the optimum change date. Changing the oil on-the-fly involves a set of new oil-filters, two tanks, and a pair of 2-way valves. When the engine-tech pulls the levers basically the engine's scavenge oil-pump pumps the old oil out of the engine - when the oil-pressure has dropped to zero for a few seconds he hits the valves that connect the pump intake to the 'fresh' oil-tank and does the same with the valves that switch the old and new oil-filters. For a short period the old and new oil filters are running in series - then when we have full pressure with the 'new' oil we bypass the old oil-filter and switch to the new one. Then they take out the old oil-filters and fit new ones in readiness for the next changeover. The old oil filters are sent away to the labs and analysed for any bits of 'shrapnel' that could hint at a future bearing/piston-ring failure. --Tanuki. Is it reality? or is it Prozac? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted January 19, 2012 Share Posted January 19, 2012 Very similar to my profession - biggest I've worked with is 10MW, never RR though. The big ones tend to drive propellers rather than generators in my industry though Quote Link to comment Share on other sites More sharing options...
landroversforever Posted January 19, 2012 Share Posted January 19, 2012 The big RR diesels are used for generators in locations where the 'local' power just can't be trusted. Oil-changes are arranged by taking a sample of the oil every week and sending it to the testing-lab; within a couple of days they analyse it and tell us what the level of metallic contamination/reserves of the various protecting-agents in the oil are. They keep a history and can forward-project the time to the optimum change date. Changing the oil on-the-fly involves a set of new oil-filters, two tanks, and a pair of 2-way valves. When the engine-tech pulls the levers basically the engine's scavenge oil-pump pumps the old oil out of the engine - when the oil-pressure has dropped to zero for a few seconds he hits the valves that connect the pump intake to the 'fresh' oil-tank and does the same with the valves that switch the old and new oil-filters. For a short period the old and new oil filters are running in series - then when we have full pressure with the 'new' oil we bypass the old oil-filter and switch to the new one. Then they take out the old oil-filters and fit new ones in readiness for the next changeover. The old oil filters are sent away to the labs and analysed for any bits of 'shrapnel' that could hint at a future bearing/piston-ring failure. --Tanuki. Is it reality? or is it Prozac? Thats pretty cool Quote Link to comment Share on other sites More sharing options...
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