Aragorn Posted December 21, 2009 Share Posted December 21, 2009 I've been wondering about this, with winter here and many posts on various forums about their landrovers taking ages to heat up in the cold weather. It was my understanding that when starting the engine, the only water thats being circulated is the stuff immediately round the block/head and the stuff in the heater matrix... The thermostat would be closed, stopping the radiator making any difference to the engine temperature. So barring the slightly colder starting temperature of the water/block, why should the engine take longer to heat up? Surely the stat stays closed, and the engine heats up in pretty much the same time as normal, obviously it'll take a tiny bit longer as its heating the water from 0c rather than say 10c? I've seen people suggest removing the viscous fan, or checking its not siezed, but again, even if the fan was running at full bore, the stat should simply close and hold the engine at 90c or whatever its setpoint is? Is there something else at play? Or is it just that there are tonnes of vehicles with slightly dodgy stats? Or perhaps the engines taking the same time as normal to heat up, but the desire for heat in the cabin is greater so it changes the perception of the warmup time? I know i havent noticed any difference in the A4's warm up time, and the disco is currently in bits so i cant say i've tested that either. Kev Quote Link to comment Share on other sites More sharing options...
reb78 Posted December 21, 2009 Share Posted December 21, 2009 I keep wondering this. Maybe its that massive expanse of air around the engine in the land rover (and most older cars) unlike the modern ones cocooned in their soundproofed insulated engine bays? All that freezing metal and cold air wooshing around a fairly vast engine bay (in comparison to modern cars) might explain it. I put a sheet of card across the front of my tdi 110 the other morning - it hasnt made any difference to warm up time and only really makes the temp go higher when you want it to cool. Guess my thermostat is working properly! Quote Link to comment Share on other sites More sharing options...
David Sparkes Posted December 21, 2009 Share Posted December 21, 2009 You have to distinguish between the more modern cars you run and have hands-on experience with, and the large estate of older Land Rovers, with engine installations designed before you knew one end of a screwdriver from the other. :-) Note I mean year of design, not year of build. The design that made the heater matrix the only bypass circuit when the thermostat is closed is modern, in this context. This is also associated with air blend heating systems, where air temperature is controlled by blending heated and unheated air. Older engine designs had a bypass circuit built into the engine, so it didn't matter if the heater was on or off. This means that even when coolant is flowing through the heater matrix, it is not the full flow because some coolant is also flowing through the bypass circuit. There is a side effect of this, because of the reduced flow through the heater matrix it's easier for any solids in the coolant (rust or foundry sand) to drop out of the coolant and gradually silt up the small bore pipes in the matrix. This of course reduces the heater output available. There's more. As emission regulations come to the fore there is a stronger requirement for the engine to warm up faster. Part of the design approach to achieve this is to reduce the amount of coolant flowing when the thermostat is closed. To do this and avoid hot spots in the cylinder head requires the coolant to flow rapidly round the system, so it never stays in one place long enough to overheat. As the heater matrix is now part of this circuit there is a need to minimise flow restriction, so the matrix tubes are designed with larger internal cross sectional area. The combination of the continuous flow, plus the faster flow, plus the larger tubes, means silting is less likely to take place. Thus modern designed heaters are more efficient than older designed heaters, even though the modern design may be 10 years old. HTH Quote Link to comment Share on other sites More sharing options...
BogMonster Posted December 21, 2009 Share Posted December 21, 2009 There are a lot of 300Tdi engines whose thermostats are working but not working 100% properly - if you change the stat you usually notice an improvement. At one stage I used to change mine annually - it's an easy job and only costs a fiver. I don't use the 110 as a daily drive so don't bother now. I think the reality is that the Tdi engines are just extremely efficient - witness the MPG you get out of a two tonne car which is usually as good as or better than most of the whizzy new common rail engines pushing something similarly heavy. If you have a 300Tdi and park it in a garage or other shelter (no airflow through the rad) with the heater on full, the temp drops away in no time - simply because the engine is putting almost no heat into the radiator at idle or low revs and the 2 kw or whatever the vehicle heater puts out, takes all the heat out of the coolant in no time at all. Even with the heater on normal speed it only takes a few minutes for the gauge to drop away into the cold. I think the bypass "jiggle pin" in the thermostat probably doesn't help either - but as already said there is a lot of cold air around the engine. Warmup time is more or less related to EGT which is related to engine load - if you have an EGT gauge fitted and potter around town you'll be lucky to get north of 200 degrees for very long and it will take forever to get up to temp, whereas on the open road 500-600 degrees is more like the average EGT so the engine warms up 3x as fast. Quote Link to comment Share on other sites More sharing options...
Bull Bar Cowboy Posted December 21, 2009 Share Posted December 21, 2009 I've been wondering about this, with winter here and many posts on various forums about their landrovers taking ages to heat up in the cold weather. I know i havent noticed any difference in the A4's warm up time, and the disco is currently in bits so i cant say i've tested that either. Kev Well, I can assure that your A4 will take longer to warm up when the ambient temperature of the coolant is 0C than when it is at ambient 20C in the summer……… unless of course you have some magical power that defies the laws of physics…. I have noticed that both the Volvo and the Jeep take a few miles longer to get up to temp in this colder weather………..but the Volvo is slightly quicker as it has a more compact engine bay and electric fans………… One of the biggest issues with WAX stat type thermostats as used in older LR’s is hysteresis …………. Couple that with a miniature aeroplane propeller (viscous fan) continually forcing very cold air across the face of the engine and it will definitely take longer to come up to stat temp (if ever) ………… then the stat opens and f’off cold coolant is immediately circulated within the block, but the stat doesn’t close immediately due to hysteresis …………. and so the cycle continues……….. Quote Link to comment Share on other sites More sharing options...
Aragorn Posted December 21, 2009 Author Share Posted December 21, 2009 Some interesting points! I think bogmonster has hit on a good point with EGT's and Engine load, and the thermal output of a diesel motor. Both the A4 and the Disco are petrol, so tend to run much hotter anyway. You'd only really notice the time a diesel takes to warm up in the winter because your freezing and want some heat in the cab. Thinking about it, my dads old transit would take a good 10mins to come up to temperature, but you only noticed it in the winter, as you couldnt see out the windscreen and your fingers were numb If its icy etc your perhaps also likely to be driving slower, further reducing the thermal output. BBC: I know it will take longer, but not longer by enough that i'm starting to think "whats going on here its taking ages to warm up". A few miles down the road and the temp needle is off its stop and the heaters are starting to emit hot air. Given bogmonsters point, are your Volvo and Jeep diesel or petrol? It does mean though, that assuming the stat is in good working order, that removing the viscous fan or fitting a radiator muff will make very minimal differences to the warm up time, and changing the stat would be a better option if you think your motors taking a while to warm up? Quote Link to comment Share on other sites More sharing options...
Quagmire Posted December 21, 2009 Share Posted December 21, 2009 On mine i stick the rad muff on the front- although i leave the flap open otherwise it gets too hot on the motorway at cruise when up to temp. I find that reducing the amount of cold air that can whistle through the engine bay allows my 3.5 to warm up almost (but not quite) as quickly as normal. Normally takes around 5 miles in this weather, and i have an electric fan. I always cold start on LPG and have done so for about a two years with no probs, until today... -6deg and no warmup = frozen vap unit Quote Link to comment Share on other sites More sharing options...
BogMonster Posted December 21, 2009 Share Posted December 21, 2009 Petrol engines do warm up quicker but most Jap diesels are far better than LR - my Ranger has a nuclear heater that puts any Land Rover to shame and that is only a naturally asthmatic 2.9 diesel. My V8 Discovery has a good heater though just a lot of cash to pay for hot air Quote Link to comment Share on other sites More sharing options...
western Posted December 21, 2009 Share Posted December 21, 2009 my 200tdi is warmed up after about 2 miles, no rad muff or any other covering to assist, heater is good too, the stat has a bypass until engine is fully warmed & stat opens. Quote Link to comment Share on other sites More sharing options...
gazelle Posted December 21, 2009 Share Posted December 21, 2009 The TD5 seems to take 20-25 minutes to get up to temperature. - Why the difference to the 200TDi? Quote Link to comment Share on other sites More sharing options...
GBMUD Posted December 21, 2009 Share Posted December 21, 2009 I think it rather depends on where and how you drive. In my 110 Td5 for example, when I get to the end of my road I tend to go in one of two directions, left out of town or right and then through the town centre. If I go left there is a short 30mph section followed by national speed limit up hill. From a cold start there is warm air coming from the heater after about 2 miles - something like 2-3 minutes - especially if I am towing a small trailer. If I go the other way, through town, the speeds are lower, I use less throttle and spend more time coasting up to traffic lights or dawdling along behind old ladies at 20mph. That way I need to drive at least twice as far and for up to 15 minutes before I start getting heat out - and then it is accompanied by an increase in speed as I go out of the other side of the town. In short, the more fuel you can burn in a shorter time the faster your engine will heat up. Remember that running the heater on a Landrover diesel can remove all of the heat generated at tick over and will actively cool the engine when coasting as there is no fuel being burned then. HTH Chris Quote Link to comment Share on other sites More sharing options...
gazelle Posted December 21, 2009 Share Posted December 21, 2009 Thanks Chris, A very clear post which explains that it is nothing to do with the engine type. It makes sense too and I have definitely learned something today. Cheers Martin Quote Link to comment Share on other sites More sharing options...
Quagmire Posted December 21, 2009 Share Posted December 21, 2009 I drive down a big hill, sit at some traffic lights, then a short blast a 50mph for 1/2mile, then its 60mph the remaining 32 miles to work Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted December 22, 2009 Share Posted December 22, 2009 My V8 Discovery has a good heater though just a lot of cash to pay for hot air Stick SWMBO in the passenger seat. Much cheaper... ...'till she gets the credit cards. Quote Link to comment Share on other sites More sharing options...
gazelle Posted December 23, 2009 Share Posted December 23, 2009 Thanks Chris, A very clear post which explains that it is nothing to do with the engine type. It makes sense too and I have definitely learned something today. Cheers Martin And as a result I can now get the truck warm in half the time. Thank you!!!! Quote Link to comment Share on other sites More sharing options...
V8 Freak Posted December 23, 2009 Share Posted December 23, 2009 With the V8 I get some temperature in the heater within 5 minutes but the engine is not up to temperature at present for approx. 10 mins.... In the summer months I don't really notice or care how long it takes or if it's different as it's usually windows open to release the excess heat ! Although new, the heater doesn't really keep up with heating the whole 110 at present.. Maybe there are just too many other air holes for the warm air to escape through and the cold to invade... Neil Quote Link to comment Share on other sites More sharing options...
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