Alan willcocks Posted October 4, 2013 Share Posted October 4, 2013 Hi, I'm moving radiator and expansion tank to rear of challenge truck, can I blank the bleed pipe from thermastat housing and just connect the small pipe from expansion tank direct to radiator and and larger pipe to bottom hose seeing the rad and header tank will now be higher than engine. Alan w Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted October 4, 2013 Share Posted October 4, 2013 You can but the engine won't self bleed very well, i had to bleed mine several times until i got the all the air out Quote Link to comment Share on other sites More sharing options...
simonr Posted October 5, 2013 Share Posted October 5, 2013 I would leave as many bleed points in the system as you can - you inevitably end up with air locks! Once you've run it for a bit, if you find you keep getting air in one bit of the system - run another bit of thin tube from there to the top of the rad so it can self-bleed. Also, remember to use as big bore tube from the front to back as you can. Liquid flowing through a tube encounters a pressure drop inversely proportional to the bore. Your water pump runs at low pressure - and it's easy to end up with almost no flow through the rear rad! If you use bigger pipes than standard, the extra distance will make less difference to flow. Si Quote Link to comment Share on other sites More sharing options...
tacr2man Posted October 6, 2013 Share Posted October 6, 2013 might be worth fitting a ewp in line Quote Link to comment Share on other sites More sharing options...
Team Idris Posted October 6, 2013 Share Posted October 6, 2013 You'll need the thermostat bleed, or the slightest head gasket leak will really screw the engine up. But I get around it with 2 header tanks. The front one has a blanking cap, rear has the pressure cap. And a 1/2" bsp filler/bleed in the top hose at the engine end makes life a whole lot easier Quote Link to comment Share on other sites More sharing options...
Alan willcocks Posted October 6, 2013 Author Share Posted October 6, 2013 Thanks for all the replies, sounds like its best to keep the bleed from the thermastat housing, I think I'm going to mount radiator on top of trayback with the header tank slightly above top of rad, run large bore pipes under car, plumb largest pipe from header tank to lowest point of top hose like it would be normally, then run a smaller hose from thermastat housing to the rad and y it into header as normal. Think this should solve bleed problems. I was hoping I could get away with not running bleed hose to back of car but sounds like its best to. Alan Quote Link to comment Share on other sites More sharing options...
De Ranged Posted October 6, 2013 Share Posted October 6, 2013 All I do is when I weld it up if there are any high points I weld a bit of plate ontop of the tube and drill and tap for a bolt, thread seal will seal it If your truck is doing road speeds you are going to want to beef up the fans... at speed you get a vacuum behind the cab, this will steel the air from the fans, I either use either Audi A4 fans, these things are mean if you start them on the floor they will fly... unfortunatly they have a huge draw and we haven't figured out how to get the soft start to work best answer we have found is switch them on the negative with a 60amp relay Another option is add another radiator done this on a mates lexus hilux daily, 2 side by side, T pipe in and same at the bottom and just a couple of cheap fans, this has worked really well... sits at 86C happily on the road Have run setups with and without electric water pumps.... the only one we've used is the Craig Davies one with the controller, a very nice system, set and forget it monitors the temp and increases - decreases the flow from the pump to keep it to the ideal These arn't necessary your water pump will flow enough so long as its good Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 7, 2013 Share Posted October 7, 2013 Roof scoops remove the need for extra fans, I've known two TDi's with rear rads (one Tomcat, one Dlander) and roof scoops, with no assistance from extra pumps or fans both worked fine. Also the two racers (one Isuzu, one LS1) had rear rads and roof scoops and they worked lovely too. The LS did make use of the fan a bit, but it can generate twice as much heat as the others! Quote Link to comment Share on other sites More sharing options...
elbekko Posted October 7, 2013 Share Posted October 7, 2013 The LS didn't need the fan while driving, in fact the temperature dropped quite a bit. Not sure if Mouse had a thermostat though? Probably not. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 7, 2013 Share Posted October 7, 2013 The LS didn't need the fan while driving, in fact the temperature dropped quite a bit. Not sure if Mouse had a thermostat though? Probably not. Pretty sure it did, removing the thermostat is a bad idea. Quote Link to comment Share on other sites More sharing options...
greenstream Posted October 7, 2013 Share Posted October 7, 2013 Hey Fridge Please do explain ! I was going to ditch the thermostat on the 4.6 but you make me think again. Morten Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted October 7, 2013 Share Posted October 7, 2013 You can't have nothing either a stat of some value or a thermostat replacement plate but nothing= cavitation = bad for enginr Quote Link to comment Share on other sites More sharing options...
De Ranged Posted October 7, 2013 Share Posted October 7, 2013 If we are pulling them for any reason, mainly due to overheating easy fix is to just cut the guts out.... removing the whole thing will create too much flow if the rad is close to the motor this can cause overheating as the coolant isn't in the radiator long enough to loose heat.... done it once on a rear mounted one and the temp never heated up that was on a 350 chev hilux Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 8, 2013 Share Posted October 8, 2013 As Nige and DR say, there's several reasons removing the stat can be bad. How it was explained to me is that without any restriction / back-pressure you can get steam pockets in the head. If the engine is running correctly it should work fine with a proper thermostat fitted. Quote Link to comment Share on other sites More sharing options...
zim Posted October 10, 2013 Share Posted October 10, 2013 I agree with the above about removing the stat meaning cavitation, but when you rear mount a rad you are adding back pressure. You now have an extra 12ft of probably 38mm hose that is giving you back pressure. I've run my 4.2 and now 4.6 without a stat for ages now, heater circuit is blocked as well. I have a bleed point on the engine, but no little hose returning from a high point. The top hose on a v8 is pretty much the highest point though. I've rolled it many times and never had any issues with air locks - touches wood. G Quote Link to comment Share on other sites More sharing options...
zim Posted October 10, 2013 Share Posted October 10, 2013 I agree with the above about removing the stat meaning cavitation, but when you rear mount a rad you are adding back pressure. You now have an extra 12ft of probably 38mm hose that is giving you back pressure. I've run my 4.2 and now 4.6 without a stat for ages now, heater circuit is blocked as well. I have a bleed point on the engine, but no little hose returning from a high point. The top hose on a v8 is pretty much the highest point though. I've rolled it many times and never had any issues with air locks - touches wood. G Quote Link to comment Share on other sites More sharing options...
elbekko Posted October 10, 2013 Share Posted October 10, 2013 Pretty sure it did, removing the thermostat is a bad idea. I remember the temperature dropping massively when driving on the road in freezing weather, sounds to me like it didn't have a real thermostat. A drilled plate, sure. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted October 10, 2013 Share Posted October 10, 2013 Yes, but Rolling it is a tad much to get the F air locks out though innit Zim ? Nige Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted October 10, 2013 Share Posted October 10, 2013 Yes, but Rolling it is a tad much to get the F air locks out though innit Zim ? Nige There's a lot to be said for keeping it simple Nige, a quick roll to release an air lock sounds quick and simple Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 10, 2013 Share Posted October 10, 2013 I remember the temperature dropping massively when driving on the road in freezing weather, sounds to me like it didn't have a real thermostat. A drilled plate, sure. Did it have a real temperature gauge? Quote Link to comment Share on other sites More sharing options...
elbekko Posted October 10, 2013 Share Posted October 10, 2013 One of those LED bar things IIRC, probably something you fabbed up? Apart from that, no. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted October 11, 2013 Share Posted October 11, 2013 One of those LED bar things IIRC, probably something you fabbed up? Apart from that, no. Yeah, that was a makeshift expanded-scale kinda affair, I'm not sure it counts as reliable evidence Quote Link to comment Share on other sites More sharing options...
elbekko Posted October 11, 2013 Share Posted October 11, 2013 Fair enough Quote Link to comment Share on other sites More sharing options...
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