Firefly Posted May 16 Report Share Posted May 16 Yes use the caps as you suggested, if you are refilling the system you could fill the rad and replace the cap & then continue filling the header tank to required level. Although I fill mine just using the header tank, its the only cap. The physics of the restrictor. Imagine you have a 12 dia. hose and fitting in the thermostat housing, the amount of fluid the water pump would push thro` into the header tank is significant, turning your header tank into a 2nd radiator which will do little to cool the fluid, but raising the engine bay temp. The 3 mm restrictor obviously limits the flow of fluid, but is sufficient to bleed the air out of the rad and engine. In fact I have noticed very little fluid if any circulates below 3000 rpm. If you have a spare hour or two do the calcs to see the difference in the flow rate between 3mm dia. and 12mm dia. that should convince you. 😵 Link to comment Share on other sites More sharing options...
Iain T Posted May 16 Author Report Share Posted May 16 (edited) I agree given a constant pressure the flow rate will vary with the cross sectional area of the bore. As you say it's all to reduce the volume of fluid getting into the header. I've found both a brass Y and T piece one of which will enable the tank outlet to be joined to the s/steel pipe going into the pump. Fortunately all three fittings, heater, s/steel return pipe and tank outlet are all 16mm or 5/8". Iain Edited May 16 by Iain T Link to comment Share on other sites More sharing options...
Firefly Posted May 16 Report Share Posted May 16 All the more reason to restrict the flow. Fluid like most things takes the path of least resistance, and its going to find circulating thro your h/t easier with that bore of pipe, than fighting its way thro` the rad matrix. Mac. Link to comment Share on other sites More sharing options...
Firefly Posted May 16 Report Share Posted May 16 Sorry Iain, just realised you are talking about the pipe from the bottom of the h/t, not the bleed from the from the thermostat housing to the top of the h/t which is the one that needs the restriction, confusing myself now. 🤔 Link to comment Share on other sites More sharing options...
Iain T Posted May 16 Author Report Share Posted May 16 Confused......have a beer🍻 I think I have it all sorted and a friend has an array of taper taps for the thermostat housing elbow fitting😁 Iain Link to comment Share on other sites More sharing options...
Firefly Posted May 16 Report Share Posted May 16 🍻 or two 🙂 I was going to wait for you to ask about the t/h fittings. I used 1/8" bsp, you can imagine its not very thick, and so that it ended up facing in the right direction, I used a lock nut (thin nut) on the inside with sealer. May have used a brass penny washer under the lock nut, its a while ago now. You are definitely heading in the right direction. Mac. Link to comment Share on other sites More sharing options...
Iain T Posted May 16 Author Report Share Posted May 16 (edited) 18 minutes ago, Firefly said: I was going to wait for you to ask about the t/h fittings. I used 1/8" bsp, you can imagine its not very thick, and so that it ended up facing in the right direction, I used a lock nut (thin nut) on the inside with sealer. May have used a brass penny washer under the lock nut, its a while ago now. You are definitely heading in the right direction. Ma Already onto the locknut and thread sealer! I think the housing is cast iron so it'll be like drilling and tapping grit! I can feel a list of goodies is required although I'm not sure when I'll actually do it. Fortunately a friend has a Bridgeport and lathe in his garage, lucky bu**er. Iain Edited May 16 by Iain T Link to comment Share on other sites More sharing options...
Peter Truman Posted May 17 Report Share Posted May 17 iain I have a bleed screw at the Heater Assembly very near the high point, I probably should have put it on the inlet manifold inlet to the heater, rather than the heater outlet to the pump return, but hey air always finds the highest point on a water main UNLESS it air locks/blocks the pipe, & that's a real bug**r nothing to do but drain the main and start again.! When I refill the cooling system I leave the bleed open till the engines hot and the coolant is just at the top of the bleed then seal it with a screw. The bleed is only a 1/2 Yorkshire T with the offtake having a brass nut turned round pushed into the offtake and silver soldered into it. I took the idea from a Renault R8 Gordini I had when working on a BP oil refinery in Montreal, Canada 1967, Expo Year? Renault had a bleed screw on the heater matrix at the high point located just below the windscreen. The Renault R8 had a deep V bonnet and when driving fast on the Decarrie freeway in a torrential rain storm the water would build up in the V once it flowed back thro the air inlet dumping water all over me and passenger. Link to comment Share on other sites More sharing options...
Iain T Posted May 17 Author Report Share Posted May 17 Peter, an interesting and simple solution. I have a bleed screw arriving today or tomorrow that will fit into the Davies Craig temp sender adaptor next to the thermostat. It'll be interesting to see how that vents and has any effect. In theory if the system is filled correctly and given the position of the pump there shouldn't be any air cavitation to reduce efficiency. Iain Link to comment Share on other sites More sharing options...
SpitFire6 Posted May 19 Report Share Posted May 19 Hi, I fitted mine centre and as high as possible. A bleed valve on the thermostat housing. Heater valve was deleted last century. Link to comment Share on other sites More sharing options...
Iain T Posted May 20 Author Report Share Posted May 20 13 hours ago, SpitFire6 said: fitted mine centre and as high as possible I have considered fitting a small 100mm diameter horizontal header on the heater casing but not sure where the matrix etc are. Four small rivnuts would do it. Iain Link to comment Share on other sites More sharing options...
Peter Truman Posted May 20 Report Share Posted May 20 Iain the front and rear covers to the heater case are only held in place by spring clips, I don’t think they wouldn’t come undone but good engineering surely requires a solid bolted jointing if your going to bolt the header tank to it as it would be quite heavy full of water Link to comment Share on other sites More sharing options...
Iain T Posted May 20 Author Report Share Posted May 20 Peter, only half full to allow for the air gap but the point about a solid mounting is valid. I have enough occasional rattles and don't want any more! Link to comment Share on other sites More sharing options...
johny Posted May 20 Report Share Posted May 20 Perhaps it could be fixed by the rear fixing bolt for the rocker cover that you can see in Peter pic above? Link to comment Share on other sites More sharing options...
Iain T Posted May 20 Author Report Share Posted May 20 I'm still weighing the options and benefits over cluttering up the engine bay. Peter's simple vent is excellent but doesn't self vent or give a head of water. A tank next to the clutch mc could be plumbed in quite discreetly other than the small hose to the Davies Craig adaptor next to the thermostat housing. Iain Link to comment Share on other sites More sharing options...
SpitFire6 Posted May 20 Report Share Posted May 20 Hi Iain T, Sounds like you are fitting an electric water pump EWP. How are you plumbing it so the heater still functions? Cheers, Iain. Link to comment Share on other sites More sharing options...
Steve P Posted May 20 Report Share Posted May 20 Mine is fitted between the master cylinder and heater box and is Riv nut/bolted to the bulkhead. S Link to comment Share on other sites More sharing options...
Iain T Posted May 20 Author Report Share Posted May 20 (edited) 24 minutes ago, Steve P said: Mine is fitted between the master cylinder and heater box and is Riv nut/bolted to the bulkhead. Yep, it's the logical place to fit a header. As I said I've two unused M6 rivnuts on the bulkhead and three M4 or M5 on the horizontal panel I can use. I'm sure I could design and make an appropriate support bracket. Iain Edited May 20 by Iain T Link to comment Share on other sites More sharing options...
Iain T Posted May 20 Author Report Share Posted May 20 1 hour ago, SpitFire6 said: Sounds like you are fitting an electric water pump EWP. How are you plumbing it so the heater still functions? Iain it's Iain.....is there an echo on the forum? No not an EWP, the adaptor is in the top rad to thermostat hose to fit the DC electric fan controller. However the adaptor also has a second plugged 1/4 npt tapping I can use. Iain Link to comment Share on other sites More sharing options...
SpitFire6 Posted May 20 Report Share Posted May 20 58 minutes ago, Iain T said: Iain it's Iain.....is there an echo on the forum? No not an EWP, the adaptor is in the top rad to thermostat hose to fit the DC electric fan controller. However the adaptor also has a second plugged 1/4 npt tapping I can use. Iain Hi, my mistake. Cheers, Iain. Link to comment Share on other sites More sharing options...
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