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sounds like its airlocking.
pull the thermostat and drill the hole out a little further, check the heater lines for restrictions including a flow through check with a garden hose.
additionally....
do you still have the carb heater/manifold block/circuit hooked up?
oh and by the by.
coolant flow for most rover v8's is in through the expansion tank and out through the back of the head near the 7/8 cylinder or out via the slipping liner.
Thanks Dave for those comments. I think I have sorted out why the lower hose is getting hot and the top is not - I forgot about the heater/lpg heater pipe that comes out the rear of the inlet manifold, through the LPG and heater and back into a T piece in the lower radiator hose.
I agree, on thinking this through in light of the comments in this thread that there may be an air pocket so I will get a new thermostat, drill a hole where the jiggler would normally be and reinstall with the hole at the top and see how I go then.
Thanks to everyone for their comments - very much appreciated.
Oh - the expansion tank in my system is more of just an overflow tank - it is just a tank to catch overflow from the radiator when the pressure cap lifts - the system has no way to suck the coolant from the overflow tank back into the system as when pressure reduces the pressure radiator cap on the radiator closes so this coolant is lost.
Cheers and thanks
Garry
You say its a serpentine.
Do you have the belt routed correctly?
If the wrong side of the water pump it could run it backwards? Maybe.
Regards PhilipA
not so...Quote:
Originally Posted by 101RRS
the cap does nothing to resist lower than atmospheric pressure in the radiator (well buggerall) if you're system wont vac back the overflow bottle then you have a cap issue.
See post #4 - compares my layout with standard.Quote:
Originally Posted by PhilipA
Sorry not following that at all.[bigsad]Quote:
Originally Posted by Blknight.aus
Telling what you already know to set the scene - It is a standard radiator cap with an inbuilt spring and rubber seal that keeps the top of the radiator sealed. Pressure in the radiator (when it overheats) has to overcome the spring pressure and then opens the rubber seal allowing excess high pressure coolant and steam to escape out a pipe in the radiator filler neck which is placed about mid way between the rubber seal and the top of the radiator cap - while the radiator cap is open the coolant flows out the pipe and 2 feet down to a small overflow bottle.
As the coolant in the radiator cools the the radiator cap closes and the ejected coolant cannot get back into the cooling system.
So I am not following how the lower pressure in the system can suck back the coolant with the radiator cap closed.
Cheers
Garry
there are 2 seals in a cap. the first is up at the top under the bit you grab.Quote:
Originally Posted by 101RRS
the second is the rubber one on the face that seals and then lets you apply spring pressure to close and lock the cap.
as part of the second one there is (on the cheap version) a small hole near the center near the spring that is covered by the rubber seal, when the pressure drops this allows the coolant in the overflow tank to be drawn back into the engine.
on the more expensive version there is a third seal in the middle of the cap on the bottom that does this function.
If the top seal is knackered the coolant gets out but wont get drawn back up and in.
if the bottom seal is knackered you loose coolant as the system wont pressurise and wont recover.
https://tridon.com.au/databank/docum...iator-Caps.pdf
Dave - I did not know that [bigsad]. Thanks ever so much for taking the time to explain it and attach that link. [thumbsupbig]
I suspect I have a non recovery cap and when I go and get a new thermostat I will get a new recovery cap as well.
Thanks
Garry
From the diagrams, it appears that the purple hose is a bypass, to allow the motor to warm up while still allowing coolant circulation. When the coolant is sufficiently hot, the thermostat opens a little, to blend in some water from the radiator. When fully open, it should block off the bypass. The lower radiator hose being hot, while the top is cold, seems to be correct, and the flow should be as normal, from the top of the engine to the top of the radiator. I would suspect that the thermostat isn't operating correctly, is in the wrong way around, or that there is a problem with the bypass hose; blocked or hooked up incorrectly. You can test coolant flow by undoing the top hose at the radiator, starting the engine and revving it; should get a nice fountain. Reconnect and try removing the bypass hose at the thermostat; see if you get a good flow out of that; don't need to start motor for that one.
I assume that this strange setup is due to freezing conditions in europe, to stop the engine getting a slug of freezing water when the thermostat opens.
Good luck
Pete