Radiator overflow linked to carbs?

magicdrshoon · Jul 7, 2008

I have just replaced the rad in my sIII, which has a retrofitted 3.5V8 with a LPG conversion.

When I took the old rad out, I didn't really think that much about why pipes went from here to there, only where they went.

Now I'm putting them back, I'm starting to wonder why there is a pipe that goes from the radiator overflow (The small tube coming out just under the rad cap) into the part where the two SU carbs bolt onto.

There is an expansion tank to the right of the rad which is no longer connected to anything. I'm guessing that when it was a 6 pot the overflow went to the expansion tank.

I have been told by a work colleague that all Rover V8's have it, and it's for cooling the carb, but if this was the case wouldn't it need an in and an out to get the flow? Also it would only get the cooling if the rad overheated.

Any ideas anyone?

clivees · Jul 7, 2008

Your mate is extracting the urine.
It's a the safety release valve pipe and should be vented at the bottom of the radiator and out on to the road.

magicdrshoon · Jul 7, 2008

clivees said:
Your mate is extracting the urine.
It's a the safety release valve pipe and should be vented at the bottom of the radiator and out on to the road.

I must admit I thought it should either do as you said, or go into the expansion tank, but there was definatley a hose that came from the block of metal that the two SU's sit on, as I didn't disconnect the carb end.

It seems the perfect length to reach the old rad safety-release-valve, and the pipe from the expansion tank (the black bottle/tank to the right of the rad) doesn't go anywhere, and doesn't have any type of jubalee clip to put it on.

So if that pipe doesn't go to the rad, where do ya reckon it should go??

mondo · Jul 7, 2008

Its a Vacumme / vachoooome / Vacyoouuuume/ It sucks pipe !
should supply yer dizzy and possibly yer servo!

bigchap · Jul 7, 2008

definitely brake servo,it's just blanked off on mine.

groenendael · Jul 7, 2008

It would appear/seem that a previous owner has used the radiator outlet for the expansion /overflow as a means of accepting the vent pipe from the inlet manifold .Thus saving him the problem of soldering a length of copper pipe into the top of the rad.Hope this helps .
Hopefully some one with a similar transplant reading this is able to post a picture/s.
Have you had a look at and compared the outlets on the old radiator to that of the new one?

bigchap · Jul 7, 2008

my series 3 has a retro fitted v8,i still have the expansion tank in use.

Grippa · Jul 7, 2008

bigchap said:
my series 3 has a retro fitted v8,i still have the expansion tank in use.

Aye, mine too.

Pipe on my SUs is blanked orf an all.

groenendael · Jul 7, 2008

Series11A with retrofitted v8 and overflow in use .
In addition to the above there is a vent pipe from the inlet manifold to an additional copper pipe at the top of the radiator.
It would appear that some people blank off the vent pipe on the inlet manifold of there vehicles.

bigchap · Jul 7, 2008

i think that's for a manifold heater.

magicdrshoon · Jul 8, 2008

I just found this on eBay:

http://cgi.ebay.co.uk/Land-Rover-Safari-109_W0QQitemZ180261952456QQcmdZViewItem?hash=item180261952456&_trksid=p3286.m14.l1318

If you look at the picture of the engine, you can just about make out the pipe I'm on about, although the pipe goes to an inline coupler on the top hose of the rad rather than the pressure release.

I'm guessing thats where it should go?? I'd rather not blank it off, as it must be there for a reason.

bigchap · Jul 8, 2008

ooh,it's a bit untidy under that bonnet!,i can see the pipe you mean but have no idea what it's doing there,that's a different engine to mine anyway.

magicdrshoon · Jul 8, 2008

groenendael said:
It would appear/seem that a previous owner has used the radiator outlet for the expansion /overflow as a means of accepting the vent pipe from the inlet manifold .Thus saving him the problem of soldering a length of copper pipe into the top of the rad.Hope this helps .
Hopefully some one with a similar transplant reading this is able to post a picture/s.

groenendael said:
Series11A with retrofitted v8 and overflow in use .
In addition to the above there is a vent pipe from the inlet manifold to an additional copper pipe at the top of the radiator.
It would appear that some people blank off the vent pipe on the inlet manifold of there vehicles.

It looks like you're right! I've been chatting to a Rover V8 enthusiast, and he reckons that it's to keep the carbs at a level temperature to the rest of the engine.

As groenendael said, there should be a pipe brazed/soldered in the top of the rad to allow the return for the water to allow it to flow through the carb base.

Blanking this off wouldn't stop the landy from running, but it would run better with the outlet connected to the rad (but not the pressure release obviosly!!).

groenendael · Jul 9, 2008

groenendael · Jul 9, 2008

I'll get the hang of this one day .The above picture (after much adoo

) is with reference to the vent pipie from the inlet manifold to an additional copper pipe at the top of the radiator.Does this answer your question Magicdrshoon.?

aimbones · Jul 12, 2008

The water jacket in the inlet manifold is normally either connected to the top of the rad or to an expansion tank depending on how the systems plumbed up - this is to allow air bubbles to clear the system and not cause air locks - you can get away with a length of pipe thats blocked off provided you open it up to bleed the system whenever you disturb it. The outlet under the pressure cap on the s3 rad should go to an expansion tank as it vents water as it expands and allows it to be drawn back in as the engine cools - depending on how the conversion was done will dictate what the correct connections are for your landy

magicdrshoon · Jul 12, 2008

groenendael said:
I'll get the hang of this one day .The above picture (after much adoo) is with reference to the vent pipie from the inlet manifold to an additional copper pipe at the top of the radiator.Does this answer your question Magicdrshoon.?

Absolutley!! Bang on! So now I just need to get myself a blow gun and get soldering! At least I have the old knackered rad to practice on! I've never soldered anything bigger than a wire before... first time for everything!

magicdrshoon · Jul 12, 2008

aimbones said:
The water jacket in the inlet manifold is normally either connected to the top of the rad or to an expansion tank depending on how the systems plumbed up - this is to allow air bubbles to clear the system and not cause air locks - you can get away with a length of pipe thats blocked off provided you open it up to bleed the system whenever you disturb it. The outlet under the pressure cap on the s3 rad should go to an expansion tank as it vents water as it expands and allows it to be drawn back in as the engine cools - depending on how the conversion was done will dictate what the correct connections are for your landy

Thanks for that! I thing the guy who did the conversion didn't realy understand and saw another conversion that had the pipe soldered in, and when he got home just put it onto "A" pipe that was in the top of the rad!

ETC7867 · Jul 18, 2008

Off memory the coolant pipe is needed on the V8, its connected to the Pent House Vent, as said earlier its to keep the manifold temp stable and to stop air locks in the cooling system.

Radiator overflow linked to carbs?

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