unionjack Posted August 20, 2015 Share Posted August 20, 2015 I've looked in the manual, looked at the diagram, read the threads on here, and STILL can't get my head around this valve system in the neck. Give me am overflow tube and normal cap any day. I have a lot of water frothing out of the cap, to the extent that it's not driveable, sprays all over the drivers side windscreen. First job is to sort out this valve business. I have a spring, sleeve, and locking ring with rubber seal beneath. The spring is very rusty and weak, I have no idea how stiff they should be, but I guess I need a new one first. Rubber seal on locking ring is not all that bad, sleeve looks fine. Cap has no seal, should it have? The filler neck has many cracks so the cap can not be screwed down very tight, but I assume it doesn't need to be? The main thing is, I'd dearly love to know exactly how it works. Quote Link to comment Share on other sites More sharing options...
paul_bish Posted August 20, 2015 Share Posted August 20, 2015 I've looked in the manual, looked at the diagram, read the threads on here, and STILL can't get my head around this valve system in the neck. Give me am overflow tube and normal cap any day. I have a lot of water frothing out of the cap, to the extent that it's not driveable, sprays all over the drivers side windscreen. First job is to sort out this valve business. I have a spring, sleeve, and locking ring with rubber seal beneath. The spring is very rusty and weak, I have no idea how stiff they should be, but I guess I need a new one first. Rubber seal on locking ring is not all that bad, sleeve looks fine. Cap has no seal, should it have? The filler neck has many cracks so the cap can not be screwed down very tight, but I assume it doesn't need to be? The main thing is, I'd dearly love to know exactly how it works. I had that issue with my QL, well still do. So any suggestions would be very helpful Quote Link to comment Share on other sites More sharing options...
unionjack Posted August 20, 2015 Author Share Posted August 20, 2015 I can understand why a dodgy valve may allow some leakage under braking etc. I can't see why it would cause heavy frothing out of the cap, seemingly in cycles of several minutes. When the cap is removed, with engine running, I can observe the water level rising and falling by quite a bit. What could make it surge like that? Quote Link to comment Share on other sites More sharing options...
mike30841 Posted August 20, 2015 Share Posted August 20, 2015 There was a thread on this a couple of years ago. I had the same problem with my OXD. I believe the frothing is down to localised boiling - the engine waterways on mine were clogged with crap and scale, I eventually removed about 1/2kg!! With that done and the radiator re-cored and the cracks in the neck repaired, the frothing was resolved, but it still squirts water out of the cap on a fairly regular basis, sometimes even before the engine has warmed up properly. The fittings in the neck were missing, so I have replaced them, with a new spring (these were available from Mike Humphreys of Yorks MVT, not sure if he has any left), but it has still not cured the problem. I have never experienced this problem with my QL. I am not entirely clear how the thing works, but I believe as pressure builds up, the central tube is pressed downwards against the spring and away from the seal, allowing excess pressure to escape through the vent holes in the cap. The manuals do not show any form of seal in the cap itself. As I said, I am pretty sure that the foaming results from problems with scale, rather than being related to the cap, but from previous threads, I am not sure anyone has ever really got to the bottom of this one. Mike. Quote Link to comment Share on other sites More sharing options...
unionjack Posted August 20, 2015 Author Share Posted August 20, 2015 Thanks Mike. I can't see how a seal on the cap could possibly work against the top of a castleated nut. Localised boiling - My rad has been re-cored, but today I heard what seemed to be boiling inside block or rad with the engine idling. So, maybe. I'm tempted to have an overflow pipe fitted into the neck and ditch this system. Quote Link to comment Share on other sites More sharing options...
retriever Posted August 21, 2015 Share Posted August 21, 2015 I found that if you only fill rad to just cover the fins it helps. If you ever have to replace the rear core plug then flush out the block and use a stiff wire to loosen up the silt at the back of the head. The rad cap should just lightly push the coller down onto the spring. I also never ran with a thermostat as I found it caused the water to surge as it opened. Quote Link to comment Share on other sites More sharing options...
mike30841 Posted August 21, 2015 Share Posted August 21, 2015 Just spotted Mike H. has the springs on Ebay - http://www.ebay.co.uk/itm/BEDFORD-MW-OX-OY-Military-Radiator-Neck-Spring-/381369666340?hash=item58cb674b24. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.