Bulletin Board - Message Water Pump I have just bought a RV8 and noticed that when the car is sitting in the garage, after a run there is a small amount of coolant on the garage floor. When I had the car MOT I asked the garage about this, they told me that it is not leaking when running but appears to leek when the car engine is stopped and cooling down. The car has sat for the last month not a leak. Can anyone explain to me why this happens and how can I stop it? Jim Greenhill 24 February 2010 @ 16:33 Under topic: RV8   Reply(ies) received for this Message Water Pump If you have air conditioning that is likely the cause - no problem Hugh Boddington 25 February 2010 @ 09:01   Water Pump Jim, Hugh may be right but it wouldn't be coolant from the A/C, just plain water. Another simple check would be to tie a small drinks bottle over the end of the overflow pipe for a while and see if you catch anything. I do this, when I top up my V8 to check that I am not siphoning coolant out as if the reservoir is overfilled the BGT V8 has a tendency to eject coolant. That sounds tight but if you like me use a specific coolant instead of water with antifreeze it saves throwing it down the drain so to speak Graham Cornford 25 February 2010 @ 14:25   Water Pump First off,there isn't an overflow on the RV8,it pipes into an expansion tank. Second, I've had this same problem and mine was due to seepage between the bottom hose sections (2off) and the metal intermediate bottom pipe between them. Solved by tightening the hose clips, once you've got at them. Geoff Coley 25 February 2010 @ 15:41   Water Pump Jim, whereabouts under the car is the puddle? Just to clarify Geoff's point, there is of course an overflow pipe from the neck of the RV8's expansion tank, which discharges to the ground (or if you haven't re-routed it, on top of the chassis rail!). If the leak is definitely coolant, check as well that the bearing of the water pump is dry and also that the bottom section of the bottom rad hose has not had a groove worn in it by either the anti-roll bar or the edge of the rack housing - it runs very close to both of them. Also, the ends of the metal connecting sleeve between the two sections of bottom rad hose can corrode back, resulting in a leak even when the clips are tight. Clive W. has a replacement in s'steel I believe. Stuart Middlemiss 26 February 2010 @ 01:21   Water Pump Stuart is absolutely correct. You can eliminate the header tank overflow discharge quite simply, actually. This actuates only when the car is hot after turning off the engine. The quantity of scaulding water is roughly one liter and ejects itself in a smelly cloud of steam which seeps up through the bonnet edges and looks quite dramatic. If it's not the airconditioning water, which is tasteless, by the way!! it can only come from tha areas Stuart mentioned above. Peter Garton 26 February 2010 @ 06:45   Water Pump If it is the water pump leaking through the bearing I know from experience you get a thin line of water marks (usually bluish white) across the underside of the bonnet. Took me ages to work out where it was comming from! Kev Lillywhite 27 February 2010 @ 11:00   Water Pump Hi, Sorry for the delay, the snow up here is keeping me busy and I have not looked at the MG since posting. I can confirm it is not A/C as it is a British Spec car, so no A/C. The very small puddle on the garage floor is under the cross member quite close to the middle but nearer the offside. I have never seen any splash marks on the underside of any of the engine bay, but since purchase in December I have only driven it to the MOT station and back (18 inches of snow in the drive. don't know when I will get out to play). I will look at the suggestions and thanks for the assistance. No one has explained why this does this only when cooling and not running? Jim Greenhill 02 March 2010 @ 00:15   Water Pump Hello Jim, The reason the overflow occurs when you stop is that the water flow stops and hot areas in the block cause nearby static water to boil. The steam expels water above and it may be sufficient to overflow the expansion tank, especially if a zealous owner keeps it overfilled. Some degree of thermo-siphon flow remains when the engine is stopped. This is enhanced by greater temperature differences which can be maintained if the electric fans are not controlled by the ignition. This is the case on most modern cars and the reason the fans run after switching off (or even start up after switch off). I've re-wired my 74 B GT V8 to behave this way and have thereby eliminated my previous water loss. Many modern cars go a step further and have electric water pumps which keep the water flowing without the engine running and so fully eliminate local boiling and the consequent water loss. Note that the pressurisation of the system helps the problem by raising the boiling point, but doesn't eliminate it. The RV8 has a relatively high water temperature at normal running so is already close to the (pressurised) boiling point even before localised heating takes place when the engine is stopped. Bob Owen 02 March 2010 @ 08:24   Water Pump The RV8 cooling system has an expansion tank to enable coolant in the radiator to expand as it gets hot through a rubber tube connecting to the bottom of the expansion tank. As the engine cools, coolant is drawn back into the radiator thereby maintaining the correct coolant level in the radiator. A second rubber tube is connected to a spigot immediately below the expansion tank pressure cap which enables excess fluid to overflow and discharge below the car. When cool, the correct level of coolant in the expansion tank (with the radiator full) is between a quarter and a third full – see “Coolant Level” marker in the diagram in the RV8 Owner's Handbook. Overfilling the expansion tank can lead to syphonage of the coolant via the overflow pipe. I have created a webpage with diagrams taken from the RV8 Owner's Handbook and Repair Manual. http://www.v8register.net/subpages/rv8coolingsystemnote030310.htm Victor Smith 02 March 2010 @ 09:06   Water Pump Jim, Could you let us know where the coolant level is in your expansion tank as that will help us continue our remote analysis of your query? Victor Smith 02 March 2010 @ 09:20   Water Pump Hi, Coolant level when cool is at the level marked on the expansion tank. Garage said it is coming from water pump but only when engine is stopped and not leaking when running. How can this be? Jim Greenhill 08 March 2010 @ 22:16   Water Pump I would suggest that your water pump seal is marginal. When running the pump rotor will partly self align and this may result in a better seal. Also small amounts of water may radiate and evaporate while the hot pulley is spinning. The garage should have a pressure test set and can pressurise the system while the engine is stationary and cold to allow easy examination for leaks. I suspect you need a new pump. Bob Owen 09 March 2010 @ 14:53   Water Pump Jim, I've had My RV8 three and a half years now, when I bought it and drove Her home, the same symptoms happend, coolant on the garage floor. At first I assumed the PO could have over filled the radiator, no such luck! I went through all the procedures, air lock, cylinder head gasket, etc. I started to think I'd bought a dud! Then someone asked Me about its history, being low milage and 12 years old, it had stood virtually unused for the two years previous to Me buying it, and the guy told Me he'd had a similar experience. It turned out the radiator was chocked up with silt, and He replaced the radiator and cured the problem. I took out the radiator, had it re-cored at a cost of £85, re-fitted it and Bingo! She's run like a dream since then. Hope You get to the bottom of this problem Jim, all the best. 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