DC_ Posted April 24, 2008 Share Posted April 24, 2008 Hi gang, I recently changed over my expansion tank due to a seam cracking on it and thought that was the end of my worries, Today after a little fun offroad and a drive back along the bypass i noticed for the first time since i've had the car the temp gauge just over the half way mark. When i got home i checked under the hood and there seems to be excess pressure building up in the cooling and it forced water over the top of the expansion tank (dont ask me where it came from) Any suggestions? Too much water in it? Thermostat? Not really too clued up on the techy side but if made easy i will give it a go. Hoping it's nothing too serious as i have a run on in may. Help DC Quote Link to comment Share on other sites More sharing options...
disco_al Posted April 24, 2008 Share Posted April 24, 2008 the gauge on mine sits just above half way (but then it does run on gas, so will be slightly hotter than normal) the only time i get coolant out of the bottle is if it is overfilled slightly, and that is usually as a result of the system pressurising as normal and forcing it out through the easiest point (thankfully not the engine ) where is the level in the tank when cold? Quote Link to comment Share on other sites More sharing options...
DC_ Posted April 24, 2008 Author Share Posted April 24, 2008 the gauge on mine sits just above half way (but then it does run on gas, so will be slightly hotter than normal)the only time i get coolant out of the bottle is if it is overfilled slightly, and that is usually as a result of the system pressurising as normal and forcing it out through the easiest point (thankfully not the engine ) where is the level in the tank when cold? It's usually just above the half way mark when it's cold, there's a wee plastic tower type thing in the tank and it's above that, Also noticed since renewing the expansion tank it holds some pressure in the system even when cold..............is this normal?? Quote Link to comment Share on other sites More sharing options...
disco_al Posted April 24, 2008 Share Posted April 24, 2008 most cooling systems will retain pressure, even when cold. you will usually get a little "hiss" when removing the cap, a bit like opening a semi-flat bottle of coke. if in doubt get the gas in the header tank tested for combustion gasses. Quote Link to comment Share on other sites More sharing options...
DC_ Posted April 24, 2008 Author Share Posted April 24, 2008 Hmmmm that means a trip to the garage........... Quote Link to comment Share on other sites More sharing options...
disco_al Posted April 24, 2008 Share Posted April 24, 2008 IIRC the plastic tower is the upper level of coolant? i am sure someone will correct me if i am wrong. check the fins in the rad as well, just in case they have got blocked with mud n associated cr*p, that would cause it to warm up more than usual. Quote Link to comment Share on other sites More sharing options...
DC_ Posted April 24, 2008 Author Share Posted April 24, 2008 Cheers Al for the quick replies. I'll make sure i clean the fins out as much as i can, The temp never kept rising and i'm thinking this might be hopefully the norm and i'm just not used to it as maybe my old expansion tank was in need of replacement. It's the pressure thats concerning me the most. Hopefully if i reduce the amount in the tank then it might solve the prob. Quote Link to comment Share on other sites More sharing options...
disco_al Posted April 24, 2008 Share Posted April 24, 2008 no problem, i was concerned when i first got the v8, as my old 200tdi very rarely used to get as far as 1/4 on the gauge. Quote Link to comment Share on other sites More sharing options...
DC_ Posted April 24, 2008 Author Share Posted April 24, 2008 I'll check it later when it cools down and see what the level of water is like. If it's just at the top of the (tower) then i think that's where i remember someone saying it should be Quote Link to comment Share on other sites More sharing options...
paintman Posted April 24, 2008 Share Posted April 24, 2008 Cooling systems are supposed to pressurise. Problems are when it starts to throw water out of the exhaust or out of the header tank & that usually means overpressurising due head gasket problems (or liners but that's more common in the 3.9 & bigger engines). That top hose in that case is usually rock hard. Overfilling can be a cause of water exiting the header - water expands when hot & its got to go somewhere! Check the condition of the pressure cap, they get weak as they get older, don't allow the system to pressurise properly which will also cause the system to run hotter, & should be replaced periodically. A coolant test for the presence of exhaust gases - although not infallible - could be worthwhile as would a pressure test of the system. Blocked radiators - internally and externally - are also a common cause of overheating. Quote Link to comment Share on other sites More sharing options...
DC_ Posted April 24, 2008 Author Share Posted April 24, 2008 Told ye i would be back paintman Well since posting this avo, I've taken the grill off and cleaned the fins of any mud that was on, replaced the cap from the tank with the original one i had on the cracked tank (will order a new one though) Taken it to get a wee jet wash and all was fine, So................how long would you say a good run was to test it out to see if it was something as daft as too much water in the system? I was driving for around 15 mins there washed car and 15 mins back down the bypass Quote Link to comment Share on other sites More sharing options...
paintman Posted April 25, 2008 Share Posted April 25, 2008 Drive as normal & keep an eye on the level & the temp gauge doing anything abnormal. Quote Link to comment Share on other sites More sharing options...
DC_ Posted April 25, 2008 Author Share Posted April 25, 2008 I'm heading for a forum member tamara and he's having a look over it for me, Testing it under pressure. I have everything crossed that it's a simple air lock? Took it for a run yesterday and after cleaning the rad and replacing the cap all seemed well..................................................too many beers now to reply Sensibly Quote Link to comment Share on other sites More sharing options...
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