lee boy Posted May 20, 2007 Share Posted May 20, 2007 Having some big problems with my N reg 300tdi disco. It keeps over heating BIG time, but only if the expantion cap is done up- when left loose it runs fine. The heater doesn't work either just blows cold. I have drained and flushed the whole system, the water runs through fine. I've put in a new thermo stat and temp sensor. All hoses go solid when engine runs, so the water pump is working. I can leave my disco running for hours and it dont over heat but soon as i drive it heats up well quick. Once over heated, I undo the expantion cap and it sounds like a kettle- once the cap is off it has used some water. I have used a sniffer and it dont look like head gasket plus no smoke, no water in oil and no gunk in oil cap. Need some serious help please Quote Link to comment Share on other sites More sharing options...
RRX Posted May 20, 2007 Share Posted May 20, 2007 Could be a cracked head, if you start the engine up with the cap off do you get any bubbles coming out of the header tank? Quote Link to comment Share on other sites More sharing options...
lee boy Posted May 20, 2007 Author Share Posted May 20, 2007 no none that i have seen,some one told me that it could be the heater valve not opening which is causing a air lock, could that be true? Quote Link to comment Share on other sites More sharing options...
JimAttrill Posted May 21, 2007 Share Posted May 21, 2007 As there is no valve on the heater that can hardly be your problem. The coolant runs through the heater matrix no matter what. The 'heat' setting is an air flap. But you should take off the plug on the thermostat housing (I hope it is not a plastic one, for your sake) and check that there is no air in there. Sounds either like the head gasket or (worse) a cracked head to me. I hope it is not the second... But that is the only way that the tank will over pressurise and boil in the header tank. I am glad to see that you have changed the thermostat as running these engines without a stat will cause overheating. Clutching at straws - the Y piece isn't blocked - that can cause funny symptoms. The expansion tank caps also stop working which causes the coolant to blow out. Quote Link to comment Share on other sites More sharing options...
keithjh Posted May 21, 2007 Share Posted May 21, 2007 I Had this happen on my 300tdi disco, it was the head gasket, if i was you i would take the head off and have a good look not a long or difficult job to do. Regards Keith Quote Link to comment Share on other sites More sharing options...
Jason2 Posted May 21, 2007 Share Posted May 21, 2007 I Had this happen on my 300tdi disco, it was the head gasket, if i was you i would take the head off and have a good look not a long or difficult job to do.Regards Keith ** I have a mate who had the same problem-He has been running his now for nearly 2 years with the expansion cap loose with out any problems Quote Link to comment Share on other sites More sharing options...
the_blasons Posted August 29, 2007 Share Posted August 29, 2007 Having some big problems with my N reg 300tdi disco. It keeps over heating BIG time, but only if the expantion cap is done up- when left loose it runs fine. The heater doesn't work either just blows cold. I have drained and flushed the whole system, the water runs through fine. I've put in a new thermo stat and temp sensor. All hoses go solid when engine runs, so the water pump is working. I can leave my disco running for hours and it dont over heat but soon as i drive it heats up well quick. Once over heated, I undo the expantion cap and it sounds like a kettle- once the cap is off it has used some water. I have used a sniffer and it dont look like head gasket plus no smoke, no water in oil and no gunk in oil cap. Need some serious help please HI, Just had the same problem as you had. i changed the head gasket anyway, took a while but didn't look like the gasket had gone. when i came to refill the coolant, found that the heater matrix wasn't filling. therefore air-lock, tried filling by the book method but still wouldn't fill, so put hose pipe into the matrix itself and quickly replaced hose onto the head. seems to have sorted problem. regards guy Quote Link to comment Share on other sites More sharing options...
stu666 Posted August 29, 2007 Share Posted August 29, 2007 Hi, Yep another person with the same problem. I had the head gasket done and still had overheating as you describe. I changed the rad as it was shot (few fins left) and hey presto no problems since. Good luck. Quote Link to comment Share on other sites More sharing options...
Suggsy Posted October 27, 2007 Share Posted October 27, 2007 Having some big problems with my N reg 300tdi disco. It keeps over heating BIG time, but only if the expantion cap is done up- when left loose it runs fine. The heater doesn't work either just blows cold. I have drained and flushed the whole system, the water runs through fine. I've put in a new thermo stat and temp sensor. All hoses go solid when engine runs, so the water pump is working. I can leave my disco running for hours and it dont over heat but soon as i drive it heats up well quick. Once over heated, I undo the expantion cap and it sounds like a kettle- once the cap is off it has used some water. I have used a sniffer and it dont look like head gasket plus no smoke, no water in oil and no gunk in oil cap. Need some serious help please Hey lee, I have the same problem done both head skim/gaskets and still same result did you find a resolve regards Suggsy Quote Link to comment Share on other sites More sharing options...
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