Guest diesel_jim Posted December 27, 2006 Share Posted December 27, 2006 So, finally got my red 90 on the road (the one i'm selling blatant plug!! ) anyway, took it for a spin yesterday and it started to overheat (temp guage rising towards the red), got home before anything got too hot and started to investigate. The heater also stopped pumping out hot air, and after opening the bonnet water is starting to seep out of the cap on the expansion tank. top hose is fairly hard when squeezed, bottom one not as much.i stuck my fingers through and felt the radiator fins, they wern't that hot. I thought the thermostat, so whipped it out, stuck it in the kettle and watched as nothing happened. Great i thought! so got another new one today, put it in and exactly the same thing. drive it "gently" and the guage stays in the mid way position, but no heat from the heater, give it some wellie and it instantly starts climbing to the red zone, still no heat from heater. Sooo... what's the great educated forums' opinion? another dodgy thermostat or a duff radiator? (water did pour out easily from the rad when i pulled the bottom pipe off) or worse, damage in the engine? (although i can't imagine, seeing as the heater doesn't get hot to start with). with the cap off of the expansion tank, rev the engine and there is a bit of water movement (not loads of bubbles but more like a "flow" of water, like the pump is working properly) Cheers all! J. Quote Link to comment Share on other sites More sharing options...
Les Henson Posted December 27, 2006 Share Posted December 27, 2006 Air trap I would say Jim. Bleed it from one of the heater hoses. Les. Quote Link to comment Share on other sites More sharing options...
Guest diesel_jim Posted December 27, 2006 Share Posted December 27, 2006 Cheers Les, i'll give it a go. Quote Link to comment Share on other sites More sharing options...
Guest diesel_jim Posted January 7, 2007 Share Posted January 7, 2007 OK, so today i made sure it was parked on a level surface (wasn't the other week and made me think maybe it caused an airlock). removed the heater hoses, blew the heater through with the hose pipe, then gently filled it right up. undid the header tank. undid both rad and thermostat filler cap things. filled it right up. took it for a spin. within 3 miles the temparature needle is in the mid way position. gave it a little spirited driving (not much, only doing about 65~70) and within a mile it's up in the red. and the heater is still blowing barely luke warm water. so got back home. thought i'd remove the thermostat completely (eventhough it's a brand new one) excactly the same results. with the header tank cap off, revving the engine doesn't give any bubbles (as if the head gasket had gone or cracked block pressurising the system) and no water appears to be leaking/getting burnt (level stays the same until it blows out the top of the tank if it gets too hot), but you can see a "movement" of water, so i assume the pump is assisting the water around OK. Anyone got any bright ideas? maybe the radiator is totally sh@gged, it's fairly old but came off of my old 90 when i installed a TurboD rad (full width) and bigger intercooler, and i don't recall any overheating issues. maybe a mouse crawled into it when i had it stuck in the garage and it's blocking one of the pipes? When i did get back home. the top rad pipe was hot and hard LOL! but the bottom one wasn't so hard, and /fairly/ warm. heater pipes were hot-ish, but not too pressurused. when i removed the header tank cap, the top hose instantly became soft (as all the water boiled and overflowed) Any help is muchly appreciated! Jamie Quote Link to comment Share on other sites More sharing options...
T1G UP Posted January 7, 2007 Share Posted January 7, 2007 I'd say air lock but you've looked into that. So it's pump ,cause it's not circulating, and or rad to me. Quote Link to comment Share on other sites More sharing options...
simonb Posted January 7, 2007 Share Posted January 7, 2007 If the rad and thermostat housing vent hoses are clear, then with expansion cap off, fast idle say 2000rpm, should produce enough bleed water to roughly agitate surface of water in expansion tank and produce water sploshing past the neck of the tank. I suspect you either have a partially silted radiator - if its done more than 100k miles it will be past its best and or the bleed from the thermostat housing is blocked. Air will collect in the housing, thermostat won't be completely immersed in water and will either open very late or not at all. A 300Tdi will take at least 5-6 miles (at 40mph) and perhaps 10 mins to get the thermostat to open from cold. If its getting hot before this then I would say blown head gasket and combustion gas in coolant causing steam and overheating. To fill a 300Tdi, take the plastic plugs out of the rad and thermostat housing. Fill through expansion bottle till water comes out of radiator hole. Refit plug, continue filling till it comes out of thermostat hole, refit that plug and then fill to level in expansion tank. A 300Tdi will automatically self bleed if both vents hoses are clear. Quote Link to comment Share on other sites More sharing options...
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