davidlandy Posted September 8, 2007 Share Posted September 8, 2007 I suspect that my head gasket may have gone stopped when coolant was leaking from the top rad hose, so topped it up - it took a fair bit. noted that when running and rev it, you can see bubbles in the expansion tank. then temporarily a white foam that disappears quickly. theres no trace of oil in the water or milky residue on the oil filler cap. what do you think? Quote Link to comment Share on other sites More sharing options...
Les Henson Posted September 9, 2007 Share Posted September 9, 2007 There's about 9 different ways a head gasket can blow, so no oil in the water or water in the oil is no reassurance. If the radiator hoses go rock hard after a short while with the engine running and a continual stream of bubbles into the expansion tank all point towards compression loss into the water jacket - usually via the head gasket. If your engine is a 300TDi, then they have a reputation for cracked heads, so if you strip the head off you would be wise to get it crack tested. Les. Quote Link to comment Share on other sites More sharing options...
davidlandy Posted September 9, 2007 Author Share Posted September 9, 2007 There's about 9 different ways a head gasket can blow, so no oil in the water or water in the oil is no reassurance. If the radiator hoses go rock hard after a short while with the engine running and a continual stream of bubbles into the expansion tank all point towards compression loss into the water jacket - usually via the head gasket. If your engine is a 300TDi, then they have a reputation for cracked heads, so if you strip the head off you would be wise to get it crack tested.Les. Thanks Les I thought it was the HG with regards to the cracks - where do they normally go? is it something that can be seen, or does it have to be tested only to find them? Quote Link to comment Share on other sites More sharing options...
Les Henson Posted September 9, 2007 Share Posted September 9, 2007 Sometimes they are visible - such as between valve seats, but not always. Cetramic motor seal may cure a cracked head, but I've not tried it. Les. Quote Link to comment Share on other sites More sharing options...
simonb Posted September 10, 2007 Share Posted September 10, 2007 Thanks LesI thought it was the HG with regards to the cracks - where do they normally go? is it something that can be seen, or does it have to be tested only to find them? 300Tdi is supposed to have bubbles flowing across the top of the water as the bleed hoses from the thermostat housing and rad vent into the tank. My 300Tdi head had cracks from the glow plug holes running back away from the valves, smaller cracks round the injector holes and also cracks between the valve seats. You will need to clean away the carbon deposits to check for cracks...despite the cracks there was no loss of compression or water leaks - it depends how deep they go. Quote Link to comment Share on other sites More sharing options...
davidlandy Posted September 10, 2007 Author Share Posted September 10, 2007 Hmmm I'm gonna run it up again and check - it may had been an airlock from when the top hose was leaking and i may had not toppped it up fully....??? fingers crossed wots the correct way to top up the system from scratch to ensure no air in there? Quote Link to comment Share on other sites More sharing options...
Les Henson Posted September 10, 2007 Share Posted September 10, 2007 Start the engine and slowly fill the system (well not TOO slowly). Once full, take it for a drive for 20-minutes or so to get it up to temperature and check the level again (careful how you remove the tank cap). Any air in the system should have been expelled by then. Les. Quote Link to comment Share on other sites More sharing options...
davidlandy Posted September 10, 2007 Author Share Posted September 10, 2007 do u fill it by the expansion tank cap or the little plastic bunged hole on the thermostat housing top? Quote Link to comment Share on other sites More sharing options...
Les Henson Posted September 11, 2007 Share Posted September 11, 2007 Fill it by the tank cap. The plastic screw on the top of the thermostat housing will snap if you try to remove it or it usually does). Mind you - X-Eng do some rather sexy looking alloy replacements. Les. Quote Link to comment Share on other sites More sharing options...
freeagent Posted September 11, 2007 Share Posted September 11, 2007 any plumbers merchants should be able to supply a brass blanking plug to fit the thermostat housing for about a pound... Quote Link to comment Share on other sites More sharing options...
Gromit Posted September 11, 2007 Share Posted September 11, 2007 Once full, take it for a drive for 20-minutes or so to get it up to temperature and check the level again I fitted a new rad a few weeks ago. Each day, after a full temp run, the level was down a bit. I'd refill and it'd do the same the next day. Took about 3 days to settle down and expel all the air, even though I'd been careful when filling it initially. Quote Link to comment Share on other sites More sharing options...
simonb Posted September 11, 2007 Share Posted September 11, 2007 The WSM states the following for filling a 300Tdi. Remove rad and thermostat housing bungs. Fill through expansion bottle. When level reaches rad top, insert bung. Keep filling until level reaches thermostat bung, refit bung. Keep filling until level is correct in expansion tank. B&Q do 1/2" BSP brass blanking plugs which can be used to replace the naff plastic ones. Quote Link to comment Share on other sites More sharing options...
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