Ivan Posted December 13, 2005 Share Posted December 13, 2005 Have mentioned this before but think it was on the old place. Earlier this year I fitted a 300 Tdi to the 90 (was 2.5 Td). The temp gauge would not work with the new engine so I fitted a Racetech gauage and sender. Problem is that the engine appears to be running hot. The gauge shows the temp rising to the 100 mark. I replaced the thermostat, no change. I took the centre of the thermostat out and it was all fine. It never got hot and the highest it ever got to was just under 90 after a long run and then being sat in traffic for 30 mins. Now that winter is here the wife was complaining that it never got warm and the heater was putting out luke warm air (temp gauge never rose much above 40). So, I fitted a new thermostat. Car warms up great but the temp now rises to 100 again and it will go higher if you push it. I fitted a temperature probe into the header tank and took the car for a drive. The temp probe was showing 84 whilst the gauge was showing 100. So I fitted a new sender (from racetech). The gauge still shows the temp rising to 100 and over. I did suspect the thermostat was not opening properly but I have just fitted another brand new one and am having the same problem. My only possible thought is that the water pump is not moving the water fast enough does this sound feasible ? Anyone got any clues or ideas as to what's going on ? Thnx Ivan Quote Link to comment Share on other sites More sharing options...
LR90 Posted December 13, 2005 Share Posted December 13, 2005 Ivan, I'm not sure I understand what the problem is? 100 doesn't sound wrong and that is the reason the system is pressurised to prevent it boiling. Is'nt a TDi thermostat set for someting like 103 degrees. Quote Link to comment Share on other sites More sharing options...
Ivan Posted December 13, 2005 Author Share Posted December 13, 2005 Trev The thermostat should open at about 84 degrees. So I would expect the engine temp to be running at arond that point (as thermostat opens and closes). Problem is, if it's running at the 100 mark during winter, it's going to be running higher than that during the summer. Also if you start to drive it at more than 55-60 Mph the temp continues to rise. Whereas without the thermostat it's not a problem. What's confusing me is the fact that the header tank is reading 84 whilst the gauge is showing 100. I thought that the sender may have been u/s which is why I fitted a new one. But the new one shows the same symptoms. From what I have heard on here Tdi's are overcooled so should never run that hot except when there is a problem. Without a thermostat the engine runs really cool, with a thermostat I would expect it to run hotter than without but not around the 100 mark. does this make sense ? Ivan Quote Link to comment Share on other sites More sharing options...
oneten110 Posted December 13, 2005 Share Posted December 13, 2005 Tdi stat is marked 88, which presumably is the optimum operating temperature for the engine Quote Link to comment Share on other sites More sharing options...
simonb Posted December 13, 2005 Share Posted December 13, 2005 (edited) Correct, see my reply on int forum. With the Racetech gauge u can see the thermostat opening. Around town it will probably be shut. On my 300Tdi i can do 5-6 miles at 40mph before the thermostat opens, and thats with an engine preheater which heats the water to 60 degrees. Stuck in traffic u can see the gauge showing the thermostat has shut and then reopen as you get underway again. The water temp should never go past 90 degrees even flat out foot to floor up a motorway hill... The bleed pipe on the thermostat housing, the one on the rad and the combiner are clear aren't they??? Edited December 13, 2005 by simonb Quote Link to comment Share on other sites More sharing options...
Ivan Posted December 14, 2005 Author Share Posted December 14, 2005 Simon I'll check the pipes but they were brand new when the engine was fitted. Ivan Quote Link to comment Share on other sites More sharing options...
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