BreakMyWindow 1874 Report post Posted April 24, 2007 Hi, I have an e39 528ise nz-new fsh, blah blah blah When driving for lengthy periods on the motorway, or on very cold days, the coolant temp goes down, like almost back in to the blue zone. It also takes longer than normal for the car to reach normal operating temp (coolant temp half way) the car never overheats (according to the guage anyway) thus leads me to believe the thermostat is stuck open. My questions are, will this affect the engines condition in anyway? should i get the thermostat replaced? im thinking because the m52 is an alloy block and head lump, the frequent change in coolant temp will have an effect on the engine, and the engine oil ? like warping or cracking ?? afaik its only when the engine is overheated that you start warping cracking things ?? thanks for any constructive/helpful feedback :-D Quote Share this post Link to post Share on other sites
Jazzbass 1 Report post Posted April 24, 2007 The E39 did need to have thermostats replaced, IIRC. Mine has had two (before I got it) according to the service history. As 3P says - low cost easy job & certainly worthwhile. Quote Share this post Link to post Share on other sites
BreakMyWindow 1874 Report post Posted April 28, 2007 thanks, ok will replace the thermo alongside when the coolant gets replaced. Thanks for help fellas :-) Quote Share this post Link to post Share on other sites
