S60 Thermostat problems

[simonbyard]

Sorry guys, re-posting here - think I had this posted wrong the first time

I have a problem with the ECT sensor on my S60 2001 2litre petrol. Usually, it never reads past half way on the gauge (even though I know the engines getting hotter), and sometimes, when the car is pushed hard, the gauge will suddenly show no reading at all - eventually coming back after car is driven a little kinder for a few minutes. Only once did the gauge seem to work properly, and show a high temperature when it was getting real hot. Could this be caused by having no thermostat? Reason I ask is that I havent long had the car, and was getting suspicious it had no stat for a few reasons.
1. At motorway speeds from cold, the gauge would hardly reach 1/4 way up - in slo traffic, it would reach half way, then when driven faster again at a constant speed, would drop right down.
2. Suspicious amount of sealant sticking out the the thermostat housing join - where it would not be needed if a stat and a properly fitted rubber seal had been fitted.

Sure enough, I popped the stat housing today, and no thermostat inside. Typical!

Anyway, just wanted to see if not having a stat would effect the sensor reading - can't see why it should, as when a normal stat is in place and up to temp, if allows water through anyway without affecting the sensor - but I'm sure I read somewhere that it could.

[priapism]

No thermostat would result in the coolant flowing way too fast to cool effectively. It costs like $8 to replace and takes about 4 minutes, swap it and I bet lots of things get better. If not it's likely your temperature sending unit.

[simonbyard]

thanks priaspism - I already got the stat, thanks - will have car back on road next week and see if that cures the temp gauge issue. was just curious as to whether it screwed the reading was all - as to the over cooling, yeah means the car's in warm up mode way too long, and gives crap gas mileage, as well as poor performance. I hate it when u buy a car, then find the previous pwner couldn't even be bothered to do the most basic maintenance - like u say, the thermostat costs nothing to put in.