Anyone running without a thermostat?

Just wondered if anyone is running the engine without a thermostat, if so what is the temp of the oil when warm

This was the cause of my problems! one sticking thermostat dispite being 1 year old.



I replaced the thermostat with a diesel one, which opens up at 71 degrees compared to the petrol thermo of 87 degrees.

Runs perfect now

Dont suppose you have the part number for this please sounds a good idea !!

I've already fitted the thermostat. VW main dealer quote 2 types, 87 and 71 degree thermostats, one petrol and the other diesel.

Oh right thats easy enough, cheers !!!

Just as an experiment I ran the can without a thermostat. The oil temp. while driving at 70mph  remained at 78 degrees and I noticed that the engine performed with more power, however the water temp remained on 0 which is cold, no heat at all. In town the oil temp went up to 90 degrees and the heater performed as normal.

I also tried a 80 degree thermostat from Halfords (diesel 1.5) but put back the 70 degree thermostat as the performance was better than the 80 degree.

if you take the stat out the water by-passes the rad and just goes round the block/head!!! vveeeeyyyyy bad!!!!

M7R said

if you take the stat out the water by-passes the rad and just goes round the block/head!!! vveeeeyyyyy bad!!!!

It's the other way round. When the stat opens it allows water to circulate through the rad. Without one, the water will always be going through the rad and will take longer to warm up..

i believe its also due to the way it flows as with out the restriction a open stat makes the flow rate is screwed up, i kinda remeber how it works from year 1 uni... ops:

You're both ? right. Think of the thermostat as a T valve, when its cold (closed) it flows the water just around the engine (secondary/bypass circuit), when its hot it diverts it all to the radiator (the primary circuit). So removing the thermostat means that you get approx half* the flow into the radiator all the time, with no temperature regulation.

* In practice, the water will follow the path of least restriction, so it might be 1/4 or less the flow, through the radiator.

The car definitely run better on a lower engine temperature (70-80 degrees) at all speeds, however I can't stand the cold. If they developed an independent heater system the first thing I would do is sling the thermostat. If I'm not mistaken, highly modified rally engines are made to run cooler.

Yes, the cooler an engine's cooler is, the more power is produced (assuming the oil is reasonably up to temperature, and also the engine block is warm/hot too). In fact, modern cars have electronically controlled thermostats to more accurately manage the temperature. And racers have been more closely controlling the temperature of the coolant, to seek out more power.

I didn't know that, very interesting.