Thread: TDi Thermostat

Originally Posted by bicubic

Well it's not having any ongoing problem (temp sits just off centre where it always sits) but it did blow out the top plastic plug in the thermostat housing (why I did not change it out is another story–stupid plastic piece of... ). Thankfully the coolant alarm fired and the rest is just an annoying history. I lost the seal on the water pump (which I replaced with a new OEM pump) but the previous pump seems okay. The P gasket has just started to leak which I'm connecting to the 'incident'. It was a roadside repair far from home and thankfully I was carrying a water pump and all the bits.

Anyway... this made me realise that a full 'book' service history misses a lot of the stuff mentioned here, so I'm switching to pre-emptive time-based servicing as the 'ole girl has very low k's. The overflow bottle is being replaced in this round too—bugger that splitting somewhere far away.

I was just interested in the thermostat discussion before I replace it but maybe I'll just keep it OEM.

the only thing I different is to bore out the bleeder hole or the bleeder widget to 3/16th it aids in the initial bleeding of the cooling system

Here in the States there is a brand called MOTORAD, an Israel company that manufactures thermostats. The replacement listed for the 300Tdi is 319-192, there is also a 319-180. The last 3 digits of the part number indicate the degrees F where the T-stat begins to open.

The issue I'm having is that the Tdi measures 178 degrees F at the T-stat housing (by the sender) and the VDO gauge shows about 192 F. I've enlarged the wires to the gauge to 14ga, to reduce any possibility of resistance being the issue.

I'm also trying to actually INCREASE my running temperature to around 200 degrees F as I seem to get better performance from a warmer engine. I live in a colder climate and the engine seems to run cold. Blocking the Radiator, in the winter, has no effect on raising the engine temperature .

I've seen in VW Tdi and Ford diesel forums where they are running 203 degrees F for better performance. Ford actually calls out the 203 for there diesel pick-up engines, I think the 7.3L.

I've actually combined MOTORAD parts (mostly the wax pellet) to devise a 198, a 203 and a 205 degree F Thermostats. I've ran the 198 with no ill effects for over 4000 miles and have just installed the 203. All flow ports in the various T-stats I've configured, are the same EXCEPTING the 205, it is larger than the normal ERR 3291.
Any thoughts ?

Dennis