They don't run cold, well not the tud3 (which is TOTALLY different to the XUD in every way, complete different series) the tud3 has a hot stat in it and in addition has Serious heat transfer to the water. I once got on to boiling point with no water in it in a matter of about 90 seconds from starting (fresh head on, checking all okay before fitting rad etc) and nearly warped the head, sizzled good....
Unless the stat is sticking, they warm up VERY quick and have a notorious overheating problem though that's more to do with seepage into the coolant from head gasket issues from the wet liners moving in the 1.4 alloy block. The 1.5 cast block doesn't heat as fast and behaves more like an XUD. It's got a different head design with the glow plugs and injector positions reversed as well.
My xud warms up to feel heat from the heater by the end of 2 local roads and is hot on the gauge within 10 mins (fully up to temp) which I think is reasonable. The tdi engines run COOLER and have a lot of trouble warming up if you just let them idle. All tdi engines by nature will run cooler as they have less heat transfer to the head and less friction in/out of the pre-chamber, it's why they are more economic. Energy is lost to heat in a IDI more than a TDI. The runner temperature is governed by thermostat choice and I just changed two on a TDI which as I recall were only 87 degree ones, nothing specially hot. The gauge can be misleading.
Modern tdi's run so cold unless under power that in gentle driving they won't warm up, so they have to have a diesel fired heater fitted to heat the car! Some of the new pug 1.4's have that as I recall.
I'll study the graphs more later, interesting!
Topic: Graph of cylinder pressure vs crank angle, where??? (Read 14566 times)
