Couple Questions


Veteran Member
Oct 23, 2008
03 2dr 5sp Golf
I think these are not really "newbie" questions but figured TDI 101 was still the place to ask. 1. Would optimal economy RPM perhaps be different on a higher milage engine? Meaning an engine that is at approximately 260,000 that probably hasn't had extensive tolerance work completed such as new rings and could have perhaps a small amount of blow by. That sort of thing. Seems that a higher milage engine may be more efficient at a slightly higher RPM and less load. This is speculation on my part and I really don't know if that would have any affect but was thinking.

2nd question, premised when I shut the engine down sometimes I note the radiator fan/s coming on immediately afterwards and if I notice this I restart the engine. I figured that the fans coming on is a sign that the engine temp needs to cool off more but didn't think that with the engine off that coolant would continue to circulate and therefore wouldn't have the intended purpose as I had imagined. This is kinda a newb question in that I hadn't committed to memory if the coolant pump was electric or mechanical. I maybe know that the pump is mechanical just hadn't confirmed in my mind yet. Also speculation as perhaps the radiator fans coming on are to prevent coolant boiling in the radiator or something. ?


Top Post Dawg
Mar 23, 2011
COLORADO (SE of Denver)
98 Jetta TDI AHU 1.9L (944 TDI swap in progress) I moved so now i got nothing but an AHU in a garage on a pallet.
1. Maybe but it would have to be up there in the 450k+.
As far as the internals go it would be head wear ( guides and carbon build up) that would be a contributor but not so much the block side.
2.once shut down there is no more heat adding to the system so no boiling.
Its typical for heat soak to turn on a fan switch. Lots of people report issues with aluminum upgraded parts being the culprit of heat soak induced fan running.
Turning off the car and the fans running wont cause any issues other than a drained battery if it malfunctions.