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Engine Fan on after turning car off?
- Thread starter bloojays1
- Start date
Draz
Ready to race!
Yep, thats why it's on. Stays on for 5-10 minutes. For me it comes on about once a week.
x_paradoxal_x
Ready to race!
Yeah I have noticed that on my diesel golf a couple of times, I was worried as well and turned the car back on and allowed it to idle down for like 5 minutes, might as well, diesels hardly use fuel when idling. Although I have not experienced this on my GTI, and I sometimes drive it hard.
McQueen77
Banned
i'm GTI, not TDI, but anyway, I notice the fan coming on more often when I'm doing short trips around town during the day when temperatures are hotter. Tonight on the way home I was driving it pretty hard, got home, idled for a few, shut it off and no fan. The other day I was running errands and doing multiple short trips with it being about 84 out and the fan came on when I got home and stayed on for a few minutes. 'Really cool story bro', I know.. Diesel or none, they've both got a turbo and it gets hot as shit, so the fan is cooling it off, no? Hence the reason why some argue that it is not necessary to let your engine idle after hard driving since the fan cools it for you?
x_paradoxal_x
Ready to race!
Yeah I have noticed it only once in my GTI. But today when I was driving the TDI, it got pretty hot hear today, like over 30 C and the fan was on WHILE I was driving, I could hear the thing and I got worried!
All of this while I was taking my driving test which I failed. I'm American, but have never really driven in America until recently. Guess I picked up some bad habits in Europe. But a hell of a time for a new car to start making noises I have already been worried about.
I didn't even drive it hard at all, but that fan was still going with the engine down. Does the Golf GTI and TDI need a better Intercooler and Intake??? I've been thinking about APR but don't want to make any beefs with VW.
All of this while I was taking my driving test which I failed. I'm American, but have never really driven in America until recently. Guess I picked up some bad habits in Europe. But a hell of a time for a new car to start making noises I have already been worried about.
I didn't even drive it hard at all, but that fan was still going with the engine down. Does the Golf GTI and TDI need a better Intercooler and Intake??? I've been thinking about APR but don't want to make any beefs with VW.
Guys, guys...the TDI has a DPF or Diesel Particulate Filter. The TDI motor injects a small amount of fuel into the filter to ignite the particulate. There is no relationship between gas motor and diesel motor fans staying on. None. For anyone who cares to know, heat dissipation is not a problem with a diesel motor, because diesel motors burn more efficiently than gas, and wastes less energy as heat.
The whole point in idling for a few minutes before killing the engine is to keep fresh, relatively-cool oil flowing through the turbo bearing to cool the bearing back down enough so it won't fry the stagnant oil that's left in it when you shut the engine down. If you're not running a good synthetic oil and you just shut the engine/turbo down hot, the elevated (and elevating) temperature in the bearing will fry the oil...coking (gumming up) the bearing. In theory, anyway...
The radiator fan on our cars doesn't/can't cool the turbo directly because the turbo is on the back of the engine and has a heat shield over the turbine anyway. Even if the fan blew directly on the turbo for that 5-10 minutes, it probably wouldn't cool the oil/bearing enough to prevent the above-mentioned coking scenario.
Exactly. Thermodynamically, the diesel combustion cycle is just more efficient: more of the heat is used to do the work of pushing the piston down, and less is left to escape as waste heat into the coolant. This is why the folks in Canada and our northern states sometimes have trouble fully warming up their TDIs in the dead of winter: after the combustion cycle does the work of pushing the piston down, there's just not enough waste heat reaching the coolant to fully warm up an engine that's as cold as they sometimes get in those climates...
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McQueen77
Banned
Wow, I feel dumb now. Thanks for the info though man, good post:thumbsup:
xHeartcoreboyx
IceCream GTI
I let it idle for couple minutes down and was surpriced that my oil temp actaully went higher ( we have the sensor for that in euro models)..
sometimes i just drive slowely before coming back home from a spirited drive..isnt that better than idling?
also if the fans dony kick in when i turn it off, is that an indicator that i did a good job in cooling stuff down?
Sent from my iPhone with typos.
sometimes i just drive slowely before coming back home from a spirited drive..isnt that better than idling?
also if the fans dony kick in when i turn it off, is that an indicator that i did a good job in cooling stuff down?
Sent from my iPhone with typos.
xHeartcoreboyx
IceCream GTI
I am soo getting the apr ic soon =|
Sent from my iPhone with typos.
Sent from my iPhone with typos.
The engine oil temperature went up because the oil was doing its job, which was drawing the heat out of the turbo bearing and carrying it away to the rest of the engine and/or the oil cooler where it ultimately dissipated. If the oil temperature sensor was located at the oil discharge point on the turbo (instead of wherever it really is), and you could see what the oil temperature is at this, the hottest point for oil on the engine, you'd probably crap yourself. It's kind of amazing that any kind of conventional oil could ever survive that kind of thermal abuse. That's one of the main reasons that they fill our TDIs with synthetic oil...
It's not better than idling, but any kind of operation that keeps oil flowing through the turbo bearing without adding heat to the turbo is better (for cooling the bearing) than operating with a load on the engine.
There are two different (and more-or-less unrelated) reasons that the fans could go/remain on after shutdown:
1) The engine coolant was hot enough to require the fans for cooling to prevent a coolant discharge.
2) The computer decided, based on various conditions and/or sensor inputs, and without knowing that you were about to shut down the car, that it was time to conduct a DPF regeneration cycle. Once the cycle is initiated and the DPF has heated up, unless the car is traveling at a speed that provides enough airflow around the engine to keep everything around the DPF "happy", the fans will run to provide that airflow...even after shutdown.
So, if the fans don't kick on, then the engine coolant is cool enough, and there is no DPF regeneration cycle taking place...
Well, I feel kind of stupid. I just noticed that you are not driving a TDI at all. That means that you can ignore everything that I just said about DPF regeneration in 2) above. Only 1) applies to your situation...
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