Author Topic: Should I let my diesel warm up before driving? (Read 22870 times)

Jettagli16v · « **on:** January 19, 2009, 06:36:30 pm »

I saw something months and months ago (tdiclub.com) before I even bought my TD,
and it said that warming up a diesel engine before driving is useless because the diesel engine does not build temperature at idle.

Certainly, you want to let it idle for at least 15 seconds to allow the oil to get everywhere.

My EGT (Pre-turbine, spruce/VDO) also does not seem to climb until I start loading the engine.

Any advice?
It feels so wrong to start a cold car and just go,
but I will do it if your sage wisdom supports it!

Thanks GTD!
-Brad

Smokey Eddy · « **Reply #1 on:** January 19, 2009, 06:47:17 pm »

I'm going to go with let the turbo see oil and then go. So depending on how cold it is (the viscosity of the oil, if you're running synthetic i guess it doesn't matter...) would determine how long to wait. I would not start the car up, go inside, wait 10 minutes and then go because YES efficient engines take forever to get hot because they are burning so little fuel.

Diesels are renown for burning such a small amount of fuel on idle.

jtanguay · « **Reply #2 on:** January 19, 2009, 06:54:59 pm »

if the temp was -20C or below, idling for a minute or so will ensure that oil is getting to where its needed. using a synthetic you could probably just drive away normally with about 5-10 seconds.

the key here is that you do not want to load the engine while cold. sometimes you need to when going uphill, but try your best not to. thats how most damage occurs, and on TDI's extra sooty deposits will be going through the motor when the EGR is open...

Rabbit TD · « **Reply #3 on:** January 19, 2009, 11:17:22 pm »

Quote from: "Smokey Eddy"

I'm going to go with let the turbo see oil and then go. So depending on how cold it is (the viscosity of the oil, if you're running synthetic i guess it doesn't matter...) would determine how long to wait. I would not start the car up, go inside, wait 10 minutes and then go because YES efficient engines take forever to get hot because they are burning so little fuel.

Diesels are renown for burning such a small amount of fuel on idle.

Boy that's sure the truth, I just started my new 1/6 T//D on the hoist with a cooling system with about a quart and a half of fuel in a big coffee can to feed and return lines and after probably 12 minuets or so running it mostly idle and quick blips it looks like the can is just about where it was when I first started, my leaf blower uses more than that :lol:

Vincent Waldon · « **Reply #4 on:** January 20, 2009, 01:07:17 am »

I've read somewhere once (or twice) that at idle the average diesel engine is running at upwards of 100:1 air/fuel. Contrast that to a gasser 's stoichiometric 14.7:1, even at idle, and you start to understand one reason why they they sip so little fuel just turning over, and hence make very little heat.

Anyone remember "How To Keep Your Rabbit Alive" by Richard Sealey, with the fantastically detailed drawings? Way ahead of the "XXXX for Dummies" books, full of great advice, and with with the occasional dash of SoCal counterculture: Richard stated that the proper warm-up time for a cold VW engine is *exactly* as long as it takes to roll a new... er... cigarette.

Sorry, OP, I digress... yet again! :lol:

Jettagli16v · « **Reply #5 on:** January 21, 2009, 07:43:05 pm »

HAHAHAHA,
I should have given more info, as half of that is not relevant to my particular diesel!

1) I live in FLORIDA... -20C?

(Just kidding, this is good for the general discussion, just not me specifically!)

2) Going up hill?? (See #1!)

Anyways,
It seems like I was thinking straight.
I have not been on Full Synth on this car (burning a lot of oil, and can barely afford the Rotella she drinks) so I always wait for the oil light to go out (never more than 2-4 seconds after I am off the starter) and let her sit until the smoke decreases appreciably. Then I always run with light throttle and shift by 2000 - 2500 until up to regular temperature, then put my warm-up lever in, and ..... Boost away!

My EGT does not move from the bottom (250F) until I am driving... Idle will not move it.

Thanks!
-Brad

Smokey Eddy · « **Reply #6 on:** January 22, 2009, 03:38:50 am »

Quote from: "Rabbit TD"

Quote from: "Smokey Eddy"
I'm going to go with let the turbo see oil and then go. So depending on how cold it is (the viscosity of the oil, if you're running synthetic i guess it doesn't matter...) would determine how long to wait. I would not start the car up, go inside, wait 10 minutes and then go because YES efficient engines take forever to get hot because they are burning so little fuel.

Diesels are renown for burning such a small amount of fuel on idle.

Boy that's sure the truth, I just started my new 1/6 T//D on the hoist with a cooling system with about a quart and a half of fuel in a big coffee can to feed and return lines and after probably 12 minuets or so running it mostly idle and quick blips it looks like the can is just about where it was when I first started, my leaf blower uses more than that :lol:

Your leaf blower prob gets 2 mpg.

DCC · « **Reply #7 on:** January 22, 2009, 08:07:52 am »

I usually get into the car, start it, and then I fasten my seatbelt, turn on the radio, etc, etc.

That gives some time to the oil to get everywhere. After that (a minute or so) I just start driving gently till it gets to proper temperature.

dillenger1 · « **Reply #8 on:** January 22, 2009, 08:21:07 am »

I read in that add that they use a tablespoon an hour at idle

Op-Ivy · « **Reply #9 on:** January 22, 2009, 10:34:19 am »

It's more than a tablespoon for sure. When I used that Moly lubo diesel purge stuff it took about 30 mins before it finished the can.

The can was probably half a litre. Can't remember.

79rabbit4dr · « **Reply #10 on:** January 22, 2009, 01:37:22 pm »

well dang, I use a block heater but still let it idle for 5-10 min because I've got a 10 month old and want the car to be as warm as possible - but I noticed that it took for ever to warm up and wondered if it was worth it. Guess i'll quit wasting fuel and just go, warms up quicker that way anyway!

and i'm in Rexburg Idaho, 0-20 degrees for the past few months.

jtanguay · « **Reply #11 on:** January 22, 2009, 02:28:00 pm »

Quote from: "79rabbit4dr"

well dang, I use a block heater but still let it idle for 5-10 min because I've got a 10 month old and want the car to be as warm as possible - but I noticed that it took for ever to warm up and wondered if it was worth it. Guess i'll quit wasting fuel and just go, warms up quicker that way anyway!

and i'm in Rexburg Idaho, 0-20 degrees for the past few months.

best thing about VW/AUDI vehicles is that the temp gauge doesn't need to be anywhere near operating temp to actually get decent heat out of the vents. normally you can turn the heat on when the gauge just starts to move, and get lukewarm air.

zyewdall · « **Reply #12 on:** January 22, 2009, 06:40:46 pm »

It somewhat depends on whether you have to let it warm up before it will move to....

My VW will take off, with pretty good power, with only 30 seconds idling. It's good to give at least that much just to get the oil flowing everywhere.

My Mitsubishi has no power if cold started (especially at below freezing) till it's warmed up for a few minutes at least -- so you Can't drive it even if you wanted to -- letting the clutch out will just stall it.

I have no idea why the two of them behave so differently...

Z

jtanguay · « **Reply #13 on:** January 22, 2009, 08:06:57 pm »

Quote from: "zyewdall"

It somewhat depends on whether you have to let it warm up before it will move to....

My VW will take off, with pretty good power, with only 30 seconds idling. It's good to give at least that much just to get the oil flowing everywhere.

My Mitsubishi has no power if cold started (especially at below freezing) till it's warmed up for a few minutes at least -- so you Can't drive it even if you wanted to -- letting the clutch out will just stall it.

I have no idea why the two of them behave so differently...

Z

could be the compression and or high CR of the vw/audi diesels.

detroit diesels are awesome. i don't know what they use for cold starting, but they will fire right up in the cold. could possibly be very advanced?

spencebm · « **Reply #14 on:** January 23, 2009, 08:54:32 am »

yeah that is wierd, our detroit always fires right up but it is a sorry excuse for a diesel! no power