Why am I hearing this horrible rattle when cold?

[SpeedFreek]

I have a 2005.5 Jetta with about 66k on it, when its colder out that about 30*F the engine sounds really rough for a few seconds. Then it starts sounding normal and runs fine. I always let my glowplugs fully cycle before I start it and it still has the rattling noise. This morning it was 17*F on the display and I started it after letting the glowplugs fully cycle and it was shuddering and making some horrible noise and I got an emergency message on the MFD telling me to turn it off because of coolant problems. So I shut it off and check the coolant which was perfectly fine and start it again and it ran fine all the way home.

Are my glowplugs going bad? Should it shudder that much? How bad is that rattling noise?

 

[Jason D]

The clatter is normal. Mine sounds the same way when its cold out. As far as the coolant issue, I have no idea.

 

[Antsrcool]

research the term "DMF" its a possibility its failing on you

 

[SpeedFreek]

I dont understand why after two winters of starting up and running smooth at below zero tempatures it begins doing this now. This morning when I start it I plan on cycling the glow plugs a few times to see if that does anything.

As for the DMF I understood that if it was going to fail it would at a much lower mileage. Also why would it only be brought on by cold tempatures with the clutch out for only about 30 to 40 seconds when the car has been sitting all night?

 

[velociT]

I wouldn't think cold engine clatter has anything to do with the DMF.

All diesels are noisy during 'winter' startups. Youtube a few diesel cold starts. Some strokers/cummins sound HORRIBLE when starting in below freezing temps.

 

[SpeedFreek]

I tried cycling the glow plugs twice this morning and this afternoon when I started it and though the temperature was warmer (30*F) there was much less rattling than letting them cycle once. I didn't get the coolant warning again but that could all be due to the warmer temperature.

I would really like to get this straightened out before it gets colder, how can I test the plugs and can I pull anything useful with vag com? I will hook it up in the morning before I start it and log whatever happens but what specifically should I be looking at?

 

[roadhard1960]

A diesel is louder when cold. Your engine light should come on if the glow plugs have issues. I start my car in the winter the same as I start my gas cars. I turn the ignition to engage the starter and the car starts. I sometimes sounds like a cup of marbles but it smooths out and quiets down as the engien warms up. If it is really cold I will make use of the glow plugs in the proper fashion.