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View Full Version : Engine Knock on Colder days? Oil Pressure?



Bvulic
11-16-2010, 08:50 PM
I recently changed my oil and decided to run ow-30 for the cold winters here in Chicago. And shortly after, I get a slight knocking noise that can be heard int he interior only while completely stopped. Any ideas? Once the car moves, It doesn't make the knocking sound. b5 a4 1999.5 85k

walky_talky20
11-16-2010, 08:54 PM
What is the oil temp when you hear the noise? Stone cold? All heated up? When you pop the hood, where is the noise coming from?

Bvulic
11-16-2010, 09:04 PM
Pretty much stone cold. Probably 1-2 notches above 150 degrees. I don't necessarily hear it when I pop the hood. Its relatively quiet from the inside too the only time I hear it is when I turn the radio off. Its kind of annoying, and my oil level is fine. is this viscosity ok to run in the winter? I was almost positive it was.

walky_talky20
11-16-2010, 09:16 PM
I like 0W-40. The second number is the viscosity when hot, which isn't really affected by outside temperature. The first number is the important one when considering severe outside temps.

2 ticks above 150F? That should be about operating temp. I'm thinking your 30 weight oil isn't heavy enough when the oil gets hot, and it's causing a little bit of extra top end noise. It is probably just a little bit of lifter noise at idle. I'd definitely try a 0W-40 or 5W-40. Also, having the oil pressure checked is always a good idea on a 1.8T due to their propensity to clog the pickup screen.

Bvulic
11-16-2010, 09:22 PM
Hmm. Yeah thats exactly what I was thinking. its very minimal but I'm very picky when it comes to random noises. I think I might switch back to 0w-40 if I can soon. I also sent you a Pm if you'd like to help out. Thanks a lot.

FNK
11-17-2010, 07:15 AM
This look like oil pressure,
At idle the oil pressure is at minimal but when using higher RPM it doesn't make noise, as more oil is moving and hydraulic lifter stay full. Symptom of oil pressure.
There is just too much distance between surfaces of your hydraulic lifter, therefor oil with lower viscosity cannot hold.
Your Oil pump isn't bad.

I'd change the oil for 5w-40 right away. From there you can conclude if the noise get away or not.
Then if you like, you can start lowering the viscosity again until the noise is apparent again.

Bvulic
11-17-2010, 05:51 PM
great idea, I think 'Im going to do that. Except I hate doing things twice. This is so lame lolll

Bvulic
11-17-2010, 05:54 PM
Thanks for all the help guys.

stack
11-17-2010, 06:09 PM
i looked at some technical service bulletins.

they said knocking is normal at cold start. cold days.

FNK
11-17-2010, 06:25 PM
Mine knock too, only for ~ of a second, but only when I didn't ran the car for a couple of days. Otherwise it's completely silent (the knocking is gone).

Bvulic
11-17-2010, 06:26 PM
Hmm yeah Thats believable. but I do think it has something to do with the viscosity of the oil I used . because it started happening right after my recent winter oil change. Thanks for helping out Stack. Its very very minimal almost not noticeable but Im real ocd about noises in my car. Need everything to be perfect.

Bvulic
11-30-2010, 09:31 PM
UPDATE: I recently changed my oil again and replaced it with 10w-40 mobil 1 fully synthetic this time around and the problem has stopped. Thanks a lot!

FNK
12-01-2010, 08:01 AM
Great news, thank for the feedback!

walky_talky20
12-01-2010, 09:46 AM
Thanks for updating the thread. This is why I only recommend *W-40 weight for the 1.8T. The turbo gets the oil hot enough that a 30 weight oil thins out too much when it gets to full temp. At least for some of the oil brands.