Oil filters

**Drew63** · 14th February 2016, 01:11 PM

Hi, can anyone shed some light on this pls? I just changed oil and filters on my 1991 TD42. I took the oil filter closest to the front of the
engine off first, this was dirty as expected. I then took the second filter off, closest to the fire wall. This filter was clean. Can someone
let me know why this has happened? Cheers.

**NissanPatrol.com.au** · 14th February 2016 01:11 PM

**threedogs** · 14th February 2016, 03:59 PM

Hi Drew at a guess Id say the first filter is doing its job and doing it well.
Can you also pop over to the intro ,just something the forum asks of us all
polite and ,,,,no harm done though enjoy lol

**nissannewby** · 15th February 2016, 10:41 PM

I have a circuit I will take a pic for you.

**Drew63** · 16th February 2016, 05:19 PM

Thanks, that would be great.

**Col.T** · 16th February 2016, 06:55 PM

G'day all,
we think it amazing.
Had a td42 for about 300k and NEVER saw one clean filter with the other black as usual on a diesel at servicing. Not sure if all is working normally that that would be possible.
Can't see that there could be a blockage in the oil system without causing major problems.
Not sure how one filter could be bypassed whilst the other one's not but until the Newboy puts up a circuit diagram we'll have to wait.
Mysterious.
Col.

**nissannewby** · 16th February 2016, 07:23 PM

I thought it had more detail. Dont quote me on this but the front filter is your main filter with a bypass in the housing. If the front filter starts to clog the rear filter will then get some flow. There has also apparently been issues with anti drain back valves on some filters. So I wouldnt stress to much.

**graeme1969** · 16th February 2016, 07:27 PM

Gday. I had the same issue when I used the repco equivalent filters once. Haven't used them since as I didn't think it seemed right so just stick with ryco now.

**Drew63** · 16th February 2016, 11:33 PM

Thanks for all the input. I Removed the new second filter today and found it to be in use, so i think the issue was an anti drain back valve in the repco filter i had. Will keep you all posted as to what it's like at the next filter change.
Thanks once again.

**Drew63** · 16th February 2016, 11:36 PM

Thanks nissannewby, handy chart to have, and thanks for taking the time. Cheers

**Snafu** · 21st February 2016, 11:21 AM

Don't muck about with cheap filters personally I only use Donaldson filters.

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