Driving to work today in the TD I began smelling diesel. When I got to work, I opened the hood thinking I'd see leaky return lines. Instead I saw a wet left front inner fender and diesel dripping from the second fuel filter bracket. Looking closely I could see no leaking lines. Lucky for me I had a 24mm wrench in the car and a spare secondary filter. I took the existing filter off and replaced it. Once I turned the filter upside down I saw the source of the leak--two cracks in the bottom of the secondary filter slightly rust colored. They were pumping out a fair amount of fuel. I'd guess maybe a cup every 5 or ten minutes, probably more at high rpm's. The filter is at least 4 yrs old. I'm thinking water accumulated in the bottom of the filter and rusted it through? I've never experienced that before.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

4 year old filter! It was time for a new one anyway.

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Cell posted the same thing a few months ago.
http://www.peachparts.com/shopforum/diesel-discussion/307329-pinhole-leak-secondary-fuel-filter.html


This pretty much proves to me how important a proper fuel water separator should be installed in diesel engines. The fuel quality is hit and miss, and the potential of water is great. The shallow bowl of the stock MB fuel filter is worthless and could only hold so much water.

Using an aftermarket fuel filter setup like Stanadyne or Racor would help this situation.

Here is also a link to a fuel filter mod using a Baldwin filter that can be drained out periodically.
http://www.peachparts.com/shopforum/diesel-discussion/225004-lower-micron-fuel-filter-mod.html



.

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1983 123.133 California
- GreaseCar Veg System

4 years ?, I thought I was pushing it waiting over two years to change ours. Would never have admitted on the forum as to waiting two years until now.
I waited so long in hopes of putting one of those fancy water separators that a friend showed me on his cummins onto our wagons.

At least you had the parts and tools prepared ahead of time. I wondered how long a person should wait to change their fuel filter. I only changed ours cause of the time it had been on there.... otherwise no performance loss with the old filter and no gain with the new one.
I guess you established a maximum period they will work until. Maybe the water froze in combination with the rust and caused the cracks?

Yes, freezing probably occurred. I only replace fuel filters once they start plugging up, or I guess now when they rust thru

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

You mean I don't have to change fuel filters every 3000 miles when I change oil?

DOH!

I change mine every year - valve adjustment.
Unless forced to replace them sooner.
.

Mine started leaking recently too --after a hard freeze.

I've not seen actual numbers for a 123 but I think about every 10k - 15k miles or so is pretty standard for fuel filters. So as whunter stated at each valve adjustment is a good time to do it, or every 3 to 4 oil changes(assuming 3000mi intervals)

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Why? Because the hood is already up?

What's with you and your one line criticisms dude. Do you ever help, or just criticize everyone else's posts? I also notice you said it to me and not whunter!?

I stated that it was a good time to do it because, the valve adjustment interval is also about what I've heard for fresh fuel filters.

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I'm pretty sure this is the third filter I've put on the TD. One when I bought it, one when that one plugged up and one today. So that's about one every 4 yrs and 40k miles. Tango has a point. What's the rationale for changing them? It seems to me that the interval is entirely dependent on the quality of fuel you buy. You may have to change them every month or once every 10 yrs.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

It's too bad MB went away from this W115 300D lashup:

http://www.peachparts.com/shopforum/diesel-discussion/312101-w115-300d-1976-spin-fuel-filter-help.html

As pointed out, it's the same filter as is used on the VW 1.6. It's a huge filter with a built in water trap and drain at the bottom. Me like.

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80 300SD (129k mi) 82 240D stick (193k mi)77 240D auto - stick to be (153k mi) 85 380SL (145k mi) 89 BMW 535i 82 Diesel Rabbit Pickup (374k mi) 91 Jetta IDI Diesel (155k mi) 81 VW Rabbit Convertible Diesel 70 Triumph Spitfire Mk III (63kmi)66 Triumph TR4a IRS (90k mi)67 Ford F-100 (??)

It's not so much his point, it's the passive-aggressive one liners that irritate me. that seems to be all he posts. They're not helpful, just critical.

I realize that filters can go much longer than 10k miles or much shorter, I've been on both ends of that. But it's preventative maintenance. Some folks don't want to deal with filter changes on the road. You don't run your tires completely flat before you fill them up properly. You're also loosing performance as the filter clogs. So to maintain a well performing machine you may not want to wait until the filter is completely clogged. Also if you've got water collecting in the both, who's to say your not injecting water into your engine. I personally wouldn't go 40k miles on a filter. Avoiding possible added stress to the IP, possible water collection, and miserable roadside conditions for changing a filter is worth the $8 for a filter. But that's just me.

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There was an add-on water-in-the-fuel indicator kit for those VW 1.6's, too. Had a little sensor deal that went in the bottom of the filter, where the water drain was.

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1981 Mercedes 300TD, 1994 Honda Civic Del Sol
http://mefi.us/images/fuelly/smallsig-us/67195.pnghttp://mefi.us/images/fuelly/smallsig-us/103885.png