Are there any tricks for the DIY diesel filter replacement in my '87 wagon?
I have been having faltering and some stalling and have a brand new KN filter. Seems to be getting enough air but having stalling issues at higher than idle. No smoking.
I DID mix about 50% (5 gal) of some fuel that has been sitting in the tank of my boat, about 50-75 gallons of biobor treated fuel, that is probably 3 years old.
OK, PERHAPS that is why the car is running crappy. I have since filled up twice which is why I want to try the filter first.

How do I do it?

Sorry, K&N AIR flter

Pretty likely the old fuel is causing the problem, but anyway:

To replace the main (spin-on) filter, loosen & remove the top center nut, disconnect the hard plastic vacuum line from the vac pump, and slide the filter straight forward. Pull it upward, keeping it upright so you don't spill fuel. Replace both O-rings on the hollow center bolt. Fill the new filter with clean diesel, or Diesel Purge. Re-install. When starting the car the first time, keep the pedal near the floor until the engine fires and starts revving. If you don't fill the new filter, you'll likely kill the battery cranking away, as the lift pump slowly fills it up...

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Dave
Boise, ID
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hey gsxr, I have a 93 300D and was wondering, and I'm replacing my fuel filters, which one do I do first, the plastic one (primary??) or the larger one (secondary?) I was under the impression that the primary was the larger one and the secondary filter the small plastic filter. And how often should they be replaced?

On big diesels, the primary filter is the one on the engine that does the main filtering. On the Mercedes', it seems that the primary-secondary is in order of flow, meaning they call the little pre-filter the primary.

I usually replace my primary/main filter at oil changes unless I forget, almost never change the little pre-filter, I can see it is clear/clean. If I'm changing both, I do them at the same time.

Rustdust:
The old fuel shouldn't affect it, unless there is some water or other problem with the fuel. Could be air getting in the system, clogging filters usually are evident when you lose power and have no smoke/no power at full-throttle, sometimes a hunting idle follows highway driving until the fuel filter passes enough fuel to get the pressure back to normal. Can also be the fuel strainer in the tank.

If you want to upgrade from that crappy K&N to a real cold-air intake, AKA: the original filter system, I have one I can sell you. Better filtration, cold outside air, and more than enough ariflow for a stock 603.

When replacing the main filter, I usually fill it first with clean ATF to reduce the wear on the starter & battery, I keep a quart in the trunk just in case I ever have to change a filter on the road, might not have enough ghusto in the battery to self-prime on a cold day.

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Gone to the dark side

- Jeff

Along with what Jeff said above... I change my main (spin-on) fuel filter at 25kmi intervals. I think the official factory specified interval is 30kmi. (?)

The little plastic one, well, if you can see inside it, you probably don't need to change it unless it's got crud in there. But I usually end up changing it at 25kmi as well, unless it looks remarkably clean. If you can't see inside (some are opaque instead of clear), change it at the same time as the big spin-on filter.

When I changed mine, I had a hard time getting it out because some lines were in the way. What I didn't know was that there was fuel leaking out the entire time because I didn't take off the fuel hose that runs to it. Needless to say, it was a mess. It might help to put a bag underneath the spin-on when you take it off to catch any leaks, if you are concerned about making a mess.
I had to go back and take it off again to fill it with fuel the next day, and this time when I took off the fuel hose to plug it, it barely leaked at all. Oh well. Must be a gravity issue.
It might also help to crack the fuel lines at the injectors to get some of the air out if it takes too long to crank. Luckily I have a good battery!
..I learned from my mistakes!

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Dan
2005 E320 CDI - 246k
1987 300SDL TD05-16g, Herlevi pump, Elbe manifold, 2.47 LSD - 213k
Past: 1987 300D - 264k

BTW - Decent price on WIX filters (air, fuel , oil , automatic transmission ) at www.filter1.com. I am only a satisfied customer .