Fuel filter effeciency

[cad58y]

1986 300SDL in CC storage for the last 10 years. Recently got it running without much trouble. Changed all fluids and replaced primary and secondary fuel filters. Drove it about 15 miles and noticed that the inline filter contained a large amount of sludge/sediment (looks like rust). My question is how effective are the filters in protecting the fuel injection system from damage. I plan to drop the tank and have it coated but am concerned that i may have already caused damage. Thanks, Bob Smits

[Diseasel300]

If it's just sediment (probably from a bio infestation), the filters will do a decent job of keeping the crap out. Be aware that the filters can clog quickly and leave you stranded.

If there is water in the tank from storage, you need to be worried about destroying the injection pump and fuel injectors. The filters won't protect you from water content.

[Diesel911]

Originally Posted by cad58y

1986 300SDL in CC storage for the last 10 years. Recently got it running without much trouble. Changed all fluids and replaced primary and secondary fuel filters. Drove it about 15 miles and noticed that the inline filter contained a large amount of sludge/sediment (looks like rust). My question is how effective are the filters in protecting the fuel injection system from damage. I plan to drop the tank and have it coated but am concerned that i may have already caused damage. Thanks, Bob Smits

It is not an infrequent occurrence on all diesels and the Stock Filters normally do well at protecting.

You can coat the tank if you want to but if it is infected you need to use something like Startron with an enzyme to eat up the stuff or a biocide to kill it because that infection is also in your fuel lines and tubing.

The stock spin on fuel filter is a 10 nominal micron filter. That means on the first pass through the filter it will filter out 50% of the 10 micron particles.

If you go to the WIX filter site and look up the one for your year and model it will give you the filter rating. It will be in nominal microns or there is a newer rating that I cannot remember the name of.

On my year and model there is room for a larger Spin-on Fuel Filter and one that filters out smaller particles.

DELIVERYVALVE filter mod
Lower Micron Fuel Filter Mod

http://www.peachparts.com/shopforum/diesel-discussion/225004-lower-micron-fuel-filter-mod.html

If Water got all the way to the inside of the Fuel Injection Pump and sits over night it can cause rust. But, if water got in while you are driving you would notice as it would run badly.

From what I have read on the form the water issue is rare. The stock filter has about 1/2 quart of capacity before water would get out of it.

I cut one of my larger used filters apart and after over one year of use I found about a teaspoon of Water in the bottom of it.

[cad58y]

Thank you. I am going to cut the filter open to better examine the sediment. I did add a biocide several weeks ago when I started the project.

[strelnik]

Originally Posted by cad58y

1986 300SDL in CC storage for the last 10 years. Recently got it running without much trouble. Changed all fluids and replaced primary and secondary fuel filters. Drove it about 15 miles and noticed that the inline filter contained a large amount of sludge/sediment (looks like rust). My question is how effective are the filters in protecting the fuel injection system from damage. I plan to drop the tank and have it coated but am concerned that i may have already caused damage. Thanks, Bob Smits

When you re-do the tank, go to the places that have lifetime guarantee and actually put a brass tag on your tank. I had that done for my expensive Citroen. DS21. Additionally, a tank redo will include a stripping all the way to the terne (yes, this is the proper spelling) metal base and destroy all such bio parasites. Don't forget to also blow out the fuel line near the first fuel filter. Or you can soak the filters in diesel purge for about an hour to dissolve anything that might be lingering in newly-installed filters.


It is definitely worth it to do this.


My friend Philly Joe drops highly-concentrated lye solutions in tanks after draining, bubbles the at 40 psi for an hour and rinses twice. With a small bore sight camera he is able to check all surfaces and clean everything out.


Good luck!

[cad58y]

I cut open my primary filter and it definitely has rust particles in it. I will be dropping the tank today. Are there any tricks/precautions I should know. I did this on the 81 SLC a couple of years ago and getting the tank out was a PITA.

[Diseasel300]

It isn't too horrible. Remove the rear seat, pop the plastic plug out of the rear bulkhead covering the fuel sending unit and unplug it. Drain the tank, disconnect the hoses from the bottom, remove the false wall in the trunk, remove the retaining bolts on the tank, and pull it out through the trunk. Be aware that the vent line may fight you a bit (mine did!).

[cad58y]

After a bunch of interruptions(like replacing the engine on my 64 Bonneville) the SDL is back on the road. Removing and cleaning the fuel tank wasn't too bad. A lot of crud on the bottom. I ended up using a Bill Hirsch sealer. Their etching product did a great job prior to applying the sealer. The fuel gauge hadn't worked for some time so I took it apart. The float was stuck so I cleaned it carefully. My question is now the gauge works 90% of the time but will occasionally swing to empty for a few minutes and then return. Is this a poor connection somewhere? Leaving Wednesday driving the SDL on the Texas Tour. Thanks , Bob

[97 SL320]

Does this car have a float and lever or the long cylinder sender?

If lever and float type with resistance traces printed to a ceramic base, they are probably worn off in spots.

If long cylinder, it it probably sludged up and might clear with use. The cylinder type has 2 resistance wires and a float that rides up and down creating a electrical path. VDO is a common brand and used on lots of other german ish cars.

[cad58y]

This was the long cylinder type sender. It was so sludged up that the float was stuck. After cleaning the float moved freely. I will be putting 500 to 700 miles in the car next week so will see if it clears up. Thanks, Bob

[vwnate1]

Keep using a fuel additive and the sender will likely return to proper service after a few tank fulls .

Always use a clear plastic primary fuel screen and as soon as you see debris in it, CHANGE IT .

? What "biocide" did you initially use ? .

Startron's biocide is good for light infestations or as a prophylactic measure but the real dead is Biobor, that's what finally killed off the fungus in my coupe .

[jsp300D]

you need to clean the tank.