1985 300D Fuel Filter Questions
 

I want to replace the fuel filters on my 300D. I read through a few posts and got kind of confused. I'm still a newbie to the world of diesel fuel and would like some advice on what to change. From my understanding there's a spin-on type which is also located near a clear/opaque looking filter. I'd like to change at lease one of these but I'm not sure how much of a pain they would be. Any parts/procedure advice would be greatly appreciated!

thanks!!
Brian

There are two fuel filters. A "spin-on" and small opaque or clear "in-line" filter.

They should both be changed at the same time. Both can be purchased right here on "Fastlane".

1. The in-line filter is the easiest of the two (they both are easy) as all you have to do is loosen the little clamp on each end and remove the old one. Replace with a new one and reclamp.

2. The spin-on filter is located just behind the power steering fluid reservoir and is removed by loosening the large hex head on the top of it. Then just spin it off. It is not encased, and is FULL OF DIESEL so be careful not to spill all over. (voice of experience)
Do not overtighten as you need to "bleed" it later.
You can fill up the new filter with diesel before you put it on, but you can also just use the hand pump when you have finished replacing both of them.

Now unscrew the hand pump and pump until you do not see anymore bubbles coming out of the hex head on top of the larger spin-on filter.

Tighten hex head and you are done.

Thanks!
 

sounds like a piece of cake! i'll order up the parts right now!!

cheers!
brian

There are 2 things I would add to the excellent run down given by Dieseldaddy. First have a roll of paper towels on hand. Bunch up a few sheets and place them below the filters to catch the diesel that will be coming out of them, especially the spin on filter. Also, I would wear some latex or vinyl gloves to protect your hands.

odonnebj,

"If it ain't broke, don't fix it" Ever hear this expression?

If you do not have any fuel starvation problems, the filters are OK and do not have to be replaced. Just carry spares with you and if you notice a loss of power on a long hill, replace the primary (inline) filter just because it is easier and costs less. If you still notice the power loss, replace the secondary (can) filter. Unless you get dirty fuel, you probably won't need to replace the fuel filters you are using now for thousands of miles. New filters don't filter any better than used filters.

If you get a dirty load of fuel like I did in CO on RT76, (first station from CO-NB state line), the new filters will plug almost as fast as the old ones. Lucky I had spares because I had to replace 3 filters in all because of the dirt in the fuel.

P E H

Just a few more tips. I always use the clear inline filter as opposed to the opaque, because if you suspect any kind of fuel problem like dirty fuel or an air leak, the clear lets you check it at a glance. If you have the early version spin on housing with a 22mm head hollow screw, and it leaks when you are done,replace it with an upgraded 24mm head hollow screw unit. You'll never get the leak to stop. You can bleed the system by tightening everything up and pumping the hand pump until you hear a little squeaking sound with each stroke. Then start the car. If it runs a bit and dies, repeat the procedure. Last tip is in regard to the hand pump. If you start to pump and it gushes fuel with every stroke, replace it to save future grief of air in the system. Also you can check for restriction with the hand pump. If you pull it up and it sucks back down on its own, you have a restriction in the line or tank.

Good luck,
Peter

Forget bleeding
 

To avoid having to bleed the fuel system you can fill the main filter (cannister type) up to the brim with either Red Line Diesel Catalyst or plain old diesel fuel. Then put it back on and tighten the top bolt (remember, not too tight!) and start the car and give it gas immediately. That will save you the hassle of using the hand pump.

Aaron,

How do you give a Diesel "gas immediately"? I thought they all ran on Diesel fuel. LOL

P E H