Fuel Filter Upside Down?!

pryord · pryord's Garage

So, this is something like my third question for the board related to my simple tune-up. However, you've all (Superman, JW, pwd72, etc.) been a great help. Here's two more questions:

My old filter had a slight flair in the housing at the top end. When positioned with the arrow pointing up, my new filter flairs at the bottom. I assumed the arrow painted on the side of the filter was to point up, not the direction of fuel flow. (By the way, which was does the fuel flow.) I put the arrow facing up. Do I have the correct filter? ..installed correctly?

When I took my tires off, I noticed the back of my wheels don't have the 901.xxx.etc code stamped on the back like the wheels on the '69 I used to have. Does this mean they are not Fuchs? They seemed to have a few other markings similar to the old wheels.

Thanks again!

Superman · 05-23-2002, 07:48 AM

The arrow does go in the direction of fuel flow. My WAG is that the arrow should point down, but you should not rely on my WAG. Instead, you can see where the fuel line comes out of the corner of the firewall, to the accumulator and the filter, then to the engine.

Something puzzles me though. I though the fittings on each end were different making upside down installation impossible.

Jdub · 05-23-2002, 07:56 AM

As Super has said, I had thought the fittings were differentially-threaded and so prevented this sort of mistake.

There are three SCs in the company garage. I will open the lids on all of them and give you my unscientific results!

Don't forget to put the installation date on the fuel filter.

John

pryord · pryord's Garage

Interesting! If the arrow is to point down, then my old filter was installed wrong.

Superman · 05-23-2002, 08:17 AM

Like I say, don't rely on my guesses. I personally would only trust my eyes. I would follow the incoming fuel lines to the filter and use this observation to determine the direction of flow, disregarding all other sources of information.

pryord · pryord's Garage

Good point. I'll check when I get home.

David

Jim Sims · 05-23-2002, 08:32 AM

Up or down arrow is not a good way to evaluate the installation; the arrow should point in the direction the fuel should be flowing. The fuel should flow towards the fuel distributor on the back of the engine: trace the lines through/from the body to the fuel distributor on engine. The fuel in the lines that go through the fuel filter should move towards the fuel distributor; orient the filter arrow to point this way. I too doubt the fittings will permit you to improperly install the filter unless they've been modified. Cheers, Jim

Noel · 05-23-2002, 08:35 AM

My 1980 SC points up. If you look in Wayne's Book 101 Projects, the photo of his SC shows the arrow pointing up.

Noel

sammyg2 · 05-23-2002, 08:57 AM

The fuel flows out the top of the pressure accumulator, down and into the bottom of the filter, then out the top of the filter to the distributor if I remember correctly. I am going from memory here.

There is some confusion on the fuel filters available on the SCs. I know of at least two different sizes. The one I needed was not redily available, so I adapted the system for the more common filter.
The only real difference is the fittings.
One has indentical fittings on both ends, one has a smaller fitting on the top. The threads are different in the filter housing itself.

rlane · 05-23-2002, 05:04 PM

CHECK BACK ON SOME OLD THREADS UNDER FUEL FILTER. oops sorry for the caps..but there were three different Bosch fuel filters that were used in 1978 alone. (ask me how found this out...hint. I can make you a good deal on two of the three!) The first one I bought looked like it was going to install upside down but one of the fittings lucklily would not fit...