Which way does the fuel flow through a Model 80 fuel filter? In the bottom to the top or the other way around?

It flows in through the larger line and out of the smaller one.

Thank you but that doesn't answer my question.

We opened up a filter off a friends truck after he has issues that were cured by a filter change and found a lot of garbage in the bottom of the filter.

I want to know inside the filter, which way does it flow. Does it flow bottom to top or top to bottom?

It would probably have to flow from top to botton, considering that the filter also acts as a water seperator, with the water settling at the bottom. If it were flowing from bottom to top, I image the flow would carry the water through the filter, which is something you don't want.

Bigboytoys . On a pressurize system the filter flow from the top to the bottom

i suspect you refer to something similar to a

Fram P3710 Spin-On Diesel Fuel Filter

No, not a spin on. The Model 80 brick filter from the factory, the one on the fire wall. We're kinda shocked to find lots of garbage in the bottom of the filter. So we're thinking the fuel goes in the bottom then out the top. Other wise he's go more issues to deal with.

So which way does the fuel flow through a Model 80 fuel filter?

The fuel flows in at the top and out slightly above the bottom. The filter has two sections, a primary near the top (filters the big particles) and a secondary, finer element in the bottom half. There is also a coalescing element that traps water. The outlet line is above the section where the water is trapped.

What about the stuff you found inside the filter? Why does it worry you?

It may tell you that the tank is dirty or that the filter was old, and it might tell you that the filter has been doing its job.

If you want better filtration, you can switch to spin-on filters with filter elements that are rated to 2 micron. I've made the switch about a year ago and haven't changed a fuel filter since (the fuel pressure is still fine) and --- unlike the model 80 filter --- haven't had any problem with this setup so far :)

I too upgraded to the older, better style filters. Starting has drastically improved as it has 2 filters instead of the 1 box filter.

That means all that garbage went through the filter and probably into the IP. Doh!

where can you get the upgrade to the spin on filter?

Try a parts store or phone up a diesel shop. Wix 33123 aren't to bad but not very low mic rating. Base has a 1 - 12 thread. If you want a better mic rating, get em to look through their catalog to find a finer one.

That means all that garbage went through the filter and probably into the IP. Doh!

Well, you found it in the filter ... There's a screen in the inlet of the IP; if things get through the filter, they can get stuck there --- and eventually block the intake ...


The 33123 is a water seperator; a longer version of that is available. You also need a fuel filter with it, like the 3674. You can get the filter bases and filters for a good price at fleetfilter, cheaper than in a parts store. You'll have to make some mounting brackets to mount the filters. Wix has the information about sizes and threads you need on their webpage.

Check out this thread: http://dieselplace.com/forum/showthread.php?t=215141.