Pre-fill or Not to Pre-fill

[Cruzer]

So I'm going to change the Fuel Filters on my CAT 3116 and I'm torn between Pre-filling the filters or not. CAT says don't Pre-fill but mechanics say DO Pre-fill them. Any advice on this topic anyone?

[EastCoastCB]

Originally Posted by Cruzer

So I'm going to change the Fuel Filters on my CAT 3116 and I'm torn between Pre-filling the filters or not. CAT says don't Pre-fill but mechanics say DO Pre-fill them. Any advice on this topic anyone?

Don't prefill. But if you must- fill with a plug in the center so you fill the filter side only.

[Bus'n it]

I put them in dry and add the equivalent oil of the filters capacity to the crankcase. I do lube the gasket on both sides though.

[EastCoastCB]

Originally Posted by Bus'n it

I put them in dry and add the equivalent oil of the filters capacity to the crankcase. I do lube the gasket on both sides though.

Yeah, the oil filters on cat go on empty, too. But op is talking fuel filter, fwiw. Cat also says put those on empty.

[Booyah45828]

This mechanic follows the oem's, and doesn't prefill filters.

There are a few examples where I do, because there's no way to prime the system by a hand pump or activating the electric fuel pump.

But those are rare cases.

[bus-bro]

I always fill them with filtered fuel, maybe just a habit. On engines that self prime it probably doesn't matter. And when you pre-fill the filter you can introduce contaminants into your fuel system.

Nonetheless, I always pre-fill the fuel filters. Lube oil too, if possible.

[TJones]

It is best to not prefill the filters as it could send contaminates directly to the injection pump and injectors.

It is ok to prefill if you plug the center hole of the filter when you add fuel. I use threaded plastic plugs that came out of the ports of some hydraulic valve I bought. I have a truck with a C15 that even with a brand new hand priming pump installed will take forever to start unless the filters are prefilled.

An engine with an electric lift pump shouldn't need to be prefilled. Turning the key on and letting the lift pump run for a while before cranking the engine will prime the system. Some engines like the ISC with CAPS may need the key cycled on and off a few times as the electric pump only runs for around 30 seconds and then shuts off.

Ted