Pre fill diesel oil and fuel filters?

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Pre filling a fuel filter is a big big big No No.

Pre filing an oil filter isn't going to hurt anything unless what you are putting in it is already contaminated. New oil shouldn't have any contaminates big enough that wouldn't pass through the filter to begin with. There are engines that say to prefill the oil filter.
 
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School me, why is pre-filling a diesel fuel filter a bad thing? I know diesels have to be bled, but that is about all.
 
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Originally Posted By: andyd
School me, why is pre-filling a diesel fuel filter a bad thing? I know diesels have to be bled, but that is about all.


The injectors are very susceptible to contaminates. Combine high pressure through a small opening and any contaminate can cause damage.
 
Originally Posted By: jhellwig
Pre filling a fuel filter is a big big big No No.

Pre filing an oil filter isn't going to hurt anything unless what you are putting in it is already contaminated. New oil shouldn't have any contaminates big enough that wouldn't pass through the filter to begin with. There are engines that say to prefill the oil filter.
They always pre-fill the fuel filters at work and have never had a problem. They do the same with the oil filters.
 
As long as you only pre-fill the fuel filter from the outside, it is fine.

For screw-on filters, many come with a plug to plug the center while pre-filling.

For cartridge filters, it is even easier. Just pour clean diesel toward the outside of the cartridge until full.

This has never caused damage to any of my trucks.

For oil filters, just fill any way you want to.
 
If you have no lift or prime pump, it's going to take a while to crank new fuel through on the starter...not good for either battery or starter.
 
I usually pre fill with lubro moly diesel purge, since the engine can run on it and its clean.

Back in the day I pre fillled with dollar store type A ATF. No issues on my old IDI diesels.
 
Originally Posted By: Silk
If you have no lift or prime pump, it's going to take a while to crank new fuel through on the starter...not good for either battery or starter.


This!
 
I have two fuel filters on my 6.7L and I do not prefill either of them. You simply change one at a time and turn the key on and off about 10-15 times and allow the fuel pump to fill it, then start the engine and let it run for a minute or so.

I do prefill the oil filter simply due to its size.
 
I never pre fill anything. Just because I don't want to. I have a in tank lift pump, hit the key to run. Let pump run for 10 secs, and start the engine.
 
If you can pre-fill on the dirty side only, then go to it.

If you are putting (potentially) dirty oil/fuel in through the clean side, then it's poor practice.

As Stinky Peterson (RIP) demonstrated in his many VOAs with particle counts, new oil isn't clean.
 
Only one I prefill is the old IDI 7.3 in my sig, it has a mechanical lift pump-I would probably set the battery cables & starter on fire, or pull all 8 glow plugs, before that old pump would fill the (roughly) 1 quart fuel filter. Fortunately both the 6.2 & Dodge can be filled with the lift pump, loosening the banjo bolt on the Cummins & turning the key between run & off, & pulling the pink wire & jumping the OPS on the 6.2.
 
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Originally Posted By: Shannow
If you can pre-fill on the dirty side only, then go to it.

If you are putting (potentially) dirty oil/fuel in through the clean side, then it's poor practice.

As Stinky Peterson (RIP) demonstrated in his many VOAs with particle counts, new oil isn't clean.


Fuel filters, I can see the benefit. But oil? Even if you don't prefill the filter to avoid contaminants, what about when you dump the jug straight into the crankcase?
 
My Jetta had a lift pump, but the one time I didn't prefill it took forever to crank it full. Maybe I could have just cycled the key, but for less work I could prefill. Mind you it was dumb-easy to prefill: install filter, and then using the vacuum extractor I used to drain the oil sump, I could pull D2 through the fuel filter. No worries about contamination.

I used to prefill oil filters, but gave it up. Not sure it does much, not with today's oils. It's only slightly longer to get full oil pressure, but otherwise it's like any other cold start.
 
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