Priming Oil and Fuel Filters

[Journey]

  On the Cat C-7 engines Cat states do not fill the oil filter or fuel filters  before installing. I have always primed my oil filters before installing. It's hard to think not. Any views on this from the DIY guys.

 

[jubileee]

I have no experience with a c7 but, I've been running cat engines in my trucks since 1965. Never primed an oil filter. We prime the fuel filters with a pipe nipple screwed in center hole so fuel has to flow down outside holes and is filtered. Those electronic injectors are expensive. Also, all my present cats have a primer pump but, priming filters saves a lot of pumping.

 

[Arch Hoagland]

I've changed oil filters on all my vehicles for the last 40 years and never primed one yet.

They all seemed to work just fine.

The only problem I ever had was with a Fram oil filter blowing apart on a Toyota Corolla. Twice in the same day after they replaced it.

I now buy my oil filters at the dealer of whatever vehicle brand I'm working on.

 

[PAHipskind]

On advice from an experienced diesel mechanic, I filled my new fuel filter and water separator with diesel fuel before installing on my 2004 Cat C7. This seemed to work with no air lock on restarting. This was necessary because my C7 did not have a hand priming pump but just a nipple for an external pump. Note however that I do not fill my oil filter with oil prior to installing.

 

[Gary RV_Wizard]

The "don't fill" advice is basically about the risk of introducing dirt when doing so. It's on the outlet side of the filter, so any dirt passes directly into sensitive areas of the engine or fuel pump. If you are confident you can do it carefully, you can certainly do so, but beware of the risk.

On Cats without the primer pump, pre-filling the fuel filter is probably helpful in avoiding air bubbles. Filling the oil filter is less valuable, since you are only avoiding a couple seconds of extra wear about once a year. Hard to believe that can have much effect on engine life, but do what you thing best.

 

[jagnweiner]

Ditto on what the others said.  I can't imagine a reason to prime the oil filter.  On my Cat, I have the primary fuel filter at the back of the coach and a secondary at the engine.  When I change the primary, I always pre-fill using the process described (block the center hole).  I'm not too worried about contamination because it is filtered as it goes in AND it still has to go through the secondary filter.  The secondary on the engine has only been changed at a shop, but I probably wouldn't fill that if I did it myself, because the prime pump is right there and there is a greater risk of injector contamination because it is the last filter in line.

Good idea on the pipe nipple. 

 

[Gary RV_Wizard]

The rationale for priming an oil filter is that the canister is empty and it takes a second after starting the engine for it to fill and oil to begin to flow on though the filter into the engine. Conceptually, the engine is running dry for that second or two. In practice, maybe not so much.  Much the same thing happens every time you start the engine, but at least there is no delay to fill the filter cartridge, which is often a couple quarts in size in a larger diesel.

I don't pre-fill mine, but I know those who swear it is foolish not to.

 

[jagnweiner]

Well, OK, I can't imagine a compelling reason to prime the oil filter. 

 

[Kevin]

I prime both fuel, and the oil. do what makes you feel better, but if you have a  mech, fuel pump and the hand pump chooses to stop working, you'll have to pull the filter off and start over again. doesn't take  much of my time to do. oh well

 

[ironrat]

Most people will have the oil changed for them, do you really think that where they take them really pre fill an oil filter?! Do you really think their engines do not last as long as someone at home pre filling their filters?

 

[Gary RV_Wizard]

LOL. I've seen (and participated in) this debate a dozen times and NOBODY has ever been persuaded to change their viewpoint.

 

[robertusa123]

The oil psi and fuel psi is very high.  Not printing leaves one big air bubbles that usaily bleeds out on start up.  Priming the filters leaves a double air bubble that slams thur the psi regular and can cause damage

 

[Kevin]

why would it leave 2 air bubbles?

 

[tugboat]

I always prime oil and fuel filters on my coach

 

[William52]

LOL. I've seen (and participated in) this debate a dozen times and NOBODY has ever been persuaded to change their viewpoint.

  Most are set in our ways and stubborn as a mule. I too will fill abt. half way when I can. The old Buick V6 would sometimes lose prime re starting with a dry oil filter.