Fuel filters priming

[sjohn116]

Read the TM's, they just say "pour diesel in new filters, install, and restart engine."

Any issues with priming, air bubbles getting into injectors, etc? I have an old JD tractor and they are very picky about air in the lines/injector body. How are the CAT 3116? Any words of advice/wisdom are much appreciated. Plan on changing filters tomorrow, don't want to mess up and take a running truck and turn it into a non-running truck due to air in the lines.

 

[Smike740]

When i replaced mine i disconnected the fuel return line at the fitting above the governor and primed until fuel came out, reconnected the hose and started it back up.

 

[Suprman]

System recirculates. Pump the hand primer till hard then crank and repeat if needed.

 

[Floridianson]

I just cracked the bleed bolt on the secondary and had no problems after pumping the primer.

 

[Floridianson]

When i replaced mine i disconnected the fuel return line at the fitting above the governor and primed until fuel came out, reconnected the hose and started it back up.

This time I tried a different way just for smitts & giggles. Removed the secondary filled new one and pumped the primer 10 times and fired up the truck. Shut down changed primary and cracked the line in pic. Pumped till fuel was coming out with little air in the mix and she fired right up. Did not crack the bleeder / test port on the secondary. Maybe next time I will try and just replace filled up primary and secondary then remove fuel line as in pic. Prime till clear fuel and see how she likes that. I do not know how true the Cat dealer was but he said they will not carry any more of those filters. I went on line to the well known auction sight and found the best prices on the Cat filter and bought 4 of them.

 

[Kbarnes0]

This time I tried a different way just for smitts & giggles. Removed the secondary filled new one and pumped the primer 10 times and fired up the truck. Shut down changed primary and cracked the line in pic. Pumped till fuel was coming out with little air in the mix and she fired right up. Did not crack the bleeder / test port on the secondary. Maybe next time I will try and just replace filled up primary and secondary then remove fuel line as in pic. Prime till clear fuel and see how she likes that. I do not know how true the Cat dealer was but he said they will not carry any more of those filters. I went on line to the well known auction sight and found the best prices on the Cat filter and bought 4 of them.

Good call. Rather than pulling both and having to prime that much more. I did mine yesterday and found my prime pump to be bad. I was able to crack the secondary bleeder and put a little compressed air to the tank and was able to get the flow needed.

I noticed the Cat service note says to run at low rpm if there is still air left. It noted it should be 15-20 pumps to prime and up to 75 of the Manifold is dry.

My truck had cat filters, but I just put on Baldwin. It's there anything particular about the Cat filters?

 

[Floridianson]

My truck had cat filters, but I just put on Baldwin. It's there anything particular about the Cat filters?

I like the fact that is comes Cat yellow and I do not have to buy a can of Cat yellow spray paint to make things look pretty.
What was the micron rating on the Baldwin? I saw where someone use a tighter micron on the primary but wonder if that puts a strain on the lift pump? Tighter micron more restriction and some filters are only push through not pull through. Believe someone said Cat secondary was 4 microns.

 

[Kbarnes0]

I like the fact that is comes Cat yellow and I do not have to buy a can of Cat yellow spray paint to make things look pretty.
What was the micron rating on the Baldwin? I saw where someone use a tighter micron on the primary but wonder if that puts a strain on the lift pump? Tighter micron more restriction and some filters are only push through not pull through. Believe someone said Cat secondary was 4 microns.

Went to baldwin site and couldn't find the micron noted

 

[Ronmar]

Had a leaking bowl And slow leak-down and replaced the primary filter with a Baldwin BF1222(one piece with drain port). For giggles I didn't pre-fill the filter. Pulled the inlet line to the governor and started pumping. It took 12 pumps to lift fuel from the tank till I started feeling fuel in the primer bulb. I have tested that before with same result. After lifting fuel to the filter it took 40 pumps to fill the primary filter and hose to the governor.

The secondary filter is larger. I would estimate it to take another 60-75 pumps to fill it. It would Probably Take another 15-20 pumps to Fill the Lift pump, fuel gallery and piping.

If I were going to fill the whole system via the primer, I would remove the fitting from the end of the fuel pressure regulator(rectangular block above the governor where return line attaches On a 3116) and pull the sprIng and plunger out. This would make it way easier to do all that pumping Till fuel starts coming steadilly out of the Regulator output port. Its a good idea to clean the regulator out occasionally anyway

if your primer doesn't work, You will probably find the flapper valve is fouled. You can reach that by removing the primary filter, it is up inside the filter hoousing and can be removed for cleaning with a philips screwdriver...

 

[DREDnot]

My understanding is what Will said. There is no cracking of lines to bleed air like many diesels. You pump the primer pump to fill both filters and the fuel goes into the gallery in the head and back through the pressure regulator and returns to the tank pushing any air in front of it. I think you guys are overcomplicating the process

 

[Floridianson]

My understanding is what Will said. There is no cracking of lines to bleed air like many diesels. You pump the primer pump to fill both filters and the fuel goes into the gallery in the head and back through the pressure regulator and returns to the tank pushing any air in front of it. I think you guys are overcomplicating the process

Well of course if you put in dry filters and pumped till the filters were full and system cleared it would start right away. I am not lazy but if there is away I only have to pump the primer 10 times not 200 times then that is what I would like to do. I also am not going to try and run the starter excessively to get a prime. I want any diesel to fire up right away no miss firing or not starting after fuel filter change. I am not a Cat expert and I do not know how air in the system affects the injectors or even if the pump can handle removing the air and self prime. All I know is like I said if what little I have to do to get the Cat to fire up right away without any problems then that is what myself will do.

 

[DREDnot]

My first time messing with an LMTV was in a storage lot trying to see if it would start. There just happened to be a mobile diesel mechanic there working on someone else's semi that had come over to check out the cool army truck. He explained how the system worked like a common rail through the head and that just pumping the primer would clear all the air out. Super easy. Once you heard the fuel whoosh through the return, it would be good to go. Every time since then it never failed to fire at the first crank. No excessive cranking or missing like a hmmwv.

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[Ronmar]

I should add that the only time air causes an issue in a diesel is if the injectors are hydraulically fired. IE: the injector pump is separate from injector and the fuel is pressurized to a point where it overcomes a spring loaded poppet valve in the injector to fire. Cant compress liquid, but you can compress air and too much air in that type system acts like a spring and absorbs all the pressure generated by the limited Pump stroke and the pressure never builds enough to pop the injector. Those systems typically must be bled To purge the air from the hard lines. They are also typically only capable of 3000-4000 PSI injection pressures...

the 3116 used Mechanical Unit Injectors(MUI) which are fired mechanically by the cam so the only effect air in the system has is that there is no fuel for the injector to fire, until the Lift pump(or priming) purges all the air and gives the injectors something to squirt. The MUI‘s are also capable of pressures in the 10’s of thousands. I have read info claiming as high as 30,000 PSI, but have not found an actual spec...

 

[Floridianson]

I should add that the only time air causes an issue in a diesel is if the injectors are hydraulically fired. IE: the injector pump is separate from injector and the fuel is pressurized to a point where it overcomes a spring loaded poppet valve in the injector to fire. Cant compress liquid, but you can compress air and too much air in that type system acts like a spring and absorbs all the pressure generated by the limited Pump stroke and the pressure never builds enough to pop the injector. Those systems typically must be bled To purge the air from the hard lines. They are also typically only capable of 3000-4000 PSI injection pressures...

The Deuce multi fuel sounds like that 3500 psi injector pop pressure, injection pump makes the pressure but we got lucky there no need to bleed the injectors. No forgetting Diesel fuel oil is a lubricant. I am not worried at all about filters changes if priming / not starting right away as I know how to fix it in most motors. I just look for the easy way. Take the 250 Cummins in our trucks. I have a small 12 volt diesel fuel transfer pump that where I disconnect the in coming line from the PT and hook it to my diesel fuel transfer pump. In 15 seconds I have pulled fuel from the tank filled the filter canister and in coming PT hose. Disconnect pump connect fuel line to PT and they always start. No pumping any primer ball or prefilling fuel filter. Some people like to put air pressure in the fuel tank. My way much easer and faster. I could do the same with the Cat motor if I just make up the fitting from fuel tank return to my pump. But here this too is to much work when all I did this time was a quick bleed of the primary fuel line to pump head. Cat just recommends priming the whole system filters included to prevent fuel contamination in the field. I use fresh clean fuel, clean fuel container and filter area so I do not worry about contamination from filter pre filling.
I just like it when I do a fuel filter change on anything and it fires right up . Makes me feel like I think I know what I am doing

 

[ramdough]

I should add that the only time air causes an issue in a diesel is if the injectors are hydraulically fired. IE: the injector pump is separate from injector and the fuel is pressurized to a point where it overcomes a spring loaded poppet valve in the injector to fire. Cant compress liquid, but you can compress air and too much air in that type system acts like a spring and absorbs all the pressure generated by the limited Pump stroke and the pressure never builds enough to pop the injector. Those systems typically must be bled To purge the air from the hard lines. They are also typically only capable of 3000-4000 PSI injection pressures...

the 3116 used Mechanical Unit Injectors(MUI) which are fired mechanically by the cam so the only effect air in the system has is that there is no fuel for the injector to fire, until the Lift pump(or priming) purges all the air and gives the injectors something to squirt. The MUI‘s are also capable of pressures in the 10’s of thousands. I have read info claiming as high as 30,000 PSI, but have not found an actual spec...

What about the 3126..... are they susceptible with the HUI pump, or are you talking about something else?


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