Hello All,

I have recently done the CAT conversion to my ´05. I have noticed that if I prime the filter it takes four or five pushes and air releases to get hard to push the primer. If left to sit for a while (without starting) it will eventually take several more primes to get it hard to push the primer again. If I run it, it will again need to be primed to have the primer button get hard to push. I don't see any leaks on the outside of the filter head or hoses.

I have no drivability issues. Actually, since changing to the CAT filter, I now have NO driveline shudder going into 5th gear (I have had the shudder for more than 10000 miles), and the Jeep starts with half the cranks it did with the old filter. I also think it is making a bit more power now. I know the statement was made that if there are no drivability issues, then don't worry about it. BUT, since the pump uses fuel for lube and cooling I think it could be an issue. It was my understanding that on my previous 24V Cummins that about 70% of the fuel supplied to that pump was rejected back to the tank, with all that extra needed to properly lube and cool the injector pump. The truck would run fine as the supply dropped, but the pump would not be getting adequate lube and cooling. I am wondering if it is the same situation with the CRD Liberty...

I did not try the prime and repeat as described above with the oem filter, but I am guessing it was as bad or worse than I have now...just not sure. When I put the CAT filter on, I also replaced the gasket above the fuel heater with the old fuel filter gasket (which was the same size but a bit thicker).

My question is whether or not this air in the system is a problem, and how many others have the same situation (whether running oem filter or CAT) I have read the thread on the CAT filter, but it isn't clear whether people with either filter can prime the system and purge of all air AND have it remain air-tight.

Can anyone prime their fuel system and purge all the air out, then have it stay out, oem or CAT filter? Should I tear it back apart again and try to fix an air leak, or should I not worry about it and drive as-is?

Thanks so much. Sorry for the long post. I'm about to take this thing to Europe and I'm trying to get it as "bullet proof" as possible before it gets hard to obtain parts and/or service.

Regards,
Mike

I'm pretty much in the same state as you. No obvious leaks. Need to bleed about once a month. Get lots of air out then. If I let it go it will do the start and die thing. I never messed with the factory so have no baseline although it never started and died before the change.

Steve

Air in the fuel (or air-foaming in the fuel) is very bad for injection pumps and/or injectors. It's more a question of how much air and for how long it was run that way. This is why you don't want to run a diesel low on fuel (no less than 1/4 tank is a good rule of thumb).

This vehicle design has the fuel filter located at the highest elevation in the system which is great for trapping air pockets but not as good for trapping water. Look at most commercial vehicles, the fuel filter(s) get located somewhere low on the frame (lower than the IP) where they make a better water trap and tend to pass air bubbles through before they develope into large pockets. It's just a quirk of this vehicle, you will have to periodocially bleed the system.

As for taking this beast to Europe, this should be a positive. You will likely have a better chance of finding parts and competent CRD techs on the other side of the pond.

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2005 Liberty Sport CRD, Lt Khaki, sunroof

Thankful to now be an EX-CRD owner.

When I replaced the OEM filter on my CRD it only took about 1/2 dozen pumps to get firm and that caught me by supprise I wasn't expecting it to happen so quick for the first bleed and then I did it again and it only took abbout 3 or 4 pumps. I never had a problem after that with air in the system causing any stalls, problems, or codes. My filter heater assembly was never anything but warm when I checked it, and I maybe I was lucky with the filrter head and got a good one. The tranny however was acting up again when we traded it off, or so the wife told me yesterday. I had just checked the fuel filter less then a week before I traded the Jeep and it had no air in the system, all that came out was fuel. I was really just checking the new bleeder valve that I had got from Greg at LubricationSpecialist, which worked beautifully by the way.

By the way all diesels flow unused fuel back to the tank, probably 70% to 80% at least when idling, at full throttle it might only be 5% to 10% maybe , maybe less. Depends a lot on the setup and what the engine is designed to do, low speed truck/bus or high speed (speed meaning rpm range) engine.

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91 MB 300D 2.5L Turbo. Her's

05 MB E320 CDI. Mine

Thanks for the replies. I think I am hearing this:

Stevesmith, you say you pump yours up to firm and then the primer handle stays firm for about a month...?

RFCRD, yes, it is my belief that air is bad too. IIRC, my Dodge had the filter up high too. I don't remember getting much air out on that one when I bled it. I think the fuel pump was designed to overrun the injector pump on that one though (although it didn't do a great job of that...that's another forum though). What I'm trying to figure out is if I have a "bad" system that I need to take apart again. I am trying to see if others have the same condition of pumping it up and bleeding, and then being able to pump it up again in such a short period. I am having no drivability or starting issues, even if I don't pump it up...just trying to figure out if I'm slowly destroying my injector pump. Yes, the competance and CRD parts will be a plus in Europe, the more-than-twice-as-much cost of those things will not be.

Old Navy, how soon after you pumped it up did you check it again. I mean, could you pump the primer handle up a few more times within hours? I don't know if this thing is designed to stay "unpumpably firm" if the system is working as it should, or if you can always get a few pumps after it has run or been sitting for a period of hours.

For example, I just pumped mine up firm in the driveway, went for a bicycle ride, came home three hours later and was able to pump it some more, say 5 or 6 times until it was firm. I have the bleeder kit from Greg, and when I crack the valve I get what seems to be a mixture of air and fuel with a "psssstt" sound to boot. Still can't see any fuel leaking anywhere though...

Thanks!

When I checked mine I could not pump it and that was about a two weeks later, maybe more then that. Sorry to say I didn't pay that much attention as to when I did it and with all going on here with working on old MB and buying the 05 MB my memory is not that firm about the time other then to say I was pleased that after such a long period it had no air in the system I could hear or see.

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91 MB 300D 2.5L Turbo. Her's

05 MB E320 CDI. Mine

I've had the CAT filter on for a bit over a year now+ as others have said,I took the filterhead to install the cat.This way you are sure to get it tight,something that is VERY difficult w/it on the firewall.After i bled it the 1st time+then once a day later,there have been no problems.With this install you rest assured the injectors are gettin CLEAN fuel.

I still have the stock filter, and the last time I bled it was over a month ago. I used a brake bleeder to bleed the system. No issues whatsoever. Works like a charm!

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Chad Hargis
Nashville, TN
2008 Grand Cherokee CRD
2005 Liberty CRD *SOLD*

Ok, thanks a lot guys. It looks like I have a pretty big air leak into the fuel system somewhere. Either that or I had a lot of air trapped after the filter install that still isn't out...but I doubt that is the case. I did the filter conversion on the bench, made sure all was clean and tight...not sure where to start or how to diagnose the leak point. What gets me is that I don't seem to have any problems with it running....runs fine, more power, less cranking to start, and no shudder when letting off the pedal after accelerating. Guess I'll just have to tear it down again and start from scratch.

Guess I was unclear. I bleed it about once a month. I don't think I've ever pumped it that it didn't take a few hits to get firm.

...that is what I was driving at with previous questions....not sure if you can get a few pumps always or if it should be tight to pump if the system is not functioning properly...

Thanks again,
Mike

When I change fuel filters on my diesels I have always used a pair of clamps on the fuel hoses and I have never had any problems with air or a fuel spill when doing it that way. Now what that has to do with air in lines I am not sure, but it does tind to make me feel better.

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91 MB 300D 2.5L Turbo. Her's

05 MB E320 CDI. Mine

Could someone shed a little light on how this thing works for me? I was told when I got the CAT filter that the system was a vacuum system, fuel is sucked through the filter. The plunger appears to be a pump creating pressure, right? If you have air and you pump what happens to the air?

Thanks
Steve

What you have been told is correct and systems which draw fuel entirely on suction are common on diesel engines. Some are aided with a low pressure electric lift pump and/or an electric version of what the hand operated primer pump does. Primer pumps draws fuel from the tank, then forces it through the filter to temporarily force feed the injection pump allowing it to pick up the prime it needs to function. Then it reverts to a suction system. While under pressure, trapped air will work it way out through the course of least resistance. This may be through the bleeder (best), or through the injection pump (not as good), or in my case through the electrical connection for the fuel heater.

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2005 Liberty Sport CRD, Lt Khaki, sunroof

Thankful to now be an EX-CRD owner.

just saw this thread,

I have been pumping my prime button every other week or so for a couple months as I had a "limp mode" that scared me into changing out the OEM filter (still waiting for time/cajone$ on the CAT). I usually get a half pump before firm, have not bothered to bleed it again as things are working fine at this point.

I am hesitant after dharv's problem, and now that the RACOR filter has been found out to be the European part on their CRD's, I'm thinking of pursuing that channel a bit more. (closer to OEM?) another topic of interest that is running around is the electric lift pump.....

At this point though, ain't broke.......
good luck across the pond,

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'05 CRD limited, SEGR, EHM, Magnaflow 18" muffler, OEM skid plates, bug guard, trailer kit, yakima cross bars and basket, CAT filter,
....more to come.....

I installed the CAT filter from Lubrication Specialists 5 days ago. When leaving work yesterday, the engine stalled shortly after starting. I assumed it was air in the filter, since that's the only thing I'd changed. After priming and bleeding the filter in the parking lot, it got me home with no problems. Checked it again this morning, and found quite a bit of air. Primed & bled the filter again. After running errands all day, the engine stalled again this afteroon. Had to bleed the air from the filter again. Going on a 200 mile trip tomorrow and plan to check it before, during & after.

I've owned this Jeep for about 3 months now, and never had a problem with air in the filter until I installed the CAT filter. I guess I'll do as Mike suggested and redo the install. This time, I'll replace the seal on top of the heater puck and hope for the best. If that doesn't work, the CAT will be replaced with an OEM, then it's going to the dealer for a warranty repair. The CAT conversion is a great idea, but the installation process may have compromised a seal. Maybe Greg (at Lubrication Specialists) should include a new seal for the heater puck in the kit.

By the way, my goal is to get at least 300,000 miles from this Jeep.

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2006 White CRD Limited (Manuf: May '06)
Ipod kit, ProVent, Fumoto, saving for lift

Mine was having the same problem until I installed a lift pump. I really didn't have any issues with my CAT filter causing this problem until the weather got hot up here - I think the heat is causing part of the problem .... just my 2 cents ...

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2006 CRD Sport 4X4, bought 6 July 2006, born 5/20/2006 1900 hrs.
Mods N Things:
235/70r16 Wrangler SilentArmor, ProVent, Gasser airbox, CAT filter, Kennedy lift pump, fuel cooler, Evic from wrecked 05 KJ, factory skidplates, towhooks, OME 2" CRD lift, Magnaflow 12256 muffler, Alpine stereo & XM "stealth antenna" install

Okay guys, I'll sum this up one more time -

Diesel fuel contains entrained air in solution.

Raising the temp of diesel fuel makes it easier for entrained air to come out of solution - true for any fluid.

Placing diesel fuel under a vacuum makes it easier for entrained air to come out of solution - agan true for any fluid.

Sucking diesel fuel across a physical vapor barrier (such as a fuel filter) where the micron rating of the filter (2 micron) is smaller than the size of the entrained air bubbles will literally strip the air out of the fuel, in addition to the pressure drop across the filter causing additional air to come out of solution.

Add to this a fuel filter that is the high point in the system, with a flow path on the inlet side that was seemingly designed on purpose to trap air, with a priming pump inlet check valve that adds flow restriction (and vacuum), and we're adding a finer grade filtration fuel filter (Cat 2 micron vs OEM 15 micron at best by oldnavy/Greg's testing) which for the same size filter element will add more flow restriction, and therefore a higher vacuum, across the filter.

That's why many people are suddenly noticing air problems after switching to a Cat 2 micron filter - with all the other factors involved, the Cat 2 micron has fine enough filtration to literally strip the air out of the fuel.

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Mitchell Oates
'87 MB 300D Diamond Blue Metallic
'87 MB 300D - R.I.P. 12/08
'05 Sport CRD Stone White
Provent CCV Filter/AT2525 Muffler
Stanadyne 30 u/Cat 2 u Fuel Filters
Fumoto Drain/Fleetguard LF3487 Oil filter
V6 Airbox/Amsoil EAA Air Filter
Suncoast TC/Shift Kit/Aux Cooler
Kennedy Lift Pump/Return Fuel Cooler

2x what retmil said

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2006 Black Jeep Liberty CRD Limited
K&N, Samco Hoses, Michelin 245/70-16 LTX A/T2, Fumoto F-102, V-Force Muffler, Mopar, Hitch, Trailer Wiring, Skid Plates, Slush Mats, Rear Shelf, Predator Stage 1, Transgo, ORM & CodeReader, Facet 40109 Pump
"IT'S A DIESEL THING, YOU WOULDN'T UNDERSTAND"
Certified Services Auto & Truck Repair

I hear ya Retmil, but what does this mean concerning using better filtration. Are you recommending that we stay with the factory filter, because changing to a Cat2 will give us more air problems?

I'm at 49,000 miles and due for my second filter change. When I changed the first filter, I was beginning to have air problems and had to bleed it every day. After the filter change, no more air problems and didn't have to bleed it for 10,000 miles. I'm beginning to have air problems again, so I'm hoping that the change will have the same results.

BTY, I have never cleaned the map sensor and was waiting for some drivability issues to show up and give me a reason. To date, fuel mileage has been consistent at 28mpg combined. Still waiting.