CAT Filter - how much air??

LanduytG · **Joined:** Sun Dec 11, 2005 6:59 am **Posts:** 188

retmil46 wrote:

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.

As for restrictions their is very little to no difference. Synthetic media filters such as the Cat filters are no more restrictive and in some cases less restrictive than OEM cellulose filters. This air thing is cause of a leak and nothing else. Replace the o-ring and things will be fine unless the puck is cracked or in some other way broken. The CRD is not the first diesel vehicle to have a vacuum system on it. Out of the 100 or so sold the percentage that are having trouble is not that big. So use blue Loc-Tite on the adapter, replace the o-ring in the puck and tighten the filter as recommended and you will not have a problem. Also do something with the fuel bleed screw so it does not get over tightened.

Greg

CATCRD · **Posted:** Sun Sep 02, 2007 7:28 pm

LanduytG wrote:

retmil46 wrote:

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.

As for restrictions their is very little to no difference. Synthetic media filters such as the Cat filters are no more restrictive and in some cases less restrictive than OEM cellulose filters. This air thing is cause of a leak and nothing else. Replace the o-ring and things will be fine unless the puck is cracked or in some other way broken. The CRD is not the first diesel vehicle to have a vacuum system on it. Out of the 100 or so sold the percentage that are having trouble is not that big. So use blue Loc-Tite on the adapter, replace the o-ring in the puck and tighten the filter as recommended and you will not have a problem. Also do something with the fuel bleed screw so it does not get over tightened.

Greg

Agreed. This is not an entrained air/vapor problem. My heater puck never leaked before I took it all apart to do this conversion. Now it weeps all around the seal and stalls every other day. I need to take it apart and replace that seal. Anyone know what size it is so I can get one in advance?

LanduytG · **Joined:** Sun Dec 11, 2005 6:59 am **Posts:** 188

CATCRD wrote:

LanduytG wrote:

retmil46 wrote:

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.

As for restrictions their is very little to no difference. Synthetic media filters such as the Cat filters are no more restrictive and in some cases less restrictive than OEM cellulose filters. This air thing is cause of a leak and nothing else. Replace the o-ring and things will be fine unless the puck is cracked or in some other way broken. The CRD is not the first diesel vehicle to have a vacuum system on it. Out of the 100 or so sold the percentage that are having trouble is not that big. So use blue Loc-Tite on the adapter, replace the o-ring in the puck and tighten the filter as recommended and you will not have a problem. Also do something with the fuel bleed screw so it does not get over tightened.

Greg

Agreed. This is not an entrained air/vapor problem. My heater puck never leaked before I took it all apart to do this conversion. Now it weeps all around the seal and stalls every other day. I need to take it apart and replace that seal. Anyone know what size it is so I can get one in advance?

Its the same size as the oem filter. 2.750 ODx 2.450 ID by .250 thick. Of course its square but you can use the same in a round.

Greg

CATCRD · **Posted:** Sun Sep 02, 2007 8:07 pm

Thanks Greg. I threw the old mopar filter away before I could measure it.

MACKJ · **Posted:** Sun Sep 02, 2007 8:40 pm

LanduytG wrote:

Its the same size as the oem filter. 2.750 ODx 2.450 ID by .250 thick. Of course its square but you can use the same in a round.

Greg

Greg,
Sorry to be pedantic, but if the cross section is square (at 0.25") then the ID would be 2.25" or do you mean rectangular cross section with a thickness of 0.25" ?

LanduytG · **Joined:** Sun Dec 11, 2005 6:59 am **Posts:** 188

MACKJ wrote:

LanduytG wrote:

Its the same size as the oem filter. 2.750 ODx 2.450 ID by .250 thick. Of course its square but you can use the same in a round.

Greg

Greg,
Sorry to be pedantic, but if the cross section is square (at 0.25") then the ID would be 2.25" or do you mean rectangular cross section with a thickness of 0.25" ?

Its .250 high as stated above. Its a .300 cross section.

greg

MACKJ · **Posted:** Sun Sep 02, 2007 9:27 pm

LanduytG wrote:

MACKJ wrote:

LanduytG wrote:

Its the same size as the oem filter. 2.750 ODx 2.450 ID by .250 thick. Of course its square but you can use the same in a round.

Greg

Greg,
Sorry to be pedantic, but if the cross section is square (at 0.25") then the ID would be 2.25" or do you mean rectangular cross section with a thickness of 0.25" ?

Its .250 high as stated above. Its a .300 cross section.

greg

Greg,
Now I'm confused...if the cross section is 0.300" wide then the ID is
2.750-(2x 0.300)=2.15"

Am I missing something here?

LanduytG · **Joined:** Sun Dec 11, 2005 6:59 am **Posts:** 188

MACKJ wrote:

LanduytG wrote:

MACKJ wrote:

LanduytG wrote:

Its the same size as the oem filter. 2.750 ODx 2.450 ID by .250 thick. Of course its square but you can use the same in a round.

Greg

Greg,
Sorry to be pedantic, but if the cross section is square (at 0.25") then the ID would be 2.25" or do you mean rectangular cross section with a thickness of 0.25" ?

Its .250 high as stated above. Its a .300 cross section.

greg

Greg,
Now I'm confused...if the cross section is 0.300" wide then the ID is
2.750-(2x 0.300)=2.15"

Sorry cross section is .150. 2.750OD 2.450ID = .300/2= .150

Greg

Am I missing something here?

retmil46 · **Posted:** Sun Sep 02, 2007 11:55 pm

http://www.baldwinfilter.com/engineer/pdf/94-6R1.pdf

LanduytG · **Joined:** Sun Dec 11, 2005 6:59 am **Posts:** 188

retmil46 wrote:

http://www.baldwinfilter.com/engineer/pdf/94-6R1.pdf

May be 13 years ago when that paper was wrote. But it mentions nothing about synthetic media which has equal or less restriction. Again its and air leak and nothing more. This whole thing is being over thought.

Greg

BankNote4X4 · **Posted:** Mon Sep 03, 2007 5:29 pm

I seem to only have issues when the engine is hot. It runs fine when cool then has issues when it gets hot. Today I tried a heat barrier (that RetMil used: Koolmat 2 1/2' ID hose). The Jeep has sat for 7 days but today it was 84 degrees today and I put it through heavy traffic, in-town driving. Normally it would drive poorly in these conditions after about 20 min. or so. Today it seemed to have no issue. I may just try a cooler(tranny style) in the return line and heat barrier on the delivery hoses to keep heat down. I'll keep you posted.

CAT Filter - how much air??

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