Diesel Place banner

1 - 20 of 44 Posts

·
Registered
Joined
·
687 Posts
Discussion Starter #1
All,


As you may have seen, I had installed a CAT filter post-OEM. http://dieselplace.com/forum/forum_posts.asp?TID=3511&PN=2 I changed the OEM filter at the same time. The past couple of "cold" starts, I noticed a engine stumble, but then the truck would run fine after that. Yesterday after work, the stumble was pretty bad, so I shut the truck off and bled from the CAT getting a minor bit of air out. I also cracked the OEM after bleeding the CAT, and no air.


This morning though, it started and as I was backing out of the garage, die it did. Bled again from the CAT and then the fuel rail service port on the front of the engine. Good amount of air from the CAT, little bit of air from the port.


The truck has always ran fine after being bled, so that is fine. I know some have resorted to the lift pump setup to cure this. I, like most, do not want to have to bleed constantly, and would like to avoid the pump. Could something be wrong? One thing I did not do was pre-fill the filters with fuel, although I doubt that is the case. Have some here had better luck not bleeding and without liftpump installs? (VR or Frank if I recall correctly??)


The post-OEM setup is what I want, but without the issues. I am sure I can get this sorted out, but could use some of your guidance.


Thanks,
MN.
 

·
Registered
Joined
·
692 Posts
sounds like air is getting into the fuel. double check all your fittings of your filter install. also did you replace the rubber o-ring on the oe filter and the water sensor. i think checking for air at your fittings on the supply side you wont get leaks becaues that side of the system is vaccum. just retighten and look prime the oe filter 30 times then crak the bleed do this 3-4 times as with a break system and air in the fuel will rais havoc in the fuel. good luck
 

·
Registered
Joined
·
432 Posts
Agree, you didn't get all the air out initially or the air is getting in somewhere. Should be no need for a lift pump. I bleed mine after install about 150 pumps on the OEM filter housing to be sure all the air was out. Has not skipped a heartbeat in 5-6 months since install. Just open the bleed screw on the housing a little and pump the SH&^ out of it until you see no more bubbles in the fuel coming out the bleed port. Start and should be good to go. If it does it again you have to check/tighten all the fittings you installed. Something is leaking and sucking air into the system.


Go back through the install instructions and see if you missed something. Don't add anything else until you find the problem as you will just keep having the same issue until it is solved.


Good LuckEdited by: Chevysrus
 

·
Registered
Joined
·
7,187 Posts
nassdmax said:
All,


As you may have seen, I had installed a CAT filter post-OEM. http://dieselplace.com/forum/forum_posts.asp?TID=3511&PN=2 I changed the OEM filter at the same time. The past couple of "cold" starts, I noticed a engine stumble, but then the truck would run fine after that. Yesterday after work, the stumble was pretty bad, so I shut the truck off and bled from the CAT getting a minor bit of air out. I also cracked the OEM after bleeding the CAT, and no air.


This morning though, it started and as I was backing out of the garage, die it did. Bled again from the CAT and then the fuel rail service port on the front of the engine. Good amount of air from the CAT, little bit of air from the port.


The truck has always ran fine after being bled, so that is fine. I know some have resorted to the lift pump setup to cure this. I, like most, do not want to have to bleed constantly, and would like to avoid the pump. Could something be wrong? One thing I did not do was pre-fill the filters with fuel, although I doubt that is the case. Have some here had better luck not bleeding and without liftpump installs? (VR or Frank if I recall correctly??)


The post-OEM setup is what I want, but without the issues. I am sure I can get this sorted out, but could use some of your guidance.


Thanks,
MN.

To my knowledge no-one to date that has any manufacturers Filter installed PRE-OEM has an air problem.


I know this has been discussed in great length.


IMHO a PRE-OEM install will give you the same benefit as a Post-OEM install without any of the headaches.


Try replumbing the install under your hood making the CAT the first filter and the OEM the second one. Maybe you can solve the problem.


T
NYEdited by: GMC-2002-Dmax
 

·
Registered
Joined
·
340 Posts
nassdmax,
I am running the same mounting system you are with a Cat 750 filter & a Perma Cool head, & with 4 months & about 3,000 miles of service I haven't had any air problems. You have apparently got a vacum leak in your installation.It doesn't take much of a leak to cause the problem you are having.
 

·
Registered
Joined
·
429 Posts
nassdmax in your pics it almost looks like you used teflon tape to seal the threads (if not I apologize now). If you did, that may be a source for a vacuum leak (you need to use a liquid/paste sealant). My Racor 660 was missing the filter gasket on my initial install and caused a vacuum leak (no problems since adding the gasket--2,000mi.). Like everone else has suggested check all your fittings & gaskets. Hope you find the problem!


Josh
 

·
Registered
Joined
·
687 Posts
Discussion Starter #7
I appreciate all of your responses.


I know the filters are good and tight, with new o-rings in the OEM also, and light grease on all the gaskets for that good seal.


Before #1 - if it still starts good after this mornings bout tonight when I go home, maybe no issue, if she stumbles still...


#1 - If it means a good bleed, then I will open the bleeders up and pump the sh*& out of it as Chevyrus has suggested.


#2 - I have never had an issue with teflon tape on other joints, but I know how "sensitive" this system is, so this may be my first... If I still get air, that's one I will go after. Any issues with barb fittings and the wide clamp? I always tighten to the point just before the housing starts to get cut.


#3 - permacool head may be less prone to air? if it comes down to that... $35 and I will change out.


I agree with you all that a lifter should not be necessary, and I would not like to post-OEM the filter. Thanks for the advice again, and I will keep you posted...


MN.
 

·
Registered
Joined
·
1,231 Posts
GMC-2002-Dmax said:
nassdmax said:
All,


As you may have seen, I had installed a CAT filter post-OEM. http://dieselplace.com/forum/forum_posts.asp?TID=3511&PN=2 I changed the OEM filter at the same time. The past couple of "cold" starts, I noticed a engine stumble, but then the truck would run fine after that. Yesterday after work, the stumble was pretty bad, so I shut the truck off and bled from the CAT getting a minor bit of air out. I also cracked the OEM after bleeding the CAT, and no air.


This morning though, it started and as I was backing out of the garage, die it did. Bled again from the CAT and then the fuel rail service port on the front of the engine. Good amount of air from the CAT, little bit of air from the port.


The truck has always ran fine after being bled, so that is fine. I know some have resorted to the lift pump setup to cure this. I, like most, do not want to have to bleed constantly, and would like to avoid the pump. Could something be wrong? One thing I did not do was pre-fill the filters with fuel, although I doubt that is the case. Have some here had better luck not bleeding and without liftpump installs? (VR or Frank if I recall correctly??)


The post-OEM setup is what I want, but without the issues. I am sure I can get this sorted out, but could use some of your guidance.


Thanks,
MN.

To my knowledge no-one to date that has any manufacturers Filter installed PRE-OEM has an air problem.


I know this has been discussed in great length.


IMHO a PRE-OEM install will give you the same benefit as a Post-OEM install without any of the headaches.


Try replumbing the install under your hood making the CAT the first filter and the OEM the second one. Maybe you can solve the problem.


T
NY

I have had one of the manufacter's filter setups in a pre-configuration and had to bleed the system every other tank of fuel to avoid air issues as well. My cure was to mount my pre-OEM filter in the "nictane" location. No more air problems. Could be that my quick disconnect line was leaking and now that it has been removed, the problem has resolved it self.
 

·
Registered
Joined
·
68 Posts
Perhaps the air is being trapped in the HIGHEST point of the system? The stock OEM and the NICKTANE locations are all lower in the system, allowing the air to pass until it accumlates enough in the high spot and then sends a slug of air and kills the engine.


I am not sure but all the things I have been reading the OEM is the highest piont in the system normally. The air bleed piont is there and it may hold a greater amount of air than your installation.


I do think pre filling the filter and getting as much air out as possible first will greatly help.
 

·
Registered
Joined
·
687 Posts
Discussion Starter #10
well now I am stupmed. After getting home last night, I pumped and bled the system quite well. I took her for a spin, and I still found air in the system. After that I took Josh's advice for the teflon paste sealant. Did a run to a meeting, ran back and checked for the presence of air.....NONE. I was feeling real good this morning when there was no stumble.

I ran into work (~1 hour) and she sat outside until lunch. She started with a stumble and then die again. grabbed the wrench and rag, and bled the air out, running again.

Tonight I am going to put a fitting between my two hoses at the filter (taking the filter out of the loop) to see if I still get these issues. If so, it is the head and not my other connections to the OEM nipples.

This does bring one thought though... Of who has used the CAT head, what sealant did you all use for the gasket between the cover and the head?

I'll get this eventually, just don't like bleeding at 7 degrees with wind howling up my backside.

MN
 

·
Registered
Joined
·
429 Posts
nassdmax that sucks! Sounds like a good idea to use a nipple and take the filter out of the loop. If you have the recources, you could put a Schrader valve on the filter unit, plug the other ports, pressurize the unit and stick it in a bucket of water and watch for bubbles. Or you could use a vacuum pump on it to see if it will hold a vacuum. Good luck!


Josh
 

·
Registered
Joined
·
6,063 Posts
Hi,


i don't use any sealant between the cover and the head (if you mean the block-off plate for the priming pump). i just use the CAT gasket. the O-ring boss fittings don't require any sealant either. as for the filter media i just put a bit of oil on the seal when i screw it on..
 

·
Registered
Joined
·
687 Posts
Discussion Starter #13
I do the same as you Nick. Good to know that there are no issues there.


I will do the bypass deal tonight. Run her for a while and see where we get. If all goes well, then it must be the CAT and not the other connections.


The suggestion of using air to "pressure test" is a good one. Just regulate the pressure low enough to not cause harm. On the other hand, the primer pump is capable of getting the pressure in the filters pretty high, and I still haven't seen any wetness around any joints.


Thanks again, MN.
 

·
Registered
Joined
·
1,558 Posts
nassdmax,


I do after 8-9 days of good running seem to collect enough air to start the stumbling you mention. If I don't bleed in a day or two after the stumble I will have a stall like you.


I'm a little lost on this. Either there's a bubble somewhere in my system that I never quite get out and the setup of our fuel systems exacerbates the bubble to a troublesome size after X amount of run time or my filter head is leaking. When I moved from the airbox to the alternator locale I left the feed line in place and ran OEM for a little over 2 weeks with no issues so i know that lines good.


So if I have a small leak, it takes it a while to build up enough air and it's coming either from the out line of the OEM to the Cat or the Cat head itself. I'm considering the PermaCool head as well(I'm thinking maybe the flatter head design might be more friendly to our vacuum systems, or even considering trying to get Kennedy to part with just one of his filter heads he's having made for his new Cat setup to see if it makes a difference.
 

·
Registered
Joined
·
403 Posts
Nassdmax, I'm posting again on this thread for 2 reasons.


One is to report that I have journeyed down to the dealer where I bought my truck, and to the much larger dealer here in town.


Showed a print of your setup to both Ser Mgrs, and both responded that they liked your setup and both made copies of the printout. Both stated that theu could see no reason that this would affect warranty, and that GM should be happy that you were trying to improve filtrarion. The regional man from GM hasn't been in yet, but my tech friend will call when he is in town.


My other reason is to get this thread back on page one and request that you keep us filled in on your air problems.


It looks as if the cat filter is the highest point in your setup, is there a bleed port on it? Also, how do you get air out of the line from cat filter to the pump? Could this be the problem?
 

·
Banned
Joined
·
6,539 Posts
My Racor is mounted under the airbox. No air issues since installed about 8 months or so ago.
 

·
Registered
Joined
·
687 Posts
Discussion Starter #17
Thanks guys... I don't know what I did wrong, but I am going back at it soon. I for now have removed it from the system and I have not had a stumble yet. Obviously something wrong with the CAT head, filter, or my connections at the head.


It is good to hear that Hoot and others with the POST-oem setups have had no issues (although non CAT head). Maybe there is something to do with the height here that we are all missing, but then again, where is the air in their setups.....HMMPH. Frank Blum has his up in the same spot (although not a CAT head), as well as others and I have heard nary of a complaint. VR seems to have my issue on a lesser scale with his CAT head. Makes me wonder if it is the CAT head design in the post-oem position. Anyone else with a CAT head up high?


Could it be that the high cat head traps the air before it is "recycled" to the tank as is the case with the OEM. My theory is that there is always air being "generated" and it is taken care of because it is recycled to the tank through the return lines. Am I all wet??


My next step is to pressure check the head and fittings with PSI and soap. If all is good there, I will find a new lower location rather than buy a new filter head. Any other suggestions?





Dirty Old Man,


Good to hear your news. That would be a great thing to have IN WRITING that there is no effect on our warranties. As far as the bleed, there is one at the "top" of the cat head. I can bleed just that and get the truck running fine. To do a total bleed, there is a fuel rail service port just below and to the left (if your looking from the front of vehicle) of the Alternator. I can get a bit of extra air out there, but it does not help the situation as I always got more air out of the filter head.





Thanks guys... Feels good to sound off.


MN
 

·
Registered
Joined
·
432 Posts
NassDmax, I have the Nictane Cat mounted in the usual position Pre-OEM (left rear fender well with the Nictane bracket), so it is as high as anyone else's using this setup. Have never had a stall or a stumble (we're talking aboutb the truck right) since the minute it was installed and we fired it up after pumping it for about 15 minutes or 100+ pumps.


If you have the same setup, it would seem that the connections is where you should look. Something is sucking air past a fitting or connection. It would be rare for you to have a defecive head, but I guess that is possible. I don't think that mounting location is the problem by itself as there are a lot of us that have the same setup with no problems.


Has to be a connection somewhere sucking a tiny bit of air that builds up over a few day or two.


Good luck, you will find it!
 

·
Registered
Joined
·
1,309 Posts
nassdmax, It looks like your filter is higher than the OEM just like mine. I installed an air bleed in the top of my filter on the discharge side. If you don't have one that is the problem. I don't use the OEM bleed at all when changing filters. The bleed on top of my secondary fills the filter and line all the way to the pump. I have done several of these without a problem. There is nothing wrong with Teflon tape except it will contaminate the system if you have to remove it. Later! Frank
 

·
Registered
Joined
·
1,349 Posts
Frank Blum said:
nassdmax, It looks like your filter is higher than the OEM just like mine. I installed an air bleed in the top of my filter on the discharge side. If you don't have one that is the problem. I don't use the OEM bleed at all when changing filters. The bleed on top of my secondary fills the filter and line all the way to the pump. I have done several of these without a problem. There is nothing wrong with Teflon tape except it will contaminate the system if you have to remove it. Later! Frank
When you install a new fuel filter, do you fill the filter up with fuel before installing it to cut down on air ?.
 
1 - 20 of 44 Posts
Top