View Full Version : How To Change a Coalescent Fuel Filter. The Proceedure, Method (CNG, Natural Gas NGV)

03-08-2010, 12:16 PM
This post contains the general instructions for changing the coalescent or coalescing CNG fuel filter on any of the Dedicated or Bi-Fuel Ford CNG vehicles. For instructions on changing the coalescent fuel filter on the 2001 – 2005 Honda Civic GX Click – This Link (http://cngchat.com/forum/showthread.php?4795-Honda-Civic-GX-Coalescent-Filters-Change-Procedure-2001-2005-Post-1-of-2&highlight=coalescent+filter+civic)

To purchase a filter for your dedicated vehicle- Click This Text (http://cngchat.com/forum/showthread.php?6183-FS-Coalescent-Filter-Coalescing-Filter-CNG-Fuel-Filter-NGV-Fuel-Filter-Dedicated&highlight=coalescent)

To purchase a filter for your Bi-Fuel Ford - Click This Text (http://cngchat.com/forum/showthread.php?6182-For-Sale-New-Coalescent-Filter-Coalescing-Filter-CNG-Fuel-Filter-NGV-Fuel-Filter&highlight=coalescent)

If you can change your cars oil, you can change your own coalescent filter. You will need a new coalescent filter, replacement o-rings, drain plug, a cup, medium to large sized crescent wrench and a metric Hex or Allen wrench set.

Perform this procedure in an area that is well ventilated and removed from sparks or open flame. The Crown Victoria and Ford Contour will need to be elevated with a jack to gain easy access to the coalescent filter housing. Choose an area that provides a hard level surface. Before jacking or elevating any vehicle, set the parking brake and place the proper blocking behind the wheels remaining on the ground. Do not rely solely on the jack to support the vehicles weight; always use appropriately sized jack stands to support the vehicle.


For Crown Victoria’s and Contours, locate the shutoff valve. The shut off valve for the Crown Victoria is located by the filter housing, which is underneath the car almost directly beneath the driver side passenger seat. If you cannot find it, follow the emergency brake cable, which passes through the skid plate that covers the coalescent filter housing. The Ford Contour shut off valve is in the trunk by the tank valves and is sometime covered by a plastic cover. The filter housing for the Contour is beneath a skid plate that is under the vehicle almost directly below the radio. If your vehicle has a shutoff valve and you have located the valve move on to step “1”.

If your vehicle does not have a shut off valve or you are unable to locate the valve, read on. Almost all of the F150, F250 and F-Series trucks as well as the E150, E250 and E-Series Econoline vans do not have shut off valves. The filter housing for the trucks and vans are located just slightly behind the driver’s seat. There is a cross section picture of the filter housing attached to this post. The housing is connected to the inside of the driver’s side frame rail.
There are two ways to depressurize the fuel lines on a CNG vehicle. First some basic CNG tank education is in order. For safety, CNG tanks have electronic solenoid valves that are wired to the ignition switch. When the ignition is off, or in the event of an accident the solenoid valves on the CNG tank(s) are closed. With the valves closed, the filter housing drain plug may be safely loosened. Only the pressure left in the fuel lines will be vented.

I was unable to write this in less than 1000 words so the instructions are attached as a PDF. Select the document image directly below this sentence to view the coalescent filter change proceedure.

Key words: Parker Hannifin, Racor, Finite, CLS112-6, CLS112-10, CLS112, 050-11-BQ, 05011BQ, 6T04-023

05-06-2010, 09:09 PM
I just got my filter today. great post I will be changing out my filter in the next few days. thanks for the filter and instructions. is there a post covering the flush?

05-11-2010, 09:28 PM
Thank you. The flush procedure is contained in the "Attached File" TSB_03183_CrownVicCNG.pdf located right below the filter housing pictures. Keep your old filter in place when performing the flush. For Bi-Fuel vehicles, use 96% or higher isopropyl alcohol. You may need to perform the flush procedure 3-5 times. If this flush is your last resort before replacing the compuvalve, you can flush a bi-fuel vehicle no more than two times using the Ford PM-5 injector cleaner mentioned in the TSB. For bi-fuel vehicles you may need to carefully remove and flush the rubber vacuum line with alcohol that attaches to the compuvalve. If this tube is plugged, rotted and or leaking this will produce rough idling, dying hesitation etc. If the tube is deteriorated it may need to be replaced. If the vacuum line is detached the vehicle will not run on natural gas. This is a common problem causing no-start issues on natural gas.

07-21-2010, 07:43 PM
I was wondering if a dirty filter would be the reason that my large Dodge 3500 van has a hard time starting in the cold weather? Would this be the case, or is there another issue at play, I was also wondering if it may have something to do with the valves? It used to start just fine in the winter but the past few seasons it gets harder and harder. Any help would be appreciated.



07-21-2010, 11:29 PM
How often do you change your filter?
What is the quality of gas you have been running the truck on?
How often do you adjust your valves?
How many miles since your last tune up?

Unfortunately many NGV owners thing they're driving a super vehicle that needs very little, if any, regular service. When you post the answers to these question we'll have a shot at giving you a more accurate and valid answer.

07-22-2010, 10:03 AM
I tuned up about 6 months ago which was 5000 miles. However, I don't think I have ever changed the filter, or adjusted the valves. I am not sure how to adjust the valves.



07-23-2010, 09:05 AM
I know this question isn't really what this thread is about, but I really need help and this was the only thread that even mentions a Contour thats been posted on recently..... so here goes anyways.

I'm a new CNG user with a bi-fuel 1998 ford contour with 68.5k miles, and I'm having some problems with the CNG part.

To start with natural gas there I flip a switch on the dash board and turn the key to the on position without actually starting the vehicle. A little green light turns on and I can hear the tank make a *dong* sound when it connects to the engine (At least I think that's why it does that..... I'm very new.) when driving with CNG the car rides very rough, and whenever I'm stopped or idling the car shakes oddly, as if there isn't a steady flow of gas to the engine. Sort of a *wump..... wump..... wump.* It also has a tendency to randomly die, which is worrisome (Although it always starts up again with no problems, even while I'm still driving.) The vehicle does not act this way when running on regular gas, it works and runs just fine.

The other, and most aggravating, problem is that after driving on natural gas for a while that little green light I mentioned starts flashing on and off and my car kicks back into running on regular gas. When this happens I am not able to start the car using natural gas for anywhere from 15 minutes to several hours. When I try to make it switch fuels I don't hear the noise the tank usually makes, and the car will try to start for a minute, and then switch itself back to regular gas and start up. I bought the car on the 16th of July, and prior to that it had only been driven maybe 3 times in the past year and a half. Could it be that the natural gas is just old?

I am very frustrated right now, and I have no idea where or to whom I would go in order to have my vehicle looked at, so if anybody knows how I can fix this myself or a good bi-fuel repair shop around the provo/orem area, please let me know!

08-02-2010, 10:27 AM
I was wondering if a dirty filter would be the reason that my large Dodge 3500 van has a hard time starting in the cold weather? Would this be the case, or is there another issue at play, I was also wondering if it may have something to do with the valves? It used to start just fine in the winter but the past few seasons it gets harder and harder. Any help would be appreciated.



Many of the Dodge vans do not have coalescent filters, check with the dealer to see if yours does. If your dodge has a coalescent filter and it has not been changed in a while, then this could contribute to your cold starting issues, however will not likely be the sole cause. Typically CNG vehicles will not start in cold weather due to the following reasons: 1. Old battery, which equals poor cranking power. 2. Worn out Spark Plugs, they generally last about 60K in CNG vehicles, 3. Plugged, sticking, worn or damaged fuel injectors. 4. Sometimes issues with coil backs or distributor cap can cause this, however more often than not, it is an issue with the injectors sticking and refusing to open in the cold weather. You could have a combination of several of these factors as well. The carry over compressor oil from the fueling station can plug up the injectors over time. The heat of the engine turns the oil into a varnish, plugging the injectors and other aspects of the vehicles fuel system. When the coalescent filter is installed and serviced regularly, it helps to prevent the oil from becoming a problem. How many miles does your van have on it? If you have high miles and you do not want to replace or pay to have the injectors professionally cleaned or serviced, then you could try performing a system flush. To do this you can use the ford PM-5 injector cleaner or Denatured Alcohol. You can use the Ford TSB bulletin for flushing the crown Victoria for a reference.

08-25-2011, 01:49 PM
I have a 2003 Crown Vic Dedicated CNG. It has been having some problems with dying, rough idle etc. (as mentioned in the "rough Idle" thread)... So, I purchased this filter from O'reilly's about a month ago, and just now got around to installing it. The only problem that I have found so far, is I cannot find the filter housing!
http://i1015.photobucket.com/albums/af278/mattsdrumset/CNG/th_DSC03101.jpg (http://s1015.photobucket.com/albums/af278/mattsdrumset/CNG/?action=view&current=DSC03101.jpg)

One previous thread mentioned that the filter housing was on the drivers side, and the e-brake cable went through the bracket that holds it on. Well, the e-brake cable goes through some brackets, but there are no CNG components that I can see on the drivers side of the vehicle. (there are actually no visible components on the drivers side of vehicle)

Here is a view looking back toward the rear of the car, there are 2 components on the passenger side of the car, I do not know what either are. Neither component looks like the above graphic of the filter housing.

http://i1015.photobucket.com/albums/af278/mattsdrumset/CNG/th_DSC03096.jpg (http://s1015.photobucket.com/albums/af278/mattsdrumset/CNG/?action=view&current=DSC03096.jpg)

http://i1015.photobucket.com/albums/af278/mattsdrumset/CNG/th_DSC03095.jpg (http://s1015.photobucket.com/albums/af278/mattsdrumset/CNG/?action=view&current=DSC03095.jpg)
With Cover
http://i1015.photobucket.com/albums/af278/mattsdrumset/CNG/th_DSC03097.jpg (http://s1015.photobucket.com/albums/af278/mattsdrumset/CNG/?action=view&current=DSC03097.jpg)
Without Cover
http://i1015.photobucket.com/albums/af278/mattsdrumset/CNG/th_DSC03098.jpg (http://s1015.photobucket.com/albums/af278/mattsdrumset/CNG/?action=view&current=DSC03098.jpg)

Could anyone point me in the right direction to be able to change this filter out?

Thank you,


08-25-2011, 03:25 PM
So I found the location of my Filter Housing, and got the filter changed. It was behind the rear axle, almost on the floor of the trunk. (you can see in the attached pictures)

http://i1015.photobucket.com/albums/af278/mattsdrumset/CNG/th_DSC03102.jpg (http://s1015.photobucket.com/albums/af278/mattsdrumset/CNG/?action=view&current=DSC03102.jpg)

Close up
http://i1015.photobucket.com/albums/af278/mattsdrumset/CNG/th_DSC03103.jpg (http://s1015.photobucket.com/albums/af278/mattsdrumset/CNG/?action=view&current=DSC03103.jpg)

08-25-2011, 03:45 PM
Your problem was it is a BAF conversion and not a factory OEM dedicated CV.

09-01-2011, 02:48 PM
I was under the impression that it was a factory install, and not an after-market conversion since the tanks all say "Ford" on them. I guess that's what I get for assuming.... it is however dedicated...

Thanks for the response!

09-17-2012, 09:47 PM
Hello NGXV,

About 18 months ago I purchased two coalescent filters for my 2001 Toyota Camry. At the time, you did not have any specific instructions for changing the filter on a Camry. Since then I have performed two changes on the Camry and this last time I took a few pictures, and can write something up on it. Back then you mentioned that you would gift me a coalescent filter if I provided you with some pictures for a tutorial specific to the Camry. I was wondering if you were still interested in doing that. Please let me know what you think? Thanks. Alex

01-04-2014, 02:41 PM
For the older Civic GXs:
How to Change your 1998-2000 Honda Civic GX CNG High Pressure Fuel Filter



11-13-2014, 03:34 PM
Just posted this video

How to Change your 2006-2011 Honda Civic GX CNG Low Pressure Fuel Filter



11-13-2014, 03:35 PM
How to Change your 2006-2011 Honda Civic GX CNG High Pressure Fuel Filter