Vacuum gauge downstream of OEM filter?

[Jim Cobler]

All this filter information is a little difficult for a first time diesel owner so I really appreciate what has been said here.

I would like to follow up on the idea of putting a vacuum gauge downstream of the OEM filter. It seems like the only way to get some feeling as to the current status of your filter. My first filter failed at 13000 miles and caught me at a bad time.

Has anyone installed a vacuum gauge? Have any pictures? Vendor, part number and price?

Thanks again,

[dmaxalliTech]

Jim, as a matter of fact, we use a vacuum/pressure gauge quite often in our diagnostics. it hooks to the port mounted near the FICM on the pass side valve cover, it has a screw on cap to keep out dirt.

Ideal vacuum for good running engine is about 3-7 in. more then 8 and your leaking somewhere, and less then 2, your restricted. I might have that backwards, its been a long day. but regardless, we do use it.

[Jim Cobler]

What is the physical size of this guage? Coult it be permanently mounted on top or near the filter? Any idea of what the guage costs?

Thanks,

[dmaxalliTech]

Jim, it has a gauge face of about 4 inches. has about 36 inches of hose, as far as permanant mounting, depends on your fabrication skills. I have one that is from Kent Moore, cost about $140.00. The only thing you would need is an adapter to connect to the connecter on the engine, you could route vacuum hose to a regular vacuum/fuel pressure gauge that you can buy anywhere. getting an adapter is the hard part, I use kent moore due to gauge being large and easy to see for blind people (me) and having the correct fitting. I will try to get the part no. of gauge from K/M and post it for you

[britannic]

My 2003 has a filter condition indicator built in to the filter housing, so I'm assuming earlier models didn't get this?

If you need a gauge, IssPro make some nice gauges 2" and bigger, that are well priced in $30-50.00 range. Cut and paste this link to your favorite browser:

http://www.issproinc.com/Home/webstore/g_m_v.html

I'm sure other manufacturers will have comparable products and of course there is always eBay!

[jbplock]

Britannic,

I'm guessing the gauge you're referring to is on the air box for measuring air filter restriction (?). Though not explicitly stated, the vacuum gauge being discussed above is for the fuel filter.

DmaxalliTech,

In another thread someone posted the Kent-Moore P/N for the vacuum gauge as J44638.
Is this the one you are using?

It would be great if we could find a reasonably priced source for just the Quick Connect fitting and then add a common ($20) vacuum gauge. In one of the other fuel filter threads, JK indicated he found an adapter but the cost was nearly as much as the Kent-Moore gauge. Personally I would like to be able to check the vacuum periodically using the OEM test fitting with out plumbing in a permanent gauge.

(Hmmm

[NickLeinonen]

are you looking at monitering fuel filter restriction or air filter restriction? for air filters, no more than 20"h20 is recomended [6.6"hg]. for fuel filters i have no idea.

[dmaxalliTech]

jb. yes, J44638 is the correct part no. I am looking at setting up some kind of a permanant gauge on mine, tieing in the the hose that feeds the connector. Gm obviously feels that these readings are very critical to filter quality, I was reading today, that if you have a high reading ( above8) replace filter and retest. I would not recommend placement of gauge in truck however because there is fuel in it. just mount it under hood. The pressure side of it is used for checking integrity of low pressure fuel system ( feed to pump side) can also be used for priming system, prime until 8-10 psi. I will post on setup when I find something successful. JK, where did you find connector?

[Jim Cobler]

I believe the gentlemen that works at Racor stated that an increase of 3 to 4 inHg of vacuum would indicate the filter needed replaced.

My idea was to permanently mount the gauge under the hood and check periodically so I could change my filter before it causes a problem but not unnecessarily.

If the gauage was not heavy, I suppose a person could just put a "T" in the fuel line between the filter and the engine and let the fuel line itself support it.

[ 03-13-2003: Message edited by: Jim Cobler ]</p>

[jbplock]

DmaxalliTech,

Thanks for confirming the Kent-Moore part number. I called them yesterday and the price is $194 plus shipping (ouch). A lower cost alternative would be nice

[Kennedy]

The only way to prime the system is with the primer pump, OR very carefully by slightly pressurizing the tank.

As for installing a gauge to this port as a permanent rider, I'd recommend against it. Yes, there are orings, and it is a precision piece, but you know how hose couplers can be, and if it leaked, it would draw in air AND dirt.

I am looking into a gauge setup that could be used to periodically check restriction.

[chuntag95]

dmaxalliTech,
You did have it backwards. Higher vacuum is restriction and low vacuum is leak.

[Kennedy]

One thing to remember in all this:

Whatever you end up with for a gauge, and wherever you install it, you should establish a baseline as where you take your measurements, and the calibration of the gauge will factor into this.

The factory provided port is a stable location that will measure restriction from the closest point to the pump. Any other location should be between the pump, and the LASt filter that sees fuel so you are reading total system restriction...

[BigLakeDMAX]

Could a vacuum guage be mounted to the bleeder screw port on the OEM fuel filter mount? Either as a removable unit to allow for bleeding or on a tee?

[dmaxalliTech]

JK, excellent point that I didnt think about because we are always on a different truck, I agree completely it is best to get a baseline on your individual truck setup with a new filter installed, then you can go from there on your readings.

As far as using for pressure testing, hand primer is the only way I would reccomend doing because its there, and I never thought to pressurize tank like JK mentioned. when hand priming system, you will build pressure in feed side, you can watch for drop on your gauge to check system for leaks etc. There is a procedure outlined per GM but wont go into boring details.

Chunt, thanks for correcting me. I checked it out and relized I was wrong, like I said, tired.

Jp, I think I can get the gauge for approx 145.00 from kent moore, dealer cost. if interested in it, let me know and maybe can work somehting out to get it to you.

[mdrag]

dmaxallitech,

I found that the height of the gauge when taking the readings makes a difference. I used the J44638 and it has a 6 ft hose. If you put the gauge on the ground vs hanging it from the front of the opened hood, the reading will vary by as much as 1" Hg between the extremes.

I believe this may be what Kennedy referred to when he posted:

"...you should establish a baseline as where you take your measurements, ..."

Since I was working alone when I took the filter restriction measurements and needed to obtain a reading at fast idle, I snaked the gauge hose between the hood and windshield and placed the gauge against the glass so I could read it from the cab - all of my measurements were obtained at this position.

[ 03-14-2003: Message edited by: mdrag ]</p>

[dmaxalliTech]

mdrag,I have to admit, I have never used this gauge anywhere other then having it sit on the core support area. I never would of thought of changes. Thanks for the observation.