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Discussion Starter #1
Has anyone installed this gauge. This gauge is mounted when looking at the Duramax engine on the left side. There is a brass fitting with a black cap on it. When you unscrew the black cap, there will be a schrader valve. To my understanding this gauge snaps onto the port there, and measures vacuum between filter(s) and pump. It is sold by www.kennedydiesel.com also there is a picture of it. I would like to know your thoughts on this and if anyone has installed; wouldn't it be better if it screw on, instead of snaps. I think it is good way to see if your fuel filter(s) are starting to plug.
 

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That gauge is from kennedy is about the best thing for that. Snap on style works just fine, and thats what the fitting is designed for, a quick connect style fitting. His guage uses a liquid filled gauge to control the movements better, and the numbers are easy to see. He had a purpose made guage made for this specific application. I have the Kent Moore gauge and the only advantage I have is I have a hose on mine that allows me to move it around, but the reading changes depending on where the guage is... so its hard to maintain accuracy.


If your shopping guages, buy the one from kennedy.
 

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Discussion Starter #3
DURAMAX DIESEL
You say you have Kent Moore gauge, is this gauge screwed on or how is it mounted to the brass fitting. The reason I'm asking I just thought of, I think I might still have a Racor gauge that might be a compound gauge (PSI TO Vacuum)if I can find it. But this gauge if I can remember has a 1/4 inch npt on the back side. Would this work, I hope I still have it. It was also fill with glycerin so the needle would stay still. I might have gave it away to someone. I will have look for it. Would appreciate if you would let me know if you think this gauge would work or not. Before I start digging.
 

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not unless you can get a fitting to mate to the one on the truck. Kennedy and kent moore are the only ones I have found. Screw on fitting will not work with out tampering with it and thats not advisable incase you ever need warranty work done on the fuel system.
 

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GMC-DMAX,

Dittos to Eric's advice. I have the Kent-Moore gauge but I would have bought JK's if it was available at the time. I also have a vac/pressure gauge permanently mounted on the input side of my post-OEM Mega filter (output side of the OEM) which I use to monitor my lift pump. Seems like you could mount a gauge on the output side of the OEM filter by placing a tee in either the fuel line or the hose feeding the schrader valve test port. I also seem to remember either Chris (chuntag95) or Tommy (abear) trying an engine mounted Glycerin filled gauge but they had trouble getting a stable reading. The non-glycerin gauge I'm using was only about $12 from www.MSCDirect.com - works great so far. I've had it installed for a little over a year and about 16kmiles.

 

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The Kennedy setup works really well, especially with the quick disconnect. I only put mine on when I want to do a pressure check, otherwise it is off the truck.
 

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Discussion Starter #7
Thanks Everyone
I think I like what BMDMAX said about only using it once in a while and not permanent on the engine. I guess I will go with Kennedy. I would have like to have use my gauge because I found the paper work last night and it cost me $82. Haven't found the gauge yet. I just might use it at the filter(s)

Thanks Again Everyone
 

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It'll be a couple weeks yet the way it looks. I was quoted 3-4 weeks a couple of weeks ago. Dials are the holdup, waiting for the screenwork...
 

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another option if you're looking to use the old gauge is to remove the scrader port from truck. there is just a soft line connecting to the back side of it so you can remove it and replace it with something (like barb to NPT fitting) so you could use your existing gauge.
 

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Discussion Starter #11
Found my gauge 30"hg to 30 psi. I also figure a way to do this job. I found I had a s/s reducting nipple 1/4" npt to 1/8" nft (npt= national pipe thread; nft= national fine thread) The 1/8" nft will screw inside the fitting where the schrader valve is. The other end of the nipple is 1/4" which I will have to get a 1/4" coupling. The biggest problem is I have to have something that is the right size and length that will push down on the schrader valve. When all the pipe pieces are together. I have a piece of plastic straw that is strong that I think will work. Or maybe I can take the schrader valve out of the brass fitting.
 

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Do you plan on running a BIG lift pump?





Do you plan on running with an extremely plugged filter?





Normal operation shouldn't take yopu across 15"hg, and I seriously doubt we'll see the day where more than 15 psi of supply psi is desired for a lift pump, so why use a gauge with 2x the expected range of operation?





Kinda like a 50 psi boost gauge on a Dmax with a stock turbo...
 

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Discussion Starter #13
Kennedy
I have this gauge and I know it isn't right for the job. But if I mark the gauge, when everything is right, then see a change in vacuum or even the psi. I will know something is wrong and to find out the problem. No big lift pump or no serious plugging of the filter(s)and also no more Hot Rod things for me, just want the truck to last now. I know you will sell the right gauge if I wanted it.
 

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What he is getting at is thats its hard to see the changes with a gauge like that. The smaller the working area of a gauge, the easier it is to see a change. YOu will have a hard time even picking up 1 or 2 lbs of pressure with yours. A good gauge, (not the kent moore either) will be sensative enough to detect .5 or less psi or .5 or less in/vacuum.
 

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Discussion Starter #15
DURAMAX DIESEL
Yes I do realize the importance of the guage. But if I mark the the gauge and then see a change, then I know something has change in the system and to find out what
when wrong. All's I'm saying is that I have this gauge and if this don't work out for me, then I will get something that will work. If this works out, then I saved purchasing and the cost.
Here is another problem I have seen lately. The company's it don't matter who. They don't have everything you want or it is back order and they never call you to tell you this or even when you order they know they don't have all of the product and don't tell you. What has happen to America business.
I really don't know if I should have said all this but it gripes me.
 

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not sure where you going with the last part, but as the first part, I agree, you can save repurchasing the gauge. But, from someone who uses one nearly everyday, its hard to see small changes with a big gauge. Lots of things will effect the reading, just the height you hold the gauge (if it has a hose) will effect it nearly 1" of vacuum. Also atmoshperic pressure, altitude and other things can change the reading....


I still would caution against making a permanant modification to the test port. If you have to take it in and the dealer cant hook to it for diagnostic purposes......
 

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If you are not doing a lift pump then I'd go strictly vacuum. Basically (using made up numbers) if you have 100° of scale (1/2 of a 200° gauge and 20 increments, you will have 2.5° of needle movement per increment. If you spread the same scale over double the area, you'll have 5° of movement per increment, OR 2.5° movement per half increment.





We are working in an area which .5"hg and even .25"hg increments are handy. The unit shown below will have added tick marks between the existing ones to help aid reference.





 

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The stock Kent-Moore gauge that I have works fine. I am certain that the one pictured above will work just great. I am certain there are other gauges on the market for a cheaper price that work better also. I don't believe the measurements being taken at this test port require a great deal of precision. Example: I know when I change OEM and Pre-OEM filters 5,000 miles ago, the reading was 2.5inHg of vacuum at idle. The reading went to 3.0 inHG at 3200 rpm (in park). I occasionally check to make sure everything is OK. Last time I checked, it was sitting at about 3.5 inHG at idle. When it rises above 5 inHG (or 4.5 inHG or 5.5 inHg), I'll change the Pre-OEM filter, cut it open and see where I stand.


As far as the gauge changing values, place it in the same place on the truck. The measurements I have made from day to day are very repeatable. Also, prior to installing the gauge onto the test port, push on the center pin. This will reset the gauge to the current days atmospheric pressure (ie. the gauge zero's out).


The key to this whole thing is the Connector the attaches to the test port. You have two options:


1) You can easily replace it with your own. Then you need to deal with the dealer if you take it in for service. (as Dmaxallitech mentions) (or else put the stock one back in place).


2) Find a source for the connector. I know of at least one person who has done this. Call Kent-Moore and find who they purchased the connector from. Kent-Moore has given this info out at least once.Edited by: OC_DMAX
 

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Discussion Starter #19
I just installed the gauge and it works fine. This gauge is a Racor gauge. At 7" hg the gauge is yellow, then at 10" hg the gauge is red.It is also metric on the other side of the numbers. It even has a clear decal that has a arrow on it to put on the face of the gauge. This is use for a reference. The Racor part no. is 18-1202. I can take it off when and if I take my truck to the GM dealer. Right now it was reading 3.5" hg
The factory installed Racor fuel filter(secondary) has about 5700 miles on it. The RK-32313(primary) fuel filter has about 1500 miles on it which is a 2 micron filter. I figure I will change both out at 15000 miles
or if my trusty gauge tells me different. I was going to put in a tee right after my primary filter an use a 3/8" copper line (9 ft) to the engine compartment. This copper line would also have been heated and insulated. I'm glad I didn't do all that work when this job will do the same thing without all the piping.
 

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I'm not sure if I would thread anything into that shrader port. If your running stock (under vacuum) dirt, small thread filings, etc can find its way through there and possibly to your pump and injectors. The quick coupler is made to install and remove cleanly. Edited by: a bear
 
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