I have a bad isolator and am going to get rid of it. I am going to run fuel to the gauge. I currently have antifreeze in the tubing and was wondering if I should flush all of it out or just hook it up to the needle valve. The antifreeze wouldn't come out with diesel pushing on it.

Also, if I do flush the antifreeze out should I treat the fuel so that it won't gel up in the winter or isn't this a problem? I was thinking about treating it like I would a winter tank. I also thought about just running an additive in the tubing like power service.

Does anyone have some suggestions on this topic?

 

The anti freeze in the line will eventually dilute with diesel and find it's way though your injection system. I highly doubt if the concentrations involved will cause a problem but it's no big deal to blow the anti-freeze out.
It makes absolutely no difference if there is air in the line to the gauge.

 

I was told that there can be a little air in the line but over 1" is bad, you won't get accurate readings.

 

What size of tubing is used for the fuel pressure gauge? I think that mine is 5/32, what it everyone else running?

 

Anybody?
.............

 

I use 1/8" tubing, the exact same kind used for a boost gauge.
There is no need for a larger line as there is no flow though the tubing, just a change in pressure.
In fact the smaller the line the faster the gauge will react.

 

That's not true, but anyway after a week or so the air is gone.

 

Even if the line was entirely full of air the difference in the readings would be less than 0.1 psi.

 

Diesel Manor told me that you only really need to even put antifreeze into the line if it's longer than 6 ft. in length. Mine very well might be longer than that. If that's the case, how do y'all suggest that I get all the antifreeze in it?

 

By eliminating the isolator and running pure mechanical.

I dunno. I always though that the lines already had the coolant in them. If not, maybe try siphoning the antifreeze in (very carefully I might add).

 

Anybody actually know the answer for sure?

 

when I ran an isolator, I used a syringe to put antifreeze in it...It worked but the isolator gave inaccurate readings so I took it off and just run the needle valve now

 

I would disconnect the end of the line at the gage, and cap it off somehow. Then disconnect the end at the isolator. Put that end in a cup, then uncap the other end and blow air thru it. that will get as much of the antifreeze out as possible.

 

I am running the isolator with the antifreeze and never had a problem. To put the antifreeze I caped off the diesel side of the isolator filled the isolator and gauge with the antifreeze as best I could. Then put the isolator with the hose hooked up but not tight in a small container hooked op the gauge but not tight and let it siphion intill I was shure it was good and tightend everything up. No air in system at all. A syringe works well it you can get one also.

 

farmer dave,

At low PSI reading less than 5 PSI, a little air will make no difference once you get over that there can be as much as a 5 PSI change in the gauge because of the air. Air compresses very easily, fluids do not so get all the air out for the most accurate readings.

Mark @ DPPI