Hey Guys, I have a question about installing a Boost/vacuum gauge, where can you hook up the vacuum to, Does it have to go to the pump or can it go anywhere branched in line, The directions on gauge says to split line & hook-up for pressure on intake & then tee in to a vacuum port? I have 1 of those princess auto gauges, GTO JOHN

Hey Guys, I have a question about installing a Boost/vacuum gauge, where can you hook up the vacuum to, Does it have to go to the pump or can it go anywhere branched in line, The directions on gauge says to split line & hook-up for pressure on intake & then tee in to a vacuum port? I have 1 of those princess auto gauges, GTO JOHN
i also have a princess auto gauge, i don't have vacuum hooked up to anything as there is no vacuum as in a gasser. ED

There is vacumn on the 6.5 TD it is just not produced like on a gasser so the only vacumn you could tap into is at the vacumn pump. The vacumn pump is primarily there for wastegate operation and EGR on the "S" motors, so if you have a mechanical wastegate controller and have an "F" motor then you don't need the vacumn pump or guage to monitor vacumn.

For diagnostics or are we talking about permanent install so you can monitor boost, for diagnostics, plug into mainline prior to the WG solenoid to see if vac pump is pulling proper vac, if low vac is seen go to rubber fitting out of back of the vac pump (see reference area pics & wg troubleshooting), no or low vac stop,

You are at a decision point replace vac pump or get rid of it; as a F truck (add that to sig) I had to stop & figger that out I don't know of any S 3500s, your vac is for 1 solenoid to control WG.

You could eliminate that problem forever by going mechanical WG control and ditch pump-lines-solenoid

But if you find vac pump is good, and line to wg solenoid is not leaking (prone to have small cracks/leaks with age) then next would be to tee into line going to WG actuator can on side of the turbo to see if vac applied to WG is happening, if not line or wg solenoid is suspect.

If wanting to get a boost reading you will need to drill & tap upper intake manifold, (see pictures area) or use a scan tool to read boost the PCM is seeing.

i think the gauge he is referring to is a two in one gauge boost/vac. same on i use. ED

i think the gauge he is referring to is a two in one gauge boost/vac. same on i use. ED

I surmised that, what I wasn't sure of was if he was planning to use the vac portion as a test gage by itself, or was installing it for boost monitoring;

Thought just occured to me as I was replying, it could do double duty, run as boost monitor when tapped into the intake, then if boost goes low, disconnect it and go for test drives with it adapted with rubber tube to read vac for diagnostic purposes,

now that I think of it, in pressure mode a boost/vac gage could be used for lift pump tests long rubber tube to the filter mgr drain air in the gage line tube should be sufficiently trapped so fuel doesn't make it's way to the gauge, especially if a even longer piece of rubber hose is used to mate to the gauge line.

Can't use it however to monitor all at once, unless ??? you put a manifold in cab and open up one at a time the line you are interested in reading, say like an aquarium air needle valve gang manifold one port to each area of interest. (I think I just thunk of my next project to try :D )

The gauge has both boost/vac. I put a new pump on last winter(vacuum) and was just thinking of monitoring it with this 2 in 1 gauge has anyone done this with the gauge from princess auto or can you only use it for boost, Thanks John.

will work as one or other, can't do both functions with same gauge at same time unless you manifold it with manifold for boost or vac and close of side of manifold you aren't looking at