DENVERDODGE04

What is the differance between electric, full sweep, and mechanical. Does the fuel, and trans gauges have to be electric to put them inside of your truck, how do they make them work to do that being electric? Thanks Guys

DENVERDODGE04

well you guys are alot of help..

Ace

This just came up in a search I did, and I can't believe nobody answered!

Electric gauges use some sort of sensor that drives the gauge with an electric current. Mechanical gauges use a tubing to connect to the pressure source/port to directly drive the gauge with actual pressure. Full sweep means the needle goes all the way around - 360 degrees. Well, usually a bit less.

Whether or not you can safely use mechanical gauges in the cab is a matter of opinion. I think if you are careful and do good plumbing it is OK. Been doing it that way in many different vehicles for many years, no problem. I would not run a mechanical fuel pressure gauge with gasoline in the cabin. Just not smart, regardless of the chances of a malfunction. I use a needle valve on the diesel fuel pressure lines for cutoff, in the unlikely event that ever become necessary, and keep a couple appropriately sized pipe plugs in the toolbox, to comlpetely shut them down, just in case. Nodoby wants to be driving around with a major boost leak. But if you plumb it right, with good routing and stress relief on the line, it'll never happen.

Never used the plugs or needle valves.

.boB

Mechanical gauges have adirect mechanical connection between the measuring port and the gauge. For temp it's a capillary tube. For pressure it's a fluid line.

Traditionally, electric gauges have a 90* sweep, and mechanicals have a 270* sweep. Over the same range, the mechanical gauge will give a more accurate reading. But, Autometer is now making some electric gauges with a 270* sweep.

Mechanical is fine for temp readings. Leakage of the capillary tube is rare. The capillary tube is physically seperated from the liquid being measured. If the capillary tube breaks, the gauge stops working.

Pressure is another matter. High pressure oil and fuel in the passenger cabin is not such a good idea. Diesel rail pressure is measured in thousands of psi. A race car would never pass tech with a set up like that. If you're going to do it that way, use nothing but AN fittings and steel braided line. That plastic tubing they give you with the gauge is trouble waiting to happen.

I prefer electric gauges because they're so much easier to install.