Boost Gauge Installation on SAAB c900

I mentioned a few posts back that I was going to put a proper boost gauge in the c900.  There is a factory gauge, and I'm leaving that connected.  I like having a vacuum gauge to watch in order to get better mileage, and I also wanted a calibrated boost gauge, so I'm putting an Autometer 3401 Sport/Comp vacuum/boost gauge in.  So I will have redundant gauges, for whatever that's worth.  (The factory gauge is only marked with colored ranges, not vacuum or boost values).

I'm also putting some gauges in the radio slot, so I decided to put the boost gauge on the windshield pillar.  The first order of business was to remove the pillar cover.  There are three plastic plugs that hold it on.

When it's removed, you get to see the actual, unfaded paint your car had originally.

Back down on the workbench, I start to get the gauge ready to install.

This is a 2 5/8 inch Autometer gauge.  I figured I'd just use one of their mounting cups and mount the thing on the pillar.

First issue - the gauge doesn't sit all the way down in the cup!  You can see the gap on the right side in the picture.

So this is an Autometer part for an Autometer gauge and it doesn't fit right?  Geez.

The problem is pretty obvious.  The mounting studs/screws are too long and are hitting the back of the cup.

Hmmm.

Looks like a job for Hacksaw Boy!

I don't know about you, but I'm always nervous when I have to...uh, 'modify' a brand-new something I just bought.

But I have no other choice.

I cut the studs down to near the surface of the gauge.  I'm not using them to mount the gauge anyway.

Now that the gauge will fit all the way into the cup, I connect the vacuum hose to the back of the gauge.

Another note here:  I didn't want the hose to pass through the back of the mounting cup where it will be visible - I want to run it through the bottom so it will be more or less hidden.

I couldn't flex the nylon hose enough to make a 90 degree bend, so I procured a 90 degree adapter.

You can see I painted the hose black so if it was seen, it wouldn't be so obvious.  I actually didn't need to do that.

I didn't need to do that, because I decided to run the hose and the wiring for the dial light through a piece of shrink tubing.

Here we have the gauge installed in the mounting cup.  The cup comes with a grommet to cover the hole in the back...well, there's still a hole to run wiring through.  Maybe I'll get a small plug to fill that hole at some point.

You can see how I ran the hose and the wiring through the bottom of the cup.  Much tidier I think, especially with the shrink tubing.

I just don't like being able to see wires hanging out.  Behind the dash or something where they're hidden, ok.  That's normal.  But not out in the open.

Now ve install ze mounting bracket on zee pillar trim.

I marked the trim before I took it off so it would line up the way I wanted.

It's not a custom fit like the pillars you can get for those Japanese cars, but it doesn't look bad.  Besides, most of them will fit a 52mm (2 1/16) gauge, and I wanted a 66mm (2 5/8) gauge for better visibility.

The rest of the installation is straightforward.

This is the turbo gauge hose which goes to the back of the stock instrument panel.  I just held my breath and cut it.  Then I put a T connector (comes with the gauge) in the line.

Run the hose and wiring through the pillar trim and down to the dash.  Make sure you don't foul the mounting holes for the trim (yes, I did the first time).

And connect the gauge line to the T connector.

Autometer provides a nice rubber boot to fit tightly over the connector to ensure there are no leaks.  If you do this kind of install with a boost or turbo gauge on your car (any make), and you start seeing "Check Engine" warnings, it's a good bet you have introduced a vacuum leak.

Just make sure your connections here are good.  I ran the car at this point to make sure I didn't have any leaks and also (!) to see that the gauge worked correctly.

Here's the gauge installed.  You can see how much easier the installation was with the instrument panel and fascia out of the car.

I still (as of this writing 2 weeks later...) haven't connected the gauge light to the car's lighting circuit - waiting to install the other gauges and cook up a lighting harness for all of them.

Now I can finally put the instrument panel and dash back in.  Installation is just the reverse of disassembly.  Good thing we labelled all the connectors, huh?  And guess what?  The clock works!  Replacing the electrolytic capacitors fixes it!

The gauge works great.  The only downside with the mounting is that the gauge relies on the screws to the pillar to hold it on - and it's a bit wobbly on bad roads.  I'm going to just use longer sheet metal screws and drive them all the way into the sheet metal behind the pillar to sturdy it up.  Add that to the list of things to do.