Saab 900 restoration/maintenance

[DennisCA]

Last week I installed the evaporator into the car, finally. Then I was attempting to install the anti-frost or cycling switch for the AC system. Digging around the right speaker I found a buncha wires for the anti-frost switch and for the re-circulation flap (I won't be installing that). But I can't see how I am supposed to mount the switch or where the capillary tube can enter the fresh air intake and go into the evaporator core.

Photos of this are not existent. I found some old forums posts dated to 2005-2008 but the image links were dead, of course. I found one pretty detailed text explanation and based on that, my car didn't get any mount holes drilled nor any hole for the capillary tube into the fresh air intake.

I can probably fab some DIY bracket to mount it though, but I wold really like photos of a factory install. I have asked around and am waiting. Yes I could just drill a hole somewhere but I want to try and keep it factory looking.

Meanwhile, I swapped the fuel filter, even reused the old banjo bolts. It really wasn't stuck very hard, I had been expecting a battle.

Only thing I got hung up on was the old washers had a rubber inside, never seen that (called a bonded seal, apparently). The new filter had regular copper washers and I suppose they will work as well.

I have assembled the AC pulley and the tensioner as well. Bolted on the compressor temporarily too to check. It looked to my eyes like the tensioner pulley wasn't aligning properly with the crankshaft pulley.

So I used my laser level to verify it. It's hard to photo but here's what I got.

The compressor pulley aligns with the crankshaft pulley, but not the tensioner.

The laser line comes in the center of the tensioner pulley instead

If I align the beam to the forward face of the pulleys it goes off the pulley itself

However it turned out to be a false alarm with the laser after all. I first realized the belt is supposed to go on the outer groove. Then I went out again and noticed that the compressor mount was slightly loose, so I tightened it and adjusted it. I also turned off the laser’s automatic leveling and adjusted it manually so it followed the pulley more precisely in the vertical direction. The car isn’t perfectly level either so that threw me off.

Now I can get all three wheels to line up quite decently with the outer groove of the compressor pulley instead.

Made my first brake line:

And got some yellow chromate passivation fluid

It's the trivalent chrome based fluid and not the Erin Brockovich stuff.

 

[Misterg]

And got some yellow chromate passivation fluid

Which one did you get?

(For smaller parts, a soak in the citric acid / sodium hydroxide "DIY Evaporust" formula will get the last of the rust out of the pits.)

 

[DennisCA]

I got it from tifoo.de a german site.

I tried dipping the parts in various stuff (muriatic, vinegar) to prep them but I noticed no difference with new zinc parts, just degreasing seems to be enough.

I've not yet found a solution aside from strong muriatic acid that leaves the part truly clean, citric acid seems to turn the rust into some black oxide that gets in the way, much like phosphoric and vinegar too.

Sandblasting seems to be the only real way I've found to get a part clean enough for say electroplating. I want to electroplate the brake calipers and if possible, passivate them too.

 

[Misterg]

I've not yet found a solution aside from strong muriatic acid that leaves the part truly clean, citric acid seems to turn the rust into some black oxide that gets in the way

There is less black with the citric acid / sodium hydroxide mix, and what there is rinses off fairly easily with a pressure washer- at worst it needs a wire brush. I've had good results zinc plating after this treatment.

 

[DennisCA]

Ah right that's the sodium citrate stuff IIRC got some of that too somewhere.

 

[Misterg]

Ah right that's the sodium citrate stuff IIRC got some of that too somewhere.

This stuff:

(But note that I've mostly used sodium hydroxide for the mix, rather than washing soda. The one bath I made up with washing soda has given me some odd results - parts are blacker and there's some sort of sludge forming. I'm sticking to NaOH for the mix in future.)

Thread 'Home made "Evaporust" formula'

Jul 27, 2024

I came across this video, a famous YouTube gunsmith has published a rust removal recipe that uses the same chemical mechanism as Evaporust. For those who don't know, EvapoRust uses chelation instead of acid and has the advantage of not damaging the base metal. It works great but is very expensive. This guys formula is slightly acidic but a fraction of the cost and lasts longer.

I've watched this YouTuber before, he comes across as honest, so worth trying his mix.

• RIP

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[Haz87]

I've worked on loads of cars with those Bosch filters and never have I seen the use of bonded seals. They are great for sumps etc, but I don't know if I'd want them near fuel. Regardless, "normal" copper crush washers are absolutely fine and the proper washer to use.

 

[mr haynes]

Dowty washers are normal.
I've had situations where copper washers don't work but dowty do, and that is with using supposedly quality parts.

I hope your banjos are totally sound, mine developed a hidden pinhole causing air entry and lots of head scratching over poor running. The banjo fittings are not a normal readily available standard size

 

[Seadog]

Sandblasting seems to be the only real way I've found to get a part clean enough for say electroplating.

It still leaves mineral salts in the surface. A thorough wash with distilled deionised water shifts those.