by "Urambo Tauro" (urambotauro)
Published 12/18/2017 at 12:15
by "Urambo Tauro" (urambotauro)
Published 12/18/2017 at 12:15
Tags: saab 900
; project
; wrenching
STARS: 10
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What a lovely day! A little over a month ago, we got the engine running. But something went wrong. So we got to relive the thrill a second time.
Back in October, for the first time in about a dozen years, the engine ran (thanks to a new fuel pump that took way too much work to function properly), so we let it run for nearly half an hour. This allowed us to check the charging system, the cooling system, and keep an ear out for anything that would point us in the direction of further repairs.
It ran pretty good! The thermostat opened and coolant circulated, and one of the cooling fans came on too. But it wasn’t charging, so we pulled the regulator out of the alternator, found it out-of-spec, and replaced it.
But just as soon as were we were ready to test the charging system again, a new crank/no-start scenario reared its ugly head. Two steps forward, one step back. It was something in the ignition system.
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Long story short, we found a bad crank sensor , which prevented the coil from firing. The sensor was unavailable, but we were able to buy a part of the part- the very guts of the sensor which were the source of our problems.
The sensor was a huge pain to get to, on account of its location behind the crank pulley/harmonic balancer, which was all tightly placed near the firewall. Access was such a pain in the neck that we decided to replace a few more parts to avoid tearing into it again any time soon.
All four drive belts had to be removed, and sure enough they showed some cracking, so we replaced them. The harmonic balancer was in the way too, and had some hard, dry, cracking rubber, so we replaced it. And the oil pump was right behind the crank sensor, so we decided to take it one step further and replace the pump O-ring and “front” main oil seal.
As for the sensor, my brother was able to solder the new pellet to the old sensor’s wiring, heat-shrink it, and assemble it into the old bracket head, good as new. Everything went back together with a few new parts (including a new tensioner pulley to replace the old one’s crunchy bearing).
We poured in some fresh coolant and gave it a crank, but it didn’t want to start. It had fuel... and spark was being delivered to the plugs... so what gives? We pulled the spark plugs out, and found a lot of moisture in the cylinders ( pleasedon’tbeaheadgasket pleasedon’tbeacrackedblock ). We weren’t sure if it was condensation from sitting for several weeks, or maybe just unburned gas. But it wasn’t pooling, so we cleaned the spark plugs to make absolutely sure that they would fire, and put it back together.
This time it fired up! It ran a little rough at first, but evened out, as shown in the video above. So I want to say that it was probably just condensation giving us some trouble there.
We let the engine run for about a good hour this time. It got up to temperature, opened the thermostat, the cooling fan came on and turned itself off again, the heat inside the cabin worked, and you know what else? It was charging now too.
Now we can finally move forward to the next repair. Not sure if the holiday will give us more, or less time to work on it, but if we don’t get anything done for the next couple of weeks, I think this is a good note to finish out the year on.
"shop-teacher" (shop-teacher)
12/18/2017 at 23:07, STARS: 1
That’s some really good progress!
"Urambo Tauro" (urambotauro)
12/18/2017 at 23:18, STARS: 1
Well, it already WAS running before this sensor went bad, so this was kind of an unwelcome detour. I wanted to be doing brakes by now...
But, this forced us to take a closer look at the belts and reconsider putting them back on, and it gave us a good excuse to change some oil seals. Plus that pulley, and balancer... yeah, it’s good to have that stuff done.
"shop-teacher" (shop-teacher)
12/18/2017 at 23:28, STARS: 1
You changed a lot of important parts while you were at it, so it certainly wasn’t wasted time.
"ShaunInYVR" (shauninyvr)
12/19/2017 at 16:11, STARS: 1
I *JUST* had my crank position sensor replace on my ‘92 900S Convertible. You did all the right things when you were in there, so well done! I didn’t do mine myself because I don’t have the tools to get at that big bolt. But I do pretty much everything else myself. It’s a great car, you’re going to love it. The forum on saabnet.com is really good if you aren’t on it already.
"jimz" (jimz)
12/19/2017 at 16:19, STARS: 1
9 years in Catholic school means I immediately put your post title to the melody of the Memorial Acclamation.
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