Clutch does not reply

One of the things I really wanted to do was to get the clutch to work. You see, when the engine is on, I cannot put the car in gear unless I mash the shifter into the gear. Now that is not the way I envisioning shifting gears. When I press the clutch pedal, it moves without any effort at all for the first 2/3rds of the travel. Then, there is some resistance. But that is still too soft, as in I can push the pedal down to the bottom of its travel with my hand.

My first instinct was there is air in the lines. So, I need to bleed them. Even thought it looks rather rusty, I do not think the clutch master cylinder is leaking because I filled the reservoir in the weekend and it has not come down since. So, I proceeded as one would always do in a master-slave cylinder clutch system: find the slave cylinder,Then break its bleed valve loose,and then bleed the fluid out of it until all the air is out. As I was by myself, I chose to use my old mighty vac pump,
to bleed it out. So, I pumped and pumped and pumped. Nothing. I was pulling quite a lot of vacuum and still no sign of any fluids. I even took the slave cylinder bleed valve and it was completely dry inside.

My plan was not going according to the plan.

After consulting with some friends, we narrowed down to the master cylinder. Something was fishy with it. One possibility was it could not return to its unpressed position, so the little hole in its housing never gets in front of the plunger, which then cannot pump it. Broken spring perhaps? We could go over other possibilities, but in the end the master cylinder is probably boink. So, we need to inspect it, perhaps even remove it. So, here is where it hides:
To get to it, I have to take the vent duct out, which, as I learned today, is a single piece that goes from one side of the cabin to the other. Now, to get the duct out I first need to get the kickpannel out of the car I need to get the knee board out, which is also a single large piece.
And, to take it out, I need first to remove the center console. So, I think I will leave that for another episode...

...or may just add to this episode later on when I do take all those guys out. Stay tuned.

BOV (CBV) me - II

Well, today I replaced the BOV (ok, CBV but who cares?). I was surprised how quickly I was able to take it out. I mean, in less than 10 minutes I was removing from the car the hose the CBV was connected to; that is a huge improvement from the last time I did this. So, maybe getting to the clutch will not be as bad as I originally thought. I guess that having taken them out in recent history, so they were not stuck to each other, also helped a lot. And in no time I had most of the hoses, specially those that go from and to the intercooler, out,
And then got the hose that goes from the air flow meter to the turbo inlet,
Until I finally got the hose with the CBV out to a more easily manageable position.
Here is a closer view of the old CBV:The clamps that hold the BOV to the hoses are some plastic weird clamps. I really really do not like them because they are not very fun to take out. But, take them out I did and swapped in the new BOV: Putting everything back together was not hard to do nor worth mentioning, so I shall not mention it. Only thing to be careful is to make sure the vacuum hose that controls the BOV does not get crushed as the other hoses are put back in place.

BOV me

Today let's talk about the blowoff valve (BOV) used in the Saab. Ok, the stock one used in this car is actually a compressor bypass valve, or CBV, but I have heard both being grouped under the generic name of BOV. I know one can get off eBay a nice shiny metal one that is a direct replacement, or a custom one that can be mounted somewhere more convenient or dramatic, like this one: but for this chapter the factory one is the object of my attention. So, here is how it looks like:As you can see, there are two large ports and a smaller one (the nipple on its top). The large port that rests against my palm, port A, is connected to the pipe that goes to the compressor inlet of the turbo. The other large pipe, port B, is routed all the way to the throttle body. Finally, connected to the little nipple, port C or just the nipple, is a hose that goes to the plenum of the intake manifold. Let's see how it works. If we turn it so that port B is facing us, we can see a piston inside the BOV housing. By default, it presses against port A, closing it. So, air cannot flow between ports A and B.
No, how does it open? If we apply vacuum to the nipple, it will open the piston. That is fine, but why would we need this extra piece of hardware? To explain that, let's talk about what happens when you are under boost and shift gears in a car with throttle plate.

When you let off the gas pedal, the throttle plate shuts, separating the volume from the turbo compressor outlet to the intake to the volume inside the intake manifold. That also tells the engine to slow down, so it is not producing as much exhaust as before. That exhaust powers the turbo. The engine is still running so it will use some of the air that is inside the intake, which will create a lower pressure area inside the intake as not much air is moving around the throttle plate.

But, let's go back to the exhaust. It is, as we mentioned, not generating as much energy to power the turbo as before. So, the turbo cannot pump as much air as it was doing before you backed off the gas pedal. However, now we have air between the turbo and the throttle plate that was compressed when you were in full power. It has to go somewhere. Between a closed throttle plate and the turbo, which is not getting as much power as before, the path of least resistance is back through the compressor stage of the turbo.

So, we have air trying to go backwards through the compressor wheel. That can cause the wheel to slow down and even spin backwards.

Then, you finished shifting and once again stomp on the gas pedal. Throttle plate is open. Between the turbo and the low pressure area in the intake, the path of least resistance now is through the intake manifold. Also, exhaust is now trying to power the turbo. Still the turbo now has to fight with the air that was trying to escape through its compressor and persuade it to reverse flow one more time.

That is a lot of persuading... and time wasted. And, depending on your turbo, it can only take that so many times before snapping.

What if we could provide a path for this air that is trying to escape that is more attractive than going backwards through the compressor wheel? One possible solution is to let the air dump to atmosphere, which is what the BOO does. A lot of people like to do that because they enjoy the sound of the air being dumped to atmosphere.

Another option is to feed the extra air ahead of the turbo, which is what the CBV does. Problem with that is it does end up feeding hot air to the compressor side of the turbo, which then heats it up an additional amount because of thermodynamics. A possible solution is to suck this extra air after the intercooler, where it would be somewhat cooler. One of the main benefits of using a CBV is that no metered air is being thrown away so we do not end up having a rich mixture.

The rain, boss the rain!

After my problems trying to clean the stud threads in the turbo downpipe collar, I decided to up the game and switch to caveman mode. According to the tape and die box I had previously bought, the dies have the outside hexagonal shape of 1" bolts. So, I decided to get a socket and then use a ratchet wrench to persuade it. I first went to Lowe's and they only had 12pt sockets. Those can be very convenient but a 6 point socket has a better load distribution.My next step was an auto parts store like NAPA or Advanced Autoparts. There I found a 6point 1" socket, 1/2" drive just like I wanted. It fit the die perfectly (add photo here).

With that new weapon in my arsenal I went back to the Saab and tried it out. I still had to put a lot of elbow grease but it worked flawlessly... as in I did not break any stud or crossthread them.The weather was not looking very inviting. Dark clouds filled the sky.Still, I pressed on hoping I could finish it before the upcoming rain. When I started putting the stainless steel nuts and lock washers I bought (I replaced the rusty factory lock nuts with those because they are easily found and can take the heat), to my pleasure they threaded in quite effortlessly. So, my effort paid off.Then it started to rain. Having my tools -- camera included -- having an unplanned bath was not on my list of things to do today. After careful consideration, I decided the actually tightening of those nuts could wait for another day.I covered the car and walked home. Yet, I felt that what I planned to accomplish today was done.

Clean up your mess!

Today I had some free time and decided to clean up the threads in the collar thingie that clamps the downpipe to the turbo elbow. As you can see on the picture below, they have seen better days:I found out the thread size is M8x1.25, so I bought a tap and die set and started chasing the threads. It was not as easy as it sounds. The main problem was just to start the thread right. The last thing I had in mind was to crossthread it. So, quite a few times I would feel I started it just right but then, after a few turns, would take it off to inspect the threads. Eventually I was satisfied enough to continue.

Because I did not want to crawl under the car and disconnect the downpipe from the bottom of the transmission, I was not able to turn the die the way you would normally do. In fact, I had to take the handles off the die holding thingie so I could turn it in the space I had. Still I could only do about 1/6th of a turn at a time. Good thing the dies I used had a hexagonal body as opposite to round. Also, Those threads were really dirty and I felt like I did not have enough strength to keep on turning. I really need a better way.
Incidentally, I also managed to lose the little screw that would hold the die to its holder. Shame on me. I know where it is but I need a magnet.

Next thing is the brake fluid reservoir. I wonder if it is leaking. I think what I need to do is fill it up to the maximum level and then see if it drops. Let's be honest: I can take a picture just like the one below every day or week or whatever, but it is much easier to monitor when the fluid is level with some mark.

Last in the list is the shifter. You see, my shifter knob is falling apart completely, to the point of being useless. I have been trying to figure out how it was attached to the shaft. Well, today I found out by chance. I was trying to figure out how to remove the shift boot so I could treat it (and maybe resurrect it before it is hopeless) and it fell out!
Looking inside it, it turns out the knob is just pressed into place! Hmmm, I think I may be going back to the 900 in the yard and yank its knob. In the mean time, I still need to find a way to get the boot out. But, I am making advances...

Measuring around

If you remember, in a previous episode I found the exhaust connection past the turbo elbow was leaking. So, I decided to unbolt it and take a better look. As I removed the first lock nut, I noticed the stud had seen better days:
I think I will see if I can run a M8x1.25 die in each stud to be on the safe side. I will also replace the nuts with stainless steel ones and lock washers. Probably that is about as heat resistant as the factory ones but at least they would be clean. In any case, After a bit of persuasion, I took out all nuts and dropped the collar holding the studs.
If we look under the elbow, we see the connection is a conical one: the downpipe is press fitted over the turbo elbow by the collar with the 3 studs. So, no gasket is required here.
Underneath the elbow is the oxygen sensor.and on the top is boss that could be used to, say put a wideband sensor or EGT probe. Hmm, ideas .Time to do some measurements: first we have the temperature sensor used by the ECU. I was told at SaabCentral that it is between cylinders 2 and 3. Another way to find it is the connector that goes to it: it is blue.I unplugged the connector and found its pins were rather filthy. I do not know if they are corroded or just covered with some hardened goo.One way to see if the sensor is working is to test its resistance. You see, the temperature sensor is a thermistor: as temperature changes it changes its resistance. In fact, as temperature increases it decreases its resistance: 2600 ohms @ 68F and 320 ohms @ 176F +/- 10%. I measured 1720 Ohm, which should be close enough (it was more like 80F).The we have the temperature sending unit used by the temperature gauge, which for some reason is not moving. So, I thought on starting by checking if the sending unit was working. As before, the best way is to measure its resistance. According to my multimeter, it is 440 Ohms at the same temperature as before. Is that right? I don't know because I do not know if the curve is linear or not; the only other data point I have is 51.2 Ohms +/- 4.3 @ 194F. I guess that is consistent with my expectations: the resistance to drop as temperature rises. Still, I would love to get more data points or a plot of the curve. At least I am not getting an open or infinity...
In any case, that is how far I went today on the Saab.

Quickies

Today I did a few quick things. First I installed the airfilter, finally. Until today I was rather concerned about sucking something into the turbo even though the car has been sitting in a paved car park ad never went above 2000 RPM during my tests. I ended up buying a K&N airfilter off ebay, which arrived yesterday. And then I bought the clean and refill kit they sell for their filters. While I was there, it felt like a good idea to clean out the airfilter housing.
It also felt like a great idea to fill up the break/clutch fluid reservoir. I was going to bleed the clutch but it did not look very inviting unless I took the air hoses in front of the engine. But at least I did fill it up. Interestingly enough the CEL went out. I cannot say if the events were related though.
Before I started the engine I also wanted to satisfy my curiosity and measure the resistance in this coolant temperature sensor:As you can see, the multimeter is setup to Ohms. For some reason I would expect the reading to be a bit higher than that. I guess I need to check that further.

Idling around

Yesterday I decided to do a few quick things to the Saab after I got home. First was to make sure ever hose clamp was tightened. Second, I solved the vacuum line mystery. It goes indeed to the BOV, specifically there is a nipple on its top and that is where the hose should be connected to.After some effort, cursing (not every effective because I do not know Swedish curses), and a conveniently long pair of pliers, I was able to finagle the hose until it attached to the nipple on the BOV:Next in line was checking the oil. It still looked nice and clear. So I topped it off to the "full" mark and started the engine once more. The engine light (CEL) is still on; I really need to find out what it is trying to tell me. But, another thing I tried on it was to rev the engine to, say, 2K RPM and let the car return to idle on its own. As it can be seen in the following video, it had a bit of a slow response time. In fact, it almost stalled.

I do not know what is causing that but will have to check later on. A vacuum leak perhaps? While the engine was on, I went to the engine bay and solved another mystery that was annoying me for a while: whenever I would accelerate above idle, smoke would come off the right side of the engine bay. I checked that side of the engine until I noticed something rather telling:As you can see in the above image, the elbow on the turbine exhaust side of the turbo is not really tightened to the downpipe. Could that be the source of smoke? The carbon deposits on the connection would tell me so. But, let's check it as I rev up the engine (just a bit, up to 2K, as I am not comfortable in going any higher until I find out why the CEL is on):

That smoke sure looks like it is coming from the connection, eh? I think I will get new stainless steel nuts, lockwashers, and run a die on the studs to clean them up before tightenging it all back together.

All in all I thought it was a rather successful day. Next on the list:
1) Put an airfilter in the car. So far I have been running the engine without an airfilter:Reason is because I do not know for sure if the airflow meter (AMM for you picky ones because it is of the hot wire variety) is working right. This way I can actually swap it with and ebay one I have that is supposed to be good. But, I think I need to stop being a lazy ass and put the airfilter already. Unfiltered air and turbos do not like each other... or like each other too much. I bought a K&N airfilter off ebay for the car. This morning I washed it and am letting it dry. Once I get home, I will spray it with the K&N oil thingie, clean the airbox, and drop it in there. That should make me (and the car) breathe a bit easier...
2) Learn how to bleed the cooling system.
3) Find out why I have the CEL on.
4) Bleed brakes and clutch.

Light shopping

Today I went junkyard shopping for a few parts and to check the underside of a Saab 900. First, my shifter is in a bit of a bad shape. As you can see, even the plastic with the gear indicator is gone. I also think there are more issues I am not aware of.The 92 900S that is sitting there has a much nicer looking shifter,
For now I only took the plastic cap; I will try later and see if it will work on mine. Maybe I need more, perhaps even the entire shifter. The other item I took was the coolant overflow tank.As you can see on the picture to the left, mine looks rather nasty. I do not know when I will have time to replace it. Tomorrow? During the week? We will see.

In addition to that, I wanted to see if the junkyard staff damaged the bottom of the transmission. You see, they have this awful tendency to puncture a hole in oil and transmission pans to drain them out. Well, there is no suck a pan in a Saab. If they try to puncture a hole they will destroy the transmission case. From the following picture, I think I may breath easier. The yard seemed to have located the drain plugs and just removed them. I can use this transmission if I chose to do so.
Next thing is the cover in the front of the transmission, on the right side. I did not open it, but I plan to and inspect its inside. But that is for another episode.
One thing I was not aware of is that the N/A does not use the long transmission filler tube the turbo does. Instead it is a bolt/plug. I did not remove it but I wonder what lurks underneath it.