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Timing chain checkup, boost oscillation, transmission whirring

3K views 3 replies 2 participants last post by  egres_svk 
#1 · (Edited)
Evening gentlemen,

I have a couple of issues with my 9000 2.3 CSE (formerly 2.3 LPT auto '93, now 2.3 FPT Stage 2 manual '93-'96 depending on which part of the car you are looking at :D )

I have quite strong electronic and mechanical background, usually I do my troubleshooting, find out what part(s) can be causing issues and if possible measure their function, if not possible, swap them for some other used/new parts (my friend is a Saab maniac with half a garage full of used parts). Lately I do not have so much time for playing with the Saab, unfortunately it is also my Daily Driver, which means that putting it into the garage, disassembling it into pieces and waiting for new parts if needed is a bit problematic. Not impossible, but I try to avoid it at the moment.

So.. enough talking, off to the questions. I should probably start by stating that the car has 230 000 km on the clock, it was rebuilt 20 000 km ago (disassembled to pieces, new crankshaft bearings, refurbished hydraulic valve lifters, replaced two timing belt plastic guides for used ones from another engine, because they were practically eaten through and replaced tensioner for refurbished one - it was stuck). Engine was put together and it seemed that the chain tension is good and the tensioner was not sticking out more than specified 11 mm).

If you would kindly watch this video - would you say the timing chain looks way too loose? I plan to pull the tensioner out tomorrow and do the proper check of how far is it extended, but for now I have only this video. Tried to look down the engine with light, mirrors, etc. and see if the balance chain is (also) loose and/or the gears on it are chewed up, but that is impossible without removing the timing cover.

Timing chain video: http://videobam.com/nZMid

Engine noise on idle (no cam cover) http://videobam.com/AIRpT

Other issues:

- sometimes cranking time is in order of 5+ seconds. Happens only on cold/first start. If I turn it off and start again, it is immediate. After starting like this there is a petrol smell from the exhaust - most probably from all the unburnt fuel from first rotations without combustion. So far I have checked spark plugs - seem OK, injectors (one was clogged a little, changed it, still the same), fuel rail pressure jumps to 3 bar immediately after turning the key to position 1 and stays there, after turning the engine off it drops to 2 bar in ~2 minutes, so it seems the pump and one-way valves near it are fine.
Next possible solution will be reflashing the software - at the moment running Stg 2 from Trionic suite. I will drop back to factory settings and if it is OK, try to load Stg 2 again. During this I am also going to replace the chips for new ones - the old need quite high programming voltage and to be honest I do not trust them very much because of the next issue:


- there is a turbo pressure area, where the boost oscillates. Low boost (approx until 1/3rd of the yellow Saab meter) is stable. Medium boost (1/3 of yellow until 3/4 of yellow) is oscillating one milimeter up and down usually, Full boost (end of yellow and first half of orange) is again stable. I can swap my gauge for one with bar/psi dial, so I can tell you exact area which is problematic if needed. I was again suspecting fuel delivery - either the pump or the return valve, but it seems it is holding 3 bars nicely and increases with throttle. I have my fuel gauge in engine area, have to strap a camera to it and go for a ride to be sure. Main suspect is again the software. (I am running T7 APC by the way with the needed HW modification to ECU and frequency modification in Trionic Suite).


- after replacing small vacuum hoses for silicone it got a little better, but now I believe I have a boost leak somewhere - I can hear it very good in narrow alleys with windows down - turbo builds the pressure longer (but goes to full pressure, so the leak should not be big), and near to the end of the yellow part of boost gauge I can hear very strong hissing. With this hissing, the blow-off is kinda shitty.. when I build up less pressure and let go of the throttle, the blow off is nice and strong as it should be. I will swap the BOV just in case it is faulty. Actually, first I will stick its output to plastic tube between turbo and air filter where it should be originally. If the hissing gets less audible, I will know it is BOV. Oh and almost forgot - lately this oscillation changed.. normally it oscillated relatively slowly, one second higher boost, one second lower boost and repeat. Now it is probably 0.5 seconds. Could be something boost leak related, not sure.


- biggest issue that bothers me is metallic whirring noise on hard acceleration and hard engine breaking. It is very strong on hill roads going downhill for example ~60km/h in 3rd gear, but I can hear it on any gear. If I add a little throttle to stop the engine braking, noise stops. Pressing on the clutch pedal - it stops (therefore I suspect transmission/diff). If I help the engine brake with normal brake, it gets less noisy. My guess would be the pinion bearing in the gearbox or possibly something with the differential. Clutch should be OK I believe, it was re-padded during the engine disassembly (but springs on it were not changed). But theoretically it could be the clutch also, why not. I have a replacement gearbox, but am not really looking forward to doing the replacement. If I have to replace the timing chain, engine will be out of the car anyway, so I will swap it then. I don't thing this particular noise is the timing chain, because it does not happen when the car is stopped/idle/revving in neutral. Must be coming somewhere from clutch/transmission/diff.
I will look if I can find the video where I tried to capture the noise..

- and I found this today - there is a small leak between exhaust manifold and turbo flange. While waiting for the oil to burn away (some leaked there when I did the quick engine test without cam cover), I found it was bubbling - see video for location. Seems that gasket is either cracked or not present at all, I will have to check. Would you say that it is possible some oxygen will find a way inside the exhaust gases and will mess with lambda measurement? Actually, come to think of it, I will just in case replace the lambda also, to see if it does not help with the boost oscillation issue, dammit.

Exhaust manifold gasket leak - http://videobam.com/kvBHD


Many thanks in forward for reading/trying to help, please feel free to ask more questions about particular issues, I will provide as specific information/pics/videos as possible.

EDIT:
Some more things to clarify - I have spare DI cassette, does not make a difference. I also had black cassette (I know, no knock detection when used) and that one was starting better. I was also suspecting leaky injector, that would build up petrol inside the cylinder and then make it too rich to ignite, but they seem to be OK... And the crank position sensor was swapped without any change to boost/start issue.
 
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#2 ·
Well, $#@*... measured the chain tensioner today, 12.5mm, which means there will be a new chain before the end of the year.

I hope this replacement will solve the whirring/rattling sound that I believed was coming from transmission on hard acc/deceleration. Theoretically it could be the loose chain. I don't think it is the cause of long cranking and boost oscillation, but that is not so big of a deal.
Calipers Measuring instrument Technology Electronic device Tool
 
#3 ·
Congrats on doing engine work. Although in My opinion ..you actually did a poor job of it.
No !? New chain(s) Guides or Sprockets. That IMO was less than clever as those are inexpensive Vital parts.
Not yet experienced a failed chain? Don't wait too long.
Timing chain And All Sprockets can be done in car.
You refurbed the lifters? Yikes! I've bought OEM brand New ones for 16$ the full set.
Fresh clutch disc But Not the Pressure plate?
A fair guess you didn't replace the Slave either.
No matter you will soon enough, when you replace the trans.. It needs it. She's worn out or Broken, but time/mileage will tell, definitively.
Some possibility that 'someone' Effed up the trans/intermediate shaft / tripod reinstall though.
Boost oscillation Can be from software. Not likely if you used the T5 'wizard' :)

It's possible the T5 valve was/ is faulty as well.
Turbo to manifold leak is only noisy not harmful per se..
One can fit an O2 sensor extender :) to make even a failed Sensor read correctly for the ECU.. Cheap; a few $ and easy.
Saying that as clearly Cost seems paramount here.
 
#4 · (Edited)
Yeah.. how to say it.. the way that my engine was rebuilt is the main reason why I am going to do it again, this time alone and properly. Entire rebuild was a mix of a lot wrong information and hurrying up to have it finished. Not good.

So, yes, you are correct. There will be entire new timing and balance chain kit including all sprockets. Lifters are already reserved in shop for me, will be replaced. New water pump is also on the way. Clutch and pressure plate were from well working donor car, we will see how it looks when I remove it from the car. I have another backup clutch set. Not replacing the Slave or at least accompanying O-rings was monstrously stupid - yes, I experience pedal not returning all the way back from time to time.

APC is fine, checked in another car.
o2 sensor will be checked against another car in following days and both will be checked by oscilloscope to see signal and response. I plan to install a wide-band sensor in a couple of weeks - like to be informed about what is going on inside the engine.
 
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