Hey guys. Would you say timing chain is on its way? Engine has roughly 230 000 km on it, it was rebuilt 20 000 km ago (disassembled to pieces, new crankshaft bearings, refurbished hydraulic valve lifters, replaced two timing belt plastic guides for refurbished ones, 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 11mm) The thing is, that car at the moment has a couple of issues which I am trying to sort out when I have some time. - sometimes cranking time is in order of 5+ seconds. Happens only on cold start. After starting like this there is a petrol smell from the exhaust - most probably from all 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. Next possible solution will be reflashing the software - at the moment running Stg 2 from Trionic suite. 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. Next 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 weaker, 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. - main 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. 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 it, 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 dont thing this particular noise is the timing chain, because it does not happen when the car is stopped/idle. Must be coming somewhere from clutch/transmission/diff. I will look if I can find the video where I tried to capture the noise.. Thanks in forward for reading/trying to help ;)
Posted on: Sun, 28 Sep 2014 15:33:39 +0000
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