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Car Forum / Saab Cars / June 2006Saab 900 Classic Timing chain issue
I have a 1989 Saab 900 16v NON-Turbo with 155K miles on it. Recently its begun to make some noises that appear to be related to the timing chain. I was hearing some random but frequent "pinging" noises when the engine was warm. The sort of sound you would get from striking an exhaust pipe with a screw driver. They sounded like they were coming from the area of the timing chain. Thinking it might be related to timing chain tension, I replaced the timing chain tensioner. The tensioner was extended 8-9mm. It is my understanding that 11-12mm would indicate a timing chain requiring replacement. With the new tensioner, I now have a loud, persistant rattling noise. This noise is more what I would think a noisy chain to sound like. I removed the new tensioner just to check the extention and make sure it was operating correctly. It measures 8-9mm as did the old tensioner. So, I need to understand what situation I am now faced with. Is the chain worn to the point it requires replacement? Are the guides worn? Is there life left in the chain in spite of the noise? Can the car be driven without fear of chain breakage or am I living on borrowed time? Advice much appreciated, jim > Thinking it might be related to timing > chain tension, I replaced the timing chain tensioner. The tensioner [quoted text clipped - 4 lines] > check the extention and make sure it was operating correctly. > It measures 8-9mm as did the old tensioner. I'm trying to come up with a scenerio in my mind that makes sense based on your description, and I'm not finding one. Kind of a rattly, shuffly noise? > Is the chain worn to the point it requires replacement? > Are the guides worn? > Is there life left in the chain in spite of the noise? > Can the car be driven without fear of chain breakage or am I living > on borrowed time? Well, it doesn't sound like a normal noise (from here). Do you have a local Saab Specialist you could take it to? Where are you located? > Well, it doesn't sound like a normal noise (from here). Do you have a > local Saab Specialist you could take it to? Where are you located? I once had a noise that I feared was timing chain - couldn't hear it with the bonnet up, but you could at certain revs if you drove alongside a wall or solid fence with the drivers window down. Drove me nuts, but it turned out to be a loose heat shield between the manifold and starter motor. Replaced a couple of nuts and problem solved. As, suggested, you really need someone who knows what a duff chain sounds like, or maybe listen to someone elses car that is known to have a good chain setup. > I once had a noise that I feared was timing chain - couldn't hear it > with the bonnet up, but you could at certain revs if you drove [quoted text clipped - 4 lines] > sounds like, or maybe listen to someone elses car that is known to have > a good chain setup. I have a second 89 Saab 900 that is in good health, so I know what it should sound like. > I'm trying to come up with a scenerio in my mind that makes sense based > on your description, and I'm not finding one. Kind of a rattly, shuffly > noise? To describe the current sound, the words rattle and clatter come to mind. Pretty consistent regardless of RPMs. > Well, it doesn't sound like a normal noise (from here). Do you have a > local Saab Specialist you could take it to? Where are you located? There are some local SAAB guys, but I've found in the past that I frequently know more about these cars than they (a scary thought). I also suspect they will be quick to diagnose it as a worn chain and be quite happy to perform major open heart surgery. I am contemplating replacing the upper chain guide (cheap and easy to do) in the valve cover before considering the more drastic chain/guide/sprocket replacement. > I have a 1989 Saab 900 16v NON-Turbo with 155K miles on it. > Recently its begun to make some noises that appear to be related [quoted text clipped - 22 lines] > > jim Hi, You can hear a slapping chain with the car stationary. Open the bonnet (hood or whatever you call it) accelerate the engine to say 4000 revs. If you stop the acceleration suddenly listen for metallic noise. Repeat and decelerate gently you should not hear a noise. Under acceleration the chain is tensioned so it is the moment acceleration stops that it will move. If it helps at all. Regards Charles PS. I don't think you are going to hear a worn chain as such only as a loose chain the hits other parts anyway.  SignaturePlease remove _removeme_ to reply. > You can hear a slapping chain with the car stationary. Open the bonnet > (hood or whatever you call it) accelerate the engine to say 4000 revs. > If you stop the acceleration suddenly listen for metallic noise. Repeat > and decelerate gently you should not hear a noise. Right. Sounds like if you put a handful of nuts & bolts into a metal bucket and swished them around rapidly. Well, maybe not, but kinda close. You know it once you've heard it, kind of noise. I like the heat shield suggestion too, that's kind of in the neighborhood and might be it. Does it happen at just one specific RPM? > Under acceleration the chain is tensioned so it is the moment > acceleration stops that it will move. Right. > PS. I don't think you are going to hear a worn chain as such only as a > loose chain the hits other parts anyway. Agreed. And if it was that worn, his tensioner would be more than 9mm out. I'm really interested to hear what this turns out to be. > Right. Sounds like if you put a handful of nuts & bolts into a metal > bucket and swished them around rapidly. Well, maybe not, but kinda > close. You know it once you've heard it, kind of noise. I like the > heat shield suggestion too, that's kind of in the neighborhood and might > be it. Does it happen at just one specific RPM? I'm pretty sure this is chain related, as the new tensioner has changed the nature of the noise. Now clatter and rattle rather than pinging. Constant rattle regardless of RPMs. > You can hear a slapping chain with the car stationary. Open the bonnet > (hood or whatever you call it) accelerate the engine to say 4000 revs. [quoted text clipped - 12 lines] > PS. I don't think you are going to hear a worn chain as such only as a > loose chain the hits other parts anyway. Hi Charles- The metallic "pinging" has largely dissappeared after the tensioner replacement and been replaced by a rattling sound that is pretty constant regardless of RPMs. Still some trace of the pinging upon deceleration. I'm wondering if it could be the upper chain guide in the valve cover. >> You can hear a slapping chain with the car stationary. Open the bonnet >> (hood or whatever you call it) accelerate the engine to say 4000 revs. [quoted text clipped - 18 lines] > replacement and been replaced by a rattling sound that is pretty constant > regardless of RPMs. In which case we all hope it is the chain and not something worse. This and your other messages (and rereading your original post) now point more to a chain. I take it you can hear the noise with the car stationary and the hood open ... in which case you should be able to tell if rattles come from something else. > Still some trace of the pinging upon deceleration. > I'm wondering if it could be the upper chain guide in the valve cover. I have avoided passing comment as to what part it may be ... as I have only done a chain (well I did the complete engine) in a 1983 900 and yup the chain was long gone. I am not familiar with the engine in your car ... tween cams for example hence I am keeping quiet. You sound capable of replacing the parts you mention yourself ... if you can afford them go for it. BTW. Effectively with the wear on sprockets, guides, the linkages of the chain and the lobes of the chain you end up with a chain which is physically longer and feels even longer because of the sprockets. Any length of it that has to travel in a straight line will produce movement and hit the guide. ============================== Do a process of elimination of what else is nearby that could produce a rattling sound ... I had many V belts do that as parts were not perfectly aligned (do you have a V belt or serpentine belt ... probably the latter in which case it can't be the belt itself ... the belt has a tensioner too ? ...), alternator bearing? water pump? Camshafts gone? No. Oil pump ... I doubt it would make any noise. Power steering pump? I am just taking some wild guesses above in case you get a pointer. Regards Charles SignaturePlease remove _removeme_ to reply. > The metallic "pinging" has largely dissappeared after the tensioner > replacement and been replaced by a rattling sound that is pretty constant > regardless of RPMs. The rattling, if it was the chain, would change with engine speed. > Still some trace of the pinging upon deceleration. > I'm wondering if it could be the upper chain guide in the valve cover. Do you have a stethescope you could use to isolate the location a bit more precisely? Mechanics' stethescopes aren't expensive (15 or 20 bucks maybe) at your local Napa or whatever, and you can touch the probe to different spots to try to get a good location. That will help a bunch. Dave Hinz > Do you have a stethescope you could use to isolate the location a bit > more precisely? Mechanics' stethescopes aren't expensive (15 or 20 > bucks maybe) at your local Napa or whatever, and you can touch the > probe to different spots to try to get a good location. That will help > a bunch. My wife was a nurse and has a rather nice stethescope. I wonder what punishment I would receive for getting it greasey? >> Do you have a stethescope you could use to isolate the location a bit >> more precisely? Mechanics' stethescopes aren't expensive (15 or 20 >> bucks maybe) at your local Napa or whatever, and you can touch the >> probe to different spots to try to get a good location. That will help >> a bunch. > My wife was a nurse and has a rather nice stethescope. I wonder what > punishment I would receive for getting it greasey? If it says "Littmann" on it, don't even think about it. I won't use mine for anything other than patients, and computer hard drives. If it's a sprague, probably OK. We're talking $250.00 vs. $25.00 or so. If the word "cardio" is on it, don't even admit you know it's there. OK, here is the next installment on this investigation. Seeking to eliminate the simple (& cheap) possibilities, I replaced the upper chain guide located in the valve cover. I had seen mention on the web that these harden with age and can be noisy when engine is cold. The old one indeed had hardened to the point of being absolutely rigid. In fact it snapped in two when I removed it. The new one is a quite flexible piece of rubber. So OK with that in place, fired up the engine to idle speed. Noise still there. No change. Rats! This noise is so loud and pervasive that I can only isolate it to somewhere on the engine block. Well, I played around a bit while sitting there puzzled and noticed that the noise would go away if I turned the steering wheel all the way over to either wheel lock. So I began to wonder if the steering pump was the culprit. I removed the belt on the steering pump and low and behold the noise dissappeared. So I guess I'm looking at either the steering pump or the pulley wheels. So I have the following questions: Does it make sense that the steering pump could make this noise? What is involved in changing out the steering pump and/or pulley wheels? Any/all advice appreciated, jim >I have a 1989 Saab 900 16v NON-Turbo with 155K miles on it. > Recently its begun to make some noises that appear to be related [quoted text clipped - 22 lines] > > jim |
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