I know this sounds weird, but I recently replaced my main and connecting rod bearings, and my oil pump (chasing down a phantom oil pressure problem; long story), and after reassembling everything, the engine is making a godawful racket, which my stethoscope tells me is coming from the upper timing chain area. The strange thing is that I didn't touch the chains (other than noticing they are pretty loose, which isn't too surprising for an engine with 182,000 miles) or the tensioners. It's hard to believe the incredibly loud noise coming from the timing chain was pure coincidence, but I can't think of any connection between the work I did and the chain noise. It's definitely MUCH louder than before I did the work. Any ideas?
Also, is it safe to drive the car with the chain apparently slapping so violently against the guides (which I didn't remove)? I've put about 200 miles on the car since putting it back together, with no apparent issues, but I'm a little concerned that the upper chain tensioner has failed. Is it difficult to replace? Thanks.
quick question - did you damage the oil pan at all? oil pump pickup tube clearance to oil pan is critical. pull the valve cover and make sure that oil is flooding the cam bearings and covering the chain.
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Originally Posted by Rick
asleep is a stream of off-color and low-cooth jokes in person as well. I've been recycling jokes I heard from him for years. He is known by my friends as "the sick fuck."
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Originally Posted by trmn8r
seems like you just killed someone with your Daewoo Lanos Asleep. lol
u may want to remove the damn guides and get a new tensioner...i kno either my guide noise got louder or i have an exhaust rattle from when i did donuts...
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quick question - did you damage the oil pan at all? oil pump pickup tube clearance to oil pan is critical. pull the valve cover and make sure that oil is flooding the cam bearings and covering the chain.
I defintiely didn't damage the pan - it's in good condition, with no dents. I haven't tried pulling the valve cover, but when I open the oil filler cap, there's plenty of oil squirting around up there, though of course I can't see the chain.
u may want to remove the damn guides and get a new tensioner...i kno either my guide noise got louder or i have an exhaust rattle from when i did donuts...
How hard is it to replace the upper tensioner? Is it just a matter of removing the valve cover, passenger side engine mount, cam sprocket cover, and unbolting the tensioner, or is there more to it? I'm reluctant to remove the guides with the chain so loose, so I'd do both the tensioner and the guides together or not at all. Still baffled as to why the noise has gotten so much worse after replacing the bearings and oil pump; maybe it's just a coincidence, but the odds against that seem pretty high...
There is bulletin that Nissan issued regarding the chain guides. In it, it states to remove the guides and toss them, not replacing them. My nissan was making a rattling noise and that's what Nissan said to try. There is at least one guide up top which is pretty easy to get to, and at least one below which is not so easy to get to. Try searching for the bulletin. I used to have it but the gremlin ate it....
There is bulletin that Nissan issued regarding the chain guides. In it, it states to remove the guides and toss them, not replacing them. My nissan was making a rattling noise and that's what Nissan said to try. There is at least one guide up top which is pretty easy to get to, and at least one below which is not so easy to get to. Try searching for the bulletin. I used to have it but the gremlin ate it....
Yeah, I've seen the bulletin, but again, I'm reluctant to just remove the guides without replacing the tensioner too, because the noise got so much louder all of a sudden, that I don't think it's being caused by a chain that's simply stretched over the years. I suspect the tensioner isn't functioning correctly, or not at all.
on a 94 altima, you can safely remove the upper guide and toss it. no harm and no foul. the chain doesnt really stretch in these engines. i know of a guy on this board, cant think of his name right now, that checked his chain after 175k+ miles and measured it against a new one and found no difference in length. theyre supposed to last the life of the engine after all. the tensioner on the other hand - if the engine hasnt had regular oil changes and/or gunk got into the oil gallies from work being done, can quite possibly be blocked and not getting tense as it should when under pressure.
the tensioner on the other hand - if the engine hasnt had regular oil changes and/or gunk got into the oil gallies from work being done, can quite possibly be blocked and not getting tense as it should when under pressure.
Now that's the first theory I've heard that makes some sense. In the process of the work that I'd done, I may have dislodged some gunk, and it's now in a galley blocking the flow of oil to the tensioner. Hmmm... that can't be good. Any idea how much risk I'm taking driving the car effectively without an upper tensioner? If your theory is correct, it wouldn't make any sense to replace teh tensioner. As for as the upper guide, sure, I suppose I could remove it to decrease the noise, but this wouldn't address the fact that my upper chain is effectively not being tensioned.
Now that's the first theory I've heard that makes some sense. In the process of the work that I'd done, I may have dislodged some gunk, and it's now in a galley blocking the flow of oil to the tensioner. Hmmm... that can't be good. Any idea how much risk I'm taking driving the car effectively without an upper tensioner? If your theory is correct, it wouldn't make any sense to replace teh tensioner. As for as the upper guide, sure, I suppose I could remove it to decrease the noise, but this wouldn't address the fact that my upper chain is effectively not being tensioned.
im not sure what the oil pressure hole behind the oil tensioner looks like or id say remove the tensioner and hit the hole with pressurized air to dislodge anything that might be there or down the path of the galley. at that point you can replace the tensioner as well because what would be the point of reinstalling the old one? removing the tensioner altogether would create LOTS of noise and you would end up changing the timing of the cams as well. i would try to see if you could remove the tensioner and then go from there. might save you some hassle if the compressed air works for you. you would however, with the valve cover removed be able to see if the tensioner is receiving oil. i would at least remove the valve cover and have a looksie while someone cranks the engine.
im not sure what the oil pressure hole behind the oil tensioner looks like or id say remove the tensioner and hit the hole with pressurized air to dislodge anything that might be there or down the path of the galley. at that point you can replace the tensioner as well because what would be the point of reinstalling the old one? removing the tensioner altogether would create LOTS of noise and you would end up changing the timing of the cams as well. i would try to see if you could remove the tensioner and then go from there. might save you some hassle if the compressed air works for you. you would however, with the valve cover removed be able to see if the tensioner is receiving oil. i would at least remove the valve cover and have a looksie while someone cranks the engine.
Thanks; sounds like it's worth trying to clean out the galley that delivers oil to the tensioner. I'll also try to see if I can determine if the tensioner is receiving oil by removing the valve cover. Hopefully it'll be obvious, and not too much of a "judgement call."
I told you to remove the guides and change the tensioners.. I will put money it being that. What oil do you use? weight? viscosity? changing your coolant temperature sensor will help you also... even though it is not related to any of your matter at all; it costs 15 dollars and your engine will run better. OH I forgot to mention your PCV valve most likely should be replaced.
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I told you to remove the guides and change the tensioners.. I will put money it being that. What oil do you use? weight? viscosity? changing your coolant temperature sensor will help you also... even though it is not related to any of your matter at all; it costs 15 dollars and your engine will run better. OH I forgot to mention your PCV valve most likely should be replaced.
I know you told me to change the guides, but when I noticed how loose the chain was, I was concerned that removing the guides would be asking for trouble. I don't remember your mentioning to replace the tensioner, but you probably did. I didn't replace the tensioner or the chains because my only goal was to fix/rule out the possible causes of the lack of indicated oil pressure, and having a slightly loose chain didn't concern me, as long as it didn't put the engine at risk. But I'm really baffled why the noise has increased so drastically since replacing the oil pump and bearings. asleepaltima's theory that the oil passage feeding the tensioner is plugged is the only one I've heard so far that makes any sense, and if he's right, replacing the tensioner wouldn't have helped anyway. I don't understand why the tensioner would have suddenly failed, simultaneously with the other work I did to the engine. I wonder if there's a way to rig the tensioner to stay permanently in at least a partially-extended position to provide some tension to the chain, if it isn't getting oil. Sounds like this engine is really on its last legs, doesn't it?
To answer your other questions, I'm using Castrol 10W40, the same oil I've always used, and changed every 3K miles since I bought the car with 64K miles on it. No telling what the previous owner did. I do wish I had replaced the PCV valve like you told me; not doing it was really stupid. I just got in a hurry to put it all back together (and the auto parts store I buy all my parts from was out of stock), and thought afterwards that I'll just do it later. Big mistake, now that I know that I have to remove the power steering pump again to get to it. What an idiotic design.
I'll take a closer look at things this weekend, and then decide what to do next.
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