# Broken Timing Chain?



## denis_the_theif (Jul 31, 2010)

Got a bit of a problem, so anyone with any ideas, would be much appreciated.

I own a Nissan Xtrail 2005 in Canada, just over 200,000km. For nearly a year I was problem-free. Then it all started to change.

3 weeks ago: a few times when starting the car a loud scraping sound started to appear, it would just go away after about driving 1 minute. And it didn't always happen. One time it happened, I looked under the hood, seemed to be from the direction of the alternator, or the main belt, at least in that vicinity or that side of the engine.

2 weeks ago: the engine started with that scraping noise again, then it went away after driving a minute and was replaced by a moaning sound which changed in pitched based on the speed. So I took it in to my mechanic. He didn't seem too sure what the problem was but he changed that belt - the serpentine belt. After that the scraping noise never came back but the moaning sound was still there but it was soft, I could only here it sometimes at low speeds.

This week: I drove home and the moaning sound was louder. Then the battery died. I charged it and it would die again. Then I decided to take it to the shop, it died on the way, so I charged it for 15 min, then I made it to the shop and I left it there. The next day the Mechanic said it was the Alternator. Today he changed the Alternator then he said the engine needed to be replaced! Likely because of a broken timing chain.

Based on what I have described, what do you think is the problem? I believe my mechanic is honest but I think sometimes he's in a rush and is unfamiliar with solving some of the difficult problems. If it is the timing chain that is broken, do you think it can be fixed rather than replace the entire engine?


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## rogoman (Dec 16, 2004)

If the timing chain is broken or has skipped several teeth, the engine would not be able to run at all and there would most likely be bent valves. If you're able to start the engine and it idles OK with no rattling in front of the engine, then the chain assembly is most likely OK.


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## denis_the_theif (Jul 31, 2010)

Thanks. I have had no problem starting it. But it is a little noisy. Hard to describe, kind of a groaning sound. But the pitch of this sound goes up and down along with the RPM.

Any ideas?


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## rogoman (Dec 16, 2004)

Try to isolate where the sound is coming from; is it from the front at the timing cover or under the valve cover. It could be one of the external accessories such as the alternator, power steering pump or the water pump.


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## denis_the_theif (Jul 31, 2010)

Thanks for the responses.

I went to the shop after the mechanic had changed the alternator and now it won't start at all, I couldn't drive it away, which is what he told me. 

I am having I hard time trying to understand this. I had no problem driving it there, except I had to charge it twice from another car. Now, it doesn't drive. I have no explanation and I can't understand this. He said something like it skipped teeth on the gear and the best solution is to replace the whole engine. Just to me it would seem hard to understand how the timing chain and the alternator would go at the same time.

Can a timing chain and an alternator be connected in some way? I wonder if the mechanic thought the alternator was broken but it wasn't and then realized it was the timing chain after the alternator was replaced. 

Is it possible a mechanic could damage a timing chain when he replaced the alternator?

Otherwise, I was really unlucky to hava a damaged timing chain and a damaged alternator at the same time.


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## rogoman (Dec 16, 2004)

There is no connection between the timing chain and the alternator. To check for skipped teeth on the chain, he would have to remove the front timing cover and check all the timing marks on the chain assembly. If there are several skipped teeth, then there's a strong possibility of bent valves; this can be verified with a compression test followed by a leak-down test.


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## denis_the_theif (Jul 31, 2010)

Thanks, I should have asked how the mechanic determined this.

But I did find an article stating that the sound it was original making, a loud scraping sound, could be an indication that the timing chain is about to go.


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## janarth (Oct 14, 2004)

It is hard to believe, the timing chain skipped after so long, unless driving with no oil, or some thing else happened to it! Mine 230k I changed the alternator at 210k along with tensioner and drive belt. Similar sound problem. Now I am into chaninging control arm, both are gone. Where is the mechanic- is it a dealer? Xt won't start if knock sensor is bad also. Do you get a code or any sort?


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## denis_the_theif (Jul 31, 2010)

janarth said:


> It is hard to believe, the timing chain skipped after so long, unless driving with no oil, or some thing else happened to it! Mine 230k I changed the alternator at 210k along with tensioner and drive belt. Similar sound problem. Now I am into chaninging control arm, both are gone. Where is the mechanic- is it a dealer? Xt won't start if knock sensor is bad also. Do you get a code or any sort?


Mechanic was not a dealer. I'm not sure about the codes, I should have checked first but I didn't.

It ended up 16 hrs labor to change engine, maybe that's high. Part of that was because the sensors and so many other parts were not part of the used engine so there was labour in swapping all those parts. Not sure if that is customary that the sensors and other parts (not internal ones of course) were taken out.


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## quadraria10 (Jul 6, 2010)

Wow and ouch. Did you ever get a second opinion? Were there really no codes that came up with your check engine light? Is it possible that it was the immobilizer part of your antitheft system that was at fault. I have read elsewhere about some mechanics being unfamiliar and stumped by this. If it goes your car will not start, and turning the ignition will do nothing-- no dash light will come on and the engine will not even attempt to turn over. Its as if you have a completely dead battery. Happened to me the coldest day of the year last winter. I thought the car had died. Left it for an hour or so pondering calling a tow truck, when low and behold I got to turn the ignition back on and the dash came back to life. However it was showing a code-- which turned out to be the immobilizer. I cleared it myself manually and its never come back again. I think it might have some connection to dropping my keys in salty slush and not fully drying it before inserting into ignition. I later sprayed some WD40 into it to be safe.


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