Timing Chain issues on 2001 Infiniti Qx4

[primetime125]

Hi i'm new here,

The Nisaan dealer said my timing chain and water pump are bad. Its making some very slight grumbling or knocking noise very feint. Not very noticeable unless your right next to the car, so its not making a crazy noise or loud or anything. The dealer said it needs to be replaced. Since the water pump and timing chain or both directly related I can see how this would be possible. My question is, Is this a super immediate concern? Can I wait a little while before I do this? Or is it an immediate emergency. The timing chain job is like 2 grand at the dealer. The dealer said I shouldn't just replace the water pump and not the timing chain too. They said I should do both since they're both related. I wanted to just change the water pump. Is this true? Do I need to change both the water pump and the timing chain? Or can I just change the water pump.

Thanks,-dave
Modified by primetime125 at 2:41 PM 9/18/2009

[primetime125]

I'm pretty sure the noise is the water pump. I really dont trust that they're saying I need a new timing chain. Those should rarely if ever need replacing.

[anthonyerco]

I am having an issue with vibration when coming to a stop sign or light. Took my 02 QX4 to a shop and they checked my motor mounts and they were good. They seem to think it’s an issue with timing chain which I find hard to believe. I haven’t really seen anything online about timing chains causing vibrations like this without making noticeable noise. It’s intermittent. Gets worse when AC is kicked on. I’ve replaced compressor, alternator, idler pulley, belts, fan clutch, fan clutch bracket. Not sure what the F else it could be. Not about to drop 2 grand on a timing chain though. Sucks because my QX4 still looks showroom new with only 100k miles on it. Really wish I could figure it out. s*** is driving me nuts. A timing chain really shouldn’t need to be serviced. Did you end up doing the chain and water pump? We’re you experiencing any vibration?

[MisterH]

The thing about bad timing chains is there's only two possible things to go wrong:
1) It has a bad link that has become stretched and the chain is loose. When it becomes stretched it tends to bang and flop around but once it's in this condition it's never intermittent.
2) The timing chain tensioner is worn. This has a greater likelihood of wearing out than a chain and if worn out will most likely be noticeable when the engine is cold.

When you have a mystery sound coming from the engine one of the best diagnostic routines is use a mechanic's stethoscope. Once your mystery noise occurs you should get under the hood and listen with the stethoscope.

[anthonyerco]

There’s no noise at all. Just vibration

[mdmellott]

There’s no noise at all. Just vibration

This is a long shot of a guess but worth a quick look. There is a block of steel with a rubber mount attached to a heavy gauge sheet metal bracket, called a dynamic damper assembly, that is located at the end of the transmission just before the drive shaft. Under certain operating conditions, harmonic vibrations are created in this area of the drive train which the damper absorbs so that no vibrations can resonate. The sheet metal brackets have been known to rust out, causing the damper weight to fall off. It's worth taking a look to see if it is still intact on your QX4.

[AlanAZ]

I had an idle vibration in my QX4 two and half years ago (135K miles, sketchy maintenance history) bad enough that automotive knowledgeable friends would comment on it, and we'd a discussion about engine mounts.

That was until I cleaned the engine with BG EPR 109 (20 oz for 20 mins), to address the oil consumption issue and restore compression. Immediately changed oil and filter after with Valvoline Maxlife hi-mileage full synthetic 5w30. Old oil came out BLACK (all other vehicles I have done this on, the oil came out brown), as a precaution, I changed the filter again after 500 miles. It did restore compression and power greatly, reduced oil consumption somewhat, and idles much more smoothly -- I have no thoughts of changing the mounts. There was a price to pay for all this goodness, prior it didn't leak oil on the ground, now it did. I immediately replaced the oil cooler seals, and I now see oil dripping from the lower rear corners of the valve covers. My thinking is that it removed sludge that prevented these leaks, but also removed it from small oil passages that prevented full lubrication and caused vibration.

After I replace the valve covers, at the next oil change, I plan to run another dose of it (~3.5 yrs after the first, and only because the oil came out so black.)

[rgk]

Anthonyerco, you're right that the timing chain would be more likely to make noise rather than cause vibration.

It kind of sounds like an idle speed/fuel trim issue. The engine will vibrate if it's idling too low and struggling to stay running. It might be as simple as a vacuum leak. Eliminate simple problems before moving to complex ones.

I suggest getting a scan tool and checking out the real time stats - what's the fuel trim? How low is it idling?

If that sounds too overwhelming, just take it to a reputable independent shop, not a dealer. It sounds like you took it to the wrong shop, if the first thing they recommend is an involved and expensive timing chair repair.

[anthonyerco]

Anthonyerco, you're right that the timing chain would be more likely to make noise rather than cause vibration.

It kind of sounds like an idle speed/fuel trim issue. The engine will vibrate if it's idling too low and struggling to stay running. It might be as simple as a vacuum leak. Eliminate simple problems before moving to complex ones.

I suggest getting a scan tool and checking out the real time stats - what's the fuel trim? How low is it idling?

If that sounds too overwhelming, just take it to a reputable independent shop, not a dealer. It sounds like you took it to the wrong shop, if the first thing they recommend is an involved and expensive timing chair repair.

What is fuel trim? Lol....

The idle is normal. Doesn’t Bog. I’ve noticed when I’m in reverse and turning the wheel to back out of a spot, it gets worse. Otherwise it’s intermittent. Sometimes it’s harder than others, sometimes it doesn’t vibrate at all. Spark plugs were done about 10k miles ago... I do hear a hiss now, but it sounds more like a bearing hiss, not a vacuum leak hiss. I figured if it was a vacuum leak, the check engine light would come on. I am not familiar with any Nissan products but I can assure you this will be my last one. I have always wanted one of these and I found a little old lady owned one in perfect condition. Within 3k miles, EVERYTHING started going wrong. Idler pulley, alternator, belts, ac compressor, Valve cover gaskets are leaking now, replaced front struts, lower control arms and sway bar links. Still kinda clunks over bumps lol. I love this car so much but damn, This vibration might be the last straw.

[Mike W.]

What is fuel trim? Lol....

Fuel trim is how the FI system is adjusting the mixture. It's got a baseline from the MAF, temp, throttle position etc. But it reads the O2 sensor and fine tunes it. That fine tuning is fuel trim. It can be either rich or lean. I think typically it can be ~25% more or less.