2003 Nissan Altima Engine Rattles?

Question

Hi,
I have 2003 Nissan Altima 3.5. Initially the engine rattled during the cold start up but now the noise comes while accelerating as well.I got the oil changed twice, the noise on acceleration is gone but the cold start up noise is still there. Can anyone help me and tell me what we should do. Our mechanic says that we should get the engine changed. I am not ready to believe that there is such a huge problem with the engine. Because we have had no other problem with the engine except for this noise and it has only run 80,000 kms.
Tks

Answer 1

It sounds very much like valve rattle to me given that it evidences itself under the circumstances you describe. There are all sorts of things that can cause this, some of which are easy to address, and others that are much more expensive.

Let's start with the easy ones first. Are you using the proper grade of fuel? If it calls for high-test you must use high-test. Is the gas you are buying partly methanol (85 percent gasoline and 15 percent methanol). This can cause a valve rattle in high performance engines as well. If either is the case, change your fuel.

Have you ever changed the timing belt and tensioner? Nissan uses what are called interference engines which, without explaining that in detail, means that if the timing belt ever breaks valves can collide with pistons causing catastrophic damage to the engine. At 80,000 miles you are certainly due for a belt change and should have the belt tensioner examined as well.

Does it put out any smoke on start-up--white smoke in particular. This would indicate that you have worn and leaking valve guides and that once you get a little oil in the gaps when the engine warms up it would take up some of the slack in the seal and quiet down. It would also stop smoking at that point.
Does it only do this when the engine is cold--and not when you restart it after running it a bit? That would also be an indicator. It might also indicate a leaking hydraulic lifter if your engine is so equipped, but I have not looked at the design of your Altima to know.

I used to have an old Chrysler LeBaron convertible, which were notorious for valve tap on start-up and leaky lifters. I found that adding a quart of Slick 50 to the oil did wonders in addressing that.

These days I have an XK8 that taps everytime I use the methanol/gasoline blend. In my area the stations are not required to tell you whether they are selling blend or not at any given time, so long as they put up a notice that the fuel may be blended. However, it is easy to tell the first time I hit the accelerator, and thereafter I have to drive much more slowly until that tank is used up, as I do not want to damage my valves.

Answer 2

yeah, unfortunately, with a real nasty sounding knock, chances are, it's a serious engine problem.

But first...

Are you positive it's the engine? I know that sounds dumb, but have you popped the hood and actually sought where the noise is coming from? Try that. You'd be surprised how many people think their engine is going when all they did was forget to secure the thing that holds the hood up. It could be anything under there, so give it a once over. If it turns out that it's still the engine, try some Lucas oil treatment. It's in a white bottle and is very thick. Pour it in where your oil goes and it should quiet it up for the time being.

If the mechanic is telling you that it's in need of an engine rebuild, make sure to get that statement backed up independently by other mechanics. An engine rebuild/transplant for that car will not be a cheap operation.

Answer 3

A Technical Service Bulletin (TSB) was published for earlier Altima models that had timing chain guide wear and caused a rattle at idle coming from the front of the engine where the timing chain cover is located. The repair was to replace the timing chain guides.

Answer 4

If it's an upper engine knock, have the head serviced.
If it's a lower enginge knock, it's either time for a rebuild or to replace it.

Answer 5

fix'in to blow...you'll believe it's serious when you are walkin'...changing the oil helped because the new thicker oil helped cushion the bearing as it flops around on the crank shaft. after cooling down ,all the oil drains back into the crankcase and on the initial startup there is no oil to cushion again untill the oil pump starts pumping up the oil. it will not go away but a thicker oil may hide it for a couple weeks...it will not heal itself and the damage could be catistrophic and cause thousands of dollars in damage if you ignore the noise and keep driving it.

Answer 6

have someone to crank it while youre listening to the motor. check where the sound is coming from either the low end or the high side. if its the low end you have a bearing going out, if its the top the lifters are collapsing on it. drain a quart of oil out and replace it with a quart of marvel mystery oil it reallys does wonders for and old engine.

Answer 7

had a similar problem. turned out to be a cracked heatsheild ask your dealer to check that out

Answer 8

PI-PI