cold engine knock

Anyone else with a s/c engine notice a bottom end knock when cold starting?
Mine raises hell for a good 5 min before it warms up and quits.

No, I don't have a problem running mid-grade gas.

If you don't get rid of the knock by changing the gas then have the timing adjusted.

With an SC he should only be using premium anyway so changing gas is not an option.

I don't have this problem but I'd say since its an SC, you should still have a nice fat warranty.... take it back to the dealer and let them check it out.

I didn't read the message very well.

Check the timing.

If it is the timing, why would it only do it when the engine has sat overnight? Once it is at temperature, it will not do it upon restart. Also, I do run 93 octane fuel. And as a bonus, I have had it checked by two local dealerships. Both say that Nissan is aware of the noise and that it is normal. So I am just wondering if any other S/C owners are hearing a similar noise. I need to add that it is worse when the outside temp is below 50 deg F. Start it on a warm day and it is not as noticable.

I think the Nissan mechanics are dissmissing it as the valve clattering the engine makes when its first started up. But that only lasts for a few seconds not 5 minutes.

The reason I suggested timing check is that it sounds like it may be the engine misfireing. The reason it goes away after 5 minutes is that the catalitic converter heats up enough that the engine goes to closed loop mode and the misfireing stops.

Checking timing is something that only takes a few minutes to do, and if you have a timing light you can do it yourself and save some cash. Many engine problems can be caused by the timing being only a degree or two off.

If that doesn't fix it take it to the dealer and have them diagnose it because the engine sholdn't be making any wierd noises for 5 minutes.

I will give it a look. Can you tell me how many degrees each of the marks represent. and, is the yellow mark TDC? Thanks.

Yes the yellow mark is TDC. Each tick is 5 degrees.
Hook the timing light pickup on the #1 cylinder spark plug, it's the closest to the front on the passenger side.


[5 6]
[3 4]
[1 2]


The specification for the Xterra is between 13 and 17 degrees before TDC. So you should be around the third tick mark to the right (driverside) of the TDC mark.