On cold start (about 60 degree weather) last week, the engine shuddered and knocked violently, with plenty of valve clatter...sounded like it was going to tear itself off the mounts. Immediately shut it off, and restarted. Same thing. Third time, started and ran fine; no problem of any kind since.

Last oil change 2500 miles ago; no history of oil consumption or engine problems. '03 Touring auto, stock, 76000 miles, maintained by and beyond the book (great car...more fun per mile than any car I've owned).

Happened once before, thousands of miles ago. Otherwise never a problem, regardless of temperature, or whether it's been sitting for several days.

Maybe oil starvation on starting, but wouldn't that be a consistent problem?

Thanks for your thoughts.

 

I would think that is a timing issue, nothing to do with oil. Did you get any malfunction lights? I would suspect a crank or cam sensor first maybe one of the connectors for a sensor is loose or wet inside.

 

could be the sprocket issue if the clatter only lasted a second...

 

Take it to a dealer...

 

i've read up on cold start engine chatter in many different nissan platforms. From my understanding it is due to the lack of oil circulation on a cold start up which causes a butterfly valve to flap up and down untill secreted in oil. This is common with many 350z's, Sentra's, Altima's and Maxima's. I dont know if it is a design flaw, or a faulty part, but does happen from time to time with mine also. It sounds like a chatter/knock sound for approx 3-5 seconds. Sounds terrible, but hasn't seemed to affect anything longterm. Mine has only done it a handful of times in 4 years though.

 

The timing chain tensioner on the vq motors are oil pressure driven. When you start the car there is no oil pressure for a second so the timing chain actually clanks on the timing case and makes a very loud engine banging noise until the tensioner pressures up. All the vq's do it.

 

If your engine detonated that badly your knock sensor would catch it, throw a check engine light and retard timing, so its not knocking or detonation.

 

Sorry, 97, I should've described the sound as 'extreme clanking' or something; didn't mean knocking re detonation.

Thanks for everyone's input. Off to the dealer in the next few days for the "final word." I'll let you know if they have anything to add.

 

the motor wouldn't just JUMP timing though. check valve clearances