Engine Knock when cold

[skinny2]

Just bought a 2008 SE with 15k miles a couple weeks ago. Have been letting it warm up for 10 minutes or so because it's been so cold and I hate the cold. Tonight when leaving work, I only let it idle a minute or so before taking off and during acceleration I notice a somewhat loud knock/clattering sounds (a bit like a diesel). There's no sound at idle even on start-up.

Here's the funny part: I drove an '09 Pathfinder prior to buying this one and noticed the same noise. I started it cold and drove off and thought something was wrong. That Pathfinder had several issues (nasty rattles, turn signal didn't work, etc.) and later found out it had been in a major collision. So I thought perhaps the engine had an issue as well.

So it would seem at least on the two Pathfinders I've driven, they both make a noise when accelerating cold. So...is this normal? Is this actually an internal engine noise or perhaps something in the exhaust? I've heard of baffles in the exhaust or closing off part of a dual pipe to assist in heating the engine. Anyone have input? It stops making the noise right about the time the temp gauge moves off drop-dead cold.

Thanks for any help. Just want to make sure I don't have a bum truck.

[fat_frog]

Mine's doing the same thing. I bought my '09 last Feb. While it was cold, the engine made the same loud ticking sound. The sound was gone during warmer months. This winter, it comes back again. I can hear the noise/sound for about a mile. Once it warms up, the engine runs smoothly. I wouldn't call it engine knocking, though. Knocking is much louder.

My wife's '09 Murano (built in early 2008) does not seem to have this ticking/clunking. ....makes me wonder if something is wrong with mine as well...???

[disallow]

Just bought a 2008 SE with 15k miles a couple weeks ago. Have been letting it warm up for 10 minutes or so because it's been so cold and I hate the cold. Tonight when leaving work, I only let it idle a minute or so before taking off and during acceleration I notice a somewhat loud knock/clattering sounds (a bit like a diesel). There's no sound at idle even on start-up.

Here's the funny part: I drove an '09 Pathfinder prior to buying this one and noticed the same noise. I started it cold and drove off and thought something was wrong. That Pathfinder had several issues (nasty rattles, turn signal didn't work, etc.) and later found out it had been in a major collision. So I thought perhaps the engine had an issue as well.

So it would seem at least on the two Pathfinders I've driven, they both make a noise when accelerating cold. So...is this normal? Is this actually an internal engine noise or perhaps something in the exhaust? I've heard of baffles in the exhaust or closing off part of a dual pipe to assist in heating the engine. Anyone have input? It stops making the noise right about the time the temp gauge moves off drop-dead cold.

Thanks for any help. Just want to make sure I don't have a bum truck.

My 98 civic used to do the same, dealer called it 'piston slap'. It was a well known issue on the D16Y7 engine I had. Not sure if it is prevalent on the VQ40. I have not noticed it on my 05, but will listen for it next time.

How cold is it where you are at?

[fat_frog]

Apparently it's a very common "issue." I just looked at ClubFrontier; there are many threads discussing about the same cold startup noise. Some have taken to the dealers... Some have tried 10w-30. I didn't see a very clear solution for it. Maybe I'll visit my local Nissan dealer to see if they know anything about it.

[MonkeyMike]

mine has sounded like that every day this winter. definitely agree with the "diesel" sound. kinda makes me worry about it.

~mike

[skinny2]

How cold is it where you are at?

Well it was about 20°F last night which is the warmest it's been and partly why I didn't let it warm up much before driving off. It's been hovering around 10° mostly but I let it idle 10 minutes or so and have never heard the clattering sound. When I test drove the '09 it was in 30's. After I drove the '09 I stopped and spoke with a Nissan service writer to ask about these engines and he said they shouldn't be making any noise like that.

The common factor seems to be just starting up and driving off gives the noise. It really sounds like a cold diesel engine which I would be very excited if it really WAS a diesel....but my mpg meter says it's a gasser I might try running synthetic on the next change as Nissan's service intervals are a little light for my taste. But maybe they know something about this engine I don't

[SilverGhost]

I can't speak directly to this being a specific problem with the VQ40. I've noticed a bit of noise on startup during cold weather (+20F is about as cold as it ever gets in Houston, TX). But warming it up for a couple of minutes takes care of that. Driving off immediately after startup was never an advisable procedure, with any vehicle I've owned, EVER! You just don't do that.

Generally speaking, after owning 50 or so vehicles during my life, piston slap is common on startup during cold weather in engines with hydraulic valve lifters. Lower viscosity oil (0-W30, perhaps), and/or an engine heater helps gobs! I spent a winter in Minot, ND, where ambient temps dropped to -30. Trust me, it's difficult to crank any engine at those temps without the heater and low-visc oil.

Personally, I'm not worried about it on my '06 LE.

[eieio]

i agree with SilverGhost........
"piston slap" or not, i think it's terrible to just start up a cold engine, stick it in gear & drive away. a couple of minutes of warm-up assures better oil circulation & lubrication, before putting it under load. this can only be a benefit in the long run. i've heard many times that the majority of engine wear occurs prior to being warmed up. makes sense to me!

[SilverGhost]

i agree with SilverGhost........
"piston slap" or not, i think it's terrible to just start up a cold engine, stick it in gear & drive away. a couple of minutes of warm-up assures better oil circulation & lubrication, before putting it under load. this can only be a benefit in the long run. i've heard many times that the majority of engine wear occurs prior to being warmed up. makes sense to me!

Well said!

[bbermann]

One of the great benefits of synthetic oil is in cold weather starts.

[fat_frog]

I don't have any scientific proof to say who's right. But, when I search for the answer for a question: how long should I warm up a car?, majority of answers seem to be "start the engine, run it for 30 to 60 seconds, and start driving gently."

[url=ttp://www.motherearthnews.com/Ask-Our-Experts ... rm-Up.aspx]Should I let my car warm up each morning?[/url]

Google Search: How long to warm up car

Educate yourself on the topic as much as possible, and decide, I guess...

[skinny2]

Well, we can argue all day whether driving a "cold" engine is good or bad. IMHO, if it doesn't have adequate oil pressure and flow within 30 seconds or less it has problems (either mechanical or design in nature). My normal routine is for the engine to run about 30 seconds before I back out of the garage. If it's really cold, I will let it run longer to warm the cabin because I hate the cold. I'm not talking about hammering on the motor when cold, but accelerating slow and easy, which is when my PF engine is making racket for several miles.

Either way, some engines are designed to have some cold start noises and it doesn't appear to hurt them. I've had two GM V8's that are known for CSK (cold-start-knock) and have seen many with hundreds of thousands of miles and no problems. I've been around the block when it comes to owning/driving a lot of different vehicles. Beyond my diesel Dodge's or VW, this is a new noise to me.

[macbell7]

There was a similar topic on here a while back about a ticking sound coming from engine, but this was directed towards what grade fuel people were using. If your pumping 87 octane in there it seems to give that little chatter sound. Try running a couple tanks of 91 to see if that cleans it out a bit and gets rid of the chatter. It is recommended in the manual to use Premium fuel in the pathfinder. Mine does it faintly, not enough to make me worry about fixing something.

[LittleStevie]

I'd agree with the suggestion to run 91 octane or higher fuel. The "diesel" sound you hear might actually be dieseling...that is, premature ignition of the fuel in the cylinder. I've noticed pinging/knocking when running 87 and 89, even though the engine is supposed to adjust timing to avoid knock.

[skinny2]

I've been running 91 so I don't think that's the problem. Didn't do it at all today. Temps were in 40's and I didn't warm the engine more than what it takes to get situated and drive off.