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vq35de Cold Start Thump & Rattle


Piranha

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This only happens when the car has sat for a day and started cold, an initial thump comes from around drivers foot well area, there is also an initial grinding / rattle / rasp sound that lasts for about a second, then back to a quiet engine.

 

2003 engine on 40k last oil change July 14, not burning oil, nice and smooth running.

 

The thump & rattle can occur together but often its one or the other.

 

I have read on some forums that it could be to do with a return valve in the air filter, others have said its linked to the timing chain.

 

Some have said dealers state as long as the noise lasts for 1 - 2 seconds its not a problem.

 

Since the weather has started to warm up a bit, i also get a slight wiff of petrol fumes outside the car not sure if this is related or its running rich.

 

Any one had similar problems

 

 

Thanks

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I've not heard this described before :surrender: It'll be interesting to know what it is.

 

 

Continuing research at the moment

 

This is the rattle sound I am hearing https://www.youtube....h?v=kWqxyQkPwVg

 

 

Also read this which does make sense, sound like I have the former and not the latter:

 

If you have a VQDE engine (2003 to 2005) this is not an uncommon problem and there is a TSB from Nissan explaining it. On a cold start one of the intake VTC (valve timing control) sprocket units can make a rattling sound for one second until it re-indexes. My 2004 did this every now and then for the ten years I owned it. I never bothered to replace it, as apparently it causes no long-term harm. I couldn’t find the 350 Z TSB

 

 

This engine has a timing chain guide that tensioned by oil pressure, but it also incorporates a ratchet mechanism to keep it from losing tension when the engine is turned off. A problem with this unit will cause a more pronounced marble-in-a-can knocking sound that persists for longer than a few seconds at start up

Edited by Piranha
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Identical to the sound I get.

 

And as you said only on cold starts, I have had it since I bought the car so I'm not too worried about it.

 

Yeah if I start it again a couple of hours later I don't get the rattle , it starts and purrs like a new engine.

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I found this:-

 

VTCTSB_zpswkhsovki.png

 

I've continued searching on both issues and both seem very common with the majority stating they've had it for years and its not a problem.

 

Its most likely my car is developing a few creaks n groans related to age, a bit like me :)

 

Its going in for rear brakes, drop links and bushes next week, so I will get the oil and filter changed just in case, as some people refer to a dry start up issue linked to oil pump.

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I just wondered if it's anything to do with that, maybe someone else can through some light on auto boxes? It might be worth PMing Zmanalex.

 

It could be linked, i don't have any codes up though and engine runs like a dream, only had car 5 months so experienced more cold starts than hot LOL, I could see this quite easily disappearing during the summer.

 

Cars still under warranty, so will get it checked out next week just in case there is pending mechanical failure.

 

I will leave it with them over night so they can cold start to reproduce

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