Loud Crunch On Cold Start!

[R33Turbo]

Hi guys,

I get a loud crunch for about 1-2 sec everytime i start the engine and also loud tapping sound (sounds like pistons) when i first start my car in the cold morning. Now if i was to warm the car up, take it for a drive then turn the engine off to start it back up again to look for the sound, the sounds gone away due to it being warmed up. Hence, why is the reason i can't take it to any mechanic to show the issue.

Ive only noticed this loud crunch for 1-2 on cold start after ive changed my oil to 'Elf Synthetic Oil 10W50'. This is pretty much all the relevant information i can provide from my knowledge, and also that the sound is coming from under the hood on the passengers side, kinda sounds like its coming from the head area on the passengers side where the turbo is and all.

Could it be that im using a real thick oil, hence is why its making weird noises on cold start till its warmed up?

Note: The crunch sound is only for about 1-2 sec on cold start and not constant whilst idling in cold or driving.

Much appreciated for any helpful response.

Edited June 14, 2008 by R33Turbo

[nizmonut]

need a better decription of a "crunch" dude...

example

is it similar to some one standing on a aluminium coke can or like some one scrunching up a chippie packet,or someone crunching first gear??????? could be the starter motor drive not retracting quickly enough on start up cause the lithium grease on the shaft is cold and thick?? who knows.

Edited June 14, 2008 by nizmonut

[R33Turbo]

well i shoulda made it clear before, it sounds more like someone quickly crushing a aluminium coke can

[R33Turbo]

actually it could more sound like short 'gear crunches' as well.

Basically, if the sound dies down after warm-up, it wouldn't be engine head related or anything severe right? So it wouldn't do any harm driving it around?

Edited June 14, 2008 by R33Turbo

[nizmonut]

i think you will find the rattle and the crunch will dissapear if you have rices for breakfast instead of cornflakes, a snap crackle n pop from the exhaust is usually a good sign of a nice flowing exhaust, however in this case drop the gluten from the crankcase and run some thinner oil as obviously what is in there isnt protecting the mechanically moving bits on startup.

[R33Turbo]

oh alright, thanks for your input nizmonut. So you think thinner engine oil might resolve the issue? So the one im using right now 'Elf Sythentic Oil 10W50' is too thick or what?

any other inputs would be much appreciated.

[nizmonut]

yeah well im running 25w50 mobil 1 in my gtr and starts on the first cylinder to reach TDC, no knocks rattles, purrs beautifuly so yeah i guess so.

and dont be fooled by the advertising of "synthetic" a federal court ruling allowed the oil companys to label highly refined mineral oil as synthetic.... so you dont always get what you pay for. make sure its says 100% fully synthetic as apposed to

just synthetic

Edited June 14, 2008 by nizmonut

[R33Turbo]

anymore suggestions please? u gotta be kidding me if no one have experienced anything similar to this?

[paulR32gtr]

its not your starter motor sticking? is there actually a sound that continues on while the car is warming up?

[R33Turbo]

its not your starter motor sticking? is there actually a sound that continues on while the car is warming up?

Nope, as i mentioned above the the 'crunch' sound which sounds like 'gear crunch' is only to be heard for 1-2 sec after engine start then goes away. However, if i turn the engine back off and on to hear the sound again, it will still be there (when the car has not yet warmed up properly). If its been warmed up properly, you would not hear the sound regardless of how many times you turn the engine on and off repetitively, hence is why i cannot show the mechanic as i got to drive there with my car.

[-_-StRyDeR-_-]

yeh id take a wild guess at starter motor also...

you could always leave the car with ur mechanic over night?? drop it off real late and get there early in the morn to watch them start it, so u know they aint taking it for a thrash...?

[blind_elk]

hence is why i cannot show the mechanic as i got to drive there with my car.

Leave the car overnight with the mechanic. That's the only way you will demo it to him.

nizmonut, you really using 25W50 oil? 25 is waaayyy too heavy, and 50 ain't much better.

PS - how about just having ONE thread on the problem.

[tridentt150v]

turn your aircon off and see if the noise still happens

[R33Turbo]

what do you mean by turn my a/c off? like disconnect the whole thing? cuz my a/c will obviously be off when im starting the engine in the 'cold morning'.

[R33Turbo]

Leave the car overnight with the mechanic. That's the only way you will demo it to him.

nizmonut, you really using 25W50 oil? 25 is waaayyy too heavy, and 50 ain't much better.

PS - how about just having ONE thread on the problem.

Im planning on doing that if i have time for it, however can't do it at the moment. Does that mean 10W50 is real heavy compared to average oils as well?

[blind_elk]

what do you mean by turn my a/c off? like disconnect the whole thing? cuz my a/c will obviously be off when im starting the engine in the 'cold morning'.

If you had your A/C on when you last turned off the engine, it will still be on when you go to re-start. Make sure you turn it off before actually cranking the engine.

10 is a bit heavy for starting (which is the only time it's important), but not too bad. Nissan's spec is 7.5W30 - you'd probably be slightly better using a 5W40.

[R33Turbo]

oh alright, thanks for ur help there blind_elk... so ppl are suggesting it could be the 'start motor' dying out, maybe it could be... then again it could be cuz my oil is to thick for the weather these days if thats wat ur saying blind_elk...

i think i'd try thinner oil to see if it goes away....

If it was the 'starter motor', where is it? how much to repair or replace?

Edited June 15, 2008 by R33Turbo

[Tomei_33]

If you had your A/C on when you last turned off the engine, it will still be on when you go to re-start. Make sure you turn it off before actually cranking the engine.

10 is a bit heavy for starting (which is the only time it's important), but not too bad. Nissan's spec is 7.5W30 - you'd probably be slightly better using a 5W40.

isnt nissans spec 7.5W40? maybe im wrong

[Munkyb0y]

you're wrong

genuine nissan is a semi synthetic 7.5w30

Edited June 15, 2008 by Munkyb0y

[GeeTR]

yeah well im running 25w50 mobil 1 in my gtr...

Dang