Nasty noise from engine...

[pat93]

Nissan: 240sx: 1996: Mileage:100100, Manual: engine: KA24DE

Yesterday I was thinking about doing paint job on my lovely s14 96.I was chilling and exciting to see her in nice paint, but heaven may be hate me.While I was driving and about home I started hearing knocking sound from the engine. It is not usual knocking sound that you heard from almost every old car. It is louder than that.

I took a v. clip and put in you tube.This sound is really kill me; I'm really worried that my motor is done.Engine oil is there, and regularly change with either Purple or Mobile 1.I really hope that some of you heard and know what it is..

http://www.youtube.com/watch?v=V59xfnaUVRk

Thanks in advance.PS. I dropped my car at mechanic shop they said they don't know untilthey start investigating, so I think It would be great if I had some idea whatis gonna happen including possible cost of fixing it.

[AZhitman]

Pat - Does it do thsis on deceleration? Or on acceleration?

Accel = knock.

Decel = Piston slap or bearing damage.

[pat93]

I do appreicated you super quick response.I am sorry that I forget this information.

Accelerate engine I couldn't I heard it, but may be because the engine sounditself is louder than the knocking sound.but for sure, once I release the gas and engine decelerating;there is no knocking sound until the engine is running idle.

hope this make sense

[AZhitman]

THat might actually be good news.

Any chance you can go check it out before the mech gets into it? Could be as simple as timing chain slap (bad tensioner).

Almost sounds like an injector, but a little loud... You can tell by disconnecting each injector plug one at a time and see if it goes away.

[pat93]

THat might actually be good news.

Any chance you can go check it out before the mech gets into it? Could be as simple as timing chain slap (bad tensioner).

Almost sounds like an injector, but a little loud... You can tell by disconnecting each injector plug one at a time and see if it goes away.

I have some basics but this might be little beyond my knowledge.So, to verify if this is about timing chain slap (because of bad tensioner) or injector.Go start the engine unplug injector plug one by one and see if the sound is gone and put that one back and unplug the next one.

If none of them make sound goes, the sound is nothing to do with injector; thus it is about tensioner.

how hard of changing the tensioner?is the process almost as long and complicate as the process of changing timing belt?

Thanks you again..pat

[OldmanPurdy]

Well there's two tensioners upper and lower with the upper being easier to get at. Basicaly you have to remove the valve cover, distributor, and upper front timing cover to get at it. If you are intrested in trying it download a copy of the service manual and have a look at what you would be getting involved in, good luck.

[bimrtech]

It sounds like you have the very common KA24 upper chain noise.

There are two chains on that engine.It has been years since I have worked on one of those engines, but I do remember changing the top chain on those twin cam 240's and altimas often.

Pull the valve cover, you should see a guide between the two cam gears. pull the guide off and put it back together. the sound should be gone. If it is, change the chain and tensioner and put the guides back on.I think I remember another guide on the opp. side of the tens. as well.If you know the sound it is very easy to diagnose this issue.

I actually bought a 96 240sx years ago for 500 bucks due to this guide breaking off, getting stuck between the chain and gear and breaking the chain.

good luck!Joe

[pat93]

Yesterday I start fixing this from the easiest one by remove the top chain guide. Yes! the top chain guide is the root cause of this. I incline to chain guide because while the car running idle I put my ear next to the spot that has guide, oh it is right there! Once I remove it, the sound is gone with the guide. I am kind curious why it just start rubbing between chain and guide; it was there without rubbing?

I hope somebody see this message in future because the mechanic shop charged me 60$ for diagnostic and end up convince me to change timing chain, spockets, tensioners with the quote 1100 ! sob.

240sx forum is Rock!

Thanks every every single comment!

[driftingmy240sx]

timing chains do stretch. this is a come problem with the ka24. i have found it can also help to run a slightly thicker oil to eliviate some other chain noises.

[insightsmoke]

heh awesome, I have this same noise in my 92 and this will save me much diagnosis time.