knocking noise coming from the plenium

[TYL3R hez]

I have had the car since last october of 2010, and everything has been beautiful!
But today I heard a loud knocking noise coming from the backside of the plenium or however that's spelled.
Honestly I have no experience on these engines, and would have searched it up before hand. Only I had no idea what to look up!
at idle it sounds like water being sucked through a valve. Then when reved to 3000rpm it starts knocking.
(almost like a lifter tick) only its really loud and does not sound healthy!
I changed my oil and it did not seem to quieten at all.
Could this be the isc valves, I know they are on the sides of the engine but still!
I wanna get an idea what's wrong before being forced to...*holds breath* "take it to a shop..."
Help me out please
hahahaah
OH Its a 1990 2+2, made in 02/90
so could the "soft spring" failure be a problem too?
thanks in advance!
-tyler

[TYL3R hez]

bump

[TYL3R hez]

anyone
little help?

[Ace2cool]

Maybe you could post up a video of the noise? How would you describe it? More of a tencil tapping a desk, a hammer hitting a rock, or a hammer hitting metal?

[TYL3R hez]

kinda like a pencil almost. I tried taking a video but the sound quality was horrible
you think it's something serious?
I mean the car has no lose of power at all!
And when driving you can't even tell it's there!

[es.biggs]

It could be anything...the soft valve issue in most of the early cars has been corrected (according to advice in this thread: early-model-z32-s-t524697.html) How many miles do you have on your engine?

It's really hard to tell you anything over this but if I had to narrow it down and guess, I'd say you have dirty/sticky lifter(s) or you have a worn VTC spring.

Lifters are easily fixed by cleaning the engine with a pint of ATF mixed in with your oil running for a half hour, or buying a "flush" product, Both require oil changes shortly after the treatment - but they are cheap ways to possibly prevent a big bill from the shop. If you end up needing new lifters or VTC springs, you might get a really expensive est. from a shop. If you were any closer to the Matthews/Charlotte area, I'd like to take a look for you man, but right now I can't afford to drive out there with the way gas prices are climbing :/

[TYL3R hez]

I will flush it today!
and let you know if anything else goes on
thanks alot dude!
And the car is drivable and heck it actually runs good!
SO if need be I could possibly meet you somewhere and you may could lend me a hand!

[TYL3R hez]

using my best judgement I would say it's prob my lifters.
being a 90 with almost 160k on it it's about time for some new ones.
At least I hope it's lifters

[es.biggs]

If it's lifters, you should be able to clean them up with ATF and it might make the noise go away. There's been a few threads about it, and it works. Z1 also sells a flush product that a few people have had success using, so that's another option. If you want to meet up sometime man that'd be cool, PM me!

[TYL3R hez]

wouldnt using a oil additive in it help?
like the stp oil treatment
or since I use full synthetic that would be a bad thing

[nissanfreak12]

Marvel Mystery Oil, I live by that stuff. Honestly, stay away from the STP stuff. What mr. Biggs is talking about is your lifters could be gummed up and you need something to ungum them, why atf works so well. Try the mmo, that really does work, worked great for me if this is your issue.

[GerryO]

I quieted a sticky lifter at about 165K miles in a few minutes by adding about 1/2 quart of synthetic oil. It's more slippery than the dyno stuff. Not too long after I switched to Castrol 20-50 synthetic blend and things have been quiet ever since.

Knocking at 3,000 rpm doesn't sound like a sticky lifter.

[nissanfreak12]

that is the time the vtc kicks in, guessing here, that would be the issue, since he is already useing synthetic. Truthfully, vtc springs are cheaper and WAY easier than lifters. These should have been changed at 120k timing change, if you want to see, just unplug the vtc solinoids and see what happens.

[es.biggs]

^^good idea! I forgot about that trick lol

I agree that because it's only 3k and up it sounds like VTC but I thought the noise should be present at idle too?

[nissanfreak12]

^^good idea! I forgot about that trick lol

I agree that because it's only 3k and up it sounds like VTC but I thought the noise should be present at idle too?

This is true, its a theory here, but what if his engine is starving for oil at the higher rpm's when the vtc kicks in? For all we know it could be he pcv system on the fritz, really noisy injector, or even a pissed off leprechaun trying to get out.

To OP, really try and get a video so we have some idea what it is.

[TYL3R hez]

the tick is present at idle !
It gets louder at around 3-5k then Im guessing because of the engine noise you cant hear it after about 5krpm
I put the marvel mystery oil in it yesterday so I will roll 1000miles on it then change my oil and if it dont fix it then buy the stuff from z1 to clean it out.
If that doesn't kill the culprit I will start addressing lifter's and vtc springs etc.
Can anyone give me an idea of how much something like those would cost.
"parts wise"

And my camera is packed up in storage in a 18 wheeler trailor so finding it...not possible anytime soon

[nissanfreak12]

If you have it at idle my guess is VTC springs. Usually lifters make noise all the time and doesn't change tone or pitch the higher the revs. If MMO doesn't do anything, which you should notice a diff after 20 or so min of driving. If not then I would really look at VTC. Since I had all this fun recently with them the springs and seals will cost roughly 15 dollars. They have the heavy duty spring which are 26 for both. Original one work good. You need to pretty much remove everything like you would doing a timing belt except the crank pulley and the lower cover. The two upper covers, the inlet pipes from the radiator and so on. I would really change the thermostat and the bypass hoses while you are there, especially if they are bulging at all.


When was your timing belt done and by who? This is a great time to do a 120k timing belt which roughly cost 550.00 at conceptzperformance, that comes with everything you need including the springs and seals. This is an area not to go cheap in, trust me. If you do the work yourself, which is not recomended if you really don't have mechanical skill mainly cause the timing issue, you can get it done in a weekend and about 600.00. If you just do the springs and seal, a day and about 50 or so dollars.


Lifters can get very expensive and very time consuming since you have to take the timing, valve covers, cams, and preferebly the heads off(makes life easier), at this point you might as well rebuild the engine, at least the heads, which is in the ballpark 1k or more just in parts.

[TYL3R hez]

If you have it at idle my guess is VTC springs. Usually lifters make noise all the time and doesn't change tone or pitch the higher the revs. If MMO doesn't do anything, which you should notice a diff after 20 or so min of driving. If not then I would really look at VTC. Since I had all this fun recently with them the springs and seals will cost roughly 15 dollars. They have the heavy duty spring which are 26 for both. Original one work good. You need to pretty much remove everything like you would doing a timing belt except the crank pulley and the lower cover. The two upper covers, the inlet pipes from the radiator and so on. I would really change the thermostat and the bypass hoses while you are there, especially if they are bulging at all.


When was your timing belt done and by who? This is a great time to do a 120k timing belt which roughly cost 550.00 at conceptzperformance, that comes with everything you need including the springs and seals. This is an area not to go cheap in, trust me. If you do the work yourself, which is not recomended if you really don't have mechanical skill mainly cause the timing issue, you can get it done in a weekend and about 600.00. If you just do the springs and seal, a day and about 50 or so dollars.

honestly I don't know because I have only had the car since last october.
The guy lied about alot of stuff being done to it as well.
So its hard to tell when anything was done at all...
I do know the coil packs and plugs were replaced prior to me buying it!
One of my clips on the front left coil pack is broke.
And I have a z1 aluminum driveshaft which there was 130983059 other things he told me it had that it didn't!

I am going to buy the stuff from z1 on friday and run it then change my oil.
I noticed today the tick had gotten quieter but still noticable!


Lifters can get very expensive and very time consuming since you have to take the timing, valve covers, cams, and preferebly the heads off(makes life easier), at this point you might as well rebuild the engine, at least the heads, which is in the ballpark 1k or more just in parts.

[nissanfreak12]

Try and unplug the VTC's, see what happens, that can real quickly tell you whats going on. You may still have a tick, but it shouldn't change after 3k

[TYL3R hez]

unpluged the vtc's and nothing changed so its probably a lifter

[TYL3R hez]

http://www.youtube.com/watch?v=WSbdnfT2OXA
it sounds just like this in the video but it does not change after unplugging it

[nissanfreak12]

Did you unplug both? Could possibly be the other side having the issue.

[TYL3R hez]

yeah nothing
it's still there!
I just bought the stuff from z1 and i am running marvel right now.
is my methods overkill?

[nissanfreak12]

I guess we will see, its possible you just have a dead lifter, we just dont know. I still think it lies in the vtc's, its just really hard to diagnose in painted black letters on the screen. But, if your noise sounds just like the one in the video, then there is your answer. Lifters have more of a repetative tick, listen to most hondas, especially the older ones, vtc's have a rattle like the video. Very rarely do these type of nissan lifters go out, and thicker oil and some additives make a difference.

If you can take a long screwdriver or something to act as a stethoscope and try and pin point where the noise is. You will still hear it, but in certain areas it will be more pronounced, mainly where the main cause of it is. Just be very careful on moving parts like the fan and the belts. If the noise is right by the #1 and #2 cylinder, then more than likely its the VTC. Let us know what you find.

[TYL3R hez]

thanks alot i will reply tonight after some test
and me puttin the z1 stuff in it wont kill my engine will it?????

[TYL3R hez]

I AM PRETTY DARN SURE ITS MY VTC'S !
CAN anyone answer my previous question about the z1 engine cleaner and it maybe being too much after the marvel mystery oil treatment?
I would love to know if there is a write up on how to replace the vtc's!!!

[Ace2cool]

I would definitely change the oil between the Marvel Mystery Oil and the Z1 engine flush. Using both additives would dilute your oil to the point it may not protect your engine effectively.

[es.biggs]

I'd try it man, that flush product from Z1 is cheap and easy - if it doesn't fix the noise at least it will have cleaned up the insides or your engine a bit.

If it's a VTC issue you will probably need either new springs or new intake cam gears. I researched a little and it looks like the problem lies in the gears. I tried to find an article that showed how VTC operated and was very informative, also explained why it makes the rattle noise, but I can't find it :/ if you have the time try searching around for information on it.

I'm not sure what it means that the noise stays there even when the VTC solenoids are disconnected. It would make sense that it's not VTC related because of that, but again I don't remember how it all works so I can't say for sure.

I'd try the flush first man, maybe use some thicker oil with your oil change to see what happens. And I definitely agree about the screwdriver stethoscope...listen to all the valve covers to see if the noise is more prominent in one valve cover than another. Then stick the screwdriver on the timing covers where the intake cam gears are (on the inside/top of the V shape) and see how it sounds. Try to isolate it!

[Chattzx]

Where is the solenoid to disconnect the VTC gears?Is it by the knock sensor harness?

[nissanfreak12]

Where is the solenoid to disconnect the VTC gears?Is it by the knock sensor harness?

It doesn't really disconnect the gears, just the solinoid the keeps the oil pressure into the gears. The driver side is pretty much right by the detonation sensor connector, they look almost identical and even connect teh same way, very easy to accidently connect to the wrong one. The passenger side is literaly on the shock tower. It should be covered in a white sheath and if you follow the wires they will lead to the back of the intake cam cover. If you have a 96, you will not have the VTC.