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PostPosted: Tue May 24, 2016 10:35 am 
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Joined: Wed Jun 22, 2011 6:35 pm
Posts: 14
Location: Salisbury CT
Was wondering if anyone may have any ideas about my problem. I started my 350z the other morning and it made an unusual noise upon start up and now there is a noticeable rhythmic tapping sound coming from my best guess is the top of motor. When you press the gas peddle the speed of the tapping increases. After reading a lot of threads on the internet about this, it seems that it can be one of many things, but first I must go back and narrow down where this noise is coming from. To me it just seems obvious that I hear it right at the top of motor. I haven't driven it since and I am making arrangements to have it towed to Alfano Nissan in Torrington, CT. Am I wise to bring it to them, they have done all my oil changes and I purchased the car used from them or should I look for someone who may specialize with z cars?
Thank You


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PostPosted: Tue May 24, 2016 1:13 pm 
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Joined: Wed Feb 29, 2012 11:44 am
Posts: 588
Location: New Haven, CT
Not sure how to fix it, but the noise you describe sounds like a bad hydraulic lifter.

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Justin
1986 Z31 NA 2+0


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PostPosted: Tue May 24, 2016 1:35 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 14779
Location: CT
If you intend to fix it yrslf, surely you must locate the precise location of the noise. You can do that with a stethoscope ~ they sell mechanical steths at any car parts store or you can use a long screwdriver or socket extension or such, like Beethoven did when he was going deaf. Just hold one end to your ear and place the tip at different places on the running engine until the tap is loudest. BE CAREFUL OF MOVING PARTS (fan/belts/etc).

I agree your description sounds cam-related ~ 1/2 the engine speed, rhythmic, and speeds up with engine RPM. Maybe a bent valve, a stuck lifter, something with the distributor or the oil pump, or maybe a broken spring on the camshaft variable timing mechanism.

If you intend to let Alfano correct the problem, you needn't bother locating the source of the noise yrslf. They will tell you what they find when they correct it.

Q#1: How does the car run since the noise has begun?
Q#2: Have you done a compression test on all 6 cylinders since the noise began? A low cylinder would indicate a bent or chipped valve or a blown gasket (they can sound just like taps, at one-quarter engine speed (each time the piston rises on compression stroke).

Frank T

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PostPosted: Tue May 24, 2016 5:05 pm 
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Joined: Wed Jun 22, 2011 6:35 pm
Posts: 14
Location: Salisbury CT
I have not driven it since hearing noise. Should I take it around the block to see if there is a difference? I do not have the capabilities or technology to do compression test.


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PostPosted: Tue May 24, 2016 7:00 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 14779
Location: CT
Well, because you don't know exactly what's making the noise, it's probably not a good idea to drive it around. If it is a valve sticking open (or a slipped timing belt/chain) and you're *just* kissing a piston with it, they may be able to save it if you haven't done too much damage yet.
Any click or tap could be two pieces of metal kissing each other (or a blown gasket imitating a click). I guess it's safest to just let the pros do the worrying.

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PostPosted: Tue May 24, 2016 8:19 pm 
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Joined: Wed Jun 22, 2011 6:35 pm
Posts: 14
Location: Salisbury CT
Thank you Frank.
I feel sick to my stomach, is that normal for z people or am I over reacting. :(


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PostPosted: Tue May 24, 2016 9:33 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 14779
Location: CT
Yup, perfectly normal. It's a psychosomatic reaction from thinking someone you love (your Z) is very sick.
Console yourself with the knowledge that whatever Man makes, Man can repair. Even a worst-case scenario can be made right. If there's a warranty involved, it might not even cost you anything.
Hey....they might even give you a 370 as a loaner! 8)

And look at it this way ~ if they fix a top-end problem, your engine is good-to-go for another billion miles.

In direct answer to your question, YES, there are options other than the place you mentioned. Our Club gets discounts on parts and service at some Nissan dealerships, but that's not one of them. How close are you to North Haven or Old Saybrook, for example? Middlebury and Fairfield might also give us discounts, but I've not keep up to speed on that. Others might know if County Line and Miller's discount our Club.

Also, we have an independent Z speedshop full of CTZCC members and Club Sponsors in New Milford who we recommend (RDZ on Danbury Road). They do excellent work on many of our members' Zs and are experts on your V-6. Here's their website: http://rdzmotorsports.com/

If you're driving yrslf nutZ worrying about it, you can perform a simple check to determine if it involves a blown gasket or not. Open your (COLD) radiator cap and look for any signs of oil floating around in there. Also pull your oil dipstick and check for any signs of engine coolant on it (it would be frothy like a milkshake). If either of those conditions exist, your problem is probably only a blown gasket. They would pull the head off, clean out the cylinders, pop a new gasket on, replace the head and flush the radiator and block. New coolant and an oil change and you're on your way. Probably cost you about six dollars in any normal state, but because you live in CT, you can expect it to be slightly more. :roll:

While you're under there, also give a few tugs on all your engine pulleys to see if any of them wobble or clunk when you try. Probably best not to have the engine running when you do that, tho.

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