Here are the symptoms again. The car will not do it, if it has been sitting for more than 8 hours. I start it, and no tapping. But...If I drive it for about 5 minutes, I hear it when I come to a stop. But, it goes away after about 5-10 minutes. This noise only lasts in spurts of 5-10 minutes. If the car sits for about 1-5 hours, and you start it. It will tap. But, if I drive it for another 5-10 minutes, it will stop. Sometimes I can hear the tapping as the motor is turning just doing about 35 mph, after 1 hour of driving. Maybe I am just listening too close. Please help! I think the video amplifies the noise about 2x. If you guys need any more info let me know.

http://autos.werd.com/dmontzmax/MCC%...thatsound1.mov

http://autos.werd.com/dmontzmax/MCC%...thatsound2.mov

 

If it was the valvetrain it would get louder as the engine reved and higher pitched. In the 2nd clip it didn't seem to increase in volume or pitch when you reved the car. I'm going to say there is a crack in one or both of your exhaust manifolds, 2nd gens/Z31's had a problem with cracked front exhaust manifolds too. Another way is to pull the front valve cover and examine the lifters/valves themselves. Also what oil weigh do you use? Try running some 5W30 or 10W30 to see if the tapping gets louder or not, then check the engine's oil pressure. Believe it or not when I forgot to torque down my front exhaust manifold my maxima sounded simular to that.

 

I use 20/50 because the mileage is sooo high(230k) I am scared if I go any lower it will cause a problem. Thank you for your input. This is what I need. I hope it is not valvetrain, and just the exhaust. Lordrandall heard it, and said it was exhaust.

 

yup, sounds like that. i had the same problem, and got my manifold and studs replaced. it made a world of difference. i had a thread up not too long ago regarding this subject. i think it was called 'blew exhaust manifold'.

 

How much did the whole fix cost you? Did you do it yourself?

 

My exhaust leak has gotten really bad too. Same symptoms. I even get a whistle when im at WOT ! Its also made my exhaust sound like trash

 

woah!! since when could you buy a diesel 3rd gen?!?!

 

Yup, sounds like a bad exhaust leak to me. Probably have a broken stud or two and blew the gasket between the exhaust manifold andt he head.

It sounds too fast for a VTC tick. I had a broken stud on each bank, and it would get louder as the engine revved. IT would also whistle at anything over half throttle. But if I put my ear down near the intake manifold, I could hear the putting of the exhaust leak, especially when I revved it. Dare I suggest putting a tablespoon of oil down the spark plug hole of middle cylinder of each cylinder bank, then checking for any white smoke to blow out?

You can also feel an exhaust leak, but only do so when the engine is cold! Try feeling up your manifold and finding each nut, there should be 6 on each manifold. I had problems with the oone stud toward the passenger side of the manifolds on each one.

 

cant you spray stuff through the intake too to make the engine smoke, i forgot what they used. i wanna say throttle body cleaner or soemthing but im not sure..

 

Thanks! I am now about 75% sure it is exhaust, I am going to see if I can check the back bolts. The fronts are all in place. Goes to show that the 3rd gen boys know whats up. Someone on the General forum asked if I had cleaned my throttly body...WTF???...I have never heard a dirty throttle body do that.

 

Yeah, I had a lifter noise that had similar symptoms, but it was not even nearly as loud as that

 

Jeff and Matt where are you? I would like to hear your opinions.

 

with the engine running, check under the hood if you can smell raw exhaust fumes

 

How do you check if the studs in the exchaust manifold are okay?

I think I have an exhuast leak and my engine putters at idle...

I want to check the studs on my exhaust manifold, anyone have a how to

or pics of what I need to be looking for ?

 

It really sounds like VTC clacking to me. In the 2nd one, are you reving the engine near the end or is it another car? It's actually easy to see if it's the VTCs or not. Just use a tube or put your ear right over the Left and right VTCs assemblies(buldge in the valve cover) The noise source will be pretty clear. It's hard to tell what the noise is though as the video didn't show up. If you amplify the injector click, it might get that loud too but I doubt it's that.

Usually a stud, leak will screech(like a slipping belt) then seal it'self off when the engine warms up. How many studs are broken??

It's odd because even a stud leak/vtc tick/injector tick should all increase in frequency when you rev the motor.

 

i think it sounds like one or two broken studs because after your motor warms up the manifold expands an plugs the gap back up. I had the same problem and had it fixed. I was caused by bad injectors creating backpressure. just replaced 5 bad ones. ran me 8 bills for injectors and I had my girls brother do my exhaust studs otherwise a shop said it would run around a g or so.

 

You guys brought the post back from the dead. Since this post, I have grounded the VTC's and do not have the noise. For all that said VTC you were right.

 

I've recently had my front manifold snap three bolts, and I had them all replaced with the upgrade bolts you can obtain from your local nissan dealership, and if your experienced at mechanical jobs and know how to tap an engine block then go for it, but I didn't feel up to the challenge so I paid the local shop roughly $350 to replace all of them, if the bolts are snapped in the back then plan on doubling that fee, the back manifold is a pain in the a** to work with, and then trying to tap it would be nearly impossible, you would almost have to host the entire block out just to get to the back exhaust. Anyways Good Luck