Bad noise comming from valve cover.

[grantf]

So, my car is back together. it runs, way better then before I pulled the head, but the engine is making a sound I don't like at all. It is sort of a "wirring" sound. sort of like metal is scraping during rotation. the frequency and pitch increase with higher RPMs.

Please note that this was happening before I did any work on the car. As a matter of fact I thought it was a vacuum or exhaust leak a while back before I started the work. With the hood down at higher rpms it sounds almost like a low whistle.

A little more info: when I removed the head the number one dimple was in between two chain links, not centered on a bright link (i could not find a bright link). the chain guides are looking a bit worn, but the plastic was still there and the chain seemed tight.

Any ideas?

[roy-73-240z]

You can check out this link and see response #2.

http://www.classiczcars.com/forums/thread42652.html

I had this happen on a 72Z I had where one of the cam oilers (see pic) holes was plugged up with sludge and the cam lobe was not getting oil and caused the grinding noise. The cam oiler shoots oil on the cam lobe and keeps it lubricated. I removed the head cover and I took a paper clip and removed the sludge from the cam rail oiler hole and that cured the problem. You have a 280Z but it should be the same design. Good luck.

[grantf]

hmm, interesting. I do have a spray bar. I also think that I have a cam that self oils I can see little holes on the cam lobes. the upper side of the head has always looked super clean and well oiled, but I will take a look at it tomorrow. It costs nothing and well worth a look.

Edited July 14, 2012 by grantf

[240260280z]

Sounds like a whirring buzzing belt or bearing. Worn lobes "clack".

[5thhorsemann]

I have to agree with Blue, it doesn't sound like valve train noise, the frequency is too high. Look at the belts and check the timing chain, something draging or rubbing against it. Chain tensioner? A stethiscope would help you out to narrow the culprit down to a specific area of the motor. My stock alternator was making that sort of noise and transmitting the sound to the motor via the brackets. FWIW

[Zedyone_kenobi]

Get a wooden stick (like a sawed off broomstick), and put one end on your ear. Then move it around to the alternator, water pump, AC pulley, etc. When you hit the object making the noise you WILL hear it.

[Zed Head]

It does sound a little bit like an alternator going bad. Or, if you have AC, check the idler pulley.

You can start and run the engine for a short while with the belts removed to see if it's a noise from something belt-driven. With the alternator belt off the water pump won't be turning so don't overdo it.

[grantf]

Thanks guys for the ideas. It's good to know about other tests. I fear it may be the timing chain, but I will examine further. I have AC but there is no belt on it right now, never has been since I owned the car.

[olzed]

Alternator bearing??

[rcb280z]

Boy if it was a mid 80's Buick I would say power steering pump but.... Sorry man don't mean to make light of your situation but you have to admit it sounds pretty close to that. On a serious note I would have the alternator bench tested. If you have an Auto Zone there, they don't charge. If it was metal on metal (internal engine) it would have a higher pitch sound, from what I have experienced.

[ZCurves]

Don't forget the belt tensioner bearings. Inspect cam-oiler anyway.

[LeonV]

Don't forget the belt tensioner bearings. Inspect cam-oiler anyway.

The alternator pully does the tensioning. There is no dedicated belt tensioner on the L-series.