L24 Nasty engine noise. What is this? (video attached)

[Tomzern]

Hi!

I just got my L24 running after sitting for several years. The head looked very clean underneath the valve cover, and I went over all the valves and adjusted them to .25 and .20mm as the FSM says. I then took out all the spark plugs and let it run on the starter for about half a minute before I started it.

It runs nice, but I have this nasty noise coming from the engine. I have read about other having problems with noise from the valvetrain, but this is a bit too much or what? I am not very experienced with this engine, so that is why I am asking you

Any ideas?

Kind regards,

Tomzern

[240260280z]

Pull valve cover and look at lobes...and oiling ....easy to do

If all good then

Pull one spark plug at a time while idling to find which cylinder is associated with the noise.

[Mark Maras]

Maybe a compression check too.

[Zed Head]

Did the engine run before without the noise, even for a little while, then the noise appeared after the valve adjustment?

Kind of sounds like an exhaust leak, especially as you backed away.

Also possible that you didn't get the lash quite right. Might be worth re-measuring.

[Tomzern]

Thank you guys for helping me:)

I have not had it running before, but the guy who owned the engine before me said it was making this noise when he used it several years ago too. I hoped adjusting the valve lash would do the trick, but when I went over with the feeler gauge there was only one valve that needed just a tiny bit of adjusting because the opening was too small..the others were perfect according to FSM.

I have only adjusted them with cold engine though, but can it really be this noisy just if I am off by say .01mm on one valve?

Is it a common problem that the oil rail for the valve train is blocked?

A friend of mine suggested it may be a worn valve guide..Any thoughts on that?

I will try all your suggestions during the weekend and update as soon as I have done it.

Thanks again,

Tomzern

[AZ-240z]

I'm in the exhaust manifold leak camp.

[zKars]

Sure sounds like exhaust.

Check the three stud downpipe flange seal. I've seen the flanges be warped before, but appear to tighten down normally, that leave a tiny gap. Doesn't take much to let that noise out.

[Jeff G 78]

I tend to agree on the manifold leak theory. It doesn't sound like engine.

If you don't have a stethoscope, place the blade end of a large screwdriver or pry bar against the valve cover and put your ear against the handle end. Move from cylinder to cylinder and see if the noise changes from position to position. You should hear a constant whirring/scraping sound, but you shouldn't hear any thumping or rattling. If you do, you have a problem at that cylinder.

Nice looking car BTW.

[olzed]

Silly question, but are you using a metric feeler gauge.?

[Captain_Zeros]

Have you checked out if it has a falling-apart cam oil spray bar? They are made of a series of tubes and cast blocks swaged together and can warp, if they warp bad enough the end tubes can collide with the cams or even fall all the way off.

[Tomzern]

Now that you all lean towards the exhaust leak theory, I am starting to think that it might just be that. The story here is that I bought the car with the original L24 engine and got it running last week, but I could not get it to run on all six. After a compression test I found out that I had no compression on cylinder no. 4. I then took the head off and found out that the whole engine was worn out and needed an overhaul, so I went and bought another L24 longblock that had been standing still for a few years. This is the L24 I have this noise in now.

The thing is that the old engine made the exact same noise as the new one, and I have reused the external components. Maybe the exhaust manifold is the problem here? The gasket is brand new, so it can't be that..

Thank you Jeff I will post pictures of the car when it's up and running

Thanks,

Tomzern

[Mark Maras]

Humor me. Does the noise change when you push on the clutch pedal? Both engines making the same noise eliminates engine noise, Exaust is an excellant place to start. My long-reach stethescope is a 4' piece of garden hose held to my ear. As far as the clutch question goes, I'm just eliminating non engine possibilities for the noise.

Mark in Portland