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 Post subject: Noisy valves? NO!
PostPosted: Tue Jul 12, 2022 2:47 pm 
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Joined: Mon Jun 30, 2008 2:16 pm
Posts: 1180
Location: Ansonia, CT
While driving back from the fun car show in Kent on Sunday, June 26th, I started to hear a noise like noisy valve tappets coming from the old L24, (now with just under 200K miles), especially when the engine is running at 2500 RPM or higher. Since I adjusted the valves not that long ago, I was surprised to hear the noise from what I thought was coming from under the valve cover. So after getting the car home without incident, I removed the cover and proceeded to adjust the valves as I normally do, wishing I had three hands to do this delicate procedure; one hand for the lock nut, one hand for the adjusting nut and one hand to slide the feeler gauge. Somehow, I seem to manage to get this job done with just two hands. :roll:

After buttoning up the valve cover and wiring, I started car and took it for a short test ride, only to find out that the noise was still there. BUMMER! So, I did the same procedure again, this time carefully checking to make sure all 12 of the valve stem "caps" that are between the valve stem and rocker arm were in place and all 12 of the tension springs were in their proper locations. All were in place and looked good :thumbs_up: . Finally, I looked down into the front end of the engine checking to see if the timing chain was very loose or if anything was down there that didn't belong. Everything looked OK but I did notice that the arm of the mechanical fuel pump seemed a bit loose. I was able to move it front to back more than I thought it should move :?. Sure enough, after starting the engine up again, the noise was still there :thumbs_down: .

So now, I figured it might be the mechanical fuel pump, which, if you remember, I have had many problems with before. This Airtek model pump has the single piece stamped top on it that I found worked a lot better than the "original style" screwed top pumps that I tried previously (see my old posts on this). However, after removing the pump, the arm and spring basically fell out of the of the engine in individual pieces! :shock: After a more detailed inspection, I realized the pivot pin which holds the arm into the pump casting was not securely fastened to casting. It should have had the casting peened over the shaft to properly secure it. This, I suspected, was the cause of the noise that I was hearing.

After replacing the pump with another which seemed to have a pivot pin better secured than the other pump, I finally got the car started and running again. Yippee! My main concern now is it appears that the quality of these aftermarket parts are really bad or questionable at best.

Drive on!

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John Kish
1971 240Z - original owner


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 Post subject: Re: Noisy valves? NO!
PostPosted: Tue Jul 12, 2022 7:04 pm 
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Joined: Fri Dec 25, 2015 7:39 pm
Posts: 697
Location: Long Island, N.Y.
John you forgot to say " The tappet like noise is no longer emanating from the engine. Mission accomplished." Can be presumed? :thumbs_up:

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1985 300ZX- GLL Dark Pewter Metallic - Survivor


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 Post subject: Re: Noisy valves? NO!
PostPosted: Wed Jul 13, 2022 8:26 am 
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Joined: Mon Jun 30, 2008 2:16 pm
Posts: 1180
Location: Ansonia, CT
Oh, Yes!!! Noise Gone!!! :thumbs_up: :thumbs_up: :thumbs_up:

Thanks Howie :oops:

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John Kish
1971 240Z - original owner


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 Post subject: Re: Noisy valves? NO!
PostPosted: Thu Jul 14, 2022 7:11 am 
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Joined: Wed Jul 23, 2008 2:38 pm
Posts: 3411
Location: rhode island
For future reference.....you adjust one set of valves when hot, then let it cool down, like next day imo, and check the same valves cold. This is your engine shrinkage rate, all can be different, then adjust cold.


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 Post subject: Re: Noisy valves? NO!
PostPosted: Thu Jul 14, 2022 10:25 am 
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Joined: Mon Jun 30, 2008 2:16 pm
Posts: 1180
Location: Ansonia, CT
Interesting procedure Paul.

I've actually had pretty good results when adjusting both the exhaust valves at .010" and intake valves at .007" COLD. Early on in my car's life there were articles recommending they be adjusted hot. Later on it was changed to cold. Heck, it was less painful a process adjusting them cold anyway so I stuck with it. Besides, the whole valve adjusting process takes a bit of time to complete, especially for me :roll:, which can cool the engine somewhat during the process causing the settings to change from start to finish.

Curious, are you running an electric pump or still mechanical? If the latter, do you recall what brand and if the pump has a one piece stamped metal top or cast screwed top like the original pump?

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John Kish
1971 240Z - original owner


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 Post subject: Re: Noisy valves? NO!
PostPosted: Thu Jul 28, 2022 6:53 am 
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Joined: Wed Jul 23, 2008 2:38 pm
Posts: 3411
Location: rhode island
By the time you get to #6 it will be cold. :shock: I think I'm still running my pump from 1972, that 50 years. Would you like me to bring an original?


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 Post subject: Re: Noisy valves? NO!
PostPosted: Thu Jul 28, 2022 9:09 am 
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Joined: Mon Jun 30, 2008 2:16 pm
Posts: 1180
Location: Ansonia, CT
Paul,

Sure, bring it to Middletown. :thumbs_up:

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John Kish
1971 240Z - original owner


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 Post subject: Re: Noisy valves? NO!
PostPosted: Sat Jul 30, 2022 11:01 pm 
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Joined: Wed Apr 09, 2008 5:53 pm
Posts: 14778
Location: CT
Bring two.
8)

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1970 240Z


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 Post subject: Re: Noisy valves? NO!
PostPosted: Sun Jul 31, 2022 7:19 am 
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Joined: Wed Jul 23, 2008 2:38 pm
Posts: 3411
Location: rhode island
:shock: :thumbs_up:


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 Post subject: Re: Noisy valves? NO!
PostPosted: Thu Nov 17, 2022 1:44 pm 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 678
Hey guys,

Catching up on some older threads here. John, good catch on that fuel pump arm, I've never had one come out in pieces before, that's concerning.....imagine the damage that could do if it fell into the timing case with the engine spinning. Good troubleshooting though, and what the heck..... Now your valves are freshly adjusted (again).

Thought I'd share something with you. After I had my L26 rebuilt I replaced my o.e. fuel pump with an airtex unit(one piece stamped top). I replaced that pump shortly after breaking in the engine because it couldn't supply enough fuel under load. 4500 rpms was all my Z could manage with that pump. I put in the old one because I'd kept it and all was good again. I only replaced the pump because it had sat for 10 years with gas in it, and in my experience old fuel pumps generally quit shortly after you start using them again after an engine has sat for a long spell.

When I was talking with Vinny during the fall outing in 2016 at Ross's place I told him about the experience I'd had with the fuel pumps, and asked for a recommendation on a replacement unit should I need one since the o.e. units are NLA. He told me he had a supplier of high quality, o.e.style aftermarket ones that work very well.

That info may be useful to someone here at some point.

Jay


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 Post subject: Re: Noisy valves? NO!
PostPosted: Thu Nov 17, 2022 7:36 pm 
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Joined: Mon Jun 30, 2008 2:16 pm
Posts: 1180
Location: Ansonia, CT
Thanks Jay!

I will follow up with Vinny on this. Any snow yet? It's starting to feel like it here in CT.

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John Kish
1971 240Z - original owner


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 Post subject: Re: Noisy valves? NO!
PostPosted: Fri Nov 18, 2022 6:42 am 
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Joined: Fri Dec 23, 2016 7:11 am
Posts: 678
You're welcome John!

Yeah, we got a couple small snowfalls this week. The yard is covered currently actually, quite a few car accidents yesterday morning too due to slick roads. Winter has officially begun.

Jay


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