1977 datsun 280z Rocker Arm not on Lash Pad - Nissan Forum
240Z, 260Z, 280Z, 280ZX(T) 1970-1983 Zs - Engine and Chassis Discussion

 
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#1 Old Nov 4th, 2012, 05:04 PM
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1977 datsun 280z Rocker Arm not on Lash Pad

Hi I just bought a 1977 datsun 280z. I got it for $600.
The car starts but runs very rough.

When I opened the engine cover I noticed that two of the Rocker arms were tipped off of their lash pads and aren't compressing their springs.

It's two different cylinders, with one of the rocker arms tipped off...

Now, I am thinking If i slightly lift up the crank shaft it will give me enough space to put the rocker arms back on the springs however; I was wondering what could be the cause of the Rocker arms tripping off of the lash pads.

I suppose I am going to try to put the Rocker Arms back on, close up the engine, and try to run the car and see if the Rocker Arms knock loose again.

Just as a head start, does anyone know what would cause for this to happen?
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#2 Old Nov 4th, 2012, 06:52 PM
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It's been a long time since I had to work on an L28, but, IIRC, there is a spring that runs up from the rocker stud and across the top of the rocker arm to apply tension and keep the rocker arm down on the stud. Are these springs in place? Is there any wear on the tip of the rocker arm where it engages the top of the valve stem? Are the valves badly out of adjustment?
#3 Old Nov 5th, 2012, 02:55 AM
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Quote:
Originally Posted by smj999smj View Post
It's been a long time since I had to work on an L28, but, IIRC, there is a spring that runs up from the rocker stud and across the top of the rocker arm to apply tension and keep the rocker arm down on the stud. Are these springs in place? Is there any wear on the tip of the rocker arm where it engages the top of the valve stem? Are the valves badly out of adjustment?
Hi, thanks for responding...

The springs are in place, and there is not any wear on the tip of the rocker arms. I have not taken the engine apart enough yet to get a look on the valve stems...

What are your suggestions?

A Mechanic told me to put the rocker arms back on, turn the car on and keep it idle to see if the rocker arms will slip off again or not...

He also told me that it could be a sign of the valves being bent;

I'm going to put the rocker arms back into place, and see if they tip off again.

Mind you , I just got this car and I'm barely looking in the engine as first time. I'm a total

I suppose I'll try tomorrow to put the rocker arms back on, and if they tip off I'll come back here for support!

I appreciate your response once again!
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#4 Old Nov 5th, 2012, 12:50 PM
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Hey I've looked into it and it seems i need a valve lifter, the manual tells me it is st12070000 . I thought to myself it could be as easy as typing that in google. but I still havent found a website to buy it from... Any help?
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#5 Old Nov 5th, 2012, 03:05 PM
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"st12070000" is not a lifter; it is the special tool number for a valve spring compressor. In order to use it, you would have to remove the head. It looks sorta like a big C-clamp with a lever. As far as your engine, you have mechanical valves and no lifter. The one end of the rocker arm sits on top of the valve assy. and the other rests on top of an adjustable stud that has a locknut to secure it in place. To adjust the valves, the locknut is loosened and the stud is raised or lowered to adjust the clearance between the cam and the rocker arm. I put a link to a parts diagram at the bottom for better clarification. It's for a 79 280ZX, but it should be the same as your 280Z. The stud I'm refering to is listed as part code "13234." Your rocker arm is "13257M" and the spring I refered to is "13256M." One part you may want to look at is "13218" listed as "Guide-rocker valve." This should be the part that keeps your rocker arm connected to the top of the valve stem. It's Nissan part number would be 13210-Y7000.

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#6 Old Nov 5th, 2012, 06:46 PM
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I think the item you are referring for me to look into is a Lash Pad as its stated in my service manual.. Which seems to be perfectly intact.

The guy that sold me the car told me it over heated once and he had to repair a gasket.
He told me the mechanic that worked on it for him kind of brushed him off when he took it back to say it's running rough.

I called the mechanic personally and he told me "it has bent valves because the guy ran 10 year old gas through the engine"

Mind you this is the only mechanic that has ever worked on this car, the old owner told me his mother threw 1500 to get the gasket repair and it hasn't driven right ever since.

The old owner also claimed when he took it to the mechanic before when it was running rough, he would put his stethescope over the injectors and with just a little tap he would make it "purr like a kitten"

Now, I do believe in the story of the old owner, although I feel like the mechanic might've done a messed up job. And he specializes in these cars as well....

Is it possible to get bent valves from running super old gas through the engine?
I'm being told it's impossible by my peers.

I'm going to adjust the rocker arms using the lock screw you mentioned which by the way I am very grateful for your responses. Once they are on i'll start the car after assembling the engine and see if they get tipped off or not.

The day of selling it we were able to start the car and drive around the block a couple of times, it just didn't look like the car could make it past 40mph.

It's my first time getting deep into mechanics, and hopefully this is gonna be a successful first project. I'm also considering running a blog as i progress which would be great for a total newbie to follow up with.

Thank you smj999smj

Last edited by superwoofer99; Nov 5th, 2012 at 06:47 PM. Reason: to put smj999smj's name in
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