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Rocker Noise? or Not?

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M

MikeH

Jedi Hopeful
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Hi All, I have a noise that sounds like a loose rocker. I've been through the valve train adjustments a number of times and can't get rid of it. I appreciate that I need some valve train noise, but this noise is excessive. Is there anything else which might sound like a loose rocker? This engine threw the second cylinder exhaust pushrod, so I'm a little paranoid. Thanks, Mike

71 MGB OD & Wires
63 TR4 Surrey Top
 
I have been fighting a noise in that area for weeks. It sounded sort of like a rubbing. Turned out to be a loose intake manifold.

Larry
 
Is there oil getting up to the rockers? That could cause louder tappet noise. Also could try setting the clearances with a wire gauge rather than a flat feeler gauge.
 
Throwing a push rod could be caused by an overrev , weak valve spring or valve stem sticking in the guide. The 1971 18GK engine is the last with heavy pedestal tappets and will float the valves at about 6400 rpm. Next time you have the rocker cover off compare valve lift one to the other. A worn camshaft typically makes more noise. Also if the valve clearances do not stay where you set them is reason for concern. Might as well check the assembled height of the stems while you are looking.

Alan T
 
I agree with Doc. If the surface of the rocker is worn, a flat feeler gauge will bridge the high spots, and give an incorrect reading. On a well worn rocker, there will actually be a groove worn into the tip, and the flat gauge will only touch the unworn portion of the rocker. For instance, if there is a .020" deep groove, and you set the clearance to .015" with a flat gauge, the actual clearance will be .035".
Jeff
 
Thanks for the replys, when I had the head off, I replaced the rocker shaft, checked rocker bushings for wear, and checked the rocker surfaces for wear. For some reason my cars Vin number makes it a 71 , but it has a 18GH engine. The Bentley Manual doesn't seem to have any general data for the 18GH. Haven't overreved at all. Car has about 55,000 original miles, and I believe the original engine. I bought the car from the original owner's family. I checked the camshaft as best I could with it still in the engine. I'm going to try again this morning. My main concern is that my rockers are adjusted so that I have less chance of throwing another pushrod. I can live with the noise as long as it isn't indicating a problem. I'll keep you all informed. Thanks Mike

71 MGB OD & Wires
63 TR4 Surrey Top
 
Hi Ben! /ubbthreads/images/graemlins/thumbsup.gif
[ QUOTE ]
I can live with the noise as long as it isn't indicating a problem.

[/ QUOTE ]

The easiest way for you to find the "offender" is a follows:

Get your longest flat blade screwdriver. With motor warm and idling place tip on top of head next to V/C at #1 valve location (front). If you are right handed, hold driver handle with butt of palm down towards motor. Cup you right hand and place palm on the end of driver. Put you ear on the back of your hand. You will "hear" the valve "noise".
Repeat on the other seven. All "should" be VERY close to the same "noise". If one is not...= offender! /ubbthreads/images/graemlins/grin.gif

/ubbthreads/images/graemlins/cheers.gif
Ed
 
Ed, I've got an old pool cue that works wonderfully for just this type of excercise. I'm a lot better with it using it to diagnose engine noises than I ever was at the pool table.
Jeff
 
See, once again, these LBCs lead us towards useful endeavors and away from the "parlors of sin". /ubbthreads/images/graemlins/jester.gif

[ Reference :

"Oh, we got trouble,
Right here in River City,
With a capital 'T' and that rhymes with 'P' and that stands for 'pool'!]
 
You could also pull the valve cover, fire up the engine, let it idle and insert a five thou feeler blade under each rocker. When you hit the one that stops the big noise you are half way home to the fix. Jack
 
Just be prepared to replace that 0.005" feeler blade after the test... it tends to look a bit "peekid" after this duty. Kinda "worked". /ubbthreads/images/graemlins/wink.gif
 
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