| [GMCnet] engine clicking... header leak... [message #142106] |
Fri, 02 September 2011 12:29  |
Ek_Lektro
Messages: 167
Registered: March 2011
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Senior Member |
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Need a little advise please:
My '78 403 has had what i'm guessing is a valve clicking noise for the past year or so, coming from the top left of the engine.
Lately its become quite loud after starting up with a cold engine... and of course it dies down a bit after warming up,
but never fully goes away. i know this is pretty common, and probably a sign of eventual need for a valve job.
But recently i discovered a couple possible reasons why its been so much louder lately:
A friend helped me with some work last summer, part of which was changing the spark plugs (but we didn't get to changing the wires at that time since the shop was out of stock...) So when i was finally changing wires last week, i found that one of the spark plugs was really loose, like 2 turns away from falling out. Not sure if it was that loose to begin with, or if i'd been driving it for a whole year like that, but i put in a new plug to be safe and tightened it up.
Was hoping that this might've been the cause for the clicking noise, 'cause at times the click has such a high pitch to it, it almost sounds electrical. But no... the click remained. So i took a hose and used it as a stethoscope to pinpoint the noise, and i found out that i have an air leak between the headers and the manifold. Interestingly the leak is immediately below the particular spark plug that was so incredibly loose. Is this just a coincidence? or did something go out of whack by driving for a year with a loose plug? Anyway, i tried to tighten up the 2 bolts at that part of the header, but apparently not tight enough, 'cause i still have the air leak, and the clicking noise is only slightly dampened. I guess the next step is to try to loosen all of the header bolts, and try to tighten them up in sequence, to see if i can get rid of the leak completely, and hopefully the clicking noise will not be as severe. i don't recall there being any kind of header gasket to
replace, so beyond getting some special heavy-duty 7/16" wrench into those tight spaces, are there are any tricks to solving header leaks?
Thanks in advance for any advice!
Greg
'78 eleganza II
PS: a little history on the coach:
new Thorley headers installed in '98... Re-installed with a rebuilt engine in '02
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