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· Registered
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Discussion Starter · #1 ·
i suppose i should begin by bracing myself for bad news...but just maybe,
i have read all kinds of engine noise threads...my issue seems a bit different.
looks like i should check compression on the cylinder to add some more info,
but i don't have a helper around.
this is a new to me 305 but has lots of miles...it had a slight "click" at times mainly noticeable at idol when i got it, but i figured it was a bit of valve noise and it lacked a bit of power i thought timing or fouled plugs.
when i started going thru the electrical on the motor it seemed like the plugs were all decent and the cap and rotor a bit worn but not that bad to me.
i changed the oil while i was at it...
and just put new plugs in to begin with.
~turn the key~
"HOLY CRAP"
sounds like it is gonna break into pieces...
i checked everything i could think of.
currently
the #4 plug wire is disconnected.
it seems to be arcing just fine...the old screwdriver trick.
and the engine returns to the state of a slight knock and lacking power.
ok, i know something is wrong for sure now.
any help would be great...it is the weekend so i have some time, just worried that there is a serious problem.
oh...by the way, i tried removing the valve cover and..."man that sucked"
the rocker arms, springs, push rods all seemed fine although i didn't really tear it down enough to really be sure i suppose.
it is friday evening and i just put it all back together for now hoping for some advice.
with that plug wire off...it is good enough to call it a week.
have a great weekend even if you have to give me bad news...
 

· VINTAGE MOTORHEAD
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4,105 Posts
Pull the plugs out and get someone to help do a compression check. Pull the rocker covers off and check for rockers that are loose or that aren't moving like the others. Check all the wires to make sure they are all firing. All this is easy while the olugs are out. If everything checks out and all cylinders are nearly identical for cranking compression button it up. Double check your firing order is correct. Look jnside the dizzy cap for burn marks, damage or spark tracking. Look at the carbon contact at the top center of the cap to see if is wiped out or has no spring underneath it. Always good to check the timing even if you didn't move it
If it will start and run check around the intake and carb base for vacuum leaks. Make sure all vacuum hoses are connected.
How nasty was the old oil? Did it have fine metallic particles in it?
Check to see if you have good fuel pressure and flow and make sure fuel filter isn't clogged (do all this only after you have hooked up all the spark plug wires so no chance of fire.
Remove the radiator cap and take a good whiff of the coolant to see if it smells like exhaust fumes.
These are tests that aren't too difficult and should reveal problems if the noises aren't coming from down low in the block. You might even make sure your exhaust manfold/header bolts are not loose.
I hope you can learn what the oroblems are by checking some of these checks. Good luck! James
 

· Deputy Director Region 8
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3,008 Posts
How did it run prior to changing the oil and plugs?? Did you compare the length of the new plugs to the old plugs?? If it is a different motor or heads could be a plug length issue,, On the #4 cylinder just to be clear,, after you removed the plug wire the sound quit?? and hooked it back up the noise came back?? If so a rod bearing,,, Let us know,, Matty man
 

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2,102 Posts
one more thing to look for is a bad piston or ring,pull the pcv valve from the valve cover and watch the blowby for puffing in time with the noise. also hook up a vacuum gauge and watch for a fluctuation in time with the noise. hand trace each wire to make sure its actually where it should be.its easy to cross one if they are in thier original clips and not notice it. with the valve cover off watch the rocker arms to see they are all moveing the same amount.what kind of oil presure is it running.anything less than 30 at a hot idle is a sign that something is worn to the point of failure.good luck
 

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Discussion Starter · #7 ·
wow...i am so happy i found all you guys.
now if i can just figure out my problem.
i will do as everyone suggested...a great big..."thanks"
for all the tips.
under the hood i go,
it is great having a support network.
 

· Registered
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Discussion Starter · #9 ·
i am located in sacramento...
you gonna save me from myself...?
i am afraid that you are all right that it is a rod knock.
"crap, now what?"
 

· Registered
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1,348 Posts
Let me be sure I've got this right.

It was running ok, until you changed the oil and plugs. After you changed the plugs, one cylinder is very noisy, but it quiets down if you pull the spark plug wire for that cylinder? The plug in that cylinder looked normal when you pulled it out?

Any chance you crossed a couple of plug wires? One isn't firing at all, and one is firing just a little too early? Or you have two plug wires next to each other and they're cross firing?
 
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