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You may remember I posted this a while ago

http://www.youtube.com/watch?v=RLIav2AbM4k

knocking sound from my cobra. I pulled the kmember and oil pan tonight. I gotta say there's nothing obviously broken in there. How do I find what was making that ticking noise? Any tips or insight?

Thanks
Malcolm

you may have a cap with a blueish tint. also see if you can look up at the piston skirts/ underside and check them. look at the cylinder walls for any scuffs or scoring.

When cylinder number 3s piston was all the way down the outside of the piston skirt had a shiny silver and a darker grey. I ran my finger over it and I could feel the difference. Not a huge amount but I could feel it.

Other pistons skirts (on the outside when they are BDC) are all different. Some are shiny some are grey, all others appear smooth to the touch.
I can't see any scoring in the cylinders yet.

None of the rod caps have a blue color that I've noticed yet but the crank itself appears to have some blue color in a few places, real faint but I'm sure it's discolored.

I'll keep looking. The front of the crank by the pulleys does not have a bolt to put a socket on and turn the crank slowly so I have to tap the starter quick and it makes it hard to get the crank where I want it to look around.

Thanks
Malcolm

there should be a bolt head in the center of the aux crank pulley. i may be wrong its been a while since i worked on one.

Looks like it's hollow with a hex shape. I may have to find a huge allen wrench to fit in there and turn it.

My way of finding bad rod bearings...
Take each rod and wiggle it. when you get one that is loose you can feel the clearance between the rod and the crank as it flops around. When you get to the bad one, you will know it.

broncobowsher wrote:My way of finding bad rod bearings...
Take each rod and wiggle it. when you get one that is loose you can feel the clearance between the rod and the crank as it flops around. When you get to the bad one, you will know it.

I tried that several times last night and none of them moved any different than the others. Maybe it's not a rod bearing.

I have no clue if it'll help, but you might find a bolt head to fit in that HEX space. If you are lucky, you can use nuts on the threads to turn the bolt...something to think about if you find the need.

I pulled 4 rod caps, one out of each pair on the crank and they all look fine. Actually they look brand new, can't believe they have 25k miles on them. None of the 8 have spun out of place. When you pull one cap you can see the one next to it and it looked fine too. So much for an easy fix. Could it be a main bearing on the crank that's spun?

cgrey8 wrote:I have no clue if it'll help, but you might find a bolt head to fit in that HEX space. If you are lucky, you can use nuts on the threads to turn the bolt...something to think about if you find the need.

Excellent idea actually. I did that on my R6 (bike) when I needed to remove the front wheel. Forgot all about that trick
I ended up using a screw driver and activating the starter motor little at a time. Actually worked better than I expected.

Wonder if its in the tranny since it doesnt appear to be a rod?

Yeah I'm confused now.

How are the timing chain guides?
I know you already have the pan off, but did you try running the engine without the accessory drive belt? I have seen engine problems that were really accessory drive problems.
If not the bottom of the rod, how about the top? Any sloppy wristpins?

I can rule out transmission by holding the clutch down and putting it in gear. At that point everything inside the transmission is at a stop.
Clutch varys depending on pedal and in gear or not, should be able to rule that out.

Just so ya know its my understanding that when you have a spun bearing your oil pressure would have done some eratic movement...spinn a bearing =higher oil pressure because it blocked the oil port no oil on it makes it knock. often a spun bearing will spin more than once causeing the knock to come and go....just my 2 cents...

something to think about, a possible supercharger bearing failure? they have been known to resonate the noise down so it sounds like it is the motor making the noise.