Thread: Flattened lobe or?.

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OK so I have been working on this k5 for a bit now and after finally getting most of the problems out of the engine she ran good for a bit, then took her on a 30 mile trip, all freeway which did really good needless to say, well the next day I started her up and noticed a tick coming from the left side, so I checked the oil and it was a little low, added a bit thinking that maybe it ram dry but that didn't fix it, so I pulled the valve cover off and poured a little oil on the lifters to see if that would work and no change, I ended up locating the ticking lifter it's the third one and noticed it was a little loose so I tightened it slowly and the ticking stopped, well the next day I drove it to work and and on my way home I noticed the tick, I could hear it over the engine and it got faster as I accelerated so I get home and pull the cover off and notice that it's lose again so I do that same thing and tighten it slowly til it stopped, well I shut it off to put the cover back on an when I start it up, it started ticking again so I gave up for the night, and started doing research and it does seem like maybe the lobe on the cam might be flattened? But also could be the stud backing out or the nut backing off? When I watched the lifters they seemed to operate normally and didn't seem to look as though it's flattened? I'm not sure where to start and would like some more opinions on the matter, I have never really messed with the valve train and on know what I have read and Been told

with the valve cover off start it and see if the lifter /pushrod spin as engine is running------if not, probably flat lobe-------look at all the others also-most will be spinning the pushrods

If you're running a big cam, my bet is the stud is pulling out.

Glad you said that because I did some research on the spinning push rod to see if that was normal and yes they do but some faster then others but they all spin and will double check tomorrow, and it's a stock cam, and should have mentioned above that the engine doesn't miss or backfire, runs smoothly other then the tick

I wouldn't think you'd have the "tick" come back that quick from a lobe eroding. For peace of mind pull the dipstick and look at the oil on the stick in bright sunlight to see if you see micro particles of metal. Even better, invest in an oil filter and a quart of oil, pull the filter and cut the casing off of it to examine the filter for metal.

Yes I kinda thought do too unless it's eroding at a fast rate? And i will check the oil this evening, also if it was a bad cam wouldn't it miss and backfire?

Sounds like maybe the stud is pulling out or the nut is backing off. If you have pressed studs, they can be pinned or better yet a screw in stud.

Originally Posted by J0386

Yes I kinda thought do too unless it's eroding at a fast rate? And i will check the oil this evening, also if it was a bad cam wouldn't it miss and backfire?

Not necessarily though it could have a noticeable reduction in power. IMHO, you have a bad nut on that rocker or as has been suggested a stud pulling out. Try taking the nut from the offending rocker off and using a good chisel stake the top of the nut in 4 places starting at 12:00 and again every 90º. If that keeps it tight I'd invest in a new set of nuts.

My money would be on a bad nut. If it were a stud pulling out, it would probably be because someone installed killer valve springs and if that's the case, it won't be long before you DO roach a cam lobe or three. Stand a yardstick on edge and lay it across the tops of the studs to see if there is one pulling out.

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Originally Posted by NTFDAY

Not necessarily though it could have a noticeable reduction in power. IMHO, you have a bad nut on that rocker or as has been suggested a stud pulling out. Try taking the nut from the offending rocker off and using a good chisel stake the top of the nut in 4 places starting at 12:00 and again every 90º. If that keeps it tight I'd invest in a new set of nuts.

OK tried that and took her on a 30 mile freeway trip and no tick! So I'm guessing I need to invest in some new stud bolts! But now she's running like a champ! For now
.. Thanks for all the advice!

Originally Posted by J0386

OK tried that and took her on a 30 mile freeway trip and no tick! So I'm guessing I need to invest in some new stud bolts! But now she's running like a champ! For now
.. Thanks for all the advice!

You're welcome, glad it worked out for you and yes I'd invest in a new set of nuts, if one was bad the others are probably not far behind.

http://www.oreillyauto.com/site/c/de...ocker+arm+nuts