Sounds a bit weird but I just want to make sure I'm not overlooking something here.
When I got the Me-Ottter it was suffering a little from lifter tick at startup, but changing the oil to Rotella T6 cured that mostly. Recently, the oil change interval marker, sorry, noisy lifter is putting in an appearance again but it still stops within about 30 seconds. This is not the noise I'm talking about.
The noise is best described as having the engine sound somewhat like the old Alfa twin cam, especially one with slightly generous valve clearances. There's a noticeable mechanical clatter coming from the intake cam, and only the intake cam - the exhaust one is quiet. The clatter changes with the engine revs - ie, it clatters faster at higher revs and it's noisy enough to be pretty audible in the cabin.
And no, according to my improvised mechanics stethoscope (aka the cardboard tube from a roll of paper towels) it's not noise from the injectors either. Definitely coming from the cam area of the head.
To make matters more interesting/annoying, I'm pretty sure it got worse after the PDX a few weeks ago.
So, I guess it's time to pull the valve cover and have a good look around. Anything I should be looking for apart from lifters that seem to have larger than normal clearances and possibly marks on the intake cam?
In reply to Javelin:
Yeah, I remembered your thread as I was writing this and I was afraid it would be a similar issue...
I bet you 4 mini Reese's cups it's the exact same issue. Pull of your valve cover and prepare to weep.
Supposedly the kid I sold mine to actually did the Miata.net rebuild to all 16 lifters though. Took him like an entire 3 day weekend, but saved oodles of money, so it's not like they're that bad.
Lifters are easy to change and you can get them pretty cheap now.
My problem is that I am suffering from a bad case of "while I'm in there-itis"...
I guess I'll take a look and figure out what to do. The annoying part is that we're starting to house hunt so the spare time is rather limited at the moment. Oh well.
So I pulled the cam cover and the good news is that the lifters appear to be OK - well, mostly. In fact, they look suspicously new.
What doesn't look suspiciously new however are the cams:
In the corners of the lobes (see first pic) it looks like the hardening has worn through and the "fingernail" check suggests that both the metal changes (the "worn" areas are much rougher). There is also a lot of discolouration that doesn't show well in the pictures. The matte brown areas on the lobes in the second picture that look like oil residue are actually discolouration or embedded/baked on as the photos were taken after I cleaned the cam lobes with the appropriate cleaners. I'm also a tad concerned about the wear marks int he middle of the lobes (see arrows in the second photo).
The engine is supposedly the original engine and if it is has about 129k on it.
What say the font of all knowledge Miata?
Looks to my untrained eye that your motor suffered the same collapsed lifters mine did and they drove it until the cams started to wear badly, then replaced just the lifters.
I'd call Keith and get a couple of good, used cams ASAP.
That makes four untrained eyes looking at this then 
. This is pretty much what I suspected, too, probably with a couple of missed oil changes and/or cheap oil thrown in.
One potential issue that concerns me is that the metal that's worn off has been making a tour of the engine until the oil filter hopefully filtered it out. $DEITY knows what other damage that did. I guess I will find out if/when I pull the cams because I'd expect any damage to show up on the cam bearings.
Would it make sense to throw in new lifters with the new/used cams?
I need to get an idea of the cost of the part before I pull the trigger on this and I would prefer not to find out that throwing in a low-mileage VVT engine with VVTuner would work out not much more expensive and give me a newer engine in hopefully better condition...
Chas_H
New Reader
5/21/12 10:55 a.m.
Looks normal to me. The lobes are slightly tapered to encourage the tappet to spin, hence the wear pattern you see. Push on the tappets with a dowel. Do they collapse easily? If so, they need an oil change or replacement. If not, look elsewhere for the noise.
Do a compression test first.
BoxheadTim wrote:
One potential issue that concerns me is that the metal that's worn off has been making a tour of the engine until the oil filter hopefully filtered it out. $DEITY knows what other damage that did. I guess I will find out if/when I pull the cams because I'd expect any damage to show up on the cam bearings.
I am very much not an expert, but I think the tiny bits that would be generated by wear like this would be small enough to pass through unnoticed. But take that for what my guess is worth - nothin'...
Chas_H wrote:
Looks normal to me. The lobes are slightly tapered to encourage the tappet to spin, hence the wear pattern you see. Push on the tappets with a dowel. Do they collapse easily? If so, they need an oil change or replacement. If not, look elsewhere for the noise.
I assume you were referring to the HLAs when you suggested to push on the tappets?
They don't collapse easily - in fact, there was no movement at all. Now, I'm not exactly strong or very heavy, but even leaning on the dowel with part of my body weight elicited no movement whatsoever. Obviously they do move when the cam lobe hits them but to me it felt almost like I was pushing against something solid.
Spent more time on this on the weekend . Rechecked all the lifters (I actually used a 0.010" feeler gauge as opposed to the 0.015" that Keith recommends in his book), but there is no appreciable gap between the cam lobes and the lifters. No untoward noises from the valvetrain when you turn the engine over by had, nor are there any "reluctant" HLAs. For the hell of it I also checked the cam timing and that appears to be spot on, too.
Whoever said the noise is probably coming from somewhere else has a point. For now I just ordered some Mobil1 for track/summer use (15W50 as their 0W50 isn't recommended for street use) and I'll see if fresh oil with a good oil filter makes a difference.
Lucifer
New Reader
6/4/19 6:16 a.m.
I recommend you to do a quick check of the valve train which will tell you if there’s something physically wrong with one of the parts. If not, then it’s likely that a flushing agent and an oil additive added to the fresh oil will do the trick and silence your lifters.
Then going for the oil with the density prescribed by your manufacturer will be your best go. Again I recommend changing the oil density to other than what the manufacturer recommends can make the oil too thin or too thin. Neither of them is good for your engine.
Thought sharing this resource would be helpful: {Demonic Canoe Removed}
a canoe raising the a 7 year old thread up? Good work on the find, you crappy canoe.
Devilish canoeist with hydraulic oar locks?
I'll admit that I read the first few posts fully convinced that Tim had made another unfortunate purchasing decision.
In reply to Woody :
Well he does have another Miata, but this one seems like a good one/keeper.
Woody said:
I'll admit that I read the first few posts fully convinced that Tim had made another unfortunate purchasing decision.
I admit I had to check the date on the original post. Fortunately the current NA does only rattle its lifters for a couple of seconds at startup.
Pete Gossett said:
In reply to Woody :
Well he does have another Miata, but this one seems like a good one/keeper.
Err ... well... you know ...
It might need a little more work than expected 
.
