What did I break? <Flame suit on>
 

Driving home from work yesterday, I began to hear lifter tick that suddenly progressed into lifter CLACK. Very loud lifter clack. Driveability remained in tact, so I nursed her home on the back roads very slowly.

Drained the oil, no metal in it but I wasn't expecting any because the noise seemed to be in the head.

Pulled the valve cover and saw no apparent damage, but found this;

https://www.miataturbo.net/attachmen...ine=1429276195

https://www.miataturbo.net/attachmen...ine=1429276195


I have no idea where that bolt came from. It doesn't match any other bolt in the head, and I haven't had the engine open for several months. I can find no apparent damage to the cams or lifters, but it sounds bad. Like a collapsed lifter.

Any ideas as to what is actually broken?

Looks like a timing cover bolt?

It's a bit too big for that, but either way I really fucked up by letting it get in there in the first place. I'm just trying to assess the damage and find where to start looking. I guess I should start by removing the cams and checking the lifters.

Anyone know what a broken valve spring sounds like?

Is that the coil pack bolt?

I bet it's been riding around in there for months. The clack could be cam or lifter surfaces being trashed.

A broken valve spring sounds like zero compression, the valve will drop and the car probably won't run so hot.

Ought to be able to see that pretty easily with the VC off. Look for a loose retainer.

It's hard to say without something there for scale, but it looks like it could be one of the coil pack bolts, one of the CAS cap bolts, waterpump, waterpump elbow, etc. One of the many 12mm bolts.

Do you remember working on the car at some point and not being able to find one of those bolts, so you just replaced it? Well, you found it.

The bolt looks almost completely intact. I'm actually curious if the massive clack started on it's own, and you just got darn lucky finding that bolt while you're in there. Especially with no obvious cam scoring.

At least it sounds like an actual diesel Miata now? :party:

What's the marking on the head of the bolt (if any)?

I love you.

I'm really hoping that the bolt didn't damage anything inside. I can't find any missing bolts on cam caps, or anywhere else for that matter. I've rotated the engine with the V/C off, and it turns pretty smoothly. All of the cam lobes look perfect, and so do the lifter surfaces. The springs seem to do what they are meant to do. Cant find any loose parts either, but this clacking was LOUD. Like, I thought it was a bent rod type of loud.

Can lifters fail internally and cause noise like that?

Edit: Sav, the bolt is a grade 6, M8 x 1.25 and approx 1.25" long.

Not that I've ever personally had to deal with foreign objects rattling around inside the cam box, but I would think that if that bolt had done any sort of damage to the top of a lifter, you'd see matching evidence on the cam lobes. Eg: I'd leave the cams in and just spin them through a full rotation so as to inspect them.

That said, the second picture in your first post makes it seem that a region of the threaded portion of that bolt got hammered pretty hard. Is that really as bad as it looks?

It's not quite as bad as it looks, no. The threads are impacted, but not severely. I've rotated the engine by hand quite a few times, looking for any sign of physical damage and can find none whatsoever.

Put the VC back on and start it up. If no more noise, consider yourself lucky.

You got some karma to payback, too.

I'm going to give it a shot. If it works, I'm off to buy a lotto ticket.

How many people can leave a random bolt in their engine for months, and not destroy allofit?

At least two.

No Miata content but still relevant:

I had a 95 Z28 that just came to a stop one day. Got it home and tore into it and had broken the cam gear which then caused bent valves and so had to pull head, replace timing components, yada yada yada....

I found a 1/2" NPT plug inside the timing gear cover. It must have somehow made its way into the valve cover, then down into the lifter valley, and finally forward into the oil return holes and into the timing gear cover area.

Where does a LT-1 Chevy engine have a 1/2" NPT plug? NOWHERE! Not under the valve cover, not in the lifter valley, and not in the timing gear area. Not even on the outside of the block. Nowhere!

How did it get in there? Sabotage is the only thing I can think of. I bought the car used so who knows its history or its previous owners enemies. Or someone who really disliked me at local autoxes threw it in there since I always kept the hood up so the engine would cool down and trusted no one would fuck with it. Who knows?

Hope you are luckier than I am.

Better question is how did this bolt make it into the engine? Wouldn't have happened through a plug hole. That made me think it was one of the bolts for the cam caps but it doesn't look like it. There's no bolts missing under the cover?

Somebody at work doesn't like you.

Curiouser and curioser cried Alice.

Something is very wrong here. Now that the oil isn't hot, it feels congealed. Almost like it's turning into jello. Does oil go bad? I'm using Rotella T6, and it was changed just before I put it up for the winter.

I found this on the exhaust cam.

https://www.miataturbo.net/attachmen...ine=1429546314

https://www.miataturbo.net/attachmen...ine=1429546314

https://www.miataturbo.net/attachmen...ine=1429546314

Thats never a good site to see :noes:, sorry!
Any idea where the shavings come from? have you pulled all the lifters?

All the lifters are out, and it looks like the two lifters right where the shavings were are pretty scored on the sides. Most of the lifters are "seized" up and the oil coming out of them feels really sludgy.

Also, you can see the "stripes" on the lifter face where the cam lobe was riding on it, those are the only lifters where it's visible.

I've heard (but never personally seen) about "jellied oil" situations coming from engines that were found to have one of two things.

Either a very small coolant leak somewhere. Small enough to not cause the classic milkshake situation.

Or certain high detergent fuels/fuel additives that get into certain oils. This one's interesting for your situation, because the version I heard is that it would run fine while warm, but once the oil cooled down after being exposed to the additives is when it would "jellify".

I can't remember what was special about the oil that reacted with the fuel additives other than it was certain synthetics, from what I recall. Sorry I don't have much more, but it's kinda unusual.