I think my miata is dying

So to hell with the failed inspection yesterday, I took the miata out to the airport autocross today. It lasted 6 laps. 

My 5, which got faster each time, I was told sounded louder and louder each time. I tossed the keys to my codriver for his laps, and crossing the finish line, heard an absolutely terrible racket. He said it felt way down on power, and stalled when he put it in neutral, then limped it to the parking area. 

Morning runs over, I got back to the parking lot to find out what happened. It fired up, so I limped it to the main road and called AAA. 

It starts and idles fine, but hitting the gas pedal there is definite hesitation, and an extremely loud racket over about 1200 rpms. Like a metal can of rocks in a paint shaker kind of racket. 

Could the 1000 mile old catalytic converter have just died and the chunks need to work themselves out? Or could it be rods or something in the bottom end?

I have someone coming over to listen to it later, and see what we can see, without pulling the motor, but I suspect the motor may have had enough. 

I DID check the oil, after the fact, and there IS oil in it, almost to the top of the marks, but VERY black considering it's only got 1000 miles on it, although it's also a year old. 

I know I mentioned in July it sounded louder and not running as well, and just chalked it up to a lack of use. Bombing around on back roads did seem to make it better, and aside from my obscenely loud lifters, I hadn't noticed anything else wrong or worrying. 

So what should I be looking at? What can I look for without pulling the motor? Anyone have a 1.6 or 1.8 they'd be willing to sell me cheap, possibly on a payment plan?

Highly doubt the bottom end let go if you're naturally aspirated and it had oil in it.

Your profile says it's a '93...short nose crank failure? 

My first step would be compression/leakdown test. Then verify timing

shouldn't be. I guess it could be the crank, but by mid 91 they had the short nose crank situation fixed to the best of my knowledge. 

From what I can see with it jacked up, I've not put it on stands yet, the exhaust is still good. And it damn well better be, it was put on in April 2015 a couple months before I bought the car, with a hollow cat i replaced last inspection because the PO was an idiot. 

I'm going to order in a gasket set and start pulling it apart I think. To my untrained ear, it sounds like it's coming mostly from the bottom back of the motor. The hesitation and stumble doesn't feel like an exhaust hole, but that doesn't mean the cat isn't fried already. It's a stumble similar to when my plugs used to pop off the coils on my 91, but all that stuff is tight. Plugs, wires, VC gasket are all new within 2k miles, but I did notice (and chalked it up to an HF torque wrench)) that the VC bolts all spin free, which has been disconcerting for a while. 

When Matt gets here tonight, I'll attempt to make of a video of the noise. For now, it can sit in the car port out of the rain. I pulled the CL ad for the Vic, so it can sit as long as it has to until the problem is resolved. 

https://www.youtube.com/embed/d5i06C9heNo

So here is a cold start. Sorry it's not longer, but I don't really want to run it. 

If anyone remembers, I've asked several times and made threads about the oil pressure. In 93 its a real guage, signs point to the sensor itself being bad. Rockauto lists the sensor at $180, so I deal with the anxiety of a barely ever registering oil pressure gauge. 

I confirmed again there is still oil in the sytem. I cannot confirm how much though. Nothing on the dipstick when it's cold, but there was a happy flow when I opened the drain on the pan a little bit. 

It's up on jack stands. No signs of exhaust or block breakages, no signs of massive fluid loss. The front of my oil pan is a little wet, but nothing crazy. For as little as I drive, I would have noticed a puddle if it was leaking anything even on the gravel. 

My friend the professional didn't come by, but another shadetree mechanic did. He suspects a valve, from the noise. Valves are pricey and there are 16 of them. I think a wrecked donor would be cheaper. 

So any thoughts from the hive on the noise in the video?

collapsed lifter?

Sounds like the top end to me. Can't hurt to try this:

Mechanical oil pressure gauge kit from AA, AZ etc for < $20

Top off the oil, get a known working gauge on it and see what it's got for pressure.  That'll tell you if it's noisy because you've got low pressure and the lifters are bleeding down or if something else is going on. 

I had a hydraulic lifter in my old Hyundai get stuck after the car sat for a few weeks (I was away on business) and it sounded a LOT like that

A gauge like this one? Bosch mechanical oil pressure 

Dumb question, but how/where would I install it at? I don't care, the face can even stay under the hood, I'm just not sure where I'd tap the system. 

I'll pick up a filter tomorrow and do a change with 10w30, and get a gauge put in to see what pressures are like and to ensure everything is full and see what if any difference it makes. 

In reply to RevRico :

That should be ample, even though cheap. Replace it at the factory oil sending unit. You may need an adapter to the blocks metric thread if the gauge kit doesn't have one. Standard gauge kits are usually 1/8" NPT fittings.

Pull the sending unit out, screw the mech gauge into the hole.

Do those engines run a timing chain or timing belt? Could be a broken guide letting the chain slop around.

I'll agree that it sounds like lifter noise.  Not a bottom end knock IMO. 

In reply to Trans_Maro :  Timing belt. 

When testing my 94 I pulled the stock oil pressure sensor and installed the HF one.  As long as you have the correct threading (1/8" BSPT) it should work.  It is a real pain to get into the stock location because of the oil filter and other things in there but with a crows foot and pulling the filter I managed to install it.

Google says 90-94 Oil pressure sensor location:

My 92 sounded like that but not as bad after it sat for way too long. My guess is stuck lifter too. I just seafoamed it instead of pulling the lifters and cleaning them.

While waiting for pepboys to call and tell me my filter and gauge are ready, I decided to drain the oil and let it drop since it's cold.

I'm a berkeleying idiot who doesn't deserve a car.

I got about a quart of the blackest most foul smelling oil I've ever seen. The filter was dry. 

According to the sticker, oil was changed 6/10/16 at 129,003. Today, 9/17/17 it has 130,827 miles. 1800 miles felt safe as the car had no history of losing oil between changes. 

I've been yelling at my mother for years for doing this same thing. Is that a long enough of a timeline to lose almost 3 quarts without leaving stains?

I'm still waiting on the call my stuff is ready (sorry it's much cheaper making them find it then finding it myself) but feel free to berate me for not keeping a close eye on things and being the cause of damage. 

https://www.youtube.com/embed/ilRAx0PgpAMit's making better noises now and the gauge is showing signs of life.

Still something stuck or sticking, maybe an Italian tune up will help?

I usually end up changing my oil early because the lifters start to tick.  It doesn't surprise me at all that fresh recycled dinosaurs significantly reduced the top end noise.  To my ear, at least one of your lifters still isn't happy.  What kind of oil did you put in?  I ask because my Miata HATES Mobil 1.  I've tried it twice just to be sure (and because I'm stupid), and both times it started sounding like a Model T.  

Lifters can take some time to pump back up after bleeding down, so even if nothing is wrong, the noise may not disappear immediately.  However, with it being so low that the pressure gauge was barely reading, I have to wonder how badly you damaged the bearings in that engine...

Also, didn't you say earlier that there was definitely oil in it?  With only a quart, the dipstick had to be bone dry.  Which in my mind would make the first course of action "add oil until it shows on the stick". 

Castrol 5W30 because I had it on hand regular old dino oil, no blend or high mileage anything. 

There was oil on the dipstick at autocross when it was still hot, but not checking it cold last night. I cracked the drain, oil came out, and I closed it again. 

Within 30 seconds of firing it up with fresh dino juice the noise went down considerably, there's just that one being persistant. From under the hood, it sounds closer to the back of the valve cover. This has always been a very loud tappy motor, even with fresh oil and Lucas in it, like within 300 miles of a change, they're ticking and tapping again, so judging the noises is challenging.  

I already decided I'm done messing with it today. I'm going to give a can of seafoam a try along with ye olde Italian tune up, because at this point it can't hurt, but if it doesn't help I guess it's back to the writeup on cleaning and rebuilding valves and lifters. 

Try that Rislone. It got rid of my Miata's lifter tick. 

It can definitely take time for lifters to pump back up. I had one that took a week of high rpm commuting to come back. That was a long, long time ago and it never showed any signs of ill effects for the next 10-15 years. Replacement lifters (also used in some Kias) are pretty cheap these days and changing one is relatively easy.

If you're concerned about the bearings, pull off a cam cap. They often take damage first.

You place a screwdriver to your ear and use it like a stethoscope to find the location of the noise.

mrhappy said:

You place a screwdriver to your ear and use it like a stethoscope to find the location of the noise.

I suggest screw point towards the engine. Doing it the other way will definitely take care of the noise.. for you at least