Hey Miata friends, I’m once again back with another problem after my rebuild.

im starting to lose hope in this car sadly…

Ever since the rebuild we have had this ticking noise, it’s pretty loud. Sometimes it’s not to bad and other times it’s not to great. At first we thought it was lifter shims, so we got new shims and made sure each lifter was within spec. However, the issue still remains.

im trying to not get discouraged, but this is the second rebuild of this motor this year after the new oil pump failed. I’m hoping someone has some good news and I don’t have rod knock or bearings failing.

I posted earlier about the oil pressure acting odd. At idle we typically see 18-20psi sometimes it’ll drop down to 12 at the lowest but it tends to come back up to 18 quickly.

here is the video for the noise:
https://youtube.com/shorts/inlL1FkhiCY?si=TwZ-CUkF1fap2Hyt

 

It is a known issue and can be somewhat remedied by disassembling the lifters and cleaning them thoroughly. Seafoam may help.

My '94 ticks until it's warm. It does it every time. I've learned to ignore it.

 

I still feel like your oil pressure is low, but my only real point of comparison is my car which is running 15-40 or 5-40 on a pump with shims (I believe), so not exactly apples to apples.

IMO that sounds more like injectors or a boost control solenoid to me. I couldn't see if you had EBC or not in the video, but mine doesn't engage until a certain manifold pressure/rpm, so if you give it some revs from idle it starts to clack around at 2500 RPM or so.

Did you put new injectors in when you did the rebuild? I thought my engine was broken but it ended up being the loud clacking from the EV14 style injectors. A mechanics stethoscope (or a long screw driver) might help pinpoint where the noise is coming from.

 

The VVT engine has solid lifters, so it shouldn't tick like the NA engines.

 

Yeah, sadly i have no idea what the oil psi was before the rebuild. Sometimes its fine other times its not.
I do have an EBC but at the moment its not hooked up since we are still (trying) to break the motor. The injectors are 640cc, iv put my ear to them and while they do make the typical injector noise, its not the main noise. Especially since we ran these same injectors before the rebuild with no problem.

Ill take a better listen to them tonight and see if maybe im just crazy.

 

My bad. Didn't know that.

 

Honestly it's a pretty common misconception. I've seen a lot of people who drive NA's suggest lifter tick to people driving NB's. It's definitely a real thing on the NA's.

IIRC the 1.6 NB is the exception. I'm pretty sure it has hydraulic lifters as well.

 

To me it doesnt sound like a detrimental sound. Ive had all kinds of ticks and noises on all 5 of my miatas, and the real bad noises are definitely a lot worse. It does sound like a loud lifter assembly. Like a lot like it. is my na when it had a super stuck lifter, thought it was rod knock. The speed is also a bit different when its bottom end related iirc. It could be injectors just being super loud, maybe an exhaust leak? When I accidentally left my egr disconnected it sounded pretty bad.

 

Your valve lash may have changed, causing the mechanical lifters to tick. Valve lash is a required adjustment over time and can be exacerbated by high RPMs, weak valve springs, and high EGTs.

 

we actually just adjusted it a day before that video was taken, we were pretty out of spec and assumed that where the noise was coming from. After adjusting them all to spec we still have the noise.

after adjustment it sounded a bit better but obviously we still have an issue unfortunately :(

 

Does the car run and drive ok otherwise? I agree it doesn’t sound like rod knock, too quiet and not fast enough. It sounds like valvetrain noise

 

Having had some bent rods making ticking noises, there is one way to quickly identify this issue. On ticking = a bent rod , this post and the following one describe a dipstick method. Just make sure (as far as you can) the bottom of your dipstick is sitting on the middle of the piston. If they all sit the same height, it is not a bent rod. Could be all the rods are equally bent, but that would be pretty extreme.

 

I’ve taken apart the head and can’t find any problems, everything is timed right, VVT seems to be working good, oil is getting where it needs to be, triple checked our valve lash and everything is in spec….

all of our springs are in good shape, same with our retainers and shim cups.

With the stethoscope if I put it to the intake and exhaust manifolds I definitely hear it the most on cyl4.

putting it to the block I hear it less than I do through the head. So I’m thinking it’s just echoing into the block, if that makes sense.

we are on forged rods and pistons so I’m praying they didn’t bend with 1-5 psi….no metal in the oil outside of what we expect from the break in. (No chunks or anything gritty)

i am ,however, running out of ideas and I’m just not even sure what to check past breaking the motor down for the third time this year :/

 

Yeah, forged rods sorta rules out 'bent rod'.

If the valve clearances are ok, and there is no slop in the shims, I would be looking for valve contact with a piston - I know the non-VVT BPs are non-interference (stock), is that the case for VVT? Is this engine 'stock' in that context - no decking/skimming/high lift cams? If you go down this path use a borescope to see if any shiny/clean bits are visible. While the plugs are out, set the cam timing at its most advanced, and turn the engine over by hand looking for the feel of a touch, repeat for retarded to cover the bases.

After that I am out of suggestions.

 

You were posting about having lower than expected oil pressure earlier, correct? IIRC you were seeing something in the teens at idle? Have you drained the oil and cut the filter to see if there's any material in there?

Do you have the most recent lash measurements, and were they taken on a warm/hot engine? Any chance those were adjusted backwards (IE intake measurements on the exhaust valves)?

What pistons did you go with? Maybe it's piston slap? Kinda throwing stuff at the wall at this point.

 

yeah we were seeing some low pressure. lowest we got at idle was around 12-13 warmed up, msot of the time it would be around 18psi.

we drained the and have some stuff from the break in but nothing out of the ordinary. Filter didnt have any bits or anything concerning either

Lash measurements were rechecked and are all still in spec on a cold engine.

Our pistons are the Weisco 84mm.

im close to sourcing a cheap head for ***** and giggles, if it makes a difference then it would at least narrow it down. We were also thinking of just biting the bullet and dropping the subframe to get a look at bearings from the underside.

On that note, anyone selling a cheap VVT head? haha

 

Not sure where you are but I’ve got a whole VVT engine core. Needs to be gone though though.

Have you tried just turning the motor by hand with the valve cover off and seeing if there’s something making contact that’s not supposed to be? Rocking the motor back and forth with a breaker bar (plugs out) can sometimes tell you if a rod bearing is going.

Any new shiny spots inside the valve cover, could be a bent PCV baffle in the valve cover hitting a cam lobe. The do sit quite close, wouldn’t take much of a tweak for some contact to occur, and it would mimic the cadence of your noise but not cause a glitter bomb in the oil.

What is oil pressure like on this new build?

 

Below is sort of my noise diag check list. How the noise initially developed is often a tell. If it is there at first startup of a new eng, it’s more likely a piston over a rod bearing. If it develops after some use, even less than an hr it could be a rod more than a piston.

Engine parts contacting the chassis.
Peripheral components, loose water pump pulley, power steering pump, etc.
Exhaust leaks.
Oil inspection
Valve train components.
Then a compression test to see if a loose or damaged piston caused cylinder damage.
Then it’s usually a tear down.

 

Overfilled oil above the full mark can lead to foaming -> insufficient oiling -> loud ticking.

 

For anyone looking for closure on this thread, im afraid it doesn't have a super satisfying conclusion lol

We ended up getting a refurbished head and that fixed the problem. Im not sure if the cam or bearing were scored maybe?

With how many problems iv had over the course of this rebuild im trying to just not ask questions and be happy with a win haha