Head gasket replacement and injector troubleshooting

The time finally came to start putting things right and keeping fingers crossed that the warped head was ineed where the issue lie, and not, say, a cracked block for example.

While we were in there, I wanted to eliminate, hopefully permanently, the head hardware from the mix. A friend suggested a bolt may have stretched, and since the Mazda hardware (bolts) costs about the same as a set of ARP studs, the studs were a no-brainer.


Since I had the luxury of having my brother, an engineer at Maserati in town for the holidays (we’ll ignore the fact that he does suspension & vehicle dynamics…) I enlisted his help to get the car squared away. Here he is with the big torque wrench helping to get the head nuts tightened down on the studs. We did it in 3 different steps to 55 ft/lb (using the ARP Ultra Lube), and did the last step twice just to verify that they were correct.




Didn’t take too many detail pictures of getting the head back on, but it’s pretty straight forward. Put the HLAs back in, in the order they were removed, put the cam in and index it with the Cam Angle Sensor, put the caps on in the correct order, and torque the bolts down in the prescribed pattern, to 120 in/lb. A healthy dab of assembly lube was used on any of the rotating and reciprocating bits for the first start.


After that, it was a simple matter of making sure the seals were pressed in correctly, then bolting the gears back on (SUPER easy using the Flyin’ Miata cam tool, easiest timing belt job I’ve ever done), the timing belt, belt covers, accessory pulleys, and the intake & exhaust manifold. Note the removed Thermostat water neck / housing. More on that later.


After getting everything buttoned back up, it was time to spin the engine with the ignition & injector bank disconnected to build up some oil pressure. And here’s where I’m a bonehead: I did this without pulling the pugs, which meant that my tiny, 6 lb ETX-9 battery was fighting compression, instead of the engine spinning freely. Once we finally got oil pressure to read on the gauge, the battery was dead. Like, capital D dead. I’ve had experience doing deep discharge cycles on these batteries before, and it never works out well. We left it on the Battery Tender for a few hours to see if it could be brought back from the dead, but it wouldn’t ever charge fully and could barely crank the car. Fortunately, my local O’NAPAdvancedAutoParts had an ETX-9 battery on the shelf so we took that home and plopped IT on the charger to try again. After the family Christmas Eve dinner, I decided, because I’m stubborn, to give it 1 last shot for the night. So we hooked the battery up and attempted to fire it up again. It would crank fine, but alas, it wouldn’t fire. So we covered the basics. What do ICE engines need? Air, Spark and Fuel. We had air (even tried playing with the throttle to see if it would touch off, but no joy). We tested the spark and were getting power to the plugs. But when we pulled a plug, it was bone dry. The ECU was having the fuel pump prime, so we should have pressure, but it didn’t appear that the injectors were firing. A cursory check didn’t reveal anything wrong, but the 30A injector fuse didn’t look… right. The filament was all there and accounted for, but it was a different shade of color compared to the unused, spare 30A fuse right next to it. At this point I figured why not try and see if the problem went with the fuse, and on the next crank, she started to cough to life. Gave everything a moment and hit the start button again, and lo and behold, it was a Christmas Miracle (though, a ton of man hours, effort and troubleshooting probably helped): the Miata roared to life! High fives were shared all around and we went ahead and brought up Shadow Dash on my phone so we could keep an eye on things as it warmed up to operating temperature. This was important because, as you may remember from THIS POST, the fan wasn’t coming out quite as soon as I’d like. The working theory was because the coolant neck simply wasn’t getting enough hot water to get an accurate temperature reading to the fan switch. As I pointed out above, the temp sensor is now directly in the head:


Now that it’s reading temperature from the front of the head, and coolant is going all the way through the motor courtesy of the re-route (instead of just circulating around the #1 and #2 cylinders, as it does with the stock setup) the temperature as read by the ECU (at the hot side / back of the head) at which the fan kicked on dropped nearly 15 degrees from where it was when the fan switch was in the old Thermostat housing. I’m calling that a big win, and that mod had the exact effect I intended. It’s nice for SOMETHING to finally go right with this motor.

Merry Christmas & Happy New Year, y’all!

Wheel & Tire Clearance – Fender Mods: Part 1

If you take a close look at this picture, you can see that the fenders are actually resting on the tire. Not even on the sidewall, but actually on the edge of the tread surface. I knew it going in, but knowing something intellectually and then going and doing it are 2 different things.  I enlisted some experienced help and we (he, really… I played gopher) got to work

My buddy Michael is a body man by trade, and did about as good a job as could be done on them.


This is at full droop, but we took about 1 1/2″ off of each corner:


You can see the flare he added to the rear fenders here, in addition to the cuts. I still will want to do proper fender flares, but this’ll do just fine for now after cleaning them up.

The rears were a little more work due to having to work around an inner fender along with the outer skin. These are the relief cuts made so that the inner fender could be bent up and out of the way.



They needed some additional trimming and cleanup with various cutting and grinding wheels & stones and some edge trim, but I think the results are good. Not spectacular looking by any means, but a show car this ain’t. The fronts are very flimsy, but that wasn’t exactly a surprise. Just need to be careful when leaning over them.



EDIT: I went ahead and made another little change. I wasn’t happy with how low the inner fender was coming, so I trimmed it back about 1/2″. Now the inner fender is much more uniform, and isn’t intruding into the tires’ paths of travel. Before it was more or less even with the outer skin.


Instrumentation & Data Logging

As previously discussed, I’m using an old phone (Samsung Nexus S) for instrumentation and ECU data logging. Once I got the electronics box squared away, and figured out a good way to secure the lid (because the strap that came with it was just the worst… ratchet straps ftw!), I moved on to sorting out where my instrumentation would go and make a few mods so that I could actually power it from the car, instead of constantly worrying about draining the battery.

I picked up a motorcycle 12v to 5v USB power converter that has a handy SAE / Battery Tender port at the battery end, and a water-tight USB port on the other. The gray box in the middle attached to the kill-switch wiring is the converter. You can see the lid to cover the USB port just behind the dash cover support, as well as the routing of the short USB cable to the phone.


This is the phone cradle. I can use a zip tie at each end to keep the phone secured so we don’t have any wandering electronics. I don’t think it’ll really NEED it, but it’ll make me feel better. It takes a good deal of effort to pry it out, but it’ll give me piece of mind. The cradle was an open source design I used and modified to give it a solid back with 1/8″ holes to use for rivets, and had 3D printed last year.  As you can see, I also mocked up the LED shift light in what I believe will be its final resting location:


And here’s what it’ll look like from the driver’s seat. I really only want to see the shift light in my periphery. In an autocross car, the actual gauges are usually more an in grid affair. That it’s visible is gravy. I MAY move the phone to mount it more centered up, but I wasn’t sure I’d have room to put the shift light where I wanted.


And here’s the SAE plug for the converter, now idle due to the Battery Tender being plugged in.


EDIT: the ‘dash’ placement has already bugged me enough to fix it.


EDIT#2: I got a few questions about glare and keeping the screen out of the sun. I threw the dash cover so you can see that unless the sun is pretty low and directly to my back, it shouldn’t be an issue (and if it’s directly to my back, it’ll be in the driver’s shadow). It should do a pretty good job of keeping it mostly in the shade.


Baby Steps: Engine Update, Suspension, Interior & Electrons

I just got off the phone with the machine shop. The head pressure tested fine (ie: no cracks or pinholes), but was indeed warped. Clearly I overheated her at some point, or 1 of the head bolts stretched. They were all torqued upon removal, but alas, to be sure that doesn’t happen again, I snagged a couple of goodies from Jegs. ARP head studs & Ultra Lube + Assembly Lube for reassembling the head. This weekend I’m going to get the old head gasket shmeng off of the block, and then it’ll be time to reassemble the head and get it back to its home.


As you can imagine, the engine’s feeling a bit blue at the moment…

(awful, awful joke)

Because I clearly couldn’t put the engine back together yet, I went ahead and tackled a few of the smaller items. I did a little fettling and fitting on the suspension bushings for the rear lower control arms, as they were binding big-time (no real pictures to show there), and started getting the interior and the car’s brain-box put back together. I’ve got the battery back in place and connected, and re-ran the wires for the charger so it doesn’t run dry. All that’s left there is to secure the ECU to the wiring harness and secure all that to the box and that should be set.

Because I got fed up with tripping over it constantly, I went ahead and put the seat into the car. BONUS! I got to sit in it and make Vroom Vroom noises! (and also see what the eyelines for the gauges & what not would look like. After almost putting 1 of the studs for the dead-pedal through my foot, I also put that back in (safety third…).


I’m not sure if that’s the location I’m going to go with, or if it’ll be down towards the steering column supports, but that’s basically what I had in mind for the shift light.


And I have GOT to re-arrange that wiring (or maybe just cut it shorter) for the kill switch…

One step backwards: Headgasket

I dug into the engine to remove the thermostat housing, so that I could put the fan switch directly into the head’s coolant passages so that it gets a more accurate reading on coolant temp. To pull the t-stat housing the cam gears and the timing-mark plate have to come off. I figured while I’m there, I’ll pull the cams and find the bad HLA (Hydraulic Lifter Assembly) that’s making a bunch of clatter and replace it. So far so good, that all went fine.

Here’s the Flyin Miata cam tool coming into its own. I love it. You set cylinder #1 at Top Dead Center, and then slide the tool in and secure the cam gears, so they’ll pull off and go back on without needing to mess with setting the timing again.


This is the T-stat housing blockoff plate, and with the sensor installed:



Here’s where things go a bit south. While I was working, I noticed the oil looked (and smelled) a bit off. I thought maybe because it was sitting in the engine so long without much movement, but, while I have things apart, you might as well check, right? Right. For the uninitiated, that isn’t what oil look like. Looks like it’s mixed with something it shouldn’t mix with (namely, coolant).


Houston, we have a problem. So, SITREP:


I’m glad that I found it now. Gonna get the head decked if all the valves check out, because I might as well do it right while I’m there. I’m also contemplating switching to solid lifters while I’m here, but that expense might have to wait.

I’m definitely switching to an MLS gasket, and probably will swap in ARP head studs. Budget at the new year will determine how much further I can go with it while I’m this far in it.

At least now I have plenty of access to swap the starter out, since it’s got a dead spot that’s been getting bigger. Yaaaaaaaay! /sarcasm

Wheel & Tire Package: Part 2

I got to feeling spry and started pulling the suspension to start test fitting the new wheel / tire package, as the fenders WILL need to be trimmed to make room for the big slicks. The fenders are basically sitting on the tires (hence the jack, to take some of the weight), but damn she looks good with her new shoes!

The new package is a set of Jongbloed Racing Aero 500s in 15×10 all around, with 23×9.5×15 Hooser Formula Atlantic compound slicks. Next step will be to start measuring and trimming and measuring and trimming until the fit is right and the body work isn’t limiting the movement of the tire any longer.