It’s been a while since I wrote about my Miata on here, so I thought I’d give an update. Just to get the bad news out of the way first, the car overheated again at the beginning of June. But how’s the head gasket?
Not the Best Start to a Project
As a refresher for those who don’t know my history with the car, back in 2013 when I first bought the car, it overheated on the way home and blew the head gasket.
I’d been searching for a clean NA 1.8 liter Miata for the previous 6 months and after looking at a lot of wrecks and automatics that had been advertised as manuals, I bought my Classic Red ’95, which was accident-free, but was way behind on maintenance upkeep. After the overheat and having the head gasket and changing all major components of the cooling system, I felt pretty safe driving it. Except 6 months later, oil showed up in the coolant hoses again and it started running hot after running for 30 minutes.
I took it back to the shop and they discovered a leaky oil cooler. I had a new factory cooler installed and drove it that way for a few months until the hoses started sweating the oil out. It was then that I discovered the reason for the running hot, a hose hidden under the intake, that only leaked under full throttle.
Since then, it’s had all new Mazda hoses installed by me, even the cursed so called “devil hoses,” with the only exception to the OEM pieces being the two heater hoses, and I’d already replaced with store-brand hoses when the cam angle sensor o-ring leaked onto them. Out of preventive maintenance, I changed that o-ring as well, upgraded to a Viton Quattro ring from MiataRoadster.com to avoid any oil meeting the new rubber hoses.
Project Solo Commuter?
The car remained a fun weekend car until a few months ago when my wife got a new job. We’d been commuting in her car but being that we’d be working in different places now, the Miata was pressed into daily driver status.
“This is great,” I thought. I could make it an interesting mix of daily commuter while equipping it for autocross. Call it “Project Solo Commuter” like a funny mixture of solo in commuting alone, and solo as in the nickname for autocross. Early in June, I finally had the used AC compressor installed into the car so I wasn’t dying from the Florida summer heat. This compressor had travelled with us from the previous house we lived in to today, 4 years later. I took it to Jeff at Maztech for the compressor install. He’d previously made easy work of a power problem I was having that ended up being a jumped timing belt.
But Then…
All was well for about a week. And then I was driving home for lunch and the AC started to warm up. Hmm, strange. A few seconds later, the check engine light started flashing, I looked over at the temperature gauge and it was pegged at full hot. Fuck…
I pulled over immediately and just as I did, the telltale cloud of steam rose out from under the hood. I turned the car off immediately, trying to minimize the damage. Immediately opening up the hood, I found coolant spraying out from the heater hose, burst open, at the back of the engine onto the hot exhaust. I contacted my wife, contacted my car friends, trying to figure out what to do next.
I was actually really calm during the whole thing, which is surprising for me. Thanks, therapy. Once I went through everything in my head that I’d done for the car, I just accepted that I was stuck on the side of the road and the only thing to do was get a tow and hope for the least engine damage possible.
Being stuck on the thin bike lane was a little scary, but people seemed to be paying attention well enough. I could hear their tires rumbling over the reflectors in the middle of the road. I had no numbers for tow companies on me, so I called my insurance company. They called a tow for me and said it’d be about 45-50 minutes. So I crossed the road and stood to wait in the shade, pacing back and forth in the grass.
And waited. And waited. About an hour later, the insurance person called me back. The first tow truck had supposedly broken down. Okay, I thought, everybody has a bad day every now and then. They were sending another truck, but it was going to be almost another hour. So I waited some more.
An hour or so later, I hear back from the insurance company again. Now they were saying that the second truck got a flat tire! Wow. Okay… I don’t believe in curses, but am I cursed? They were calling a second company this time to send a third truck. So more waiting, more pacing.
While I was waiting, I got to meet some interesting people. One older man was walking down the road because his wife had had to go to her doctor’s appointment. He told me about how a cashier up at the corner, about a quarter mile up the road, had gotten confused by the math on some fuel car transaction. Some offhand slightly racist comments about the cashier’s race…
Then a very nice couple showed up with a diesel pickup and offered to pull me home. I had to be less than 2 miles from home. I remember their AC felt so amazing coming out the open truck window. But, in a moment of foolish optimism, I was sure the tow would be there any moment, so I turned them down. I think the heat was getting to me by then too, and I was having a hard time remembering the street names to tell them where to pull me. It seemed like it might be too much trouble. So I kept waiting.
Several Hours Later…
After 4 hours of being stuck on the side of the road, the third truck showed up for me. Amazingly, by then I’d made my 10,000 step count goal on the pedometer just pacing back and forth, going nowhere. Before the driver drove it up onto the flatbed, we looked under the radiator cap. No visible coolant. Uh, yikes. The driver drove it up onto the flat bed for me and took us home. He at least thought it sounded like it was running normally. I agreed.
Assessing the Damage
In the weeks since then, I’ve gone through all the stages of grief. For a week or so, I didn’t want to check into the car. The less I knew, the more functional it might still be. If you know the story of Schrödinger’s cat, you’ll see where I got the title for the article. This was no way to be.
I clung to the hope of not having seen coolant in the oil or oil in the coolant; the ugly “milkshake” appearance that usually accompanies a blown head gasket. Still am clinging to that a little bit since neither has shown up so far.
Unsure thoughts crept into my head like “Did I shut it down fast enough?” “Is this my fault?” “Could I have done something to prevent this from recurring?” On the side of the road, there had been no smell of coolant like I’d experienced in the past, even after the car came home. And the darnedest thing was the hose that burst. It was only about 5 years old. I’d changed it myself. Why would it have blown up? The underside of the CAS was dry as a bone, so it hadn’t leaked on it again. And anyway, it had blown behind the engine, not out to the side where the sensor is.
A couple weeks went by. I changed both coolant temperature sensors and I finally rented a compression tester. I hadn’t used one the last time this had happened. I was in such a panic then that I just had a shop do everything including the post-gasket change compression test. I didn’t know much of anything about these cars back then. But shops cost too much and, as much as they’ll try, aren’t going to know the best parts to use as well as I am.
Compression Testing
My brother came by and helped me do the first compression test. The plugs came out looking like cylinders 1-3 had been running lean and number 4 looks rich. Might be time to finally send the injectors off for a cleaning.
The first test came out with low compression numbers. From what I read on Miata.net and some other places, the minimum pressure for each cylinder is supposed to be 150 psi and with a minimum difference between adjacent cylinders of 28 psi. Supposedly cheap compression testers can read low, so the difference between adjacent cylinder pressures was more important than the compression numbers themselves.
The first test came out with results of:
- 150 dry
- 130 dry
- 110 dry
- 150 dry
- 150 dry, 175 wet
- 120 dry, 155 wet
- 105 dry, 120 wet
- 135 dry, 190 wet
The difference on the last test between dry and wet of cylinder number 4 is alarming, but at the same time, the deep thread adapter had gotten stuck in cylinder number 3 at the time and I hadn’t realized it. Not having the adapter on may have actually sealed the tool better to the the plug hole. I’m not sure.
Before the tests, I was expecting trouble from cylinder number 4, because with the less than ideal route that coolant takes in a Miata (and also why many owners install a coolant reroute system), it would make sense for it to be the hottest, but instead there seems to be a problem in cylinder 3.
Final Analysis
The best that my car friends and I can figure is that the hose was a freak accident kind of failure. It may have gotten nicked or I may have installed it too deep onto the pipe causing pressure to build up before the clamp; either way causing an early failure and a slow leak that’s been sneaking up on me back behind the engine where I couldn’t see it. And with most of the hoses only being 4 years old, 5 max, who would think to look? The end that blew is soft and swollen, like a hose that’s been exposed to oil, but the rest of the hose feels solid. It’s strange.
The kicker is that I’d had two brand new OEM Mazda heater hoses ready to go just a year after I’d installed the two that were in there, because I bought the whole set off all the hoses from good old Rosenthal Mazda (RIP). The hoses could have gone in with the other Mazda hoses when I changed the rest. I could have changed the two firewall grommets that had deteriorated (had new ones of those too) which have, I think, been the source of a rattle in the front end since I bought the car. But because they were only a year old and it was such a pain to reach the rear of the engine, I put off changing them. Well, they’re in there now.
It’s probably gone unnoticed as well since, until recently, an air conditioning compressor wasn’t adding to the demands on the engine and therefore the cooling system.
Adding to that, I’ve been running without an under tray for the past few years. The old one was cracked. “I’ll replace it.” Tossed it in the trash back when we lived at the other house. Never did replace it. Up until now the only difference I’d noticed was a little less stability on the rare case that I’m on the interstate. Another friend thinks this missing tray could be part of the problem. The combination of the AC compressor adding to the load on the engine, heating things up more, along with the air not taking the best route through the radiator, and then the failed hose. It’s either bum luck or a comedy of errors. Shit happens, we’ll rebuild.
Moving Forward
From a couple weeks back up to this past weekend, I was mostly convinced that the remaining problem was just head or cylinder related, but now (again) I’m not sure. I’d gotten the car all buttoned back up on Sunday night thinking that I’d drive it to work and just see what it did. “Just send it.” But yesterday morning, the car wouldn’t start.
So last night I jumped it and let it run to see if I could get the battery to charge back up. The garage was soon hazy with a slight white smoke. The more I think about that, the more it’s suggesting blown head gasket.
Since I knew sitting idling isn’t great for an engine’s health, I decided to drive somewhere about 20 minutes away and back, shifting low at 4000 rpm. I made it about 10 minutes out and started to see a slight smoky haze in front of my passenger side headlight. I was waiting at a red light when this happened, so I stopped the engine. Then I thought “turn it back on or you’ll be stuck here, idiot!” Thankfully it started, just barely. I hung a u-turn and flipped the heater to full blast, just in case, headed back home. The temperature gauge stayed at the normal position. When I got home, the engine just ran. Like normal. That said, everything seems pretty hot under there and the haze… The smoky haze worries me. The heat makes me and another friend think there could be compression gasses leaking into the cooling system, which could mean more blown hoses on the way.
So, at the end of this long tale, it’s either a slightly blown head gasket or an issue with the piston ring or valves on cylinder 3. Either I drive it and hope for the best, avoiding using the AC until I can get a tray back on the car, or just go ahead and rebuild. I think we’re heading for a rebuild. At least then I’ll know and I can build it right this time to not just run, but run at its best. I’m thinking while I’m in there I’ll change the radiator cap, the thermostat, and change the water pump out for a GMB unit since I’ve heard good things about them. I’m also considering a coolant reroute and might put ARP studs in instead of reusing the original head bolts, now that they’ll be coming out a second time. The coolant reroute is expensive, and not being a track car yet, this car shouldn’t need it, but overheating twice is enough for me. It’ll also kick me out of ever being able to compete with the car in a stock autocross class, but so likely would the steel braided brake lines and the high flow cat. So that’s how it goes. You shrug and you move on.
Lastly, for the past month, I think I mentioned I’ve been kicking myself for not changing the stupid heater hoses, being that I had new factory hoses and new grommets ready to stop the rattle. Last night, I pulled into the driveway and I think I still heard that stupid rattle! While I’m under the hood, as Marsellus Wallace would say, I’m going to go to work on the homes with a pair of pliers and a blow torch. Get medieval on the exhaust heat shields and finally kill that stupid rattle.
