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Wow, here we are, my first blown engine. Have to say it doesn't feel as bad and devastating as I had expected.
I have a 94' Classic Red miata (because the paint is very important to this story!) and it's had hot start issues since the day I bought it. After everything I've been through, it looks like it's most likely from a tired engine anyway, but I'll get to that in a minute.
I installed a MSPNP2 with a wideband a few months ago now, didn't understand the whole "base timing" deal, set it to 10 degrees (which was correct at idle) but left it on fixed timing and drove it for.. oh. i don't know. 3 days? Don't worry, it gets worse. I also couldn't figure out launch control so I set my rev limiter and spark cut at 6k RPM because who can live without pops and bangs? And used it as "launch control". All while the timing was set incorrectly and ruining the engine in the process. Went to park the car back at my shop, left it running at idle, and came back to it boiling the coolant in the overflow, and at 220+ F. Guessing I blew the head gasket or warped the head in the process somewhere.
So I bought new fans, hoping that would fix the issue, which helped.. but didn't resolve it. And STILL kept driving it.
Skip ahead a couple months while I was in another city driving around, parked it in the middle of a parking lot to take pictures, left it idling, and I look back at the car after talking to someone asking me about the car, to see it smoking out the hood and coolant pouring on the ground. Heater hose ruptured. Proceeded to drive the car back with little to no coolant 15 miles to my shop, keeping my eye fixed on the coolant temp, which never went over 170 F. Guessing there wasn't hardly any coolant to actually measure the temperature of, so I was probably getting a false reading. Not sure what kind of element the coolant sensors use though. Fixed the hose, and KEPT GOING.
A few weeks later, the car would "smoke" (steam) at idle and stop lights. Just enough to see in the rear view mirror. The car also started to smoke (burn oil) at hot starts, when it finally decided to start, and then go away after a minute.
Here are the compression test and leak down results.Cyl 1: 120 PSI DRY 85% Leak Air in Cyl 2
Cyl 2: 93 PSI DRY 90% Leak Air in Cyl 1, 3.
Cyl 3: 57 PSI DRY 95% Leak Air in Cyl 4, 3, 1
Cyl 4: 114 PSI DRY 87% Leak Air in Cyl 3, 2, Crankcase
What I'm trying to determine now is if the bottom end is worth rebuilding, and how reputable treasure coast and jegs are with rebuilt heads. I don't have a problem rebuilding the bottom end, but I don't have the time or patience to get the head done myself.
Also, I'll attach some photos of the cylinders, head gasket, and valves to see if you guys notice anything I'm overlooking. HG doesn't look blown..? But the head is warped 1/4000th of an inch between CYL 2/3. Cylinder 4 looks to also be off-centered from my untrained eye. Ring problem maybe? This cylinder was the only one to have oil in it as well. Cylinder 3 was the only one with coolant in it.. which was really pooled up.
Please don't hesitate to laugh at my mistakes, I don't mind spending money, so I only look at this as a lesson for myself and valuable experiences to avoid in the future.
Any advice or thoughts on anything I've mentioned would be more than appreciated! Thank you guys in advance.
All cleaned with a degreaser and a towel equally. Cylinder 4. Cylinder 3 that had coolant pooled up in it. Burnt valves. HG.
LOTS of detonation damage. Look how much material has eroded off the top of the cylinder 4 piston. Truly impressive damage if you're still naturally aspirated.
Detonation usually means beat up rod and crank bearings. How rebuildable it is will depend on how much damage there is down there. Even if it's bad you can have the crankshaft turned. Then obviously new pistons and rods.
When I first got my miata I was in a rush and decided to use a cylinder head exchange service on ebay. I had a few lifters missing check valves and springs, and the valve stem seals had clear imprints from being installed with an ill-fitting 12 point socket. If at all possible I would find a local machine shop to rebuild the head.
All that said, if I were in your shoes now and not planning on a power goal above stock engine limitations I'd have gotten a used engine from one of the forum sponsors that parts out miatas.
Maybe find a tuner to take care of things on the next engine. Tuning doesn't seem to be your shtick.
LOTS of detonation damage. Look how much material has eroded off the top of the cylinder 4 piston. Truly impressive damage if you're still naturally aspirated.
Detonation usually means beat up rod and crank bearings. How rebuildable it is will depend on how much damage there is down there. Even if it's bad you can have the crankshaft turned. Then obviously new pistons and rods.
When I first got my miata I was in a rush and decided to use a cylinder head exchange service on ebay. I had a few lifters missing check valves and springs, and the valve stem seals had clear imprints from being installed with an ill-fitting 12 point socket. If at all possible I would find a local machine shop to rebuild the head.
All that said, if I were in your shoes now and not planning on a power goal above stock engine limitations I'd have gotten a used engine from one of the forum sponsors that parts out miatas.
Maybe find a tuner to take care of things on the next engine. Tuning doesn't seem to be your shtick.
Gonna ask a stupid question here.. where would i find those used engines on here?
And you would think that would be a better idea than a rebuilt head and rebuilding the bottom end?
I recently blew my turbo engine and had very similar damage to yours, albeit not as severe. I'm able to rebuild mine -- but that includes new pistons, rods, etc. I would advise that you spend some more time researching MS tuning; There's no point in putting a new engine in if you don't have the knowledge to not blow it up again. Once you've done your research, I'd look to swap the motor. Unless you want to go turbo and make big power, it's really not worth rebuilding. Look at your local junkyard or order one online/scour forums and craigslist. I'd go for a newer VVT 1.8 personally (the heads flow much better). As others have mentioned, the most important thing is just doing your research. It's very easy to make very expensive mistakes if you don't know what you're doing, just keep that in mind and you'll be fine. As a side note, if you've never pulled an engine, a Miata is a great place to start -- I pulled mine in 4ish hours!
Please don't hesitate to laugh at my mistakes, I don't mind spending money, so I only look at this as a lesson for myself and valuable experiences to avoid in the future.
What lesson(s) did you learn here? I'm serious.
I bet if you listed out what you think you learned, people here could point out things you missed. You seem to be focused on fixing the result of your actions - that's just parts, sweat, and yes, money. The hard work is going to be to fix the lack of thinking that toasted all those parts. It's pretty egregious.
You need to take that bottom end to a reliable shop and have them evaluate what needs to be done to it, and what damage it has sustained. Rods, bearing surfaces, true-ness of cylinder walls, health of pistons after major overheating, size of cylinder shafts and pistons, and so on. You don't have to get them to do the work, but you need to know those things before investing another dime in it.
Based on the questions you are asking, you are not going to be able to get a quick internet lesson on how to evaluate the damage yourself. Pictures shown to the crowd won't provide the measurements needed.
Sourcing a used engine is probably your best bet, by far.
06-17-2020, 04:35 PM
Engine Rebuild/Serious need of advice.
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