$1000 overheated Miata

Well, I wanted to get some advice from you guys. I bought a 96 Miata that has recently been overheated for $1000. I'm wanting to fix it (not part it) and either sell it or replace my 93 with it. From the owner, I got that it had a coolant leak (bottom radiator hose) and as a result he ran it hot. Mechanic told him low compression and quoted him $4000 to fix it or $1500 to replace the engine. I couldn't crank it as it has a bad starter solenoid (according to owner). I'm thinking it might just be the battery. I'm bringing it home tonight and I'm trying to decide if I should either:

1. Remove and replace head gasket with new Mazda gasket. Possibly machining head if warped.

2. Replace engine with used engine. I can get an Escort engine for $280 (same block and head) with 40k miles and swap over everything.

I'm thinking I'll pull the head and take a look and go from there, but is there anything I should definitely do before I pull the head, such as a leakdown test? I don't have a tester, but I can always buy or borrow one (is that one of Autozone's loan a tools?). I took a look at the coolant and it looked like it had an oil slick on the surface. I'll be sure and check the oil for water/sludge.

BTW, I've already searched Miata.net, etc. Just thought I would get some input from the folks here.

Just so you know, I've swapped several engines, transmissions, installed turbochargers, etc, but I haven't done a lot of internal engine work. Any advice?

You can get a swappable engine with only 40K for $280? I know what I would do without giving it a second thought. The machine work alone on the existing engine would probably be that much, or more.

Well, "swappable" in that it's the same block and head. I'd have to swap over everything else. More info on that here: http://www.miata.net/garage/escort_to_miata.html and here: http://forum.miata.net/vb/showthread.php?t=266631&page=1&pp=25&highlight=escort

But, yes the Miata engine seems to cost quite a bit more so it makes good financial sense. I may just go ahead and plan on that and just open up the Miata engine when I get it on my stand.

I'd just do the swap. The engine/trans comes out easy enough, and swapping the miata bits on to the escort engine won't take more than a few hours.

If you're up for the task of swapping everything over to the Escort block, it seems like a helluva way to get yourself into a low-buck Miata.

It's a no-brainer as long as you don't see it as a colossal PITA (it would be for me, but I'm a sucky mechanic)

It's possible the seller didn't know jack crap about the car, and thinks he did more damage than he actually has. After replacing the hose and battery, I'd do a compression/leakdown test to see if the engine was even damaged at all.

...although $280 for a 40k motor is a really sweet deal.

Yeah, it seems the BP from the Escort is pretty common. The same yard that has the one with 40k miles also has two others (77k and 110k I think). All are $280. That yard is about 80 miles away so I may see if I can find one closer. We'll see.

I'll definitely do the hose and battery and see for myself how bad it is.

Salanis wrote: After replacing the hose and battery, I'd do a compression/leakdown test to see if the engine was even damaged at all.

+1. First determine if there's any damage at all. Besides the compression test, do a pressure test of the cooling system. You might be good......

buy that $280 dollar motor AND see exactly what's wrong with the one already in there.

While you're at it, get the cams reground.

Do it!

Got the car home last night. Really dead battery. I tried to charge it and found there is an aftermarket alarm installed causing the hazzards to blink, etc. I removed the alarm, charged the battery, and generally started cleaning it up. Didn't try cranking it yet as my toddler was asleep one room away, but I did pull the plugs. Lots of oil on the plug threads in 2-4. I'll try and crank it when I get home. I'm thinking the crappy alarm system was causing the starting issue as it did cut power to the ignition. Other than alot of dirt and gunk, everything electrical seems to be working (radio, windows, etc). It's even got 3/4 tank of gas!

Cell phone pic while waiting for AAA:

I miss my miata...

Isn't oil on the threads just a leaky valve cover gasket?

I thought about that, but I didn't see oil down in the hole and wouldn't there be oil on the rest of the spark plug? I'm learning as I go. I'll know more after a compression and leakdown test today...

If there was just a little bit pooled it could have been too little to notice and then when you pulled the plug it ran down on the threads. you're on the right track, I'm just telling you that shouldn't make you nervous.

OIl on the plug threads is pretty typical for a bad valve cover gasket on a Miata.

confuZion3 wrote: While you're at it, get the cams reground. Do it!

what does that do? Do you do that for performance? alter the profile or just do it to stock spec to eliminate any wear? Do they weld overlay the cams before they machine them??

I'd love to know :)

Honestly, Miata head gaskets are amazingly strong. I've had those cars pretty hot without damage. In this case, I'd check the compression. If it's bad, pull the head and get it shaved for a bit of a compression bump as well as avoiding the potential of a warped one. Reassemble and enjoy. Shouldn't cost much and it's easy.

Well, an update for anyone who cares. As I thought, it cranked right up with a charged battery and removal of the cheap alarm system. It does smoke out the tailpipe. It also smokes off the engine, but that is a leaky valve cover near the CAS. I'll be replacing the valve cover gasket soon. No bubbles in the coolant while running or anything. Can't tell for sure if the smoke at the tailpipe is oil or coolant, but I'm guessing coolant (based on smell, residue at tailpipe, etc. not sure though). It's got a pretty loud tap from the valve cover, but I'm guessing that's the lifters as my 93 does the same thing off and on. This one's louder than my 93 though. The weird thing is the compression test I did. Warmed up engine, disconnected coils, pulled Fuel Inj fuse, and ran test. I forgot and left the throttle closed and got 180psi on all 4 cylinders. This is my first compression test and tomorrow I'll redo it at WOT, but I was sure the numbers would be lower. From what I've read online opening the throttle will just give higher numbers. I don't have enough experience with compression tests to know if it's getting up to 180 quickly or slowly, but I'm only cranking it 7-8 times. It's at 180 after 3-4. I'm hoping to do a leakdown test in the near future, but I don't have the tools yet. Working on that. Thanks for all the helpful advice everyone!

Another positive note, while running I checked the AC and it works great. Better than my 93!

Normal is 193 psi min is 135. Your compression seems good and consistent, I wouldn't worry about a leakdown test. Personally, I only do those when I know I have bad compression and I'm trying to pinpoint it to blown rings, valves, or HG.

My miata had the same overheating issues too. When I first went to look at it, the owner had it idling for 45 minutes and didn't realize that it had no coolant (in his defense, he was selling it for a neighbor and). Put in some 50-50 and hasn't overheated since.

Check your oil level too. I had a pretty loud tick in mine and on a whim, I pulled the dipstick and discovered to my horror that it was bone dry. Put a couple quarts of 10W-30 in, and it went away by the next day. This is truly a tough motor to survive such abuse.

Even if your oil level is good, some Miatas will start to tick to alert the owner that it's time for an oil change.

Yeah, my 93 starts to tick after 2500-3000 miles. It's the perfect reminder it's time for an oil change.

Well, another update and more positive news. I discovered the leaky valve cover was likely caused by ALL of the valve cover bolts being finger tight... yeah. So I tightened those up. I guess someone was taking a look under there and didn't exactly button it back up. Hopefully that will help fix my leaks. Oil level showed way over full so I drained a quart and it still shows well over full. I'm going to drain it all and put in new (correct amount) oil tonight. We'll see if that helps with the smoking from the tailpipe. We'll see. And I can't find a coolant leak. I'm not wanting to run it much though until I get the oil changed. Also, found a new in wrapper Felpro head gasket in the trunk. Sells for $60-80 new so that's a nice find. And the only bad news, the "tick" is starting to concern me. It's loud and I'm thinking it might be more than the lifters. We'll see. Again, I'm hoping the oil change will make a positive difference.

If you're worried it might not be lifters, you can check the state of the existing ones with a feeler guage. IIRC, you can replace them with ones for a 1995 Kia Sephia GS for fairly cheap each.

Or.... i have an extra BP head i would let go for cheap.