Left oil cap off engine overheated [Archive] (2024)

MX-5 Miata Forum > NA/NB (1990-2005) Miata > NA (1990-1997) General Discussion > Left oil cap off engine overheated

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graylevison

21st October 2017, 22:44

Hey all, I've had my 1994 Miata for 2 1/2 years now and loved every minute of driving it until I recently overheated on the side of the interstate...I didn't realize I was overheating until I couldn't accelerate anymore and slowed to a stop. I opened the hood and realized I forgot to put the oil cap back on after adding oil earlier. I'm scared to death the engine may be seized and useless... I know the starter needs to be replaced because I was having trouble with it before. When I was driving I didn't hear any noises or anything different from a typical "coolant loss" overheat. When I tried to start it after cooling off, all I heard was a click but it didn't turn over. What do you guys think?
ANY HELP IS GREATLY APPRECIATED!!

jkelley

21st October 2017, 22:46

Is there any oil showing on the dipstick?

First thing I'd try (if there is oil) would be to turn the engine over by hand (21mm socket on the crank nose bolt).

graylevison

21st October 2017, 22:48

Yes, there is oil showing on the dipstick but its thick and very black.

3MiataFamily

21st October 2017, 22:53

And most likely oil everywhere under the hood...got some cleaning to do

DJJ

21st October 2017, 22:53

When was the last oil change? (miles)

graylevison

21st October 2017, 22:55

I replace the oil about every 3000 - 4000 miles...I've always tried to take really good care of it.

graylevison

21st October 2017, 23:19

i even add sea foam sometimes

DJJ

21st October 2017, 23:32

With 3 or 4k miles on the oil it should not be thick and black. As Jkelley said, try turning it over by hand. From the symptoms, it sounds like something like low oil or low coolant caused it to severely overheat. It doesn't sound promising.

graylevison

21st October 2017, 23:39

will I be able to turn it over manually even though I have a bad starter? The starter needed to be replaced before this incident.

22nd October 2017, 02:23

Start your search for a good used engine. I wouldn't waste any time or money on that one. :(

pacomutt

22nd October 2017, 02:24

Give Treasure Coast Miata a call. They can probably point you in the right direction on finding an engine.

gtxhawaii

22nd October 2017, 05:32

Besides the remote doom and gloom to trash your engine, actually try the suggestions above to hand rotate the engine. NOT with a cam sprocket bolt, but the crank bolt on the front end of the crankshaft. A 13/16ths? socket and 1/2" ratchet works. I don't have metric sockets big enough, so I use the one that fits from my SAE 1/2" set.
Miata blocks are STURDY, and difficult to damage. Bores scuff if the pistons got too big, or the ring end gaps were set tight. Otherwise a good head or work on the one you have is normal for a repair, if the present head is actually warped. Sometimes the gasket blew but the head didn't warp. That you heat seized it isn't hopeful for the head, however. If the engine turns over by hand, I'd try starting it with good oil inside. Sounds like it may take a new starter, but several issues much cheaper act like a failing starter. A dirty ignition switch, for one. So may a low battery or dirty battery connections.
Taking the head off is free, at best a new gasket is in the $75 range. At worst you learned a lot about Miatas, and are looking for a different engine.

pacomutt

22nd October 2017, 09:53

Besides the remote doom and gloom to trash your engine,.....

Not really remote doom and gloom, but the engine is already trashed! He lost enough oil to overheat the engine to the point that the little remaining oil has been turned into black tar. The engine continued to heat causing the cooling system to fail. The car was further driven until it could no longer make power, and seized. Most of us know what this means. Some of us who are as familiar with working on engines as we are tying our shoes might open this engine up just for fun. But not for the hope that it will ever run right again.
Next, there's the OP. With questions wondering if an engine can be turned over by hand, where to find the crankshaft bolt, turning the "cam head screw", etc., do you really think his time is better served by playing around with this engine, or sourcing a good, used engine? There are a lot of Miatas in Florida, and lots of places to source an engine as well.

wallijonn

22nd October 2017, 10:27

... I couldn't accelerate anymore and slowed to a stop.

Auto or manual tranny? If a manual, then chances are the timing belt broke.

If you did over heat then there's a very good chance you warped the heads. You could just replace the head ($$$$) but if your engine has a lot of miles on it, say over 150,000, then it is probably better to just replace the engine. There is probably a place where you would have a JDM engine installed for a reasonable price. You're probably look at about $2500.

gtxhawaii

22nd October 2017, 10:38

All good points about the OP's general unfamiliarity with engines. And resistance to following directions. But I still recommend inspection before trashing.

pacomutt

22nd October 2017, 10:46

All good points about the OP's general unfamiliarity with engines. And resistance to following directions. But I still recommend inspection before trashing.

Make you wonder why people are still resistant to an overheat warning light, doesn't it? :dunno:

paul e

22nd October 2017, 12:22

Well he says he’s mechanically inclined but doesn’t know where the crank bolt is, among other issues. I think he needs to reach out.

wallijonn

22nd October 2017, 12:52

Does the '94 have the Idiot Light instead of an oil pressure gauge?

Gray, did you "bury" (peg) the temperature gauge? If so, for how long?

huesmann

22nd October 2017, 12:54

No, '94 is the last year with the real OPG.

NoahsMyBro

22nd October 2017, 15:52

I think mechanically inclined is a relative term, and different people may judge it differently.

The OP has said he has the time and resources to work on the engine. It might be worth it to him to try opening the engine up to examine and attempt repair, even if the process will be longer, more costly, and/or result in a lesser engine than if a pro replaced the engine.

The experience gained might be worthwhile.

Back in '96 or '97 I blew the head on my '92 Saturn. I 'rented' my buddy's old heap for $100 and drove it while I spent 5 or 6 weekends taking my Saturn apart and re-assembling it with a new head. I can't even begin to describe the feeling of fear and dread when I sat down to try and start the engine the first time once we put it back together, or the feeling of joy, pride, and relief when it started right up and ran *perfectly*.

A few weeks later the engine was leaking oil in at least a few spots and I gave up and had the dealer re-replace all of the leaking gaskets.

At the end of the day, after purchasing tools, supplies, and recovering from mistakes I ended up spending pretty much exactly what I'd have spent if I just had the car towed to the dealer and let them replace the head in the first place, but I am glad for the experience and stories and wouldn't go back and do it differently.

Could be that the OP is willing to give this a try and accepts that it might not make sense from a pure dollars and cents perspective.

graylevison

22nd October 2017, 16:56

Well for one thing, my miata's oil gauge is non-functional so I had no idea I was low on oil. I would have pulled over immediately but was on the interstate....and when I say "mechanically inclined", I mean I do all my routine maintenance and change out parts once in a while...I have not dealt with a part of an internal engine as crucial as the timing belt or camshaft.

graylevison

22nd October 2017, 17:04

I think mechanically inclined is a relative term, and different people may judge it differently.

The experience gained might be worthwhile.

A few weeks later the engine was leaking oil in at least a few spots and I gave up and had the dealer re-replace all of the leaking gaskets.

Could be that the OP is willing to give this a try and accepts that it might not make sense from a pure dollars and cents perspective.

Yeah...I think you understand more of where I'm coming from than some of the other posters although I am grateful for all advice. I also have a 1979 MGB I bought non-running and absolutely loved fixing it up and enjoyed the personal satisfaction and mechanical knowledge I gained from getting it road worthy. Honestly, I don't see the point in selling it for scrap without at least exploring the problem a little further (it would be worth the same now as it would be if I did my own amateur investigation on the internal engine).

pacomutt

22nd October 2017, 18:48

Just one of many c/l ads in your area. You may be able to pick up an engine for around $300 or so for that car. No need to think about scrapping it.

https://orlando.craigslist.org/pts/d/1990-through-2003-mazda-miata/6353517143.html

Slushbox

22nd October 2017, 19:10

"Worst case (not impossible, but not a given), head and block overheated to the point off cracking and/or twisting out of shape. Rebuild or replace time."

The above is my favorite suggestion! In the last sentence, I am pretty sure that Jkelly meant: "It's time to rebuild or replace the engine." The way I read it was: "Rebuild or replace moments of time/space itself to get back to a point where this event didn't happen."

Ah! If only! :)