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Login to post Forums » Grassroots Motorsports » Miata "Oil Leaks"?

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Dec. 19, 2008 11:02 a.m. Salanis SuperDork

Okay, I have a really good opportunity that got presented to me. Coworkers know I'm into autosports and Miatas, so...

Friend of a coworker is selling a '97 Miata for $500. It is apparently in good running order, but has an oil leak. What are the most likely causes for an oil leak, that I should look for on this car?

My initial thought is a worn out crank or cam seal, or maybe a dead valve cover gasket. In which case, all the car needs is a timing belt job. Otherwise, maybe an oil pan gasket?

The car was the DD for the friend of a Coworker. She stopped driving it because she just had a kid. So this should be in good condition otherwise.
Dec. 19, 2008 11:06 a.m. jeffmx5 New Reader

I'm sure Keith will chime in soon, mine (1990, 140k mi) leaks seemingly everywhere! I think it is the oil pan gasket and/or front seal. Probably both.
Dec. 19, 2008 11:29 a.m. Type Q HalfDork

The other oil leak areas in Miata engines I know of are the Cam Angle Sensor (CAS), the "Half-Moon" seals at the front and rear of the oil pan, and occasionally, the headgasket will leake where the oil passages go through it. IIRC you have pull the engine to drop the oil pan and replace the associated gaskets and seals.
Dec. 19, 2008 11:30 a.m. Keith UltraDork

Most likely leak is a cam angle sensor, does a great imitation of a rear main seal leak but can be fixed much more easily.

Valve cover gaskets will go eventually and are easy to change and diagnose.

Front crank seal is probably the next popular place to leak, and it involves pulling the timing belt to fix. Rear mains are uncommon, it's usually a cam angle sensor o-ring drooling down the back of the head and getting into the bellhousing.

The oil pan is sealed with silicone except for two half-moon seals at the ends. Rarely leaks. Good thing, it's a royal pain to fix. It's possible to pull and replace the oil pan with the engine in the car, but the front subframe has to be dropped and you'll be fighting constant oil drool. My recommendation in that case is to pull the engine and go through the whole thing. But it's rare.
Dec. 19, 2008 11:36 a.m. GregTivo Reader

$500 '97 Miata. I'd be over that even if it didn't run!!!
Dec. 19, 2008 11:38 a.m. Salanis SuperDork

So, already having a Miata in good running order, where should I look for the oil leaks? In which locations is it worth my time to bother with, and in which locations is it not worth it?

Keep in mind that I live at an apartment and do not have a garage. A timing belt change is about the extent of what I want to bother with. I do not want to have to pull the engine.

Sounds like, if the oil is drooling down the back, or coming out from the valve cover, I should be good.

It also sounds like, if this things was a DD not long ago, that it isn't a very fast leak. I presume that's a good sign.

Thanks for the input Keith. You rock.
Dec. 19, 2008 11:40 a.m. Salanis SuperDork

GregTivo wrote:

$500 '97 Miata. I'd be over that even if it didn't run!!!

If it has a Torsen and a decent top I definitely will be. My car needs a new top. I have an open diff just sitting around, I can swap that and sell the Torsen for a couple hundred. Get a newer top out of it. And sell the car for at least what I bought it for.
Dec. 19, 2008 12:13 p.m. Keith UltraDork

Where to look? Slide a piece of cardboard under the engine and see where the oil lands. If it's dripping at the back, it's probably CAS. Feel under the CAS to see if it's wet. Definitely worth your time to fix, it's easy. Do the valve cover gasket while you're at it, it's easier to pull the CAS with the valve cover off and you'll find the gasket is probably solidified. Total time: about 20 minutes the first time you do it. Tools: 10mm socket and 12mm wrench from what I recall.

If it's dripping at the front, it's probably a front crank seal but they usually just weep enough to make a mess of the oil pan. Definitely a higher effort change, but if you're going to do a timing belt then do it.
Dec. 19, 2008 12:22 p.m. Salanis SuperDork

I'm presuming this has been sitting for a little while.

So, bring a sheet of cardboard, start the car up and see where it starts leaking? Check the locations you indicated for oil leaks?

It should be obvious if it's the oil pan, right?

Geez. I'm sick. I'm really sick that I feel compelled to buy a car the same as what I already have because it's "too good of a deal". But it is!
Dec. 19, 2008 12:31 p.m. Keith UltraDork

It's unlikely it'll actually pee while running - if so, it's more of a leak than usual. I'm trying to think of a leak that involves pressurized oil as opposed to your basic seepage. More likely, sticking the cardboard underneath and leaving it there for a day will help you. If the car's been sitting for a while, just peeking under will probably answer the question.
Dec. 19, 2008 12:35 p.m. Type Q HalfDork

For $500 just buy it. If the CAS is leaking you can change that in the parking lot at your apartment. Then clean everthing up and sell on this board for $1000 or more. If it need something more labor intensive, you can use my garage. It sounds like its a better car than the MR2 you were encouraging me to buy earlier this year.
Dec. 19, 2008 12:35 p.m. Salanis SuperDork

So, ask the current owners to stick cardboard under it, and feel/look around the locations you said, and that should give me my answer?
Dec. 19, 2008 12:37 p.m. Salanis SuperDork

Type Q wrote:

For $500 just buy it. If the CAS is leaking you can change that in the parking lot at your apartment. Then clean everthing up and sell on this board for $1000 or more. If it need something more labor intensive, you can use my garage. It sounds like its a better car than the MR2 you were encouraging me to buy earlier this year.

Thanks! I think the only thing I wouldn't want to bother with is the oil pan. But it would still be worth the money in parts.
Dec. 19, 2008 12:57 p.m. Keith UltraDork

Honestly, if you really want to know, a bit of time with a flashlight well tell you. I'd buy it regardless.
Dec. 19, 2008 12:59 p.m. Salanis SuperDork

Keith wrote:

Honestly, if you really want to know, a bit of time with a flashlight well tell you. I'd buy it regardless.

Cool. Sounds like we have a plan!

Thanks for the advice and support all!
Dec. 19, 2008 2:10 p.m. Woody Dork

I think that if a 97 has power windows, it's safe to assume that it also has a Torsen.
Dec. 19, 2008 3:13 p.m. Salanis SuperDork

Woody wrote:

I think that if a 97 has power windows, it's safe to assume that it also has a Torsen.

That's my understanding. I'm going to double check the options packaged with that. I'm trying to remember what tests work to identify a Torsen. "In gear, one wheel held or on the ground, try to spin the other wheel" works, doesn't it?
Dec. 19, 2008 3:51 p.m. Keith UltraDork

I don't think an open diff will spin in that situation, will it? The best way to test for an LSD - any LSD - is to put the drive wheels on different surfaces and hit the gas. Or call Mazda with the VIN.

Good rule for 1994 models, but 1997 "Touring Package" cars did not have a Torsen and had power windows. Check for a rear subframe brace. If it's there on a 1997, then so's the Torsen. Automatic cars are an exception as always.
Dec. 19, 2008 4:00 p.m. Salanis SuperDork

According to charts on Miata.net... either Power antenna or all the 'R' package aero bits will let me know it came with a Torsen.

I swear there is some version of the "spin the wheel" test that works on Torsens, but it's a goofy version. I just can't remember what it was. Like... they can't be spun opposite directions or something.
Dec. 19, 2008 4:09 p.m. Capt Slow Reader

life isn't fair,why is it that:
Guys who are rich, win the lotto
Guys who have hot wives, have hot girlfriends on the side
Guys who have miatas, find the $500 miatas- that run

nice find
Dec. 19, 2008 4:43 p.m. Salanis SuperDork

I just found out that it was already sold. Damn.
Dec. 19, 2008 4:44 p.m. Jensenman UltimaDork

In current news: I hate you so much.

For $500, just buy the damn thing. Le Mons, anyone?
Dec. 19, 2008 4:48 p.m. Capt Slow Reader

I wish I could say I was the one who aced you...
Dec. 19, 2008 4:56 p.m. Salanis SuperDork

Capt Slow wrote:

I wish I could say I was the one who aced you...

Me too! Then I'd at least know it was going to be put to good use!

And, I'd finally be able to see you out at track days.
Dec. 19, 2008 5:50 p.m. Keith UltraDork

If you're obsessed with spinning wheels, putting some drag on one wheel might test a Torsen. They will behave exactly like an open diff normally if there's no load on one wheel.

I didn't go to the Miata.net listing, I went to Mazda Miata: Find It, Fix It, Trick It because I know the guy who did the research found a few errors in some of the Miata.net stuff and because I like being able to isolate one thing - the rear subframe brace - instead of an either/or situation. My brain doesn't remember those sorts of details anymore.

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