Source of Unknown Fluid Leak

[millaj01]

Hi Guys,

Have a '93 GS with 137000 miles. I just started to notice a fluid leak of some kind that appears to be originating near the rear underportion of the car. Say, underneath the gas tank area maybe. I can't tell where it's coming from and I'm not in the best position to be able to jack the car up soon to see what's going on. Odd thing is it has the appearance of a normal oil leak as you'd see under the front of the car near the engine. But this is obviously not coming from that area.

The fluid in question is black and oily. It's not a ton of fluid, but enough to leave dark spots under the car on asphalt. I'm pretty ignorant in specific areas of our cars, otherwise maybe I'd have a better idea what the source might be. Any ideas what I might be looking at?

Thanks for the help!

[Daninski]

Could be rusted brake lines if it's on the drivers side.

[millaj01]

Thanks for the reply-

What I saw today was driver's side...but it appeared more towards the center when I noticed it before that. I was perhaps going to guess at brake fluid as the source, but I didn't expect that it would be blackish in color? I guess I'd see a reduction in fluid in the brake fluid reservoir too as a way to confirm, right? I'll have to check that.

Now I'm a bit nervous about driving the thing home today

[Mooneggs]

do you have leaks anywhere else under the car? could it be an oil leak dripping down on something then running along the exhaust or something?

what does the fluid smell/feel like? there's only a few fluids it could be:

power steering fluid
brake fluid
tranny fluid
oil
gas
coolant/water

[millaj01]

I've had small oil leaks from under the engine before, but not anything I've noticed recently. The small 'pool' I noticed this morning was very odd. The main portion of the liquid was clear (not rainwater), but mixed on top of that was the dark, brackish, oily liquid. I smelled the dark liquid, and it was somewhat nasty smelling...felt like some type of oil/lubricant.

One other item of note. I've suspected a gas leak somewhere for quite some time. I keep the car outside 99% of the time, but when I've garaged it overnight there is the strong smell of gasoline in the air come morning. As a result, I had a Mazda dealer look at the gas tank itself for leaks, but they didn't find anything. I was going to take the car in again soon for winter prep and have them look for something again.....a leaking fuel line? If so, what would the darker, oily liquid be?

[Mad Cow]

Maybe the rear washer tank is leaking and the fluid is mixing with and slightly dissolving grease and dirt or something. Take out the tank and check for anything wet on the bottom or rust under it.

Or it could be gas leaking and doing the same thing.

[onlytrueromeo]

Gear oil is about the nastiest smelling fluid on any car (if it a manual)

[millaj01]

Just posting a follow-up to this issue of mine. Had some stuff done to the car to prep it for winter and had the local mechanic look at it.

Basically it appears the oily spots I was seeing as leaks were a result of a small gap in part of the custom exhaust I have for the car. I have a KLZE with the proper ECU, but this combo runs rich by default....I get sooty exhaust as a result and my exhaust pipes have blackened over time. I know this is a common complaint by KLZE owners. So, my guess is that after some time this sooty discharge was building up in the exhaust and then leaking out through the gap.

Seemed like a reasonable explanation to me. My guy spot welded the area so I'm going to try and see if that did in fact do the trick.

[Mad Cow]

Just posting a follow-up to this issue of mine. Had some stuff done to the car to prep it for winter and had the local mechanic look at it.

Basically it appears the oily spots I was seeing as leaks were a result of a small gap in part of the custom exhaust I have for the car. I have a KLZE with the proper ECU, but this combo runs rich by default....I get sooty exhaust as a result and my exhaust pipes have blackened over time. I know this is a common complaint by KLZE owners. So, my guess is that after some time this sooty discharge was building up in the exhaust and then leaking out through the gap.

Seemed like a reasonable explanation to me. My guy spot welded the area so I'm going to try and see if that did in fact do the trick.

What ECU/VAF combo are you running? A proper combo won't give you any soot.

[millaj01]

What ECU/VAF combo are you running? A proper combo won't give you any soot.

I'm running a KL31 ECU with the stock VAF. If I switched the VAF would I be better off?

[Mad Cow]

The stock VAF is a JE50 if I remember correctly, so it's the right one. That's really weird then.