I’ve got an aging '94 Mercury Sable. I was under it last weekend replacing the starter motor (a task that’s worth it’s own Pitting, Plasticman must’ve designed the mounting bracket).
Anyway, while lying under the front end, just off the engine block on what I think is the beginning of the exhaust pipe, is a sensor screwed into the pipe. It has four wires running from it, three white & one black. Strangly, the black wire’s insulation was just shredded - lots of copper shining through - and the white insulation was in fine shape. Mostly out of curiousity, what is it?
While I’m at it, I there’s a lot of oil under my car’s usual parking spot. The oil-plug had a bead of oil hanging under it. The heads of the hex-bolts holding the oil pan (?, large, triangular, flat aluminum pan with “something Metric” stamped on it) also had oil on them. Do I need gaskets? Is this something I can do myself?
As for the oil thing, it may be as simple as getting a new drain plug with one of those special plastic washers that will seal it better. Either that, or the oil is leaking from somewhere else.
Chances are its your valve cover gasket(s) leaking and oil is just flowing down the block. The drain plug just makes a handy place for the oil to drip off, But to be sure you can put pipe tape on your plug the next time you change your oil
This sounds like your transmission oil pan. If it is, and the oil that is all over it is motor oil and not transmission oil, then I would look at the valve cover gasket like herman_and_bill suggested and while your at it, look into replacing the PCV valve.
They are simple to replace and will sometimes allow motor oil to be blown through them from excess pressure in the crankcase.
If your PCV valve is the cause of the oil drips (and you’ll see oil all over it and everything around it) have the compression checked - you could have blowby in one or more cylinders.
BTW - If you do any of this work yourself and you find yourself replacing gaskets, don’t overtighten the screws. Overtightening the screws and warping or buckling the cover, oil pan or whatever is the main reason leaks start in the first place. Overtightening can also cause the gasket, both rubber and cork, to be squeezed away from their sealing surfaces.
There is also a trick to repair an overtightened valve cover or oil pan if you wind up replacing the gaskets. I’ll try to post it soon.
The gizmo described is definitely an oxygen sensor. I’d tape up the exposed wire.
The pan described is definitely the transmission pan. If the oil has some redness, and there’s not a trail of oil from somewhere above the pan line, that would indicate the transmission pan gasket is leaking. If you’re really lucky, snugging up the bolts will help. I say snugging rather than tightening because, as zabrain mentioned, it’s easy to mess up the gasket and even the pan by overtightening them.
While we’re touching on the subject, there’s a proper procedure for tightening cork gaskets. Sadly, a lot of professional mechanics aren’t aware of it, causing some of them to hate cork gaskets:
The cork must be compressed in stages, and given time to set between those stages. It should take 15-30 minutes to complete the process. First, get all bolts finger tight. Then, lightly snug them. WAIT 5-10 minutes. Then, moderately snug them. WAIT another 5-10 minutes. Continue getting them progressively tighter each stage. Usually 3 or 4 stages are called for. When the cork STARTS to squish out, that’s the time to stop*. Once it’s overtightened (generally squishing out significantly, sometimes even splitting) the damage is done. Better to have it a bit loose, and snug it up a week later if needed, than to go too far.
*Some components (oil pans, valve covers, etc.) or their gaskets are designed with metal ridges or rings at the bolt locations, to prevent overtightening. On these designs, there may not be discernible squishing out.
FWIW, The oil under the car seems to be engine oil - it’s black not red. It’s literally everywhere. I’m tempted to take my car to a do-it-yourself carwash and hose everthing off. My worry, though, is that blasting water under the hood might knock something loose.
It needs lots of TLC - almost everything (except now the starter motor & battery) is original equipment. The transmission was replaced at ~60,000 miles (second Ford transmission failure out of four Ford vehicles) and the unibelt tension pulley has been replaced. (The car is 10 years old and has 121,000 miles).
A couple weeks ago, I filled it and had the very strong odor of gasoline in the cabin for the next 200 miles. Hasn’t occurred since but I’m certain I didn’t spill when filling up.
New coolant hoses are a need, I know. What should be my order of precedence assuming I can afford to dump some money into keeping this thing running?
Get a Haynes manual for the specific car. Look for information on maintenance schedules and such. This will tell you what is expected to be maintained by the owner.
You may not be able to do everything that is listed yourself, but you’ll know that a timing belt or something is expected to last so and so miles by the engineers.
Look at the car like it’s a box of Kraft Macaroni and Cheese - Just follow the directions.
Btw - of the things you mentioned, replace the hoses first. Hoses are too simple to replace to risk overheating your engine or scalding yourself on the side of the interstate. But, the manual will tell you more in detail reasons why this is important.