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1974 Ford Mustang leaking oil

My 1974 Mustang ii is leaking oil pretty bad. It nearly seized up, so I can’t drive it, but it does start and run ok. I checked the undercarriage, around the oil pan, and many other places I don’t know the names of yet, but I cannot find the exact leak. Does anyone know of a place that these cars may have leaked from in the past? Or any simple places I should first check? Thanks!

It would take too long to list all the places that could leak on this old car. Also I suspect you are not checking your oil on a regular basis . Nearly seized up but starts and runs OK - just a little contradiction there. Just clean off everything as well as you can then watch for leaks.

So I will provide a little more background for anyone interested in my OP. The car may be old, but it only has about 1500 original miles on it, is in really good shape considering it’s age, and ran great before this leak started. When I first purchased the car from the previous owner a few months ago, there were no leaks of any kind. The first thing I did was fill the car with fuel, adding a bottle of fuel system cleaner, and checked the oil to make sure it was good. It had a good 4-5 quarts in it when I purchased the car, and had no signs of leakage. I was driving home from town (about 5 miles) and noticed that the engine cool/hot gauge was starting to move toward the ‘H’. Then the engine was starting to run poorly, so I slowed down, and coasted my way home. Just as I arrived home, I noticed a very faint knocking sound, which led me to believe that the engine may have been close to seizing. Upon arriving at home I checked under the car and noticed a small leak, black in color, and coming from what appeared to be the oil pan area. After letting the engine cool for most of the day, I checked the oil and it still had about 2 quarts in there. I was also able to start the car and the engine ran smooth again, but I’m afraid to drive it without potentially causing further damage. So rather than assuming I don’t check my engine oil, can anyone help me in determining where the leak may be? This is a project car for my son and I, so if possible I would like to determine where the leak is without taking it to a garage. I cleaned the underside of the car, and there are no more new leaks, which leads me to believe the leak occurs while the engine is running. I just can’t seem to pinpoint it. Thanks again.

You started a car that you think only had 2 quarts of oil in it . That alone tells me you may be in over your head in this project. Only has 1500 original miles on it , are you certain?

You’re looking at a car that’s 24 years old…It could be the oil pan leaking, it could be the seals leaking, it could be burning the oil…I wouldn’t start it again without making sure the oil is topped off. It might be worth adding some UV dye to the oil after you top it off, then use a UV light to help find the leak

A rear main crankshaft seal leak is common on old engines from that period and would leak at that rate.

Remove the engine, then the oil pan and inspect the crank and connecting rod bearings for damage. You might also find pieces of the camshaft sprocket and valve seals in the bottom of the oil pan and blocking the oil pump pick-up screen so while you have the engine out to reseal it you may find other needed repairs.

After replacing all the engine seals clean and repaint the engine before installing.

Perhaps you could post a picture of the engine so we know which engine we are talking about.

Yes, I’m certain that it only has 1500 miles on it. The car had been in storage and a garage for a long time. I’m not in over my head, just asking for guidance from people in the community. Also, I never stated that I ‘think’ it had 2 quarts of oil in it; I checked the dipstick level after the engine had cooled, and the level on the stick was enough for me to ascertain that it had about 2 quarts in the engine. And while I understand it isn’t enough to safely run the vehicle on, I had filled the engine oil, started the engine for a couple of minutes to listen for unusual sounds, then turned off the vehicle again. The car hasn’t run since then.

Thanks Nevada_545. I actually had that same thought about the crankshaft, although I’m not seeing signs of evidence that it is leaking from there. I’ll do a more thorough check in that area and see what I can find. I’m thinking maybe an engine rebuild is in order soon.

Thanks pyrolord314. The oil is topped off now, and I haven’t started it again. I didn’t even think to try a dye to check for new leaks, I like that idea. Simple and effective.

If there really is only 1500 miles on the car the engine shouldn’t need to be rebuilt, just resealed. Also I would expect the engine to be clean enough to see where the oil is leaking from.

Just throwing out a thought, maybe full synthetic oil might swell the seals!

I notice you typed a LOT about your situation but told us nothing about the car but the number of miles. How about the engine? 2.8 V6 or 2.3 liter 4? Or a rare Mexican 302 V8? Automatic transmission or stick shift? It matters a lot if you want us to help.

Also wasn’t 1974 basically a Mustang II on a Pinto frame ?

Yes you need to locate the source of the oil leak, the sending unit if applicable would be something to look at.

Agree with barkydog. I had a oil leak on my truck last year, took a while to find it . It was a leaky sendind unit that only leaked under pressure while I was driving it .

Check the oil pressure sending switch/unit near the oil filter.

When these fail, they can leak at a pretty good rate.


Yup. The Mustang II, as it was known, was a Mustang’ed Pinto that carried the Pinto motors, 2.3L OHC 4 or the German Ford 2.8 V6. Started in 1974. The only year without a V8 - unless you have one of the Mexican models with a 302 V8. In '75 the US got the V8, too.

Generally ignored by Mustang collectors and enthusiasts because it was a pretty gutless car in a gutless era FOR cars.