I have done a search for a day now. Can't find anything to help.

The car is a 1988 Formula 305, 5 spd. Just rolled over 101k.

I have an oil leak on the drivers side rear of the block. I removed the oil sender, cleaned it up, applied some thread sealant and re-installed it. Took the car out for a drive. When I got back there was still a leak and it was not from the sender. So I have ruled that out.
I can't feel any oil around the valve cover, the rear of the intake, or the distributor base. I did, however, notice that the AIR tube that runs behind the engine is a bit oily.
There are two drips. One is at the bottom of the bellhousing. The other drips off of the clutch cylinder bracket. It is not the clutch fluid dripping. I am confident that the rear main is not leaking because most of the oil drip is external and the clutch is not slipping.
Where might this be coming from?

 

The intake could be leeking

 

Candidates include the intake manifold, distributor, and oil pressure sender.

Just because you put thread sealer on the sender doesn't rule it out. Cracked pipes/senders/fittings are quite common.

 

It could also be your oil cooler (if you have one). It's a common leak and easy to fix!

 

I have felt the back if the intake, and the distributor and both are dry. I have looked at them with a mirror the best I can too.
I cleaned off the area around the sender before re-installing it. After taking it for a drive and there was no oil around it but the leak was still there so I know it wasn't the sender.
I'm wondering if there might be a crack somewhere because I can't pinpoint the source. The mirror isn't too helpful and my hand just won't fit all the way behind the engine.
Wherever it is it is getting worse. It drips about once every second. It just seems to me that it would be easy to spot with a drip like that but I am having no luck.
Are there any plugs on the back of the block that could cause this?

There is no oil cooler on it. Though I have thought about it.

 

I have had a difficult time tracking down the different leaks on my 89 Formula 350. The mechanic that worked on my car did mention something about plugs or something like that on the back of the block. In my case, he stated he used silcone or some type of sealer on them. They were not leaking very much according to him. My biggest culprit was the rear main. It had dried up from sitting for so long. I had about every gasket and seal replaced trying to track down the various leaks. It can be very exspensive and frustrating, good luck and sorry I couldn't be more help.

 

might not of been the smartest thing to reuse the sender. it's common for them to leak at places other than the threads

 

I intended to replace the sender but the parts stores didn't have the right one. In any case, I did not find any leaks on the sender after the test drive. If it is leaking it is so slow that it is not noticeable. I am certain the sender is not the problem.

I think I will just jack the car up and get the engine as sparkling clean as I can and see if that helps trace it.

 

Well I got it cleaned up last night. Every spot that I could reach is now oil free. I can run my finger across the block and a very light, dry residue is all that remains. Hopefully I will be able to find it now.

 

I had a chance to check it all out last night. It looks like it is coming from the valve cover. It is right next to the exhaust manifold so it I couldn't see it or feel it from the top. Cleaning the block helped a lot. I couldn't tell from below before because the rear left of the block had an oil film on it. With it all cleaned up, however, there is a clear trail coming from the area directly above the manifold. Must be the valve cover gasket!

 

Well, it's not the valve cover. It was leaking but it's not the one I was looking for. So I guess I'll clean it up again and give it another shot.

 

I finaly found it! Feeling, and looking were all leading to dead ends. So I just started to take things apart. Starting with the easiest to remove, logical source of the leak, I took off the other oil pressure switch. The one just behind the intake manifold. It wasn't wet with oil. No visual indications of an oil leak could be seen and I couldn't feel all the way around it. Once I got the electrical connnector off I could see some oil right on the top of the switch. So I picked up a new switch, replaced the old, and there is no more leak. I guess the oil was dripping off of the switch right onto the back of the block so it left no visible trail from the switch, making it difficult to trace. The switch is mounted at an angle so this must be why I couldn't find it.