[rtuey]

I would very much appreciate your thoughts on the source of a major oil leak on my 3.0L engine (+230K miles). I had just replaced the gaskets/seals in the oil return tubes, and tightened down the valve covers in prep for a trip to Driver's Ed at Streets of Willow. Prior to the trip, I had not been seeing any drips on the garage floor. The DE went fine, and I made the 81 mile trip home without issue. I stayed in 3rd gear during each of the 4 runs, and don't think I exceeded 4500 rpms during each run session. There are only two sections of track where I could get much speed.

The oil level during the DE was a bit above the lower mark when cold. After the DE, I added 1/2 qt.

The next morning, I saw a pool of oil on the floor. I didn't have a chance to look for the source, but I threw cat litter down to absorb the oil. The next day, I saw an even larger pool of oil. I believe about 1/2 to 3/4 quart leaked out.

To try to reproduce the event, I put the vehicle up on 4 jackstands and let the car warm up at idle to the above the 1st white bar. I looked under the vehicle while it was running, but did not detect any leaks. The following day, I saw some minor drips. This past weekend, I ran the car on the stands up to 4000 rpm several times for about 15 seconds each time. After letting it cool for a day, I took pictures of where the oil appears to be coming. It seems just past the #6 cylinder oil return tube. Note the very oily area to the left of the oil return tube.

In the 2nd picture, there is oil found on the back of the heat exchanger. When changing out the oil return tube seals, I had cleaned up the bottom of the engine, and the heat exchangers - so this oil is mostly new.

Today, I drove the car to work (about 2.2 miles away). There were only a few noticeable drips underneath the car after the work day.

Your thoughts on where the leak is at, and how to repair it would be appreciated. It would not surprise me if it requires an engine drop replace the offending gasket(s).

[Trak Ratt]

Hard to tell after the clean up but the oil at the back of the engine on the right side could be coming from the seals for the engine mounted oil cooler, sending unit at the top back of the engine or the breather. Also, on the top back of the engine. 1/2 quart over night is a lot!! Not leaking all the time is a puzzel.

BTW, while reading the first part of your post I originally thought the new oil tube seals were leaking. <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o></o>

[OldTee]

Get one of these oil leak detector kits. http://www.google.com/products/catal...d=0CH8Q8wIwBg#

You can find them cheaper than this.

I packed mine away or I would loan you a shot. I have used it several times to locate leaks.

I am afraid you might have a cylinder base leak or your cam tower may be leaking. but you may get lucky and find your rocker seals are shot. If cam tower it may be leaking out the back from the area around the rear rockers. Or you may have an oil cooler seal leaking.

ARF
Here is a cheaper kit


second edit. When you shine the light on the area it will glow but the leak will show as a bright greenish line. The fluid won't hurt your oil or engine.

http://www.google.com/products/catal...d=0CDUQ8wIwAw#

[rs911t]

The kit with the UV light pen works well, though you can find them for much less than $120. The breather and oil sender at the front of the engine are notorious for leaks, as are the seals for the cooler. But 1/2 to 3/4 quart is an awful lot of oil, particularly when the car is sitting. Did you overfill after changing the o-rings? The sump and oil tank plugs tight and to spec? New gaskets? Check the valve covers, too. Did you install new gaskets? Are they torqued too much, too little or unevenly?

Oh ... and run it to redline at the track. These engines really are happier when run hard.

[Chopper Dropper]

Just a guess from the phot, but it could be the oil cooler leaking, been there done that!!
Dirk

[markwemple]

I too am guessing oil cooler. You'll want to check the seals but you may also want to have it pressure tested. How's your oil pressure in normal driving and how was it at the track?

[rs911t]

Originally Posted by Chopper Dropper

Just a guess from the phot, but it could be the oil cooler leaking, been there done that!!
Dirk

Yeah, should have suggested that considering the time I used the UV pen to search for leaks it turned out to be the oil cooler itself.

[rtuey]

Thanks for the excellent suggestions. I have an a/c leak detector kit, and have ordered the dye compatible with motor oil. I suspect it will point to the oil cooler as the culprit, though. Here are my new questions:
1) Can I remove the oil cooler without taking out the engine? The Bentley's doesn't discuss the oil cooler. Dempsey's book mentions it as a source of oil leaks that can be replaced with the engine out.
2) What are the steps to removing the oil cooler?

On a slightly different tack - how many inches off the ground do I have to lift the body to remove the engine? I don't have a lift in the home garage; the jack stands don't seem to go very high; and my floor jack doesn't make it past 19"

[rs911t]

The experience with my '72 is yes, the oil cooler can be removed without dropping the engine. It was a pita, but doable. I believe it was made easier in later years by making it easier to remove the ducting. But ... having since removed the engine a few times ... I think even a partial drop would make the job much easier. It's a trade off. Don't drop the engine and you must remove the intake etc. Drop the engine and I don't think you'll need to remove the intake. Gotta drain the oil either way. Partial drop? May not need to disconnect the axles or remove the intake.

[OldTee]

Lower the engine 6 to 8". Use care with the electrical harness and fuel lines. Go slow. Once the baffel is off removing the cooler is easy.

ARF