Major oil leak

[coldstart]

I have a slight problem with my 1972 911T-- I can now follow myself home by the oil trail. This oil leak started out fairly slow and I'm not positive of when it started.

I had addressed the usual few oil leaks a few years ago when I had the engine out. I also replaced the clutch and my mechanic installed a new rear main seal (I did most of the rest of the work). He was very meticulous and exact in the installation. Since then, I have had the car back to him 3 times for oil leaks (among other things) and he has replaced some oil line hoses and other components (some I had previously done, into the thousands...) that were weeping.

I am not bashing my mechanic as I know he is honest, fair and normally knows his stuff. He is out of ideas except for the main seal or the oil cooler. Either of which would require some serious work. As the car is laid up for the winter, I wanted to know if anyone had any suggestions to tackle these leaks.

Thanks for the help. These are my favorite forums! (favourite in Canada)

[ossiblue]

I take it from your post the leak is near the front (flywheel side), passenger side of the engine, is that right? Could you post a picture of the leak?

[kodioneill]

as ossiblue stated we need pictures. It would help if you clean off the engine then post pictures of the leak and give a good description of the area where you think it's coming from.

[Superman]

One of the most common and most prolific of 911 oil leaks is a failed oil thermostat o-ring. It is located in the engine case, on the top of the motor, roughly above the #6 cylinder. When this fails, the rear of the engine-mounted oil cooler gets rinsed with a large volume of fresh, wet oil. There is no way to mistake this for a failed rear (next to the flywheel) main seal. If a rear main seal fails, the oil comes out the weep hole at the bottom rear of the engine. Rear main seals on these engines rarely fail. When oil comes out of the weep hole, it is almost always coming past the transmission input shaft seal, crawling up the input shaft and getting onto the clutch assembly.

[jlex]

Isn't there a dye you can put in the oil that you can later detect with a black light? Would require you clean the case first, of course...
Hopefully, it's the thermostat gasket.... easy fix for the double-jointed

[docrodg]

There is a leak detection fluid for oil that uses a blacklight, and it can be very helpful. I have a decent rig for it that cost about 50 bucks and works great. One suggestion, if using the leak detector put it in the oil and start the car for just a minute or two at first to mix it in, then let it sit a while and see if there is a leak. If no leak evident then try idling and looking around - start looking right away so airflow does not have too much chance to blow it all over and turn the engine into a giant green glowing mess under the black light. DO not drive it until you find the leak or give up, as driving will definitely cause the green glowing mess as the stuff gets blown all over at highway speeds.

[dshepp806]

When you guys use the detection fluid, do you rid the systems oil with fresh oil, afterwards? Probably not, as this stuff is "passive"?

Curious, as I've never used it.

Best,

[docrodg]

Nah, Leave it in... it is passive. Plus having it in there helps to find leaks later.

[mossguy]

I have used this stuff and it was excellent! It pin-pointed the leaking around the oil level sender gasket when the whole oil tank was covered with oil, and also around the oil line connections. Here are some pics, but I don't have a good one under the car. The effect was as good as, or better than seen on the paper.

[vwmike911]

Originally Posted by Superman

One of the most common and most prolific of 911 oil leaks is a failed oil thermostat o-ring. It is located in the engine case, on the top of the motor, roughly above the #6 cylinder. When this fails, the rear of the engine-mounted oil cooler gets rinsed with a large volume of fresh, wet oil. There is no way to mistake this for a failed rear (next to the flywheel) main seal. If a rear main seal fails, the oil comes out the weep hole at the bottom rear of the engine. Rear main seals on these engines rarely fail. When oil comes out of the weep hole, it is almost always coming past the transmission input shaft seal, crawling up the input shaft and getting onto the clutch assembly.

Hi sorry to high jack this thread i have a oil leak above cylinder no6 on my 81 3L SC is this the probable cause for this motor as well? if so do i need to remove the motor to replace it?

Regards
Mike

[GaryR]

Originally Posted by mossguy

I have used this stuff and it was excellent! It pin-pointed the leaking around the oil level sender gasket when the whole oil tank was covered with oil, and also around the oil line connections. Here are some pics, but I don't have a good one under the car. The effect was as good as, or better than seen on the paper.

That's a Swan smoking a cigarette looking at the moon with a Comet going by...

[OldTee]

This stuff is a good way to track leaks. Did it on aircraft engines and now Porsche. Found some. Blown or leaking residue looks pale green. The source will show bright green. I would wash the engine down with varsol, then go drive 20 miles or so to burn it off. Then add the dye directly thru the oil filler. Go drive some more. Best is to wait for the sun to set, remove the rear wheels, get a good mirror, put batteries in the black light and go shopping.

[kodioneill]

Originally Posted by GaryR

That's a Swan smoking a cigarette looking at the moon with a Comet going by...

WOW, they don't have medical marijuana in Connecticut do they?

[GaryR]

Originally Posted by kodioneill

WOW, they don't have medical marijuana in Connecticut do they?

Only if you go to Bridgeport to get it......

[kodioneill]

The way I see it is, a swan smoking a joint watching the moon with a bong flying through the air, man.