oil leaks

Is it common to have to "chase" oil leaks? It seems that I had fixed one oil leak associated with the oil tank and now I think the car is leaking oil from the oil return tubes and the circular gasket at the oil drain plug. I might be wrong but I really didn't see these leaks before. Is the oil system under pressure such that the oil will take the path of least resistance. Has anyone ever replaced the oil return tubes? I have printed out a copy of the tech article from here at Pelican and it looks fairly straight forward but I would like to hear from someone that has actually done it.

Does anyone have an opinion on the oil treatment additives to seal leaks?

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No, I would never consider putting any kind of leak-sealing compound in a 911 engine! The leaks you describe can appear at any time, but are easy to fix. They are not unique to 911s or even cars, as air-cooled motorcycle and aircraft engines have the same type of malady, or tendency.

The oil return tubes are easy to replace with the two-piece aluminum collapsible design. The oil drain plate leaks are a little more trouble to fix. The plate has a tendency to 'bulge' around the holes for the 6 mm studs. If you turn the plate up after cleaning thoroughly at oil change time, you may see the 'bulges' in profile, against the flat surface of the rest of the sealing flange that meets the gasket. The bulges can be hammered flat with care. A permanent fix can be affected by taking an oversize-diameter washer and brazing to the underside of the plate at each hole location. I purchased a new replacement plate, made the washer 'mod' and had it Cadmium plated, and replaced the original plate. That particular type of leak was fixed permanently!

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Warren Hall
1973 911S Targa

I just replaced a leaking return tube on my 71T and found it was even easier than the tech article made it sound. The old one came right out and it only took a minute or two to get the new one in and the snap ring secured. And this was on the tube that was the most hidden by the heat exchanger, on my car at least there would be no reason to remove the exchanger for this job.

Yes, the collapseable oil return tubes are generally easy to install. I say generally because the difficulty depends on the year of the car. For example, on my 78 SC, I spent several HOURS trying to get one of them in, I finally had to drop one of the heat exchangers. With the combination of the heat exchanger and the air injection tubes, it seemed impossible to get the thing in without dropping the exchanger.

But, I think this is the exception, on most cars you would not need to do this.

Finally, there are quite a few different types of collapseable tubes out there, there are factory ones, and lots of different types of aftermarket ones. The quality does seem to vary, both in the construction of the tubes, and in the material used for the seals.

Brian

Thanks for the info. I can see that my car already has the colapsable oil tubes installed. They appear to be leaking at the O rings. I guess its back to the jack stands! Aren't these cars suppose to be fun to drive? See Ya!

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You may want to completly clean your motor and then try and chase down the leak,I had a similar looking leak it turned out to be coming from on top of the motor from the oil light sender Oil seems to travel all over and it can be hard a times to find the source

jryerson brings up a good point. I was recently chasing some oil leaks in my '82 SC. At first I thought the leaks were coming from the oil return tubes and valve covers. But, after trading emails with Wayne at Pelican, he convinced me to drive my car up to the coin car wash and completely clean my engine. After I had cleaned the engine and drove the car the 2 miles back to my house, I once again inspected the engine. It was then that I noticed I had oil leaks from: 2 oil return tubes, one valve cover, the oil sump plate, and the oil light sender on top of the engine. (Thanks for the advise Wayne.) Looks like I have my work cut out for me!

You know I think I will take the car down and clean it. I have been cleaning where I've worked, but one massive cleaning is probably in order.

Since I just put in 11 quarts of oil and now I have to drain it to hopefully fix the latest leaks, should I toss the new oil or drain and retain and re-use it? Since the car has been in storage for a year, I was planning on driving it about 1000 miles after the leaks were fixed and then changing everything (oil & filter) again. I would appreciate anyone's input on my plan since I'm no expert.

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Actually, you don't have to drain ALL of your oil, just the sump! The oil tank will be fine, just sitting there full! I really doubt if the sump will have more than about a gallon in it, but if you could clean the sump plate really good, then catch what comes out the sump drain plug, in a clean 200 oz. soap jug using a clean funnel, I don't see why you couldn't reuse it. I wouldn't try to save any that drains out when you take off the drain plate. All of the collapsible oil-return tubes that I have seen use the same O-rings as the factory tubes, so you will need 2 of those for each tube that is leaking, or 8 if you want to change all of them now. Also, when you put those return tubes with new silicone O-rings back in place, seated in the crankcase and cam-boxes, make sure they are lubricated ... I use clear Silicone grease, but Bosch grease would probably be OK, too.

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Warren Hall
1973 911S Targa

Hey Warren, Where is the best place to get the sump plate gasket and the gasket on the oil tank for the float?(It is leaking).

I have checked the catalogues, but I haven't seen the oil tank gasket anywhere. Do you recommend the use of a gasket sealant or a dry gasket?

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Performance Products has the oil tank sender gaskets, pn #903490 at $4.25, and it is a cork gasket, just about my least favorite type, so yes a sealer like the non-hardening Permatex spray-on is called for. For the sump-plate gasket, I get one of the latest OEM German 'kits' with the green silicone bead on the valve-cover gaskets and all of the nylock nuts and aluminum sealing rings. The sump gaskets are included, as are new sealing rings for both drain plugs. You have to watch out buying separate sump drain plate gaskets, as some of them come from Brazil or Mexico, and appear to be made of cardboard shirt stiffeners!!!

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Warren Hall
1973 911S Targa