I have seen some of the members here adding ways to drain the oil tank. 911s have a tank drain, but their tanks are mounted fairly low in relation to the engine. The bottom of the 6 tank is close to being near the same height as the top of the engine caes. Won't the oil just run into the engine case?

911's and 914.6 have a drain plug in the bottom of the case for oil that has returned to the sump. There's always some. You always drain both places.

If the car has not been sitting long after shutdown, there probably won't be much oil in the sump. The oil pump kinda acts as a one-way check valve, and while a little oil may ooze back through a tight pump, it's not that much. As the pump wears and clearances increase, more gets back through.

In place of the tank drain, 914.6 has a separable fitting in the lower oil line. You use your BIG wrenches in a tight space to open the union, hoping you're prepared for the torrent of 9 quarts draining through a big hose.

Thanks for this very helpful info One of the memers here posted this pic. I am doing a front cooler with AN lines and may do this to drain my oil.

Traditionally the front cooler is in the scavenge circuit, while the tank drain line is in the pressure circuit (tank -> pressure pump).

Having a drain at the front for the cooler and the lines is sometimes done, but it's no substitute for the standard tank drain line (you'll never drain the tank through the scavenge side...).

Having a capped Tee is definitely convenient, although I doubt it's more so than just using a separable fitting with either two female hose ends and a union ( AN-815?) or a male and female hose end. Once you get into AN-16 (or larger) hose, all the ends and fittings are expensive...

That capped Tee scares me tho, without some kind of positive anti-rotation device. Maybe the cap is drilled for safety wire on the other side where we can't see... (As long as we're being picky, that Tee should be a bulkhead Tee with the bulkhead fitting on the Tee (they also come with the bulkhead on the run) and a proper bracket...)

I chickened out on the T-drain idea when I built the race car
I like being able to split the hose, angle or point it where I want, and knowing that there are less fittings to come loose or create problems.

I actually saw a motor die once on a friend at the track... due to poorly designed oil line coming loose.

I put ALOT of money into the race motor and can't stand the idea of any unnecessary risk related to oil

(I do a full royal purple oil change every single weekend as an example of my "cheap insurance" thinking.... about 1 case on our system)

I was planning on drilling the cap for a safety wire. I hadn't thought about a bulkhead T.

Might want to look again. The bottom of the /6 tank is about the level of the lower cam cover. Plenty low for the oil to drain out of the divided lower hose. Besides, on a cold engine ta good percentage of the oil is in the case.

The Cap'n

I will be using two metric to an adapters at the tank and below the oil cooler. If I run a single an 16 line between them why not disconnect the line below the cooler to drain the oil?

because there are two separate oil systems in a 911 engine - scavenge and pressure.

The line from the cooler to the tank is the scavenge line, and it dumps to the _top_ of the tank (it's the return line).

The pressure inlet line - from the _bottom_ of the tank to the pump - is the one you have to open to drain the tank.

The scavenge line feeds into the lower part of the oil tank. (see pic) Internal passages feed it thru the filter then into the tank.....it also feeds the opposite way to the sump if left to sit for a week or 2.

Many feed lines ...tank the below oil cooler....have a steel joint that can be cracked to drain the tank if necessary. You wouldn't want to use an aluminum fitting here as they will wear out if disconnected repeatedly.

It may not need to have it but having one makes it easier/cleaner to drain. I have a aftermarket oil tank installed where the OEM tank mounts and have plumbed it with -16AN to the engine case. I did install a tee and have used it twice in a year and so far no issues and very easy to do oil changes. I suppose the cap could vibrate off under the right conditions but when I look at my 911SC and see the " S " hose from the tank to the engine is just held with clamps I don't worry about it.

Only 13 years old, did you incorporate this with your /6 build? I have just gotten my build running and considering this addition? Wondering what the factory setup was?

I did this for mineClick to view attachment

Looks slick, no interference with your exhaust pipes? Mine is vey tight in this area

None whatsoever

This is the solution I came up with. I ordered the factory oil lines from the the tank to the cooler. It came with a union. I had a face machined then drilled and tapped it for a drain plug. I drilled the plug so I could safety wire it.

Click to view attachment

I am very happy I did this. It drains very quicky and isn't messy like disconnecting fittings. I use an aluminum washer from the valve cover as a sealing ring.

Click to view attachment

That’s nice
-12 or -16? Scratch that ….. pipe thread what size?
Where did you find it?

I’ve been splitting aluminum AN fittings in my line since 2005 without issues
Probably over 150 oil changes/events

@brant I bought the oil lines from a major supplier. I cannot remember who. They were advertised as OEM. I was surprised to see the union when it shipped. I think the threads are the same size as the tank and oil cooler. M22 ?? I could dig through my receipts and find where if you want. I'm glad you have been able to get so many cycles out of your AN fittings.

Hi. See this link. Lots of good info
http://www.914world.com/bbs2/index.php?sho...p;#entry3083743

Thanks for chiming it, especially after several years ago. This is great information

Exactly what I did ,used a NPT (?) 1/8" plug as mentioned works well ,I found I got more oil out once it was warm and drained quicky after stopping engine ,seemed I had less to drain from the engine that way ,cheers.

Curious:

just how much oil is left in the system if only the sump is drained? Cannot be much as it appears to be the low point in the system TIA

Depends on wearing past the oil pump. I drain both areas to ensure a full or as full of change as I can do. I then measure that amount and put that back in as a starting point on a fresh change. Then warm the car up and check level and add as needed

Thank you, I just dumped about what I filled with, about 10 qt which might be a bit much. Will fill with 9 qt next time.

Not sure how much is left in there

That is a Porsche factory fitting... AKA a Cohline fitting. Drilling it for a drain plug is the modification.

thats what i have. aluminum washer and safety wire ez peazy

After draining the oil from the sump (and getting 10 qts) and later opening up the line to the oil cooler, I collected less than 1/2 quart.

Is it worth it to insert a "T" fitting for less than 1/2 qt?

My gut says no, leave well enough alone

I'm glad I found this thread.
I have two really big adjustable wrenches on that joint.
I put all the force I was able with my right leg and I can't get that joint to loosen.
I'd hate to strip one of the nuts.
Can anyone think of something else I can try?

AN#16 line with AN#16 tee/ safety wire. The remainder of the oil lines: T-Statt, Fr. cooler, are AN#12. B+W pic out of '80's "VW + Porsche" article.
Click to view attachment

I just open the union on the left, drain and close. Click to view attachment

@Dead Air - I use the Porsche wrenches when I break that connection. I have them both on the fittings with about 1"-2" distance between the wrench handles and then I just grab the wrenches and squeeze them together. I don't like using adjustable wrenches on fittings. You could also try reversing the wrenches to try to tighten the fitting a bit to see if it breaks free. Maybe try some penetrating oil on the fitting and let is soak overnight. Just depends on how long since they were taken apart. Good luck- it is not an easy thing to do if the car is not on a lift.

That's what I did.

I might go this route, is that 1/2" copper pipe/elbow?

I just bought one of those valves and need to plumb it as well. As to the Copper question, yes I am interested in what metal that is. Copper can work harden with the heat and over time become brittle and fracture.... which would be bad on the feed line...

I just bought one of those valves and need to plumb it as well. As to the Copper question, yes I am interested in what metal that is. Copper can work harden with the heat and over time become brittle and fracture.... which would be bad on the feed line...



Installing the Rothsport valve on stock hose can be done, just gets a little tight. The extra 2 hose clamps are to keep the bend from kinking. I replaced the oil line hose with new and there wasn't a preformed 'elbow'
Click to view attachment Click to view attachment