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zakthor zakthor is offline
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Join Date: Jun 2010
Location: beaux arts, wa
Posts: 482
Carbon Granules in Oil Tank

So I guess on saturday I'll be reenacting the Exxon Valdez accident, or maybe the cleanup.

Car is 1979 930 which is normally my daily driver rain or shine.

Took the brown beauty to its first track day last weekend, 4 sessions of 30 minutes, 90 minutes apart. I had a fine time with other novices. New tires were great: RE11A.

Hottest that engine temp gauge showed was half way between middle and red. After each session I cooled down car with light lap and then idled for a few minutes before shutting down. Engine used no significant oil during day though there were some droplets stuck under the rear spoiler. Car drove great the whole day, engine sounded great.

Oil was VR1 20w50. Arriving home I changed the oil right away - seemed like the right thing to do, end of summer and all.

Sump oil was clean, turbo sump is clean but oil from oil tank was full of little black granules. Most are the size of a piece of sand but some are quite large, say 3.5mm on longest edge. The large ones can be easily crushed with thumbnail while others are hard as rock (can still be crushed into soot with a screwdriver).

I swept the sump with finger, no granules. Swept the turbo sump with a q-tip and found nothing. Sweeping oil tank with finger there's a ton of this sandy feeling stuff in there.

Spend the week reading and learning, and worrying, and not sleeping well. Really the best and only resource for my issue seems to be this thread:

Clogged Spray Bar autopsy

What I don't understand yet is where the granules came from. Obvious place would be coking from turbo, but confused that there are no grains in the turbo sump. Could it be carbon knocked loose from pistons? (I normally drive like an old lady and have lots of snot in my oil tank fillup during the rainy fall.) What are the unfiltered paths into the oil tank? Is it just the turbo sump? Could these grains grow in the oil tank? I might find that my filter is torn because there's no way these grains came through an intact filter.

I've ordered a filter cutter, will be arriving tonight, will let me see what sort of stuff has flowed through my engine. I can cross my fingers and hope there is nothing but. At this point checking filter just for piece of mind, I hope I don't find any metal. If I find more than trace metal then I'm going to be sad.

Below are the stages and order I'm considering but I would really appreciate feedback.

Prior to turning over the engine - since I don't want to push any more dirty oil into the engine from the tank:
1) Buy a bunch of cheap oil to use for flushing and cleaning the oiling system - and a pallet of shop towels.
2) Open sump cover and feel around inside for any grains. Use undercoating gun/wand to hose off inside of engine with oil.
3) Using undercoating gun/wand and my cheap oil I'm going to wash all that nasty out of the oil tank. It'll drip back out the drain and I'll filter it and repeat until what comes out is clean.
4) How to flush out the coolant lines (spray oil in there?)
5) Is there more stuff to clean, or orifices?

After above is clean:

6) Flush out cam spray bars as described by JFairman in this post from above thread:

Clogged Spray Bar autopsy

Until clean:
a) Remove rocker covers, use a mirror to try to eyeball the cam spray holes and maybe try and clear them out with a pin.
b) Undo the cam drain plugs at the front of the engine, tubing to container under car, fuel relays out, and turn engine over for 4-5 seconds, see what sort of nasty I get out.

Start car and drive:

7) Lots of filter checks, still dirty means oil change?

8) Install inline filter between turbo sump and oil tank!

What is the best way to flush the oil line to the front passenger wheelwell (fragile threads, etc.)
What do I need to remove to get access for step 6?

Thanks ahead for advice.
Old 10-16-2014, 02:05 PM
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