The Case of Disappearing Oil, What happened to the oil level? Options

[DrinkMan]

There were a few witnesses to this event during the Oketeenerfest Scenic drive. We were driving in the group when we entered the Foothills Parkway entrance ramp curve in 2nd gear when all of a sudden, our engine made a knocking noise. I immediately upshifted and the noise went away but our oil pressure had dropped from 20 psi to less than 10 psi (maybe even 0, I didn't take the time to study the gauge). I quickly shut down the engine and pulled over. Thankfully, everyone in the group pulled over with me to help.

I pulled the dip stick and the oil was only at the bottom of the dipstick. Very low. WTF? I had 2 partial qts of Driven DT50 on board (I thought when we left home that one was full and the other 1/2, but not really). I poured both in and all I got was the oil up to the lower line. Luckily, a GREAT Samaritan in the group has some Swepco 201 and I used it to fill to top. I accidently went a little over the line but no way to lower it on the side of the road. I think I put a total of between 1 and 1.5 qts. At the time, I thought 1.75 qts but when I returned the Swepco to the the Samaritan, I noticed I had not used very much of it (I had found some oil locally to put on board just in case).

Background - Engine is a 2056 installed by previous owner ( @iankarr ) about 8000 miles ago. We have not had any oil issues whatso ever. Probably top it off a little bit to keep it on the upper line (typically 1/2 the way between upper and lower line) once between oil changes (about 2000 miles per change). When engine is warm, oil pressure runs between 20 and 40 psi (cold, higher pressure, up to 70 on cold days, cold engine). Seldom below 15 psi (over 220 degrees oil temp in very hot south Ga weather after a long high speed drive).

Before we left North Ga to attend Okteenerfest, I checked the oil. Exactly on upper line. We had a fun drive to Townsend (Blood Mtn 129 and Tail of the Dragon). Then drives to Maryville, local mtn roads and to Pidgeon Forge. Filled up gas in Pidgeon Forge at 250 miles +/-. I thought I checked the oil level because that is a habit at every gas stop but I keep doubting myself based on this event. The oil pressure dropped happened at about 120 miles +/- so we had driven about 370-380 miles since I can guarantee the oil was full.

Multiple 914 owners studied the engine and saw no drips or staining. No one following me up to that point had noticed any blue smoke from exhaust. After I filled it up and drove back to the hotel (no unusual engine noises), I was told there were some minor puffs at gear changes but nothing bad. There is a mechanical gauge on the engine and it showed 35 psi when we restarted the engine after topping it off but I checked the gauge later and it always reads 35 psi, even when engine is off so I'll need to replace that. When I took off after topping off the oil, gauge on dash went back to the usual 20 to 40 psi. BTW - at no time did the oil pressure light come on.

We now check oil level every time we park. Oil is the same. So after driving home (we stayed over in Townsend a few extra days to relax) with the same route home (Tail of the Dragon and Blood Mtn 129 again) and 380 miles from when the incident happened. Same level.

What happened to the oil? Mike ( @Dr Evil ) theorized that our oil filter had been on bypass for the last 1000 miles and when we were going around the curve, it opened up and filled up the oil filter for the first time since we changed the oil about 1000 miles ago.

Here is how our dip stick looks now. Exactly like 380 miles ago up on the Scenic drive.

(IMG:http://www.914world.com/bbs2/uploads_offsite/live.staticflickr.com-20872-1726779901.1.jpg)

I welcome all the comments and abuse, especially the witness at Okteenerfest that can pile on.

[iankarr]

Very strange. If you checked the oil level shortly after shutdown, I agree with Brant that the "missing' oil hadn't yet drained back down. It might've been a bit low to begin with and the pressure drop happened in the corner from centrifugal force exposing the pickup tube. It could be a combinaton of curves or a very long curve that created a unique situation. Otherwise, Mike's theory, or some variation of that, seems the most likely so far. What did the knocking sound like and how long did it last?

Jake Raby doesn't reccommend pre-filling the oil filter when doing a change since air isn't efficient at pushing oil through the circuit, but of course there's debate on that. Here's a thread:

http://www.914world.com/bbs2/index.php?sho...p;#entry1595700

Mark Henry as well.

http://www.914world.com/bbs2/index.php?showtopic=358747

[DrinkMan]

Very strange. If you checked the oil level shortly after shutdown, I agree with Brant that the "missing' oil hadn't yet drained back down. It might've been a bit low to begin with and the pressure drop happened in the corner from centrifugal force exposing the pickup tube. It could be a combinaton of curves or a very long curve that created a unique situation. Otherwise, Mike's theory, or some variation of that, seems the most likely so far. What did the knocking sound like and how long did it last?

Jake Raby doesn't reccommend pre-filling the oil filter when doing a change since air isn't efficient at pushing oil through the circuit, but of course there's debate on that. Here's a thread:

http://www.914world.com/bbs2/index.php?sho...p;#entry1595700

Mark Henry as well.

http://www.914world.com/bbs2/index.php?showtopic=358747

You and I had a "conversation" offline but just to fill everyone in, it sounded like a starving oil pump.

This was also not the first sloshing of oil during cornering. But usually resulted in smell, not noise and drop in pressure. Haven't done compression test yet but did some driving today to Road Atlanta including some heavy throttle. No meaningful blue smoke (actually my wife behind me did not see any). And oil level still holding steady. Close to 500 miles now since the incident without any drop in oil level. Wonder where that quart (or 1.5? Damn i wish i had paid more attention to exactly how much oil i added) is? If all the theories about measuring too soon or on a hill applied, we would be a 1 to 1.5 quarts too high. Must have dripped it, burned it (one time burn), or filled the filter. Now my normal oil paranoia with our old cars is multiplied.