Re: Accusump needed?

Ran into an issue at the track this weekend. Hard down hill braking into a hard left hander and back on the gas generated a nice cloud of oil smoke. For subsequent laps I reduced speed and throttle through the turn to stop it. From what I'm reading this could be caused by oil starvation and the solution is installing an accusump. The car is a 2003 2.7, I'm running R888 tires and has a oil pan extender. And, the AOS was replaced last fall for the 2nd time.

Does this sound right? Has anyone installed an accusump and any pointers? LN Engineering has a kit but are there other options?

Thanks!

Dave

Dave - 06 987 S coupe SG/NL; gone (but still my first love): 03 986 AS/GG/BK;



Edited 1 time(s). Last edit at 07/18/2011 02:00PM by Dave In MD. (view changes)

not address the smoking you noticed.

This arises from under some conditions the oil under the camshaft covers is forced (by g forces) into an area under the camshaft cover that the scavage pump can't reach (so to speak). When the conditions that caused this oil to accumulate are removed the oil flows/surges past/around the camshafts drawn by partially g forces and by the action of the scavage pump through the head scavage pump. The oil under these conditions then can really get aerated and the result is a lot *more* oil vapor in the crankcase fumes.

The AOS is almost certainly overwhelmed and the short version is some of this oil vapor is directed to the intake manifold and burned in the engine and the smoking is the result.

There are things you can do you minimize the likelihood of the engine smoking like saw: Run reasonably fresh oil of the proper type and grade. Do not overfill the engine with oil but do not underfill it either though. And be sure you are smooth especially in those tight downhill left hand corners.

Sincerely,

MarcW.

How big is the cloud? Some have suggested an AOS replacement, so that is worth a try. However, it did not fix the problem for me. In my case it was definitely a new issue with the motor -- no change in environment or driving. I finally did a compression test and there is a bigger problem. I have low compression on two cylinders and the oil must be making its way past the rings. But it only happens at redline upshift out of certain corners on the track, a humongous momentary cloud of oil smoke. I'm looking at replace / rebuild since it seems like it has to be the rings (or worse).

Other possibilities that have been mentioned for this symptom:
- cracked oil scavenge tube (in crank case)
- malfunctioning oil scavenge pump (in head)
- leaky valve stem seals

It's unclear to me how an Accusump could help any of this. This has to mean too much oil somewhere, either saturating the AOS, or leaking into the combustion chamber.

Thanks guys!! Replaced AOS already and it didn't fix the problem. I'm looking at the motorsports version of the AOS but it's pricy. Of course, the best advice may be: slow down and be more smooth. I just have to decide if the quick way through turn 5 is worth the money! It doesn't happen at the other tracks I go to. Just want to avoid the catastrophic failure event if I was headed that way.

Dave

Dave - 06 987 S coupe SG/NL; gone (but still my first love): 03 986 AS/GG/BK;

Track driving with its high speed/hard cornering/hard braking activity can result in the engine oil pump ingesting oil that may not be fully defoamed or even worse, if the oil pump pickup gets uncovered sucking in a bit of air. If this happens the engine will almost certainly suffer damage maybe even outright failure. Someone with a Cayman reported a failure from this very thing not too long ago (on another board) and expressed regret he didn't take the proper and recommended precautions before the engine failed.

The Accusump can prevent this from happening.

Assuming there is no internal engine problem to account for the cloud of smoke (as as the case with Trygve's car) the cloud of smoke is a result of the engine's lack of a sufficient number of scavage pumps coupled with an AOS that is overwhelmed by the heavy load of oil vapor that can occur. Whether the motorsports AOS is better in this regard I do not know. It may be just as overwhelmed but less likely to fail than the stock/factory AOS.

Sincerely,

MarcW.

[www.planet-9.com]

It's my understand that the oil cloud results from the AOS being overwhelmed with oil that gets stuck in the head and is dumped into the intake.

The accusump will help keep a supply of oil going to the motor during hard cornering but I'm not sure what it can do about getting the oil back out of the head and back to the sump. I think that was remedied in the new motor with additional oil pumps--4, IIRC.

Here's another interesting thread on a related subject:

[www.planet-9.com]

Get an aircooled 911. They came with dry sump systems.

I'd love to have a 993. But I have to admit I love the Boxster for many reasons. But, considering it.

Dave - 06 987 S coupe SG/NL; gone (but still my first love): 03 986 AS/GG/BK;

Quote
Dave In MD
Ran into an issue at the track this weekend. Hard down hill braking into a hard left hander and back on the gas generated a nice cloud of oil smoke. For subsequent laps I reduced speed and throttle through the turn to stop it. From what I'm reading this could be caused by oil starvation and the solution is installing an accusump. The car is a 2003 2.7, I'm running R888 tires and has a oil pan extender. And, the AOS was replaced last fall for the 2nd time.

I quick follow-up on my post. Installed the Motorsports AOS last week and did a 3 day DE on the same track this past weekend. Car ran terrific and out of turn 5 I was doing a power induced rotation into a short straight into hard braking for a right hander and back on the gas. Bottom line, never even a trace of oil smoke. Ran the car with the oil level down 2 bars on the display and it never dropped. In fact, I've not seen ANY smoke even on start up. It seems: Problem solved!

Dave

Dave - 06 987 S coupe SG/NL; gone (but still my first love): 03 986 AS/GG/BK;

Quote
Dave In MD

Quote
Dave In MD
Ran into an issue at the track this weekend. Hard down hill braking into a hard left hander and back on the gas generated a nice cloud of oil smoke. For subsequent laps I reduced speed and throttle through the turn to stop it. From what I'm reading this could be caused by oil starvation and the solution is installing an accusump. The car is a 2003 2.7, I'm running R888 tires and has a oil pan extender. And, the AOS was replaced last fall for the 2nd time.

I quick follow-up on my post. Installed the Motorsports AOS last week and did a 3 day DE on the same track this past weekend. Car ran terrific and out of turn 5 I was doing a power induced rotation into a short straight into hard braking for a right hander and back on the gas. Bottom line, never even a trace of oil smoke. Ran the car with the oil level down 2 bars on the display and it never dropped. In fact, I've not seen ANY smoke even on start up. It seems: Problem solved!

Dave

Dave:

Regarding your oil level, what that something you decided to do on your own or did your mechanic recommend it?
I ask since I've been advised both ways--let some oil out or add a 1/2 qt. I usually run at the full or over a bit and have never--knock on wood--had a oil plumb out the back.
I would not want to overload the AOS, but would be more concerned with oil starvation in the corners which is a real issue on these engines.

My mechanic suggested running about a 1/4 quart low. His thought was to avoid an overfill from the heat expansion. Since it has the extended oil pan, that's still about 9 3/4 quarts I believe. Don't know if that's right, but since there weren't any problems this weekend I'll stick with it unless someone convinces me otherwise.

Dave - 06 987 S coupe SG/NL; gone (but still my first love): 03 986 AS/GG/BK;

If you've got the extended sump and you're running 9+ quarts, it is less of an issue, but it's been suggested to me to run a 1/2 qt low on the stock sump which is 8qts. on a 987.

... too low for the track.
It's because of temperature.
One quart is more than 10% of the total oil volume.
Happy Boxstering,
Pedro

Pedro Bonilla
1998 Boxster 986 - 311,000+ miles: [www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)

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