johnb

Hi All

We had the 928 club track day yesterday at Castle Combe here in the UK.

My stock '86 Euro 16v Manual was flying, no problems and comments on how fast it was. running on road tyres.

I went out about 5 times for 6 laps at a time with about 3/4 hour between sessions.

The fluid levels where checked each time, and the car didn't use any oil or water.

On the 6th time I became aware of a low level rumble, very subtle but I knew something wasn't right, the oil pressure had dropped to 3 bar at 4000rpm.

So I coasted in to the pits, and found the following:
1. No oil preesure at idle (normally 3 bar when hot)
2. Max oil pressure now 2 bar at anything over idle(normally straight to 5 bar hot or cold)
3. Very rough idle
4. engine lumpy and a slight knock.
5. rev counter no longer working - strange?
6. no signs of damage externally, no fluid loss.
7. oil level at max, no loss all day.
8. oil clean, with no signs of metal
9. coolant level ok
10. temp normal

End of my track day!

Got flat bedded the 170 miles home, and the strip down begins today.

Johnb

John Veninger

Sounds like you caught it before you took out the block and crank.
Good luck with the repair.

drnick

john, sorry to see the S2 go on to the recovery truck after such a good day. i love seeing so many 928s being given beans, simply wicked as they tear down the pit straight and through the first corner!

looking back at video ive noticed oil pressure drops in my laps and im feeling paranoid about a bearing failure now as im pushing the car harder. the corner wher it was most noticeable was the sweeping right hander at the end of the back straight (tower) where the pressure in my car drops to about 60psi. one possible saving grace might be the choice of gear, i was using 4th and the rpms were lower. im not sure what the gauge was doing at quarry but im in 3rd gear there. do you remember which gears you were in during those corners?

really bad luck that youve toasted a bearing, and on street rubber - are you running with stock suspension? i wonder how much body roll contributes along with centrifugal force to shift good oil away from the pickup.

i think i might rest mine from the track untill i can fit the drysump and look at the bearings.

johnb

Hi Nick

That is a seriously fast car you have there!

My car's suspension is stock, but all new, with replacement bushes alround.

Only now at late morning have I been able to pluck enough 'get up and go' to start the strip down. The engine was a cracker, and I am really saddened that I managed to damage it.

Makes you wonder how many 928's got repaired under warranty after spirited driving when they where new.

I will keep posting as I progress thro' the strip and rebuild.

Before you go mad with accusump or dry sumping check out the following, I'm taking this route on rebuild.

http://www.crank-scrapers.com/index.html

Regards
John

SwayBar

Firstly, I'm sorry to hear of your problem!
The very first thing I would do is remove the oil filter and cut it open. If there is a problem with a bearing, you will know-so immediately once you open that filter up and spread out it's filtering material.

Vlocity

JohnB:

Sorry to hear of your problem.....I started the Accusump-Oil Cooler thread after seeing a similar drop in oil pressure on my supercharged motor. Probably the only saving grace for me is that I am running some lower RPM's since I don't need to wring the motor out as I had before.

Are you going to just look the rod bearings over or are you going to pull the engine?

Hope the damage is not as bad as you think....after reading this I think I am going to be done for the year until I can check my bearings and add the scraper and an accusump.

Ken

drnick

ken, im taking similar action and ducking for cover before my number is up! seriously, it just feels like its a matter of time.. but then again there were a lot of stock engines and cars being pushed around the track yesterday and only one failure, who knows??

john, do you remember if you were revving the nuts off it through the corners?

Fabio421

In before Kibort!!!

What type and weight of oil were you using?

DANdeMAN

I bet its 20W50

H2

I don't want to rekindle the debate on oil (no-win) but I can't envision the type of oil one uses as contributing significantly to the elimination of 2/6 failure but I guess anything is possible. You're dealing with a known 928 design flaw...perhaps the Porsche engineers never intended the 928 to be a track car? After all, in 15 years NONE were commercially produced for racing. It's a grand touring car that just happens to have a very powerful engine and great suspension, handling, etc. And there are many 928 owners who like to take928s to the track..and do very well....but most do so at risk of 2/6 failure. Given the apparent numbers who go to the track, and what appears to be a small number of cars that actually experience 2/6 failure, it does cause one to wonder though. Nevertheless, because of this one concern, I've never bought a 928 that's been tracked very much, if any.

I'm not sure if there's yet full consensus on the absolute cure for this problem although there are several approaches that seem to help (Accusump, dry sump, drilling cranks, new oil baffle/deflectors, voo-doo, etc.) Oil or not, Kibort has a pretty good record for holding his engines together. But I have a hard time believing that oil's the silver bullet (but that would be great wouldn't it? Has anyone ever had a documented 2/6 failure while running Amsoil?).

I'm not aware that there is full consensus on what the best route to resolve the 2/6 concern is.

Worse, is thrust bearing failure in the automatics. However, careful preventative maintance can take care of this. Also, a failed fuel hose and fire can be worse yet. Lots of things to watch.

Harvey

JHowell37

I believe the club sport produced for a year or two in the late 80s was intended to be used as a track car. I do agree with your comments about the oil brand having little to do with this problem however.

Vilhuer

2/6 is worse of these killer problems as normal preventive maintenance doesn't work on it. Fuel lines, cam belt and TBF are all virtually nonexistent in cars which are well maintained by owners or really reliable mechanic.

mark kibort

You know im going to bet its Mobil 1. was it??

Sorry to hear about the failure.

mk

mark kibort

With over 90 race days, and not short shifting, or doing anything but keeping off the rev limiter. ( were you banging off the rev limiter at all?) ive had not only 90 hours of ***** out brutal racing days, and 6 years of street driving, ive had no signs of any oil related issues. im alwasy at 4.5bar at the worst in the left turns at 4500 to 5000rpm range, and ive just come from my 3rd race at the famed, Thunderhill where they have a 80mph "U" turn.

I use amzoil 20-50 , scot is on his 5th race of the season and believe me, he is not beating on the car hard, but driving smart too, and he doesnt even have an oil cooler at all! (at least i have the radiator type)

what was the oil pressure during the day before the suspect running? was the oil pressure at near idle when it was hot, kind of low? it could be oil breaking down or it could be the foaming characteristic that amzoil or redline doesnt have. (or kendal racing 20-50 as Anderson uses)

again, sorry for the engine issues. its no fun tearing into these beasts.

mk(still knocking)

drnick

john, the 2/6 failure sucks, i wonder if its possible to salvage the crank and rods? i know paul anderson has installed th IJ scrapers in his current race engine and so far has not had any problems or used any oil this season. his car is in race winning form and was faster round castle combe than the 996 GT3 rs that was there, this setup might be the ticket... but im already embarked down the drysump route.

the orange car is fast in a straight line btw its just the corners in between i have trouble with there were a few fast cars at the track yesterday, im sure you were not one of the ones holding us up eh?!