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, Tue, 1 Jun 2004 09:10:08
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Over the years there have been reports that also aeros will fail similarly. Read below, I tried to gather some information related to this matter.
The following the is written by Rolf Uhr. I assume that only few understand what it states, but I wanted to copy and paste it so the source is know. The text is translated below.
Jag tror det är dags för ett klargörande beträffande bilar med T7 och trasiga kolvar.
Sedan 9-5 introduserades på marknaden har vi till dags dato modifierat över 2000 st 9-5r. Vi har hos oss i Norrköping reparerat max 10 st bilar med spräckta kolvar. 2 st av dessa har vi behövt byta blocket på pgr.av att föraren inte stoppat motorn när felet inträffat, utan han/hon har försökt köra hem eller till närmaste verkstad.
Dessa bilar har vi "hämtat" in i ett område från Skåne till Sthlm. Vi känner också till ett 20:o tal bilar ytterligare med samma problem. Av dessa 20:o-talet bilar är de flesta INTE trimmade.
Ha en trevlig helg.
MVH. Rolf Uhr
The above basically states the follwing:
After the 9-5 model was introduced until today we have modified more than 2000 pcs. I Norrköping we have fixed max 10pcs of these cars after a piston failure. Two of these cars needed a new block because the owner tried to drive to the nearest work instead of leaving the car at road side. We also know about 20 or so more cars with the same problem and most of these cars where not upgraded.
The following text is written by Johann Heuschmid to Philip Hs after his engine failure last fall. It explains partially why the viggen suffers more from this problem.
Hi,
this is the info I got from Johann Heuschmid, who is a Saab tuner for more than 30 years and is working now very closely with Saab in Sweden:
He sais there are 37 cases of broken B235R engines known to Saab. Nearly all of them are Viggen. The pistons get damaged, but not because they are especially weak. They are of very high quality, and they are coated.
There are multiple theories why this happens:
1. the B235R is identical in the 9-5 Aero and in the Viggen, BUT the way the air takes into the engine (and the intercooler) is different. Intake temperature on the Viggen under some driving conditions is 15 °C higher than on the 9-5 Aero.
2. on the Viggen, the crankcase ventilation is even more of a problem than on the 9-5 Aero, so sometimes oil is pushed into the cylinder. If there is 2% oil in the mixture, octane level drops from premium (100 Octane Shell V-Power in Europe) to regular (95 Octane in Europe). Under speeds of 110-120 mph in 5th gear, the engine may start knocking. There is only 0.2 bar of turbo pressure at that moment, so knock detection is not active. This damages the pistons as shown on multiple pictures.
This can also happen with bad gas.
3. Very many of the viggens are often used under (Street-)Racing conditions. Only very few of the 9-5 Aeros are.
4. Very many of the Viggens are tuned. But of course, they are "stock" again when they get back to the dealer for damage analysis.
Why is Saab not very aware of the problem?
1. We all know the problem mosty occurs after 3 years or so. Most Viggens are out of Warranty by then, so only a limited amount gets to the ears of Saab engineers.
2. If the problem is told to the engine engineers at Saab, they say: "This is an engine from 2000. We did it in 1998. We are now working on the engines for 2006, which are completely different".
If you use other pistons than the stock pistons:
The same problems can occur with custom forged or b234 pistons, because the B235R piston is not the problem, just the victim of the before mentioned problems. There are just no reports of broken custom forged or b234 pistons in b235r engine because there are so very few of these engines.
posted by 195.237.1...
, Tue, 1 Jun 2004 09:10:08
, Mon, 31 May 2004 18:48:39
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