One Viggen, served well done
With thanks to RJ, here’s an inside look at what happens when a Saab 9-3 Viggen gets a little overcooked. This Viggen belongs to a friend of his, and has been shown here previously.
It turns out piston #4 got so hot it overheated and fractured (pieces actually broken off). The mechanic said this was due to the fuel being injected onto one spot of the piston rather than in a mist, which ends up acting like a blowtorch on that spot and destroying it. Another piston (#2 or #3?) broke a seal and received a decent-sized crack down the side. Furthermore, cylinder #4 took a beating with quite a bit of pitting and other scratching from the destruction of piston #4.
Since a decent replacement engine wasn’t available, they decided to bore out the cylinders and put new racing pistons in. No idea how much they’ll be shelling out for it, though.
It’s good for some of us non-mechanical types to see this inside stuff, so thanks for the pics. Obviously, I’d rather see them and hear that they’re BMW parts. The premature ending of a Viggen’s bits is never good news (right, Richo?).
Mason, our best to you on the rebuild. May it be ruling the roads again soon!
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It’s costing a bit more than an arm but not quite an arm and a leg. We’ll get it back on sunset drives in no time. Thanks to MSN Automotive in SLC for the work and reassurance that it is still worth having a Viggen, especially a newly bored, race piston slinger.
And FYI it was No.1 piston that cracked. I was just flyin along on the freeway and without any noise or grinding started gushing a huge tail of black smoke followed by a complete loss of power. Basically just felt like i had run out of gas, until i popped the hood and saw oil everywhere but in the engine.
“The mechanic said this was due to the fuel being injected onto one spot of the piston rather than in a mist, which ends up acting like a blowtorch on that spot and destroying it.”
Um, no. Either the mechanic doesn’t have a clue, or this is a very loose interpretation of what s/he said.
The more likely cause is detonation:
http://www.thor-racing.co.uk/images/what_is_detonation.jpg
Was the engine or ECU modified?
And once again we can thank GM for cheapening out on the pistons in the B235R.
This is nothing new when it comes to B2×5 engines.
This is how my B205 engine looked when I blew a piston.
http://www.garaget.org/?car=9490&image=627555
I had two big holes in the engineblock and the cylinderhead whas ruined as well. Now I have a B204 engine with a B205 cylinderhead on it, that should hold much better then the B2×5 crap.
Mason…that’s my mechanic too!
Those are some pretty cool pictures - are they copyrighted? If not can I add them to the fuel injection presentation I am putting together?
It does look like damage from detonation as well. Was the boost turned up on the engine and it possibly was not getting enough fuel?
That is a pretty common failure as well on supercharged 3800 engines with a smaller supercharger pulley. Turn up the boost, it runs a little lean and before you know it - smoke!
Bernard has made the point that I would have made. The fuel injection happens on the compression stroke, thus the piston is moving when injection occurs — even if the stream theory were true, it wouldn’t be in one spot.
I’m surprised that there was no warning. Detonation would have made the car “ping” a least a little. Not like in a N/A car, but still premature. LIke the car was just a little out of rhythm.
Oh well, here’s to hoping that you get it back into good shape!!
A strange theory indeed, as the injection takes place in the intake manifold runner (in a non-direct injection engine), not in the combustion chamber.
It ought to be caused by knocking, please check
ECU, tuned?
Spark plug spec?
Air mass meter Multi-adaptation too hign? It will be every sentitive particularly when a tuned ECU fitted
OUCH!!!!!
Well he didn’t say anything about fuel injectors, although mason did use the wordage “injected”
So if the fuel came in unevenly because of blockage on the valve or something…
Injected, but not from injectors ?
Blockage on the valve (intake, I assume you mean) doesn’t really matter as the valve is already closed most of the compression cycle before combustion is to start.
Detonation (whatever causes it) and weak pistons are a likely cause.
Well, it stinks that this happened to such a nice car. However, it provides the perfect excuse to bore out the engine, install new (larger?) injectors, Port & Polish the head, plop in new valve guides, valves and seats… etc. etc…. Before you know it, it’s a new engine.
It’s nothing that can’t be salvaged. Unfortunately it takes 2 things to fix: time, and money.
Keep in mind, vintage racers keep 30, 40, 50+ year old engine blocks running in a highly tweaked state.
I’m sure a good machine shop will have the Viggen ship-shape in no time. And maybe better than before.
Hang in there. Good luck!
Tedjs,
I have a few more pics of the damage besides those posted here, and I have even higher-res versions of the ones you see, should you want them too. You are more than welcome to use any images I have- just let me know if you’d like me to send others to you, in which case I can get you my email address.
At any rate, I admit I was so intrigued by all the damage that I paid more attention to the train wreck than the mechanic’s explanation.
He may very well have mentioned detonation; I do know he said something about the fuel combustion occurring on one spot though, as evidenced by the burned piston on one side. He made the point that this was why he puts fuel injector cleaner in his cars…as to whether the mechanic is right or not, I can’t say, and you all can do a better job of judging than I.
I was so busy looking at the damage I didn’t even bother to take pictures of the turbo and rest of the engine sitting in the trunk!
Looks like lean mixture to me.
Kolbenschmidt has nice brochures on the web, where you can see the effects of various engine problems and their effects on pistons.
http://www.ms-motor-service.com/download/prospekte/kos_2006_50003973-02_en_web.pdf
Especially page 31 looks a lot like Mason’s piston.
My number one spark plug keeps getting the electrode bent over. Nothing has gone through the engine that I can tell. I put in a new spark plug and drove it 50 miles back home very carefully. Then when I got back near my home I pushed the car to near its rpm limits and it bent the spark plug again. Wrist pin? Rod bearing? or what? Its a 2000 Viggen