Have you found anymore damage on the strip down Andy?
My 3B Coupe project - Total rebuild
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This is a sticky topic.
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Well the engine is now fully stripped and I'm still non the wiser as to the cause. The crank pulley was still in tact and none of the other valves were bent, apart from the other exhaust in no.3, and that looked like it had been hit by the first one failing.
Bad news is it has bore damage from all the debris flying around so it will need a re-bore and new pistons, good news is it will be closer to 2.6 when done
I'm trying to look on the bright side here!
The block and replacement head ( thanks James
) are going for machining tomorrow so as soon as they tell me how bad the bores are I'll get the pistons ordered.
sigpic
1991 Audi S2 3B - 2.5 Stroker engine
1997 A6 2.5TDi quattro avant - C4
1976 RD250E / 350LC cafe racerComment
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good luck Andy ¡¡ come on with it¡¡
in your AAT block 83mm bore pistons are a little over 2600cc¡¡ i think¡¡
RED Mitsubishi Lancer Evolution VI TME nÂş 16 of 250
BLACK Mitsubishi Lancer Evolution VI TME nÂş 189 of 250
LWB Audi Sport Quattro projectComment
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Well the professional opinion is that the exhaust valve failed rather than any timing issues causing it to hit the piston. I've been googleing valve failures and it's not uncommon for sodium filled valves to fail as they are hollow and made it 2 halves, then friction welded together, after many thousands of miles the welds can fail. With this in mind I'm going to order a full new set of exhaust valves.
The bores have been checked and found to be spot on, the tappety noise I've heard from first start up has been put down to dodgy lifters. Both sets ( the new ones and my old 3B ones ) I ran have been checked and about 5-6 in each set were found to be not worthy of using. I have a few sets of these so I'm going to try and make up 1 good set.
There was damge to the bore on no. 2 & 3. The damage on 3 would have honed out but 2 would not. The good news is that it could be sleeved, but JE will not make a 1off replacement piston, minimum order is 4off. So it's going to 82mm and a full re-bore. The pistons are on order and should be here in about 3 weeks.
I currently have one of my kidney's on Ebay to pay for this
sigpic
1991 Audi S2 3B - 2.5 Stroker engine
1997 A6 2.5TDi quattro avant - C4
1976 RD250E / 350LC cafe racerComment
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You will have the exact same spec as my stroker 82mm JE pistonsWell the professional opinion is that the exhaust valve failed rather than any timing issues causing it to hit the piston. I've been googleing valve failures and it's not uncommon for sodium filled valves to fail as they are hollow and made it 2 halves, then friction welded together, after many thousands of miles the welds can fail. With this in mind I'm going to order a full new set of exhaust valves.
The bores have been checked and found to be spot on, the tappety noise I've heard from first start up has been put down to dodgy lifters. Both sets ( the new ones and my old 3B ones ) I ran have been checked and about 5-6 in each set were found to be not worthy of using. I have a few sets of these so I'm going to try and make up 1 good set.
There was damge to the bore on no. 2 & 3. The damage on 3 would have honed out but 2 would not. The good news is that it could be sleeved, but JE will not make a 1off replacement piston, minimum order is 4off. So it's going to 82mm and a full re-bore. The pistons are on order and should be here in about 3 weeks.
I currently have one of my kidney's on Ebay to pay for this
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Pistons are in the UK, if they clear customs they will be with me tomorrow
Spent most of the weekend cleaning the oil pump, sump, oil lines, inlet manifold and exhaust manifold to make sure non of the debris re-enters the new engine.sigpic
1991 Audi S2 3B - 2.5 Stroker engine
1997 A6 2.5TDi quattro avant - C4
1976 RD250E / 350LC cafe racerComment
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good news Andy
Are you going with OEM valves or something mroe exotic?
I've not bothered taking the sodium vlaves out of the heads I was selling after seeing this - think i'll just stump up for new valves on my build to be safe, must be soul destroying after all the work you put inPanthero Coupé quattro 20vt
Indigo ABY coupé
Imola B6 S4 AvantComment
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sodium valves have massive benefits if you get a bit hot....dont write sodium out all together!1996 Audi S2 - 295bhp and 326lb/ft - Complete Rebuild Project
1994 Audi 80 - 2.0 8v (slow but reliable!)Comment

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