Moose's Smokey Motor - THE RESULTS
Discussion
As they say a picture says a thousand words, so here's two thousand
Early stages show that miraculously there is no cylinder damage (even put the good side of a ring in the bore with the piston out and all looks good), and not a single mark on the head. Valves are coked up but look to be in good order with no signs of collision
How this can happen with such major piston damage is beyond me
Perhaps my luck is turning
Slightly concerned about the cause. Is it any more that metal fatigue ? Exhaust Valve bounce ?
Many thanks to my Spanner Monkey Banana Pete, the evening was certainly more bearable with you taking the pi55 and kicking me whilst I'm down
Cheers Mate
Anyone know the best place to pick up a new piston with rings and to be safe a new conrod and a pair of exhaust / inlet valves
Dom at TVR Power seems as good a place as any to start. Maybe TVRCarParts also
Prices anyone ?
Off to the land of nod now, it's been an "interesting" day
Early stages show that miraculously there is no cylinder damage (even put the good side of a ring in the bore with the piston out and all looks good), and not a single mark on the head. Valves are coked up but look to be in good order with no signs of collision
How this can happen with such major piston damage is beyond me
Perhaps my luck is turning
Slightly concerned about the cause. Is it any more that metal fatigue ? Exhaust Valve bounce ?
Many thanks to my Spanner Monkey Banana Pete, the evening was certainly more bearable with you taking the pi55 and kicking me whilst I'm down
Cheers Mate Anyone know the best place to pick up a new piston with rings and to be safe a new conrod and a pair of exhaust / inlet valves
Dom at TVR Power seems as good a place as any to start. Maybe TVRCarParts also
Prices anyone ?
Off to the land of nod now, it's been an "interesting" day
Edited by The Moosehunter on Friday 16th March 00:47
Blimey moose I remember seeing your car smoking at least a year ago on runs out. Come to think of it, I can't remember seeing you on a run out where your car didn't smoke a bit whilst on the 'gas'. Its lasted well then 
.
To add a name to the pot, Paul at Austec does a very nice line in high spec German touring car type pistons for the RV8 (wossner), give him a bell for price.
. To add a name to the pot, Paul at Austec does a very nice line in high spec German touring car type pistons for the RV8 (wossner), give him a bell for price.
.It needent be quite the disaster you might first think
Ouch, not looking good Moose 
This exact thing happened to my Griff this time last year. Two pistons had cracked in the same way, couple of bent valves and push rods, plus lots of lovely score marks in the bores, resulted in a full engine rebuild. In my case I know the cause which was a new cam that wasn't timed up correctly, but won't say anything more due to Ted's naming and shaming policy. Three months later, two hefty bills and a final trip to a garage that actually knows what they are doing and my car's never been stronger (touch wood! )
Hope you get it sorted soon
This exact thing happened to my Griff this time last year. Two pistons had cracked in the same way, couple of bent valves and push rods, plus lots of lovely score marks in the bores, resulted in a full engine rebuild. In my case I know the cause which was a new cam that wasn't timed up correctly, but won't say anything more due to Ted's naming and shaming policy. Three months later, two hefty bills and a final trip to a garage that actually knows what they are doing and my car's never been stronger (touch wood!
) Hope you get it sorted soon
Certainly some interesting damage there... what were the symptoms up 'til failure? Any pinking/detonation, any running on when you turned the ignition off? Looks to me like the crown immediately above the ring land has eventually failed after some period of sustaining damage (look at the different cleanliness of the ally along the break. I'd look really carefully at the bore as the ally smeared over the oil control ring implies more will be on the bore surface (a hone should sort). Additionally, I'd want to be sure more ally hasn't got through the mains/big ends (be a sod to rebuild the top end only to have it knocking when you run it up). Where did the missing section of the second ring end up? Suspect there a chunk of that in the sump somewhere unless it's bedded inside the piston?
Glad the head/valves survived.
Glad the head/valves survived.
Having found this I'd definitely do a full strip now, which obviously means pulling the lump right out but it will allay any fears about any debris floating around inside and you can inspect everything else while you're there.
On the rebuild front I'd just put standard TVR pistons back in unless you're planning some nitrous / blower in the future....
Matt
On the rebuild front I'd just put standard TVR pistons back in unless you're planning some nitrous / blower in the future....
Matt
Quinny said:
I would be almost certain that was down to detonation (pinking)
My initial thoughts exactly... I'm assuming it's the inlet side that's failed and, if so, imagine the thinner land between the cut-out and the crown wall has acted as a hot spot (the corresponding area of the intact equivalent opposite is displaying some evidence of over heating to my eyes)... think the sharp edge to the cut out prolly isn't helping to resist this either... I'd be tempted to dress that down (or go to forged pistons but that would prolly need a rebalance), Any pics of the corresponding chamber in the head?
pupp said:
Quinny said:
I would be almost certain that was down to detonation (pinking)
My initial thoughts exactly... I'm assuming it's the inlet side that's failed and, if so, imagine the thinner land between the cut-out and the crown wall has acted as a hot spot (the corresponding area of the intact equivalent opposite is displaying some evidence of over heating to my eyes)... think the sharp edge to the cut out prolly isn't helping to resist this either... I'd be tempted to dress that down (or go to forged pistons but that would prolly need a rebalance), Any pics of the corresponding chamber in the head?
It is indeed the inlet side that's failed
Photo of the corresponding chamber here...
No signs of any deteriation on the other cylinders
If this was a timing / detonation issue would this de apparant on all the others.
All removed spark plugs seem to be in a healthy condition (except one of course)
Would be nice to find a cause, as at present I am assuming this could be a stress crack between the crown and skirt of the piston that has deteriorated over time until it eventually broke through. The smooth wear on the edges certainly point to me to be a progressive problem rather than a sudden failure.
Could a faulty injector cause localised failure such as this ? How do you test one ?
Your comments, as always, appreciated
Moose
Andy,that may still be caused by over advanced timing,is that a rear cylinder thats gone(hotter running generally)detonation will pray on the hotter running cylinders 1st,i have seen this many times on the Ford xflow engine(holed piston/collapsed ring lands)as an example,due to over advanced timing and it does not always show on the other cylinders(they were rather prone to this bowl/combustion chamber in piston design),i would certainly investigate this than just put it down to piston failure alone,it may also be worth getting the injector checked it may be choked causing an over weak mixture on that cylinder hence more heat,glad its not taken the liner that should help with the costs
Edited by that daddy on Saturday 17th March 10:08
Hopefully it was something as simple as a blocked Injector on that cylinder, would fit with the symptoms. You can get them flow tested (and cleaned, serviced and balanced if need be) by someone that has a ASNU machine, if you can't find anyone local Moose take them up to Austec they has such a machine.
Quinny said:
Andy,
It is quite possible that the detonation could be on the one cylinder only, and could come from a number of sources.
Faulty injector, or drawing in air from somwhere, leading to a weak mixture.
I had this on an old Kawasaki when one of the carb clips came loose, and on a flat out run in top, at well over 140 leptons
It punched a hole, clean as you like straight through the centre of the piston.
Are the trumpets a nice tight fit in the base? was plenum tight onto trumpet base?
Worth checking for air leaks.
Good advice Quinny,could not have put it better myselfIt is quite possible that the detonation could be on the one cylinder only, and could come from a number of sources.
Faulty injector, or drawing in air from somwhere, leading to a weak mixture.
I had this on an old Kawasaki when one of the carb clips came loose, and on a flat out run in top, at well over 140 leptons
It punched a hole, clean as you like straight through the centre of the piston.
Are the trumpets a nice tight fit in the base? was plenum tight onto trumpet base?
Worth checking for air leaks.
That Daddy said:
Quinny said:
Andy,
It is quite possible that the detonation could be on the one cylinder only, and could come from a number of sources.
Faulty injector, or drawing in air from somwhere, leading to a weak mixture.
I had this on an old Kawasaki when one of the carb clips came loose, and on a flat out run in top, at well over 140 leptons
It punched a hole, clean as you like straight through the centre of the piston.
Are the trumpets a nice tight fit in the base? was plenum tight onto trumpet base?
Worth checking for air leaks.
Good advice Quinny,could not have put it better myselfIt is quite possible that the detonation could be on the one cylinder only, and could come from a number of sources.
Faulty injector, or drawing in air from somwhere, leading to a weak mixture.
I had this on an old Kawasaki when one of the carb clips came loose, and on a flat out run in top, at well over 140 leptons
It punched a hole, clean as you like straight through the centre of the piston.
Are the trumpets a nice tight fit in the base? was plenum tight onto trumpet base?
Worth checking for air leaks.
There's quite a difference between heat damage associated with weak running (as from an air leak), and from detonation or pre-ignition. The former 'just' melts things, the latter breaks 'em first. The colours in the chamber don't look weak to me, which is why I thought knock damage,maybe from too much ignition advance or from some part of the piston (the edge of the cut-away maybe) glowing and prematurely igniting the mix. What fuel you on Moose?
The colours in the chamber don't look weak to me, which is why I thought knock damage,maybe from too much ignition advance,,,,quote....Pupp,of course the chamber would not look lean it was streaming blue smoke remember(you can see the oil deposits on the valve heads),look at the original post
i am guity of doing this at times also
i am guity of doing this at times also That Daddy said:
The colours in the chamber don't look weak to me, which is why I thought knock damage,maybe from too much ignition advance,,,,quote....Pupp,of course the chamber would not look lean it was streaming blue smoke remember(you can see the oil deposits on the valve heads),look at the original posti am guity of doing this at times also
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