Replace 1 pcs of Piston/ head in my 964RS
01-06-2014, 06:16 PM
#1
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Replace 1 pcs of Piston/ head in my 964RS
As the headline says, I need to replace the piston and the head in a 92-RS
The reason for this is that the valve plate for the inlet valve broke and the valve itself went down into the cylinder. What caused this is unknown.
It resulted in that the inlet valve broke into two pieces and then of course the piece with the valve itself fell down into the cylinder. Bang bang bang.
The” good” thing is that this happened almost standing still so the rev was really low and a immediate shutdown was possible.
I now have a mark in the piston so I know that has to be replaced , the head itself has a broken valveguide with a piece of broken valve, half of it is stuck in it and some 1mm of metal missing in a place so I need a new head as well.
The car has only ~ 30000km so it’s quite a rare low milage car. The last 10 years in my possession I used it on trackdays and some trackdriving around Europe so its really a trailer queen. With that said I really don’t want to renovate more than necessary. I can hardly see any wear/tear during my engine teardown on the internal parts so send all 6 heads for refurbishing seems a bit overkill.
Here come the questions to the elite at Rennlist.
1 My thought is to buy a new complete head with valves and all and a new RS piston/cylinder . But looking in PET I can read that I need to find the piston marks - - 644-648G??
There are no such things on the cylinder or piston?? Or should I look somewhere else? Or Is this simply a reference to get the correct rods if I would need to order them to?
2 Initially I would just go ahead and ordering part no 96410391527 incl cylinder but when I cross checking this against the Porsche workshop manuals it says I have to have the same reference height/ weight as well as the other cylinders on the same bank. The piston has tolerance 1 and cylinder has height 5 and dia 3. Is this not important anymore?? How does this gets into the equation at ordering?
3 Is this the right way of approach? Meaning a new std M64.1/2/3 head + new M64.03 cylinder with piston just for this broken cylinder or do I have to do a refurb of all heads at a garage?
4 The piston has some other markings just under the large identifying marking 1 E . It says in small print 3/23. What is this?
The reason for this is that the valve plate for the inlet valve broke and the valve itself went down into the cylinder. What caused this is unknown.
It resulted in that the inlet valve broke into two pieces and then of course the piece with the valve itself fell down into the cylinder. Bang bang bang.
The” good” thing is that this happened almost standing still so the rev was really low and a immediate shutdown was possible.
I now have a mark in the piston so I know that has to be replaced , the head itself has a broken valveguide with a piece of broken valve, half of it is stuck in it and some 1mm of metal missing in a place so I need a new head as well.
The car has only ~ 30000km so it’s quite a rare low milage car. The last 10 years in my possession I used it on trackdays and some trackdriving around Europe so its really a trailer queen. With that said I really don’t want to renovate more than necessary. I can hardly see any wear/tear during my engine teardown on the internal parts so send all 6 heads for refurbishing seems a bit overkill.
Here come the questions to the elite at Rennlist.
1 My thought is to buy a new complete head with valves and all and a new RS piston/cylinder . But looking in PET I can read that I need to find the piston marks - - 644-648G??
There are no such things on the cylinder or piston?? Or should I look somewhere else? Or Is this simply a reference to get the correct rods if I would need to order them to?
2 Initially I would just go ahead and ordering part no 96410391527 incl cylinder but when I cross checking this against the Porsche workshop manuals it says I have to have the same reference height/ weight as well as the other cylinders on the same bank. The piston has tolerance 1 and cylinder has height 5 and dia 3. Is this not important anymore?? How does this gets into the equation at ordering?
3 Is this the right way of approach? Meaning a new std M64.1/2/3 head + new M64.03 cylinder with piston just for this broken cylinder or do I have to do a refurb of all heads at a garage?
4 The piston has some other markings just under the large identifying marking 1 E . It says in small print 3/23. What is this?
01-06-2014, 06:37 PM
#2
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Valve retainer failure is due to metal fatigue and is common in 964 and 964RS engines that get used on track. When Porsche & others raced these engines they rebuilt them at least every 100 hours and replaced these parts - with average lap speeds of 100mph that equates to 10,000 miles between rebuilds. Unfortunately your 30,000 mile trailer queen has been running well past its recommended rebuild interval for a race engine, hence not only would I rebuild the entire engine, I would rebuild all the cylinder heads with new valve spring retainers (we have Ti replacement sets with springs if required) and I would replace the complete set of pistons and cylinders, otherwise the next failure you will be dealing with is a failed piston with the connecting rod through the side of the block.
You don't believe me? Take a look at this P&C from another garage queen 964RS engine which failed at the 'ring, maybe that will change your mind?
You don't believe me? Take a look at this P&C from another garage queen 964RS engine which failed at the 'ring, maybe that will change your mind?
01-07-2014, 11:51 AM
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Hi Colin and thanks for the reply even due you bringing dark clouds over the future..
I know that its a "common" problem with the retainers thats why I replaced all of them just some 15 running hrs ago, (2 winters ago).
I was simply afraid of the broken retainers so I did it in preventing reason. Good that I did because a small part of one spring was actuall off at one of the springs. Thats why this failure is even more annoying. But thats another parrallell story with that supplier..
I just want to correct the milage of the car, Im talking km so in miles it should be around 18600 inkl road usage so I dont think this has gone so hard and long that a total rebuilt must be done? Yes, the retainers will be replaced again due to lack of trust as well as all packings etc but a complete set of cylinders and pistons?
Its still a std RS engine except from a better exhaust and new airflow meter/chip.
But Ok , I think I know your answer. (And I would really appreciate to get your "spareparts" list with prices sent via email)
But let´s dive into the world of porsche (Mahle) pistons/ cylinders / PET lists / workshop manuals again and my other questions. Q nr 3 is under process..
I know that its a "common" problem with the retainers thats why I replaced all of them just some 15 running hrs ago, (2 winters ago).
I was simply afraid of the broken retainers so I did it in preventing reason. Good that I did because a small part of one spring was actuall off at one of the springs. Thats why this failure is even more annoying. But thats another parrallell story with that supplier..
I just want to correct the milage of the car, Im talking km so in miles it should be around 18600 inkl road usage so I dont think this has gone so hard and long that a total rebuilt must be done? Yes, the retainers will be replaced again due to lack of trust as well as all packings etc but a complete set of cylinders and pistons?
Its still a std RS engine except from a better exhaust and new airflow meter/chip.
But Ok , I think I know your answer. (And I would really appreciate to get your "spareparts" list with prices sent via email)
But let´s dive into the world of porsche (Mahle) pistons/ cylinders / PET lists / workshop manuals again and my other questions. Q nr 3 is under process..
12-06-2020, 11:31 PM
#5
As the headline says, I need to replace the piston and the head in a 92-RS
The reason for this is that the valve plate for the inlet valve broke and the valve itself went down into the cylinder. What caused this is unknown.
It resulted in that the inlet valve broke into two pieces and then of course the piece with the valve itself fell down into the cylinder. Bang bang bang.
The” good” thing is that this happened almost standing still so the rev was really low and a immediate shutdown was possible.
I now have a mark in the piston so I know that has to be replaced , the head itself has a broken valveguide with a piece of broken valve, half of it is stuck in it and some 1mm of metal missing in a place so I need a new head as well.
The car has only ~ 30000km so it’s quite a rare low milage car. The last 10 years in my possession I used it on trackdays and some trackdriving around Europe so its really a trailer queen. With that said I really don’t want to renovate more than necessary. I can hardly see any wear/tear during my engine teardown on the internal parts so send all 6 heads for refurbishing seems a bit overkill.
Here come the questions to the elite at Rennlist.
1 My thought is to buy a new complete head with valves and all and a new RS piston/cylinder . But looking in PET I can read that I need to find the piston marks - - 644-648G??
There are no such things on the cylinder or piston?? Or should I look somewhere else? Or Is this simply a reference to get the correct rods if I would need to order them to?
2 Initially I would just go ahead and ordering part no 96410391527 incl cylinder but when I cross checking this against the Porsche workshop manuals it says I have to have the same reference height/ weight as well as the other cylinders on the same bank. The piston has tolerance 1 and cylinder has height 5 and dia 3. Is this not important anymore?? How does this gets into the equation at ordering?
3 Is this the right way of approach? Meaning a new std M64.1/2/3 head + new M64.03 cylinder with piston just for this broken cylinder or do I have to do a refurb of all heads at a garage?
4 The piston has some other markings just under the large identifying marking 1 E . It says in small print 3/23. What is this?
The reason for this is that the valve plate for the inlet valve broke and the valve itself went down into the cylinder. What caused this is unknown.
It resulted in that the inlet valve broke into two pieces and then of course the piece with the valve itself fell down into the cylinder. Bang bang bang.
The” good” thing is that this happened almost standing still so the rev was really low and a immediate shutdown was possible.
I now have a mark in the piston so I know that has to be replaced , the head itself has a broken valveguide with a piece of broken valve, half of it is stuck in it and some 1mm of metal missing in a place so I need a new head as well.
The car has only ~ 30000km so it’s quite a rare low milage car. The last 10 years in my possession I used it on trackdays and some trackdriving around Europe so its really a trailer queen. With that said I really don’t want to renovate more than necessary. I can hardly see any wear/tear during my engine teardown on the internal parts so send all 6 heads for refurbishing seems a bit overkill.
Here come the questions to the elite at Rennlist.
1 My thought is to buy a new complete head with valves and all and a new RS piston/cylinder . But looking in PET I can read that I need to find the piston marks - - 644-648G??
There are no such things on the cylinder or piston?? Or should I look somewhere else? Or Is this simply a reference to get the correct rods if I would need to order them to?
2 Initially I would just go ahead and ordering part no 96410391527 incl cylinder but when I cross checking this against the Porsche workshop manuals it says I have to have the same reference height/ weight as well as the other cylinders on the same bank. The piston has tolerance 1 and cylinder has height 5 and dia 3. Is this not important anymore?? How does this gets into the equation at ordering?
3 Is this the right way of approach? Meaning a new std M64.1/2/3 head + new M64.03 cylinder with piston just for this broken cylinder or do I have to do a refurb of all heads at a garage?
4 The piston has some other markings just under the large identifying marking 1 E . It says in small print 3/23. What is this?
Thanks