Another Project started (GT30R, fuel managenent etc)
08-28-2006, 05:39 PM
#271
Racer
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Hey Guy's
This is what i found out
something has pushed the crank forward you can see that all the cilinders exept one are scratched from one side. So crank moved front somehow, that pushed the rods into wrong position what again pushed the pistons into cilinder with wrong angle what made the pistons to scratch the wall of the cilinder from one side... I quess that what explainse why crank was hard to spin around...
Wha could cause this..I am using stock lightned flywheel with GT2 presure plate and 968 disk. Can this be involved here, witch i find hard to belive..
pics here: http://pildid.audiclub.ee/pprz/markus/
This is what i found out
something has pushed the crank forward you can see that all the cilinders exept one are scratched from one side. So crank moved front somehow, that pushed the rods into wrong position what again pushed the pistons into cilinder with wrong angle what made the pistons to scratch the wall of the cilinder from one side... I quess that what explainse why crank was hard to spin around...
Wha could cause this..I am using stock lightned flywheel with GT2 presure plate and 968 disk. Can this be involved here, witch i find hard to belive..
pics here: http://pildid.audiclub.ee/pprz/markus/
08-28-2006, 06:32 PM
#272
Nordschleife Master
uhhh OMG, talk about toast!
During assembly, did the crank spin freely with the crank, rods and pistons installed?
I guess so, because otherwise you would not had proceed..?
Mayby that also explained your low compression (extremely low piston to cyl wall clearance on one side makes for a bad seal on the other side)
During assembly, did the crank spin freely with the crank, rods and pistons installed?
I guess so, because otherwise you would not had proceed..?
Mayby that also explained your low compression (extremely low piston to cyl wall clearance on one side makes for a bad seal on the other side)
08-29-2006, 03:13 AM
#273
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when the engine was put together everything seemed normal, it spinned freely. but I noticed the the hard spin when I did the cam change. Then it was really hard to spin aroung even with the spark plug's removed!
markus
markus
08-29-2006, 09:15 AM
#275
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Yes, it look like the crank was pushed into the thrust bearing – but that will not load the pistons. There is way more lateral movement in the wrist pins than in the crank.
What did you use for piston to wall clearance?
One of the pictures shows wear/scoring right up to the top of the cylinder – this is very strange.
I didn’t see any pictures of the pistons – were the rings still intact? The badly scored cylinders may have broken rings.
A possible reason – bad ring gaps. What did you use for a ring gap? As they heat and expand they could have bound up eventually seizing the piston in the bore. That’s my long distance guess!
Chris White
What did you use for piston to wall clearance?
One of the pictures shows wear/scoring right up to the top of the cylinder – this is very strange.
I didn’t see any pictures of the pistons – were the rings still intact? The badly scored cylinders may have broken rings.
A possible reason – bad ring gaps. What did you use for a ring gap? As they heat and expand they could have bound up eventually seizing the piston in the bore. That’s my long distance guess!
Chris White
08-29-2006, 09:54 AM
#276
I handeled Markus' block repair last spring here in Finland. It was done by a local machine shop which is also used by Porsche Finland. Cylinder #1 got a new sleeve and the rest of the cylinders got new Alusil treatment.I checked the block out before Markus' father picked it up. Block seemed to be OK, at least all machine work was done as it should. So, it's hard to say what has caused this disaster, at least cylinder #1's sleeve has not been moved.
08-29-2006, 10:07 AM
#277
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My guess: Transaxle was forced against flywheel during engine installation. I think this is something that can easyly happen if you are not carfull. Never get the engine mounted on the transaxle by tightening the screws on the housing only and forcing the axle into the flywheel bearing. If you installed a new flywheel the position of the flywheel bearing might be slightly differnet and requires the transaxle to be shorter. This can be done by undoing the bolts on the transaxle-to-gerabox connection. I would strongly reccomend to unscrew those bolts after an engine installation and turn the crank a few time if you are unsure that everything fits. That will release any kind of axial tension that might be on the transaxle. It is sometimes a big struggle to get the engine aligned so that everything fits, especially when you are alone but never force anything.
08-29-2006, 10:09 AM
#278
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Well
The thing is that piston rings are ok, they where not broken during the process..
http://pildid.audiclub.ee/pprz/markus/IMG_7057.JPG
Does porsche engine have crank distance washer? could that be broken or weared out, and that caused the crank movement..
As far as ring gap, piston rings where installed just like that, mechanic took them out of the block and did the installation..I do not know did he measure the gap or not. Rings where bought from 944online.com
How typical is that the engine broke due to:
1. Bad mechanic who put the engine together.
2. Distance washer
3. Ring Gaps
4. Piston and Cilinder clearence
5. Upgraded clutch and pressure plate
Markus
The thing is that piston rings are ok, they where not broken during the process..
http://pildid.audiclub.ee/pprz/markus/IMG_7057.JPG
Does porsche engine have crank distance washer? could that be broken or weared out, and that caused the crank movement..
As far as ring gap, piston rings where installed just like that, mechanic took them out of the block and did the installation..I do not know did he measure the gap or not. Rings where bought from 944online.com
How typical is that the engine broke due to:
1. Bad mechanic who put the engine together.
2. Distance washer
3. Ring Gaps
4. Piston and Cilinder clearence
5. Upgraded clutch and pressure plate
Markus
08-29-2006, 10:14 AM
#279
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Hi Markus,
as far as I know there is no thrust washer in the engine. Axial loads, that should not occure, would be counteracted by the middle crank bearing which has some soulders. All the others are just half round shells and can not take other that radial load.
Don´t know about the other points...
as far as I know there is no thrust washer in the engine. Axial loads, that should not occure, would be counteracted by the middle crank bearing which has some soulders. All the others are just half round shells and can not take other that radial load.
Don´t know about the other points...
08-29-2006, 11:40 AM
#280
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That can be it. THis is actually second car witch has dirven out from this garage and had same failure. My friend 951 had gearbox change there also and after 50 km he lost oil pressure du to the fack that the crank was pushed front and this damaged oil pump somehow. Also hes engine was not rebuilded and the bearing what holds the crank from movement was snapped...
My guess: Transaxle was forced against flywheel during engine installation. I think this is something that can easyly happen if you are not carfull. Never get the engine mounted on the transaxle by tightening the screws on the housing only and forcing the axle into the flywheel bearing. If you installed a new flywheel the position of the flywheel bearing might be slightly differnet and requires the transaxle to be shorter. This can be done by undoing the bolts on the transaxle-to-gerabox connection. I would strongly reccomend to unscrew those bolts after an engine installation and turn the crank a few time if you are unsure that everything fits. That will release any kind of axial tension that might be on the transaxle. It is sometimes a big struggle to get the engine aligned so that everything fits, especially when you are alone but never force anything.
08-29-2006, 01:00 PM
#281
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The thrust bearing (center main bearing) won’t allow the crank to move forward. Typically if you force the drive shaft in you will trash the pilot bearing. A high clamping force pressure plate can wear the thrust bearing prematurely – and yours does show some wear – but not enough to cause a rod failure.
Ask your ‘mechanic’ what he used for ring gap – if he just installed them with out measuring then he F’ed up in a big way. The damage on the piston walls looks just like a bad ring gap. I had a customer fail to gap his rings correctly and it caused the same wear pattern – as the rings expand the ends will eventually butt together and any further expansion has to be outward against the cylinder wall. Usually the ring ends are will severely gouge the walls.
Take a ring off the piston and see if you can measure the ring gap now.
Chris White
Ask your ‘mechanic’ what he used for ring gap – if he just installed them with out measuring then he F’ed up in a big way. The damage on the piston walls looks just like a bad ring gap. I had a customer fail to gap his rings correctly and it caused the same wear pattern – as the rings expand the ends will eventually butt together and any further expansion has to be outward against the cylinder wall. Usually the ring ends are will severely gouge the walls.
Take a ring off the piston and see if you can measure the ring gap now.
Chris White
08-29-2006, 01:04 PM
#282
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I realy hope you getting your car up running again!!!
So far this is one of the best threads in the forum. Everyone can pick some information and the amount of polemics is almost zero. You not only spend a lot of time keeping us updated on the forum but even a lot more to transform your car into somthing very extraordinary.
Don´t get dissencouraged!! Keep pushing!!
So far this is one of the best threads in the forum. Everyone can pick some information and the amount of polemics is almost zero. You not only spend a lot of time keeping us updated on the forum but even a lot more to transform your car into somthing very extraordinary.
Don´t get dissencouraged!! Keep pushing!!
08-29-2006, 02:11 PM
#283
Racer
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I am using GT2 pressure plate with is rated for 650 nm and 968 clutch disk. 968 pilot bearing. My mechanic drives same combo and no failures during 2 year dirving.
When we opened up the engine we discovered that the pistons and rods where under the pressure, like something was still pushing it..the wrist pins in all chrached 3 cilinders came out with force..
Cilinders ares cratche only from one side, the one cilinder with is on top of thrust bearing is not chrached at all..
I had metal in oil in all 3 oil changes what I went through and crank was hard to spin around..
When we opened up the engine we discovered that the pistons and rods where under the pressure, like something was still pushing it..the wrist pins in all chrached 3 cilinders came out with force..
Cilinders ares cratche only from one side, the one cilinder with is on top of thrust bearing is not chrached at all..
I had metal in oil in all 3 oil changes what I went through and crank was hard to spin around..
The thrust bearing (center main bearing) won’t allow the crank to move forward. Typically if you force the drive shaft in you will trash the pilot bearing. A high clamping force pressure plate can wear the thrust bearing prematurely – and yours does show some wear – but not enough to cause a rod failure.
Ask your ‘mechanic’ what he used for ring gap – if he just installed them with out measuring then he F’ed up in a big way. The damage on the piston walls looks just like a bad ring gap. I had a customer fail to gap his rings correctly and it caused the same wear pattern – as the rings expand the ends will eventually butt together and any further expansion has to be outward against the cylinder wall. Usually the ring ends are will severely gouge the walls.
Take a ring off the piston and see if you can measure the ring gap now.
Chris White
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Ask your ‘mechanic’ what he used for ring gap – if he just installed them with out measuring then he F’ed up in a big way. The damage on the piston walls looks just like a bad ring gap. I had a customer fail to gap his rings correctly and it caused the same wear pattern – as the rings expand the ends will eventually butt together and any further expansion has to be outward against the cylinder wall. Usually the ring ends are will severely gouge the walls.
Take a ring off the piston and see if you can measure the ring gap now.
Chris White
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08-30-2006, 01:09 AM
#284
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Originally Posted by tedesco
My guess: Transaxle was forced against flywheel during engine installation. I think this is something that can easyly happen if you are not carfull. Never get the engine mounted on the transaxle by tightening the screws on the housing only and forcing the axle into the flywheel bearing. If you installed a new flywheel the position of the flywheel bearing might be slightly differnet and requires the transaxle to be shorter. This can be done by undoing the bolts on the transaxle-to-gerabox connection. I would strongly reccomend to unscrew those bolts after an engine installation and turn the crank a few time if you are unsure that everything fits. That will release any kind of axial tension that might be on the transaxle. It is sometimes a big struggle to get the engine aligned so that everything fits, especially when you are alone but never force anything.