Anyone with technical knowledge of the 928 engine want to talk?
12-16-2007, 10:42 PM
#16
Rennlist Member
its got to be a pretty bad leak to hydrolock the motor. I think i remember this failure from a while ago. wasnt something in the motor that damaged a cylinder and chewed up the head? I think that is how the rods and pistons got damaged.
Were these new rings on this motor? (besides the new piston) . did you check the ring gap clearances?
The fact that the engine just stopped when you were cranking it over is not a good sign. it probably is like what scot and I saw with the motor that he didnt change the rings and it cold have been started for a longer than acceptable period with the coil wire hooked up incorrectly.
also, since you used a used block, we dont know the clearances there. Were the coatings bad or spotty, on the piston skirts?
bummer that motor has to come out, but you wouldnt be the first one to do this! Scot and i pulled his engine 4 times... Lots of work. fortunately it was over a year's time and I like to do this kind of stuff!
Mk
Were these new rings on this motor? (besides the new piston) . did you check the ring gap clearances?
The fact that the engine just stopped when you were cranking it over is not a good sign. it probably is like what scot and I saw with the motor that he didnt change the rings and it cold have been started for a longer than acceptable period with the coil wire hooked up incorrectly.
also, since you used a used block, we dont know the clearances there. Were the coatings bad or spotty, on the piston skirts?
bummer that motor has to come out, but you wouldnt be the first one to do this! Scot and i pulled his engine 4 times... Lots of work. fortunately it was over a year's time and I like to do this kind of stuff!
Mk
12-17-2007, 04:34 AM
#17
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Mark posted
My M28/11 euro motor is non interference, I checked it. This is the manual version of the M28/12 motor (auto version) that is being used.
It would be interesting to know how the con rod got bent in the first motor; that is pretty hard to achieve.
BTW, a few people have reported ticking noises without engine problems or ever finding the cause
Marton
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I dont think the euro heads, with euro valves is a non interference.
It would be interesting to know how the con rod got bent in the first motor; that is pretty hard to achieve.
BTW, a few people have reported ticking noises without engine problems or ever finding the cause
Marton
12-17-2007, 09:52 AM
#18
Rennlist Member
How do you know? (how did you check this?) Ive worked on several of these at the block level, and they were not even close to being non interference.
one proof point is that with the heads on the block, if you depress a valve, the distance it takes to hit the piston is .3". it becomes obvious at that point to see with a .4" lift or greater, you will have an impact if the piston is ever at TDC and the cams are at max lift.
If you checked this with the engine assembled, you might have seen non-interference because the lifters were not pumped up with oil yet.
mk
one proof point is that with the heads on the block, if you depress a valve, the distance it takes to hit the piston is .3". it becomes obvious at that point to see with a .4" lift or greater, you will have an impact if the piston is ever at TDC and the cams are at max lift.
If you checked this with the engine assembled, you might have seen non-interference because the lifters were not pumped up with oil yet.
mk
Mark posted
My M28/11 euro motor is non interference, I checked it. This is the manual version of the M28/12 motor (auto version) that is being used.
It would be interesting to know how the con rod got bent in the first motor; that is pretty hard to achieve.
BTW, a few people have reported ticking noises without engine problems or ever finding the cause
Marton
HTML Code:
I dont think the euro heads, with euro valves is a non interference.
It would be interesting to know how the con rod got bent in the first motor; that is pretty hard to achieve.
BTW, a few people have reported ticking noises without engine problems or ever finding the cause
Marton
12-17-2007, 10:41 AM
#19
Captain Obvious
Super User
Super User
Are all the pistons the same tolerance group as the block?Also maybe a small bolt or something got into the oil pump and locked it up. When you moved the cams, did you pull the timing belt totally off?
12-17-2007, 12:07 PM
#20
Racer
Thread Starter
Thanks for all the reply's. I will attempt to answer all the questions posted.
The engine I assembled this time is a 1980 euro S. Six of the pistons are original to this engine. I replaced #1 as it was damaged as a result of the broken valve in the M28/12 block. I also replaced #6 with a nicer one. My #6 had some slight detonation damage. The replacement was nicer in appearance.
Both replacement pistons were in the same tolerance group.
I installed new rings on my euro S pistons when I assembled the M28/12 short block. I reused 7 of these ring sets as they had less than 1000 miles on them. They are Goezte rings.
I did not check the ring end gap. This may be my un-doing. I ordered a replacement set of rings for #1 cylinder as they were damaged by the broke piston.
I received a set of Porsche factory rings. The oil control ring is far superior to the Goezte brand! If I had known the difference prior to installing the Goetze rings I would have use the factory style.
So, Now a new question: Anyone ever had trouble installing replacement rings for a stock bore into their used engine?
Is it manditory to file ring end gaps on stock rings?
Is filing required with Porsche rings?
The reason I'm asking is I drew on my past chevy experience with ring sets. I never had to file replacement rings in a worn bore.
Now I'm thinking I may have a ring set that is tight at the base of the stroke causing the tightness I felt during the assembly rotation. I need to quit guessing now and get this thing knocked apart.
The engine I assembled this time is a 1980 euro S. Six of the pistons are original to this engine. I replaced #1 as it was damaged as a result of the broken valve in the M28/12 block. I also replaced #6 with a nicer one. My #6 had some slight detonation damage. The replacement was nicer in appearance.
Both replacement pistons were in the same tolerance group.
I installed new rings on my euro S pistons when I assembled the M28/12 short block. I reused 7 of these ring sets as they had less than 1000 miles on them. They are Goezte rings.
I did not check the ring end gap. This may be my un-doing. I ordered a replacement set of rings for #1 cylinder as they were damaged by the broke piston.
I received a set of Porsche factory rings. The oil control ring is far superior to the Goezte brand! If I had known the difference prior to installing the Goetze rings I would have use the factory style.
So, Now a new question: Anyone ever had trouble installing replacement rings for a stock bore into their used engine?
Is it manditory to file ring end gaps on stock rings?
Is filing required with Porsche rings?
The reason I'm asking is I drew on my past chevy experience with ring sets. I never had to file replacement rings in a worn bore.
Now I'm thinking I may have a ring set that is tight at the base of the stroke causing the tightness I felt during the assembly rotation. I need to quit guessing now and get this thing knocked apart.
12-17-2007, 12:28 PM
#21
Brendan
12-17-2007, 12:35 PM
#22
Rennlist Member
normally, the stock rings will fit without filling. I think you end up with around .017" gap if you put the ring down in the bores about 1" or so.
I havent had any issues using new rings in old bores. its the way to do it. (as long as they look good). also no issues with the Goetze oil ring. they have worked out well.
the tightness of the one piston you felt, could have been the issue.
How did you check for it being a non interference engine again? (see my previous post comments.
Mk
by the way, we do have the "new" 928 euro motor short block. OR, if you find out you have done some damage and want to over bore to fix cylinder issues, we have 6 good used euro pistons, one size over bore .
I havent had any issues using new rings in old bores. its the way to do it. (as long as they look good). also no issues with the Goetze oil ring. they have worked out well.
the tightness of the one piston you felt, could have been the issue.
How did you check for it being a non interference engine again? (see my previous post comments.
Mk
by the way, we do have the "new" 928 euro motor short block. OR, if you find out you have done some damage and want to over bore to fix cylinder issues, we have 6 good used euro pistons, one size over bore .
Thanks for all the reply's. I will attempt to answer all the questions posted.
The engine I assembled this time is a 1980 euro S. Six of the pistons are original to this engine. I replaced #1 as it was damaged as a result of the broken valve in the M28/12 block. I also replaced #6 with a nicer one. My #6 had some slight detonation damage. The replacement was nicer in appearance.
Both replacement pistons were in the same tolerance group.
I installed new rings on my euro S pistons when I assembled the M28/12 short block. I reused 7 of these ring sets as they had less than 1000 miles on them. They are Goezte rings.
I did not check the ring end gap. This may be my un-doing. I ordered a replacement set of rings for #1 cylinder as they were damaged by the broke piston.
I received a set of Porsche factory rings. The oil control ring is far superior to the Goezte brand! If I had known the difference prior to installing the Goetze rings I would have use the factory style.
So, Now a new question: Anyone ever had trouble installing replacement rings for a stock bore into their used engine?
Is it manditory to file ring end gaps on stock rings?
Is filing required with Porsche rings?
The reason I'm asking is I drew on my past chevy experience with ring sets. I never had to file replacement rings in a worn bore.
Now I'm thinking I may have a ring set that is tight at the base of the stroke causing the tightness I felt during the assembly rotation. I need to quit guessing now and get this thing knocked apart.
The engine I assembled this time is a 1980 euro S. Six of the pistons are original to this engine. I replaced #1 as it was damaged as a result of the broken valve in the M28/12 block. I also replaced #6 with a nicer one. My #6 had some slight detonation damage. The replacement was nicer in appearance.
Both replacement pistons were in the same tolerance group.
I installed new rings on my euro S pistons when I assembled the M28/12 short block. I reused 7 of these ring sets as they had less than 1000 miles on them. They are Goezte rings.
I did not check the ring end gap. This may be my un-doing. I ordered a replacement set of rings for #1 cylinder as they were damaged by the broke piston.
I received a set of Porsche factory rings. The oil control ring is far superior to the Goezte brand! If I had known the difference prior to installing the Goetze rings I would have use the factory style.
So, Now a new question: Anyone ever had trouble installing replacement rings for a stock bore into their used engine?
Is it manditory to file ring end gaps on stock rings?
Is filing required with Porsche rings?
The reason I'm asking is I drew on my past chevy experience with ring sets. I never had to file replacement rings in a worn bore.
Now I'm thinking I may have a ring set that is tight at the base of the stroke causing the tightness I felt during the assembly rotation. I need to quit guessing now and get this thing knocked apart.
Last edited by mark kibort; 12-17-2007 at 08:59 PM.
