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Update on my motor (from a long time back)

Ok, i highly doubt anyone remembers my post from last year about the loud knocking sound in the engine and that i was going to let it sit, blah blah blah. Anyhow I'll summarize everything as best as i can. Rebuilt the top end, had the cylinders reglazed or whatever (ausil) with new piston rings, heads were machined with new valves all the way around, etc. At this point the motor that i put together had 1400 miles on it and everything was looking great, then the motor started making really loud knocking noise at lower rpm's. So i limped it home, next day i checked all of the following; valve lift clearance, head barrel torques, exhaust nuts torques, rocker shafts, and leak down test. Everything passed with flying colors, even the leakdown on a pitch cold motor was less the 10% on all six. I came to the quick conclusion that i broke something in the case and that i was going to let it sit for a while until i got out of college and started making money again. Well it's been almost a year and i took it out and took the heads off today, this is what i see.

And i thought, how the hell could the valve have been getting stuck and contacting the pistons when the valves are perfectly fine. That's when i took a paper clip and used it as an inspection tool and sure enough, some of the oil spray bar holes were clogged in the cam housing.

This is a picture of the 1-3 cylinders for reference.

But anyhow, this time around i'm going to split the case and do everything from ground up to make sure that there's no chance of something like this again. It's going to be a slow process because i'm going to be buy stuff as i have money (almost never) but at least the pistons and cylinders sealed great.
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Old 02-10-2006, 06:46 PM
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Bummer, sorry to hear that. But, man those are pretty clear valve impressions. much better than I saw on my 3.6 that had contact! Hoping my small attempt at humor helps a little!

Cheers
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Old 02-10-2006, 07:52 PM
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I'm putting together a 3 liter and the previous rebuild had the same problem. It looked like the builder used too much loctite 574 and it got into the oil passages.

-Andy
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Old 02-10-2006, 09:33 PM
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I had that same sort of piston faint "C" mark on my 3.2 pistons once. I called them my "monogrammed pistons".
-Chris
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Old 02-11-2006, 06:16 AM
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So how do you think blocked cam spray bars caused this, ceased the rockers so the valves had to be knocked back up by the pistons? Any damage to your cam?

Steve
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Old 02-12-2006, 10:43 AM
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How do the cam lobes and rocker arms look? If there was serious oil starvation, you should see widespread damage on that cylinder's valve train. Have you inspected the valve springs for breakage?
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Old 02-12-2006, 11:58 AM
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Not sure yet, i don't work on the car at all during the week. I'm taking 15 credits this semester which means i only get like one day out of the week to mess with it. But my assumption is that the guides or rockers may be damaged and are what caused them to stay open longer than they should. I won't know for sure for awhile because i still need to finish splitting the case and such, then find a place where i can store all these parts for possible long term storage.
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Old 02-13-2006, 05:26 PM
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I split the case, plastic bits are everywhere. Appearantly the chain guides that i replaced some time back that had broken had more bits in the case than i thought.

Let this be a lesson, if your chain guides break and you take out all the big pieces, don't ever assume that there aren't more inside the case just because your not in the mood to split the case open. Btw, while one of the intermediate shafter bearing are beyond junk, all main bearings are in tip top condition, crank looks gorgeous and bearings don't show any sign of that copper color when they are worn down. At least there's some good news for once.
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Last edited by 1fastredsc; 02-19-2006 at 09:42 PM..
Old 02-18-2006, 02:46 PM
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Appearantly i had to resize the pics before posting them otherwise they come out blank, anyhow here they are.
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Old 02-19-2006, 09:45 PM
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Old 02-19-2006, 09:48 PM
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I stripped down both cam towers (including taking out spray bars). I cleaned out the spray bars, two of the oil feeds holes for the cam bearings were clogged. What's wierd is that i found no cam damage or rocker arm/shaft damage. What else could have caused my piston "mamogram"? My tensioners didn't collapse i don't think, because both of them are still stubborn as ever to compress with oil seeping out of that vent in the head of the piston.

I've got some time before i'll get back to the head and cam area of the motor, but's it's bothering me that i can't come up with a definitive answer as to what went wrong.
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Old 02-28-2006, 10:33 AM
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What the hell is all that little black gritt in the sump plate

If this is silicone I am surprised the entire engine did not grenade from oil starvation left and right. Make sure you'll clean every oil passage on the case and on the crank before putting it back together.
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Old 03-02-2006, 11:17 PM
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I believe he was saying it is what was left of the chain guides.
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Old 03-03-2006, 07:41 AM
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Quote:
Originally posted by ischmitz
What the hell is all that little black gritt in the sump plate
Chain guide bits left over from the one that i replaced since it was destroyed.
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Old 03-03-2006, 07:43 AM
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Looks like a cam timing issue ...

Eddie
Old 03-03-2006, 01:55 PM
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Are you sure that you have CIS cams in this motor?

The CIS pistons have a very high dome and can only be used with CIS cams or there will be piston to valve interference.
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Old 03-03-2006, 05:00 PM
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Well i never changed them, but if a previous owner changed them and i didn't know that would explain a lot. I assume there's a way to take a set of dial calipers to the cam lobes to see what profile they are exactly?
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Old 03-04-2006, 03:49 PM
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Check the P/N stamped on the Cams. I'll cross reference it with the Porsche PET parts catalog.
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Old 03-04-2006, 06:12 PM
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Here are two numbers i found on one cam
9301051479r
930 147.10
btw, is there a way to check if they've been reground?
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Old 03-04-2006, 08:16 PM
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Here is the part number for an SC camshaft 81-: 930.105.147.10
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Old 03-04-2006, 08:21 PM
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