Re-ring Alusils? - Page 17

Porsche_monkey · 02-12-2004, 08:01 AM

Just to confirm, we're talking scratches, not burrs, right? I was thinking more about a burr when I replied. A scratch may not be removable without going out of spec. I suspect you'll have to clean it up and live with it.

konish · 02-12-2004, 08:44 AM

All,
Thanks for the responses....I knew this thread was still strong! Anyway, they are indeed scratches...very fine, even finer than a human hair. Truth be told, I really can't feel it with my fingernail along the whole length of the scratch...just in some areas. I noticed them mostly by the shinier appearance vs the dull grey of the cyl walls. I too thought that maybe silicon particles that have come loose from the aluminum substrate may have been contributors, and who knows the scratches themselves may disappear over time. I guess what I'm basically trying to say is that as soon as the P&C's were pulled, it forze time for this set, and the scratches in their latest position may be transitory in nature. I'm assuming this because they just look so darned fresh...like they happend yesterday as opposed to hundreds or even thousands of miles ago. You'd think the exhasut gases and carbon would eventually cause these scratches to blend in with the rest of the cyl, unless of course the rings just keep re-scratching in the same exact place time and time again. Again, I'm not too worried about it, but just thought I'd ask before I have them prepped.

William Miller:
I noticed this too, and have thought long and hard about this subject as I have my '83 WUR apart as I type this. The newer WUR's also have a small bi-metallic strip that controls the resistance in the main heating element on the large bi-metallic strip. As the temp increases,it allows the contact to close which drops the resistance from 23 ohms to about 10 ohms. I figure this was to delay the WUR from coming up to pressure too fast on warm/hot days (due to the lower resistance of the heater element) allowing the motor to heat up in conjunction with the WUR instead of the WUR setting the pressure independent of engine temp. Of course when it's cold, the strip is open (23 ohms of resistance) to set the intial control pressure...otherwise on very cold days, it may take a very long time to set the proper control pressure. After the intial shove, the WUR gets hot enough to default to the 10ohm resistance on the element allowing for anice gentle set o nthe control pressure. I'm shooting for 5 min from freezing (its cold outside) to full control pressure, and I'll adjust as necessary from my initial setting. Ideally, I'd want the thing to heat up quick, with the heating curve becomng more level with respect to the time axis. I often wondered if the older WURs (or late ones for that matter) could wire in a variable resistance pot inside the car which would allow the driver to "dial in" how fast/slow they want the WUR to heat up...providing a measure of control over how it sets control pressures?

R/
Dustin

Nathan M · Nathan M's Garage

Well, the motor went back in the car at the weekend and fired her up tonight!! What a thrill, I almost daren't turn the key! Cranked for oil pressure first, then connected the DME relay and within a few seconds it was running. I still have to drive it, and I guess I'll not know for a while whether the new rings have taken to my Alusils but for now there's no smoke and a sweet sounding motor (which I had niether of when I pulled it apart). I let it run for 20 mins at 2000 rpm as per Waynes instructions, and for now everything looks good. No oil leaks either (but then it never leaked before so I'd be real pissed if it started now). Just need this damn snow to clear and the weather to improve so I can start to bed those babies in.....

Rondinone · 02-28-2004, 05:13 PM

We just fired ours up tonight. Like Nathan I was a bit nervous. Nervous about my rebuild, and nervous about my experimental alusil reconditioning.

Surprisingly, it only took about 10 seconds for the oil pressure to build. Then I reconnected the fuel pump and ignition module, and it started immediately.

It smoked for about 5 minutes during the 20 minute burn-in. After that it cleaned right up; it even smelled pretty good for an uncatalyzed motor! We drove it about 5 miles then called it a night, as several things are still out of adjustment like the throttle and shift linkage.

I'll give it a few hundred miles then check the compression, and report the numbers here. Then we alusilers can relish in our repeat-use cylinders!

Viva la revolucion!

konish · 03-01-2004, 04:46 AM

Rondinone and NathanM,
Congrtas to both of you. Its really exciting to see the inital stages of all that theory and analysis...hey, maybe this crazy idea will work! I can't wait to see the numbers on the compression tests!

R/
Dustin

William Miller · 03-01-2004, 05:35 AM

Great news guy's , I'm approaching 5,000 miles in a few weeks. I'll do some checks as well. It has broken in fine.

While we wait to hear more on these "sucess stories".
I have something that may or may not be off topic.
It's a noise.

It's not a thud, grind, squeel or knock.
It's like an exhaust tone (pulsing) but a little deeper and a millisecond delayed behind the normal rythm. (Almost like an echo.)
You can only hear it when you lift your foot off the throttle as the engine decelerates freely either in Nutral or with the clutch pedal down.
It may be there other times but I can only hear it at these times.
It's intermittant. Which may point to the cause.
When I drive to work (Engine started stone cold) I don't hear it.
If I drive again with in several hours I can heare this noise.
If the car sit's all day at work I usually don't hear it on the way home.
So you can only hear it once the engine is fully warmed up after beuing warmed once and a cycle or 2 of cooling, but not stone cold.

It doesn't really matter what the ambient tempature is as long as the engine has had a chance to cool for a while between drives.

My guess is that it has something to do with the different rates that the parts in the engine heat and cool.
Like maybe the head studs take longer to heat and cool than the cylinders and heads. There may possibly be an intermittant leak at the cylinder to head joint.
Can anyone here relate?
Has anyone had a head stud break and maybe heard this noise.
I did have my engine out once following the rebuild to fix my main seal leak. I checked the barrel nuts to make sure they were tight. (I just set the wrench to the right torque, and mad sure it clicked. I didn't lossen and retorque.)
Is that something I should do at 5,000 miles?
Anyone have any ideas?
Thanks!
What does piston slap sound like?

Porsche_monkey · 03-01-2004, 07:26 AM

Quote:

Originally posted by William Miller
What does piston slap sound like?

Usually only heard at idle. It does actually sound like slapping in the cylinders, but if your piston was not loose in the bore that would not be a likely source. Drive a high mileage Volvo 740 and you'll know what pistin slap sounds like.

William Miller · 03-01-2004, 07:32 AM

Mine are high milage, but that is not what I would describe as what I'm hearing. Is what your talking about sorta like a deisel engine?
Is it a ping or more of a deep sound?

Porsche_monkey · 03-01-2004, 07:54 AM

Not a ping. It is a deeper sound. I would expect it at idle only, on either a hot engine or a cold engine, but not both.

snowman · 09:56 PM

Professional advise on something like this is to drive it until it gets worse (a real professional will make up excuses for you to drive it longer so he can hear what it does as it gets worse) If it does get worse it will eventually get worse enough to know what is causing the sound, if not, so what, nothings wrong. Sounds like a crude diagnosis, but, unless you are NASA, you probably can't afford a diagnosis of a developing problem like the one you are describing.

William Miller · 03-02-2004, 06:04 AM

Snowman, that's what I keep telling my wife!
She hears every little squeak in her car. She immediately thinks something is going to fly apart and leave her stranded. It's an anexiety thing. I'm with you, I am very patient and try and diagnose as I drive.
If I can pinpoint the cause, effect relationship with the sound I can normally get very close to diagnosing the problem before tearing anything apart. Some things you just have to wait until they get worse.
I'm speculating at this point but I think it's a small exhaust leak or a head to cylinder leak.
I now don't think it's piston slap.
Can anyone discribe what that would sound like?

snowman · 03-02-2004, 08:22 PM

Piston slap is VERY similar sounding to loose lifters. It will start out quite pronounced, when the engine is cold, and quickly go away when it warms up (unless theres a big problem).

An exhaust leak is the most difficult to listen to, the most provoking, ie SOMETHING very bad MUST be wrong. The exhaust leak will most likely not hurt the performance much, if at all. The exhaust leak may not get worse either. But eventually it will leave its mark, a big black one.

Doug Zielke · 03-02-2004, 09:10 PM

It sure can hard to (correctly) identify engine sounds.
When my 3.0 was making sounds from a broken head stud (lower, #6 cyl.), I was absolutely convinced it was the sound of *detonation* (pinging).
Wrong!

When my pro-wrench took a drive up and down the alley behind his shop, he pronounced: "Broken head stud; right-hand lower side. Take it home and open'er up, the pieces will fall on the floor".
Right!

William Miller · 03-03-2004, 05:44 AM

Should I re-torque the head studs next time I adjust my valves.
I'm planning on doing this in the next few weeks. The rebuild will hit 5000 miles. I plan on spending some time tweeking and tuning along with compression and leakdown tests. I may also do a dye test to try and locate a very small leak.

Last time I checked to make sure the wrench would click at the correct amount, but I didn't losen them and retighten them. Maybe I should go just a little tighter.

The studs are a later style that have threads along their entire length.
I don't think I will pull or break them.

The last week it's been warm here in D.C. almost 70 yesterday. Nights have not been as cold. The noise may have gone away until next fall. Maybe I just can't hear it with the top down.

Porsche_monkey · 03-03-2004, 05:57 AM

My vote would be either don't touch them again (assuming you've done the 1000 mile retorque), or torque to the factory setting. I would not retorque to a higher setting. Just my opinion. Anyone else care to weigh in?

William Miller · 03-03-2004, 08:49 AM

I guess I need clarification on "retorque"
Is that what I did or should I losen the barrel nuts and go back thru the steps?

Porsche_monkey · 03-03-2004, 09:08 AM

I would not loosen them. Just confirm that they have not loosened off and get a 'click' from the wrench.

William Miller · 03-03-2004, 10:17 AM

That's what I did, probably about 500-1000 miles folowing the rebuild.
Will check again at 5000 miles.

Thanks all...
Now back on topic:

ANH: any news on oversized pistons?

Doug Zielke · 03-03-2004, 02:36 PM

Quote:

Originally posted by PBH
I would not loosen them. Just confirm that they have not loosened off and get a 'click' from the wrench.

Data point from the top-end I did on the "Blue Bomber"....

I removed the covers to check valve clearances and head nuts at 500, 1000, 2500 and 5000 miles after the motor installed.

There was only the most tiny fraction of tightening required on (2) head fasteners, at 1000 miles. All others were perfectly tight.

snowman · 03-03-2004, 10:09 PM

There is absolutely NO reason to retorque head studs in a Porsche. Any car that requires a retorque of head studs is because of the head gasket. Porsche head gaskets are metalic, rings, these DO NOT REQUIRE retorquing. If your Porsche DOES require a retorque, its got a problem, ie most likely a streached head stud. If it streatched once it will streach more, until it breaks.

Anyone got a reason to counter this point??