Take out Pistons and Cylinders as a Unit?

[arbita1]

I have Alusil cylinders. Do I leave the Pistons in when I remove them?

Car has 205,000 miles. Compression was good across all cylinders. I'm not sure on burning oil because I had some bad leaks. Which is why I am in the middle of this to start with.

I would like to take them apart to measure and check condition. But I don't want to cause any problems that I don't have now.

Thoughts.





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[ischmitz]

OK, while be far from a specialist let me take a stab at this: You can take the cylinders off by itself and later you need a piston ring compressor to re-install onto the pistons. Else you'll never know if you have broken piston rings.

But let's start at the beginning: Lot's of questions:

- What year are we talking about? Let's assume this is your 83SC engine.
- What prompted you to tear into the engine in the first place?
- What was it's condition, history, etc

And most importantly: what are you trying to accomplish?

In general chances are the heads need attention much sooner than the bottom end. If compression was good why not leaving it alone. If oil pressure was good bearings might be just fine.

But then again, the sky is the limit when doing upgrades to the engine

Ingo`

[Bob Kontak]

Originally Posted by arbita1

I have Alusil cylinders. Do I leave the Pistons in when I remove them?

How are you going to cut the pistons loose? I don't think this is possible.

Piston pin is in the bore of the cylinder. Connecting rod bolts may be accessed by clearing the other bank for access.

You have to remove cylinders from the pistons.

You want to do this. It's ok.

[SCadaddle]

Oh the slippery slope......

[mreid]

Remove them as a unit. With this many miles and being this deep in the engine, I would check the rod bearings, cylinders, and replace the rings. Frankly, with that mileage you should at least rebuild the heads while you have them apart.

[daepp]

Originally Posted by ischmitz

If oil pressure was good bearings might be just fine.
Ingo`

Can you explain this? It's probably a dumb question but I've seen that comment before and I don't understand it. Don't engines develop oil pressure from their oil pumps? Especially the 911? Edumucate me!

[SCadaddle]

Recalling from memory of 4 years ago, there is a procedure for installing the pistons and cylinders that I seem to remember went 1-2-3-6-5-4. So I'm thinking the removal would be the reverse of the assembly.
I'm pretty certain we removed the cylinders one at a time, and the "trick" to removing the wrist pins was to remove the pin circlips and then fashion a slide hammer tool with a piece of threaded rod 18" or so with a piece of pipe over one end of the rod, nuts and washers-----washer slightly less than the same diameter as the wrist pin on that end of the tool----on each end of the threaded rod. Have someone hold the piston while you gently pull the wrist pins out with the slide hammer by repeatedly sliding the pipe towards you and against the nut and washer at the end of the threaded rod that isn't at the wrist pin.
Then as you remove the pistons and have to turn the crank to remove the others support the ends of the rods with a pair of #64 rubber bands---loop the band over the upper stud, through the rod and then on to the other upper stud. Put another rubber band same fashion on the bottom studs and through the rods. Keeps the ends of the rods from flopping around and dinging the lower cylinder spigot of the case when you turn the crankshaft.

I)---========--------------------------(I
nut, washer, threaded rod, pipe, washer nut diagram above

[Scottc714]

Just put mine back in today. For some reason I took a couple pictures...

I do not need new pistons or rings, just replacing the lower 12 studs. So in my case it was easier to remove them as a unit.

I remove them in this order: 1,2,3,4,5,6 . pins and one circlip each come out in the direction of the chain covers.

They go back in reverse order. 3,2,1 and then 6,5,4. It becomes pretty obvious you have to do it this way so you can get at the pins.







Broken studs have caused me a lot of work on 2 different motors now.

I put a couple bends and custom grinds on a bbq skewer and pulled the pins right out.



Circlips come off with a small screw driver keeping your finger on the clip at all times to avoid them shooting off into the case.

[Ronnie's.930]

Originally Posted by daepp

Can you explain this? It's probably a dumb question but I've seen that comment before and I don't understand it. Don't engines develop oil pressure from their oil pumps? Especially the 911? Edumucate me!

Oil pressure is determined primarily by the size of the various oil passages within the crankshaft and other key engine components (not the oil pump itself) - when crank main bearings wear, the clearances increase and offer less resistance to the oil flow, and thus, overall pressure drops.

[Scottc714]

Originally Posted by Ronnie's.930

Oil pressure is determined primarily by the size of the various oil passages with in the crankshaft and other key engine components (not the oil pump itself) - when main bearings wear, the clearances increase and offer less resistance to the oil flow, and thus, overall pressure drops.

Wait...what??!! No sexual overtones?

[Ronnie's.930]

Scott, I have to watch myself more closely over here - past experience(s) errrr, dicktate that!

Butt you could read something into my "passages" comment, if you wanted to, buttofcourse!!!

[Scottc714]

You ought to be able to come up with something, seeing as were discussing rods and shafts

[Ronnie's.930]

See, my edit, bro! All is right in the world once again!!!

[Scottc714]

Good..I expect no less

[michael lang]

Originally Posted by SCadaddle

Oh the slippery slope......

My thoughts exactly!

[arbita1]

My question is more about if I should follow Wayne's book in leaving the p&c together because they are alumsil. Has anyone not done this and had bad results? On a 205,000 mile engine I feel like they should be taken apart for review.

[cabmandone]

I didn't see where you did a cylinder leak down test but you mention the compression was good. I'd probably leave them together. From the reading I did when doing my head studs people seemed to recommend keeping the P&C's together. You might bounce Henry, John Walker or Bruce (flat6pac) and see what they have to say.
You might also post this question on the rebuild forum or see if it can be moved there.

[boyt911sc]

Originally Posted by arbita1

My question is more about if I should follow Wayne's book in leaving the p&c together because they are alumsil. Has anyone not done this and had bad results? On a 205,000 mile engine I feel like they should be taken apart for review.

Matt,

An engine with 205K miles on it and that's a lot, you don't expect to re-use the oil rings. Common wisdom dictates installing new set of piston rings unless they are newly installed and good. With 205K miles on them, how much longer do you expect them to last? They are not that expensive and replacing them would be a prudent course of action. My two cents.

Tony

[arbita1]

Originally Posted by boyt911sc

Matt,

An engine with 205K miles on it and that's a lot, you don't expect to re-use the oil rings. Common wisdom dictates installing new set of piston rings unless they are newly installed and good. With 205K miles on them, how much longer do expect them to last? They are not that expensive and replacing them would be a prudent course of action. My two cents.

Tony

This makes sense. But I have alusils. And you know the debate on re-ringing alusils.

[mreid]

IMO it's actually easier to remove them as a unit. You can then inspect them carefully before you take them apart. I also agree with Tony, your high mileage engine could use some help and you have most of the work complete already. If you are worried, call Troy at EBS Racing and ask his opinion. He bored my 3.2 cylinders to 98mm and had them coated for my 3.0 to 3.2ss build for a very reasonable price. Then you will have piece of mind.