2,200 miles on rebuild, decel smoke

[Lorin]

3 hours ago, Doug Riparetti said:

I would NEVER have a block bored unless a torque plate was used, whether it's a street car, or a race car.....

 

When my Brother built my S14, we bought a torque plate, it also helps that my he owns a automotive machine shop......   

 

Since you are that committed, I hope you preformed all the machining at full operating temperature.  

[avoirdupois]

8 hours ago, HBChris said:

I know two machinists who won’t use Deves rings, they are too hard according to them and won’t seat properly.

 

Beg to differ.  Last time I checked, the factory used chrome plated top compression rings on the M10 that were likely supplied by Goetze.  (To the best of my knowledge, the chrome plating was never specifically required, but they typically came with replacement Mahle pistons.)  Chrome plating mated with a very strong iron composite block makes for durability.  In any event, the crome plating also make the rings harder to seat than the Deves (See below) especially without a good cross hatch pattern on the cylinder walls.  I have used rings from a number of different manufacturers - and fortunately, I cannot recall having a problem with any of them.  This includes the Goetze, Hastings, Perfect Circle and Deves.  I have no particular allegiance to the Deves brand.  I have used Deves on both an M10 and M30 block that were rehoned as opposed to rebored and reused original pistons.  No matter what rings are used, problems can easily arise due to poor cylinder wall preparation, poor choice of ring gaps, worn piston ring lands/poor ring fitment, improper piston to cylinder wall clearance and poor break in procedure.  Fortunately, as part of the break-in, parts usually/eventually find their own sweet spots and minor irregularities disappear.

 

Quote

Q: Are Deves rings compatible with all types of cylinders, that is, the many different materials in cylinders?

A: Yes! Different automobile makers use different materials for their cylinders: aluminum, nikasil, alusil, etc. Our rings work well with all of them. We make rings for the European and domestic aftermarket, but we are best known in the European. In fact, we are the official aftermarket suppliers in the U.S. for Rolls Royce, and are very popular for Mercedes, BMW's, and Porsches.

 

It's the Deves oil ring that looks very different from the OEM oil ring. Most manufacturers in the German market have a different type, usually a one, two, or three-piece oil ring. That's why the question comes up. Mechanics are concerned that the expander in our oil ring will put too much pressure on the cylinder wall.

If a mechanic is used to putting on a different type of oil ring, our rings do appear stiffer. That's the way it should be. Once the ring is in the engine, the heat in the engine will loosen it up, and it adjusts to the cylinder. The secret is the Swedish steel.

Q: What type of materials are your compression rings made of?

A: Deves doesn't use anything other than a cast iron alloy for its compression rings. It's a little more flexible than cast iron and not as flexible as some of the other materials that are out there. We don't use chrome plating because it's much harder on the cylinder. Chrome plated rings are also more difficult to seat. The only time Deves has a chrome plated or coated ring is when the OEM manufacturer specifies it. Peugeot, for example, has a specification that the top ring on a certain model must be a chrome ring, and that's when we would have it.

http://deves.com/faq.php

 

[Doug Riparetti]

39 minutes ago, Lorin said:

 

Since you are that committed, I hope you preformed all the machining at full operating temperature.  

You have to, it gets cold in Idaho. Heated, insulated shop......

[RD02]

You guys are cracking me up. Thanks for responding. I pulled the head off yesterday, it has to come off anyway whether it’s seals or rings, right. Didn’t have much time today but will add info tomorrow.

Robert

[TobyB]

On 3/23/2018 at 1:36 PM, Doug Riparetti said:

I would NEVER have a block bored unless a torque plate was used,

 

I believe you, Doug- your work is impressive!

 

And yes, the casting stretches and deforms around the bolts, probably to the order of a couple tenths.

In fact, I once 'scuffed up' a race block for new rings without the plate, and the distortion is very clear.  And minor.

 

Yes, it'll cost a few hp (or more) at WOT boring without the plate.  No, it shouldn't smoke excessively if you don't.

 

I also maintain, if you're going to the trouble of using the plate, that you should be using studs, and they

need to stay in place after the block's bored or the distortion will be different with a different thread pull.

 

It's good practice.  But I don't think it's the OP's primary problem...

 

t

 

[Doug Riparetti]

@TobyB.   My Brother is the machinist, not me, and yes, his work is impressive.

 

For my build, we did use ARP studs for the crank and head along with a Cometic head gasket.....

 

Edited March 25, 2018 by Doug Riparetti

[Brandon]

Smoke on deaccelaration sounds like a cylinder head problem.  Either a bad valve stem seal, bad valve guide, or cracked head.  I’d look there first.

[RD02]

Been a few days. Lots of great responses and info, thanks.  I pulled the head off last Saturday. Here’s where I might of gone outside the box. I plugged the oil return galley holes with foam rubber. Then filled the valve train box with trans fluid (it was the runniest stuff I had) to the top of the springs, and left it over night. Thinking if it was a cut seal and bad guide it would seep into the port. Next morning,  there was no seepage. So I cut some rubber and a piece of plastic to seal each port one at a time. Rotated the cam to close the valve, hooked up my MightyVac and pulled 25in of vacuum for 10 minutes on each port. I realize a running engine pulls a lot more vacuum especially on deceleration, but in my mind if something was bad there would have been some oil pulled into the port, which there wasn’t.

 

Not satisfied, today I disassembled the valve train. Eyeballed the late model seals and they were perfect. Pulled the valves, removed the seals, cleaned oil out of guides and off of the stems and did a wiggle test for stem/guide clearance. Each intake was .0045” and each exhaust was .005”. The Haynes manual says .008” is max. So after today I’m convinced my decel smoke is not from bad seals or guides. What do you guys think so far? Rings next.

     Robert

 

[LimeySteve]

My money is still on the oil rings , nice test rig though

 

[Simeon]

What do the bores look like. Post pictures. 

[kbmb02]

On 3/23/2018 at 1:36 PM, Doug Riparetti said:

I would NEVER have a block bored unless a torque plate was used, whether it's a street car, or a race car.....

 

On 3/23/2018 at 11:51 AM, TobyB said:

Fortunately, a torque plate, while not a bad idea at all, isn't strictly necessary.  It helps.  But the M10 doesn't distort all that much.  For a street build.

 

I agree with Toby, a toque plate is not absolutely necessary. And - whether with or without a torque plate - there are methods a good machinist uses to achieve a straight bore and properly-honed surface (some honing stones specific to ring type, for example).  -KB

[andyleonard]

You do good work. So unless you missed a bad/scratched valve stem, you've got oil ring problems. Your leakdown is on the lower end of perfect for a newly broken in engine so it's probably not the bore/hone since the top rings are pretty well sealed. 

 

You smelled something janky with the oil ring fit/assembly. Go there next. And make sure the oil returns behind the oil rings are open. 

 

No chance you've got the wrong dipstick in there and you're overfilled, right?

 

+1 on pics of the bore. 

 

I think you'll be back on the road with a new set of rings and a head gasket.

[TobyB]

Wow, Robert, you win.  That's good methodology- and nope, vacuum being the absence of air, a running engine can't pull more than one atmosphere!

 

Unfortunately, your prize is that you get to take the bottom end apart, because I think you've done a good job proving it's not the valve guides.

 

With that quality of work on the head, tho, it's surprising that the bottom didn't seal- unless you open it up and find

(for example)

an oil control ring upside- down.

 

Which I hope you do.

 

But I fear you won't.

 

Good luck,

t

 

[RD02]

Thanks for the support guys, thanks Toby.

 

 I did pull the pistons. Here’s more photos of the head, and then cylinders. 

 

 

 

The carbon build up on #1 is typical for all four

 

 

#2, the two scrub marks with the gap in between are from the ends of one of the oil ring scrapers or rail

 

 

 

This is #1 below, right side of the cylinder (thrust side?). Scrub marks again from one of the scrapers. At the beginning of this post I said it looked like they didn’t lay flush to the wall. You can see where this one did not scrub the wall adjacent to the ends.

 

Also, just below and just right of center of the picture is a shinny spot, corresponding with the bottom of the piston skirt when it’s at the top of the stroke. There’s also a shinny corresponding spot on the very bottom of the piston skirt. 

 

Would that be caused by piston slap, from too much clearance??

 

I could hear a knock at idle.

 

 

 

With one of the scrapers in the cylinder and the flashlight reflecting behind it you can see the gaps. Took firm thumb pressure to push against the wall. Definitely more then the expander ring could do. 

 

 

 

I thought this was interesting, posted by Avoirdupois from Deves.

If a mechanic is used to putting on a different type of oil ring, our rings do appear stiffer. That's the way it should be. Once the ring is in the engine, the heat in the engine will loosen it up, and it adjusts to the cylinder. The secret is the Swedish steel.

 

 

I found this mark at the bottom off #2. My first thought was it’s a casting flaw. Anybody know what it’s from?

 

 

 

So here’s what I found when I first pulled each piston out of the hole. All the rings were installed correctly. But only the first and second compression ring gaps on #2 were still 180* appart. On 1, 3 and 4 the top ring gaps moved almost 180* to within 1/2” of the second ring gap.

 

I checked the rings side clearance and they were within spec. Took the rings off to check end gaps and found them all way too big. Top rings from .025” to .027”, second rings from .018” to .022”. 

With sloppy fitting oil rings, gaps almost lined up and too big, smoke and blow-by right??

 

 

Qustions:

1. Is knock and shiny spot in #1 indication of piston slap from too much clearance?

 

2. What caused the mark at the bottom of #2?

 

3. Why would top ring move the way it did ?

 

4. On piston to cylinder clearance, these IE cast pistons call for .0018” installed clearance. Is that clearance “on a side”, or the difference between the two diameters?

 

I’m suspecting there’s too much clearance. I’ll take more measurements. 

       Robert 

Edited April 7, 2018 by RD02

[andyleonard]

Well, you found your problem. It looks like the rings are the wrong size for the bore. Do as you suggested and remeasure the pistons up and down the skirts and remeasure the bores top and bottom with a good dial bore indicator. Make sure the holes are round and even. This is not a job for micrometers. Correct rings will solve the smoke but you need to verify the piston/wall clearance to resolve the alleged slap. 

 

Rings move. No clue about the stain. Can you feel it or is it just a discoloration?