PeachParts Mercedes-Benz Forum - pushed in cylinder sleeve, how long till another blown head gasket?

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Pic looks to me to be a liner within a liner. The inner iron liner is the one that has slipped on the outer alloy liner, which is surrounded by coolant.

Does the outer liner (and inner liner) come out as an assembly? I would think it should.There should be a seal on the bottom of the liners to keep the coolant out. If it does comes out as an assembly, with careful setup in a press with the correct tooling, maybe the inner liner can be pushed back up flush instead of making a shim?

How would you machine a shim that is .07" thick, .07" high with a diameter of the liner? EDM? How would you chuck it?

Quote:

Originally Posted by jsap (Post 2543405)

Sorry gents for the delay. I wanted to get you a picture plus accurate measurements.

http://img508.imageshack.us/img508/9915/img5848.jpg

I measured it with a digital caliper with 0.001 accuracy.

The liner is about 0.11" thick, but the gasket sitting on top only touches about 0.07". Still, I think I'd fabricate the shim the full 0.11".

The slip depth is about 0.072"

No, I've not taken the sump off. It didn't seem to matter whether there's a stop or not. Half the machinists I've spoken to believe it won't slip any further. And one very experienced Ford machinist who races believes that wicking Loctite 290 will help to secure the liner. (Also, I don't want to drain the oil now, because when I run the engine to operating temp after installing the new gasket, there will be a bit of coolant contamination in the oil because the water jacket doesn't swell until initial warm up.)

I believe that it's a dry liner. I don't see any holes around the cylinder wall, and an aftermarket liner catalog lists it as dry. It's an open deck, if that's what you were thinking.

I believe it's secured simply by interference (friction).

Again, as to whether there's a tab or lip at the bottom, it's sort of trivial to me at this point, because I'm going to try this experimental shim repair method by hook or crook. But, the next time I remove the sump, I'll have to take a look for future reference.

All M119's were closed decks. But the last M119.98x series were open decks, but still dry. I think that's what you were thinking?

Edit: My current plan is to use Loctite 290 wicked into existing liner. I'll fabricate a ring with the dimensions above, but with the OD 0.004" smaller to allow easy fit and gap fill with Loctite 640. I'll use the 640 on both the outside and bottom of the ring to adhere it to both the exposed cylinder wall and the top of the liner.

funola,
What you see there is some cutting edge technology gone bad. The inner liner is actually an aluminum alloy. You dont just run a hone through it, diamond paste and a special polishing tool is needed. The surface is as hard as glass. The pistons are iron coated so they dont grab on the bore. A variant of the technology was used by MB racing.
Its on par with ceramic pistons in a diesel.

Quote:

Originally Posted by funola (Post 2543555)

Pic looks to me to be a liner within a liner. The inner iron liner is the one that has slipped on the outer alloy liner, which is surrounded by coolant.

Yes, it is a bit confusing to look at this image, because of the gasket remnants and because you usually don't see open deck short blocks. But it's just a single alu-sil liner inside an alu-sil cylinder. The coolant is completely outside the cylinder wall, and the liner is dry.

Quote:

Originally Posted by funola (Post 2543555)

Does the outer liner (and inner liner) come out as an assembly? I would think it should.There should be a seal on the bottom of the liners to keep the coolant out. If it does comes out as an assembly, with careful setup in a press with the correct tooling, maybe the inner liner can be pushed back up flush instead of making a shim?

The liner is indeed meant to be replaceable. However, by the time I get the engine out and sitting on a machinist's table, I can replace get a used motor with fewer miles for less money. Plus, liner replacement is not a guaranteed repair.

How would you machine a shim that is .07" thick, .07" high with a diameter of the liner? EDM? How would you chuck it?[/QUOTE]

Most fabrication machinists scratched their heads. But I found a couple who say they can do it. Who knows. I'll ask them after they make it.

Quote:

Originally Posted by layback40 (Post 2543515)

Given everything is aluminum alloy, I would be making the ring from duralium or some similar aluminum alloy. Using a steel ring may cause some galvanic problems.
That is a very good & informative pic of the problem. I have a theory on what caused it but I want to run it past a couple of colleagues first. Have you owned the car from new?
I have no experience with the loctite product you mention.
I would be checking the block & head for flatness.

No, I've had this car for 6 years, and it was made in '96. All problems began with the clogged catalytic converter, which was damaged due to the element disintegrating from road impact. (The mechanic, despite my pointing out the damaged cat, still insisted I replace the transmission control unit.)

Do you know the expansion coefficient of Alusil (AlSil17Cu4Mg)? I was hoping to use 6061. The shim will never touch the piston ring, so the only thing I'm concerned with is heat cycling and stress cracks over time if the coefficient is very different.

Alusil is a type of duralium. I dont know its expansion coefficient off hand. I have attached some info on common alloys. The expansion coefficients are all similar ~12.5, steel is much less than this.
I dont believe stress cracking will be a problem as there will be a bit of pressure on the shim.
I would be hand making it. It will probably need to be made to fit as the hole it has to fit may not be exactly square. Make sure the finished shim has no surface scratches, they are a starting point for cracks.

would it be possible, and this is just a thought, to somehow obtain a used liner and have the shop make the shim from that? Cut a slice of it and surface grind it to the correct thickness? Someone on this forum might be able to help obtain one.

Quote:

Originally Posted by weird beard (Post 2544247)

I was thinking more or less the same thing - as long as the piston doesn't touch the shim I don't see why it would have to be as accurately made as (perhaps) the rest of the liner has been made. As stated previously the piston ring(s) won't reach that part of the bore. So the only time this diameter of great importnace is when you want to dismantle the piston from the bore - and for that you'd commonly use a ridge reamer before piston removal anyway...

I thought of another - probably mad idea - that perhaps brazing in some new metal would work too. After new metal has been added to the top of the liner then the lip could be reamed to a closer fit. I'm guessing - and I mean GUESSING - that brazing as opposed to welding as a technique would be less likely to distort the liner. If this mad idea worked it would also have the potential of adhering the slipped bit in place.

The bore is a very exotic alloy. I dont know how one would cut a 7 thou slice off it very successfully. Brazing to it is not an option ~ that temp would cause all sorts of problems.

jsap,
I have very strong suspicions that the problem started long before you purchased the car. Probably at its first service.
Not wishing to go over ground you have probably covered, there is a bit of information about why the second generation went from a closed block to an open one, The motor needs to be treated very gentle when its cold and new or problems could occur. This is particularly the case when the motor was new & there were not big tolerances, At normal operating temps, because of the high thermal expansion coefficients (compared with a conventional motor), pistons & bores are ok, when cold things are tight.

Possible situation; car in for first service, motor cold. Young tech takes car for test run. Comes up to lights just outside stealer, couple of young girls in a mazda or 300z next to him. He decides to show them that he is in a rocket. Cold motor, 100 yards down the road damage is done, doesnt show for years though until a little extra pressure from exhaust blockage. Cant prove it but I dont think there is a better explanation.

It's difficult to cut a ring off of a liner, just because the ring is so thin. Any blade will deform and crack it, I think. Plus grinding it wouldn't be easy, because the process would also deform and crack the ring....

Making a shim is the best idea, but it has to have tight tolerance on the OD because the ideal gap fill for the adhesive is 0.002". Greater gap weakens the bond strength, and slows heat transmission making it difficult for the ring from dissipate its heat.

As for welding, the issue, as layback said, is dissimilar materials. On a usual alum block, liners are often iron, so there a problem. On my M119, the liner and cylinder is both Alusil, which has crazy high silicone content, and no respectable shop will dare weld on it. I read of a guy who cracked his M119 short block, had it weld back, but leaked coolant again.

As for forensics, it's hard to know. But, here's an image of the head gasket (note the clean exhaust valves from steam cleaning):

http://img148.imageshack.us/img148/2723/img5823p.jpg

The soft material de-laminated from the metal core from overheated steam. And the gasket's seal ring looks like the liner slipped recently. You can see the line where the liner used to seat against the ring. This picture doesn't show, but the ring is flat, with no level change at that line.

Btw, now that you see the gasket and roof image, I'd be interested in more forensic comments as well as repair options.

Quote:

Originally Posted by gremesmiith (Post 2671646)

As far as I know, mainly because of one owner in Texas, almost all of these, and then against the outstanding debt of a mile to the guy here in Montana, where it sat for a few years ago, it gave me. I do not know whether it is worth trying to find out who installed the cylinder liner?

Don't waste your time. Several years have passed. Who is going to warranty work that is years and several owners old? The appropriate question is how (perhaps whether) to repair.