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The block is ready to go to the machine shop for cleaning and to see what can be done with #6.

Here's what #6 looks like from the bottom. Ugly.

View attachment 2606971

Here's 1 thru 4 (picture taken from the bottom). Not bad.
View attachment 2606972


Here's 5 thru 8 from the bottom. That's #6 second from the right.
View attachment 2606973

I should mention that every one of the bearings... rods and mains... all show wear and some scratching. It's obvious that some tiny pieces of nasty shiot was circulating around in the oil. The worn metal on #6 piston and the scrapings from the cylinder walls of #6 had to go someplace. I guess getting trapped under the oil delivery holes in the bearings was as good a place as any.
I had noticed some scoring on the cam lobes too, more on one than the others. Likely #6. The blackened #6 cylinder wall tells me that there was a good deal of blow by. I wonder if piston slap may have been the clanking you've been hearing.
 

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Discussion Starter #102
I had noticed some scoring on the cam lobes too, more on one than the others. Likely #6. The blackened #6 cylinder wall tells me that there was a good deal of blow by. I wonder if piston slap may have been the clanking you've been hearing.
Could be. We'll find out once the machine shop checks it over.
 

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Discussion Starter #103
My local machine shop cannot replace the special coating on the cylinder walls. Do any of you know of a shop that can?.
 

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Discussion Starter #104 (Edited)
After many hours of searching... and not really knowing exactly what it was I was searching for... I determined that I may be totally screwed or not, depending on several factors.

My local machine shop cannot reapply the ALUSIL coating so that avenue is out, but they said they may be able to sleeve the damaged cylinder but it would depend on the existing wall thickness of the cylinders. If the wall thickness is already marginal then the boring required to accept the sleeve could weaken the cylinder leading to failure. They asked me for the current wall thickness of the damaged cylinder. I was able to get a caliper between the inside surface and the outside surface of the cylinder wall by attaching an extension to one of the arms of my caliper and then closing the caliper onto the extension before zeroing it. I then slipped the extended arm through one of the holes in the water jacket and then directly measured the thickness of the cylinder wall. It was 0.450 inches or 50 thousandths shy of 1/2".

Apparently there are 3 major wall thicknesses of dry steel sleeves, 1/16 (.062), 3/32 (.093) and 1/8 (.125). Assuming they can go with the thinnest dry sleeve, that would require they bore the cylinder by .004 thousandths less than .062 (proper interference fit for a steel sleeve in an aluminum block is minus .004"). Inasmuch as the existing wall thickness is 0.450 before boring, after boring it would be 0.392. Is that thick enough to retain the strength needed to prevent cylinder failure? I'm waiting to hear from the machine shop on that but my guess would be that it's fine for a low compression low power, low rpm engine like the 380.

If the dry steel sleeve method is determined to leave the cylinder too week after boring, there is the wet sleeve method to be considered. In the wet sleeve method the entire cylinder is bored all the way to the water jacket. This essentially eliminates the existing cylinder and an entire new steel cylinder is inserted and held captive by a ledge at the bottom and a lip at the top that is clamped by the head. The wet sleeve method is actually preferable for high performance engines but a bit of overkill for a stock 380, and I don't even want to talk about the cost.

Another alternative is to buy a used block but I have not been able to find one so far.

The final option is to replace the entire engine with a known good engine. My search indicated that for around $1K I could get an entire engine but I would not really have any way of determining if I was buying someone else's junk engine.

More later. :cautious:
 

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I've got a 380sl parts car recently purchased that has no fuel distributor. I am willing to sell the motor. I'm less than two hours from NYC, and I also might be making a trip to Mahwah, NJ 10/23 - 10/24. On other motor deliveries I've done, I've brought a hoist with me in my truck and dropped the motor on the ground. I guess if you wanted to bring a pickup truck, it's possible to slide from one to the other, or I could put the hoist on the ground like I've done before.

I will work on getting info on the car and motor.

Feel free to PM.
 

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Discussion Starter #106
I've got a 380sl parts car recently purchased that has no fuel distributor. I am willing to sell the motor. I'm less than two hours from NYC, and I also might be making a trip to Mahwah, NJ 10/23 - 10/24. On other motor deliveries I've done, I've brought a hoist with me in my truck and dropped the motor on the ground. I guess if you wanted to bring a pickup truck, it's possible to slide from one to the other, or I could put the hoist on the ground like I've done before.

I will work on getting info on the car and motor.

Feel free to PM.
Thanks for the offer, I have a hoist and a skid steer loader so moving the engine around is not a problem.
I expect to hear from my local machine shop today and if they can sleeve the cylinder and it won't cost an arm and a leg I'll probably go that route but on the other hand I could use a nice drive less than two hours from NYC. I'll send you a PM. (y)
 

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Discussion Starter #107
On careful up-close examination now that the block is sitting on my engine stand and I can get close enough with a jewelers loop to see more clearly, it appears that the block does not have heli-coils installed so I'll need to do that if I decide to use this block.
On the assumption that I do that, does anyone know where can I get a drilling fixture?
 

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My local machine shop cannot replace the special coating on the cylinder walls. Do any of you know of a shop that can?.
I've read elsewhere that Renntech in Miami, Fl can bore it out and treat it with the special coating and that it is indeed possible to repair just 1 cylinder. If so, and if it was me, I would throw the block on a truck and have them also do the crank seals/bearings and timeserts/helicoils while it's there.

 

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Discussion Starter #109
The more I read about this ALUSIL coating the less foreboding it sounds. Apparently there are two variations to the application of ALUSIL, one as a coating and the other as the actual material used to cast the alloy block.

ALUSIL stands for aluminum silicon. Tiny particles of silicon no bigger than a grain of sand are mixed in with the aluminum in some ration that I haven't been able to determine. They call it to saturation which I assume means the aluminum contains as much silicon as it can hold.

The theory being that the silicon is much harder than the aluminum so the finish process is to hone the cylinder to near final dimension with ever finer honing stones and then the final hone is done with a special paste applied with felt honing pads.

The final hone is done with the special paste applied directly to the cylinder walls with more paste applied to the felt pads. The special paste contains the same tiny particles of hard silicone which acts differently on the aluminum in the cylinder wall than it does with the silicon particles in the cylinder wall. Think of it as hosing down a cement mixture that isn't quite dry yet that contains thousands of small rocks. The water would wash away the cement between the rocks but leave the rocks in place.

The final hone does exactly that but instead of washing away the cement between the rocks it scrapes away the aluminum between the silicone particles leaving the silicon particles exposed to the piston rings with tiny microscopic holes between the silicon particles where the aluminum used to be. In actual operation these tens of thousands of microscopic holes retain oil while the hard silicon particles provide the surface that the rings actually ride on. Quite ingenious actually.

If what I've been reading is accurate, the Mercedes cylinder walls don't have a coating, the were forged using aluminum with hard silicone mixed in, so rather than need to re-apply a coating if you hone the cylinder you only need to add the final honing step of using the special honing compound applied with felt honing pads, and the final hone must be done meticulously and only for the prescribed length of time... like no more than a minute or so on each cylinder. They actually have a stylus like apparatus to measure how much aluminum has been removed from between the silicon particles because the final hone doesn't increase the cylinder bore, it only removes aluminum between the silicon particles. A standard bore measuring tool will show no bore diameter change after the final hone.

Well, there you have it... a quick course in ALUSIL blocks and how to hone them. I'm almost tempted to just hone my bad #6 cylinder to plus .5 mm and buy the special felt pads and honing compound and tackle the repair of my #6 cylinder myself. But first I'll keep reading. (y)
 

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Have you measured all of the bores ? I am curious to see what the wear pattern & out of roundness is on the good cylinders. Are there significant ridges at the top?
 

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Discussion Starter #111
Have you measured all of the bores ? I am curious to see what the wear pattern & out of roundness is on the good cylinders. Are there significant ridges at the top?
Ridges on top vary. There is one bore that measures exactly 88 mm but the others vary within .3 mm of 87.
I have no good way to measure out of round but the engine was running fine even with the screwed up #6 , and assuming I'll be able to fix #6, the engine should run even better. I don't need new engine performance from a 36 year old engine... well enough is good enough for me.
 

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Discussion Starter #112
wow... look what I found on a Porsche forum... does it sound familiar?

It started with a ticking sound coming from the engine on the passenger side, which was driving me crazy. Every time I pulled into my garage it was there. Much more noticeable after the car was warmed up. When I bought the car I had done an inspection, but shame on me for not doing a PPI, which may have caught this. The sound did not happen when I inspected it, maybe it needed to warm up more first. Everything else on the car was perfect, no RMS issues, new AOS, clutch, IMS solution installed, engine mounts, tires, all good. At any rate, I started noticing the tapping sound not long after I took possession of the car and started driving it any distance.

I brought it to a local Porsche 'expert' shop that told me it was nothing to worry about, and that I should use a different oil weight. A few weeks later I noticed it was spattering oil on my garage floor upon start. This was coming out the driver side exhaust, which meant the 456 passenger side of the engine. Some googling led me to to this site, where I learned that this was a somewhat common issue with the M96 engine,. Also that it was often mis-diagnosed as 'noisy lifters'.
 

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Discussion Starter #113
While cleaning the heads now that they are off the engine, I'm finding small oil passages that are completely clogged with dried up hardened deposits. I can actually break them out in chunks and when they're on the bench, if I spray them with brake cleaner they dissolve into a dirty oil sludge. I'm wondering if some of these passages might be involved with delivering oil to the hydraulic compensators?

Whatever their purpose, I'm guessing they're not supposed to be clogged so badly that nothing can pass through them. When I take the heads out of the cleaning tank and dry them off, I'll take some pictures of the passageways I'm talking about.
 

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Discussion Starter #114
I found were the clogged passages go... they lead to just behind each exhaust valve. Apparently the area behind (outside of the cylinder chamber) each exhaust valve is connected to the others (on that side of the engine) by the long slot seen in the photo. There are 4 passages evenly spaced along the slot that connect the exhaust behind each valve to each other. I have no idea what function they serve but all the holes were so badly clogged with crud that whatever function they were intended to perform could not have been working.

MeredesHeadBlockedPassage copy.jpg
 

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Discussion Starter #117
Look what I found more of in one of the water passages of the head. If the guys that replaced my water pump (25 years ago) were still in business (long gone), I think I'd go have a talk with them.

MercHeadMoreSilicon.jpg
 

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Discussion Starter #118 (Edited)
A poor mans head cleaner.
A Home Depot bucket with 3 gallons of Formula 88 Degreaser and 1 gallon of water with a 1500 watt electric heater that will bring the bath up to 160 F.
Three hours on each end, rinse in water and you're done. We'll see.
Look at the liquid in the bucket... it was red when I started... it's black now.

MercHeadClean.jpg
 

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Discussion Starter #120
Its not really bad but Alexandria Ocasio-Cortez would not be happy about it. ;)
Oh my! Then I'll unclog them immeidatley... and then I'll paint the heads green. Never let it be said that a 107 driver is unwilling to do his part to save the planet. 🤟
 
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