go team

I just need the oxide treatment to work. Im starting to suspect induction hardening was used on the lobes to explain the cracked lobes vs clean journals. The reasons why I believe this is the worn lobes on the cams would have shown signs of the fine cracks and of course it was very consistent wear. Imperfections get magnified when wear starts to form and that wasnt the case here.

The Machinist

If Jones is grinding undersized, they are probably hoping that the hydraulic lifters will make up the difference, or used to dealing with engines that have adjustable valve clearance. I would hope that they would induction harden the ground profile afterwards.

VRP’s product is what I was referring to when I referenced regrinds north of $3k.

I don’t like the “proprietary magic in the black box” explanation of what they do. A person in my shoes knowing what I know wants to know exactly what the hell I am putting in my engine. I respect the cost of the R&D to make a tune suited to their profile, but bill me for that, not the regrind on a set of sticks. If the cost includes the tune, then that changes everything.




All this talk of coatings has brought back a memory. Back when I was just a machinistling in the plastics compounding industry, we used a product called Armaloy to coat some of our mixer rotors.

Chrome is between 68 and 72 Rc

Armaloy is a chrome coating (with more proprietary herbs and spices ). One thing about chrome is that when it is oiled, it is slick as eel snot. Thick coatings of hard chrome are very brittle, but Armaloy puts chrome coating on at .0001-.0003 I am going to reach out and ask them about coating camshafts. I remember the stuff being flexible as it never cracked on our rotors.

Their website claims that they put it on bearings and engine components so, they might have some insight.

eschow

Hey, these are my old cams!

The Machinist

I’ve just sent this to Armaloy SE:

Good morning,

I’m doing some research for an upcoming project I might have, and I remember using your services from the Pennsylvania location through my previous employer.

The project is that of automotive camshafts.

The Mercedes Benz M156 engine is notorious for having camshaft issues related to premature wear. It isn’t uncommon for cam lobes to be worn out by 100-120k miles. Due to the silly exorbitant expense of aftermarket camshafts, and the questionable quality of the OEM camshafts, I (we) are left with few choices but to pay now or pay later, repeatedly .

These engines all have flat tappet cam followers like Engines used to in the 1960’s. So the cams run directly on the buckets, no rollers. There is a lot of flexing from the spring pressure of the valves and high speed shear going on. In the cases of spectacular failure, the tip of the lobe is usually worn right off. We have done some investigation, and the consensus is that the case was ground through during initial machining of the cams, leaving an exposed soft spot on the tip of the lobe. In one case, probably many more, we’ve seen very small surface cracks.

So, the question is, do you have a solution for us that is A) Possible, and B) More economical than buying camshafts every 100k?

Our scheme as of right now would be to have our worn cams built up and reground to factory spec by a respected artisan in that trade, and then coated with something that will prevent this type of failure.

Some of my background: I am a machinist with a focus on rework requiring precision grinding, but not in the automotive industry. The interest in this Mercedes engine is personal, and potentially of interest to many others.

V/R,

[Machinist]

go team

Hehehe eschow yes it is!

the machinist really looking forward to their reply!

The Machinist

Me too. I am growing quite tired of someone like me sub contracting this type of thing out, and marking the price of the service up 10,000% just because of the Mercedes badge.

I pretty much just want to cut out the middle man and get the product that hasn’t been stepped on.

I see it on every vendor for the Mercedes platform. One of the companies that start with a letter in the last half of the alphabet has tunes for pretty much every platform by Mercedes, and all of the ones that have the M156. The prices for these files seem to be directly proportional to the MSRP of the car starting at about a grand, and the flash loader costs an extra $600. Something about that doesn’t smell right. The minimum price for everything Mercedes on this company’s site is about $500. Aluminum trans pan? $500. Stupid. The trans case is Magnesium. It conducts heat just as well as Al. Adding an Al pan amounts to a pisshole in a snowdrift. If you want cooler bungs, weld them on the OE pan FFS. Headlight bulb? $500. Oil catch can? $500. Keychain? $500. Notice a theme?

Coming to Mercedes from Audi, so far I can say that these cars are vastly less complicated than any //S car and MUCH easier to work on. Yet everything is twice as “expensive.”

Im not against anyone making a comfortable living, but I’ll be damned if they will make a killing from me.

Maybe I just know too much about the supply side of this industry to be happy on the demand side. /Old Man Yells at a Cloud.


Reasons:

There is no reason that maintaining and upgrading an S4 should be half the price of a much more simple car like the C63.


4.2 v8 crammed into a B chassis. I was replacing a VVT solenoid that had been chewed through by a rodent. It takes 3-4 hours just to pull the valve cover. There is zero room to work.

Roomy engine bay

The timing set is on the backside of the engine.

It’s down there somewhere.

Guess what I was doing here? Replacing a bypass hose on the water pump. Yep. I had to pull the nose off.

deadlyvt

I stopped working on Audi’s for the sheer insanity of tearing the entire car apart to change some part that’s a simple job on most other cars. Those 4.2 s4s are some of the least fun to work on just seeing you post pics of it reminds me how much I hated it.

The Machinist

I feel that ****. I honestly love the car to death. I just can’t have my backup vehicle off the road and torn apart as often as the S4 seems to be. It’s why I bought my 63. The S4 has a date with a set of jack stands and a car cover until I can mess with it. It needs a bunch of little things which each by themselves is no big deal, but all of them at once, it needs disassembly.

deadlyvt

fair enough, they are fun to drive especially in the snow/wet roads. And the interiors are usually pretty nice for the given time period. The 4.2s sound pretty decent with an exhaust as well 😏

roadkillrob

I had an S4 and mostly BMW's but I am with you, the //S and ///M taxes are way lower, they are still more than standard cars from the brand, but the Mercedes tax is crazy comparatively, tunes are way cheaper, performance parts like intakes exhaust way cheaper, guess much more competition on especially the ///M platform, here it is name your price as there isn't much choice and everyone is charging the max while they can.

hachiroku

Love my B6 A4...I've had 4 of them in total. Love the B6 S4 as well, but would not put myself through a timing chain job on that motor. Also, its lacking in power hence why I favored the W211 E63 even at the higher purchase price at the time. Wouldn't mind an B7 RS4 though.

The Machinist

I heard back from Armaloy, and I immediately fired back a bunch more questions. I will be providing complete details once I have them. I promise total transparency. I have no intention of charging a finders fee.

Basically he says that they’ve been coating camshafts in industry for years and have very good results. They also coat roller bearings’ races and rolling elements too. Everything I’ve seen so far is looking good.

Paul:

It is good to hear that we are not beyond help. So, I know the others will have the same questions, so I’ll ask:

A number of times in this email I use the term lifter or bucket. Both terms refer to the same part. It’s a simple hydraulic cam follower.

With the XADC or the TDC coating on the camshaft, how long should we expect an uncoated surface (the lifter, or bucket) to last against the coated surface?

I noticed that the CoF seems to be lower than steel/steel by a significant number. Should we expect the lifters to last longer as is? They are made out of a steel that I suspect to be identical to bearing alloy.

How do these coatings deal with point load (when the cam approaches maximum lift and the pressure is at the maximum)?

How about brittleness with regard to flexibility of the parent metal?

In some cases the lifters with an older design had oil flow problems and would stop rotating in the bore causing the cam to actually wear into the bucket. I don’t know how common that failure is, but I don’t think it is as common as the worn camshafts.

My concern is that with the cam lobe now much harder than the surface of the lifter are we now going to be replacing lifters with increased frequency? The engines have 32 of these lifters and most vendors like to charge north of $30 each which I suspect to be price gouging. I think I can get them direct from the OEM (INA from Japan) for much closer to cost, but that is secondary concern.

I also know from reading the literature you provided that the coatings can be run against each other, which would be ideal, and from what I see, what I would recommend if I were in a position to recommend anything.

Lastly, we’ve got to talk about the M word. Money. What can we expect to pay to have a set of 4 camshafts’ lobes coated (lobes only) and additionally if we were to have the wear surface of the lifters coated?

Areas of special attention would need to be given to the cam journals, the oil passages, and the mating face of the cam where the drive gear attaches. No coating can be in these surfaces.

“Lasciate Ogni Speranza, Voi Ch’entrate”

go team

Having the timing chain in the back is the funniest thing ever. Those chains and guides aren’t a lifetime part and someone decided through the design and engineering chain that “the best place for this chain is in the back”!

I very much like the b5 platform and I still look out for a minty one to scoop up down the road. Biturbo quattro all the way! The audi v8 engine is quite a good engine by itself but just with the cost difference vs Audi V8’s and AMG V8’s repairs and maintenance simply doesnt add up.

The Machinist

Those engines are magnificent. Not without problems though. The RS4 got the FSI V8, where the B6 S4 still had port injection like the M156.

Both variants have similar timing sets and the same assortment of problems. The FSi has a couple of nasty little surprises though. The intake runners get plugged up with carburized oil, and they need to be walnut blasted every few years.

The direct injection injectors can fail open, so they end up dumping the whole load into the cylinder when you shut the car off and when you come out the next morning, the engine is hydro locked on gasoline.

The high pressure pumps have ****ty cam followers that wear out (at least they are easy to change and cheap to replace). Still love my B6 though. Some day it’ll see the road again.

ertech

back to another M156 with my sons car a 2013 P31 C63
I had a w211 E63 that I sold 5 years ago that had the dreaded top engine noise , I purchased it in 2010 right after Mercedes replaced the 4 cams ,adjuster, lifters and the car still made noise .
I am in contact with the owner and he had to do the whole thing again last year.
my sons car has a very light sound , I think its somewhat normal .are the cams /lifters updated on facelift cars ?
thanks guys

The Machinist

My understanding of the issue is that the M156 suffered from the cam and top end issues until the end of production. So none are immune.

roadkillrob

Yes only SLS had updated parts it seems.

The Machinist

I am still working with Armaloy on getting a ballpark price together for bulletproofing.

Right now, the information that I have is that the Armaloy coatings have a lower CoF than Steel on steel, so they should be perfectly fine running on uncoated lifters.

However, the setup would be ideal with both the cam and the lifter coated, as the coating can run against itself.

Durability wise, the TDC coating has a mid to upper 70’s in the Rc scale, and the version of the same coating with synthetic diamond tossed into the mix is north of 90Rc.

The coating is flexible with the base metal, so it will resist surface cracking as the cam flexes from the weird force and torsion caused by the valve springs.

I think the Diamond might be overkill.

As a comparison, our cylinder walls are similar in composition to Silicon Carbide.

Carbide is in the upper 60’s.

VektorPerforman

I'm a big proponent of coatings, but thinking back on challenges faced over the years with cam wear, I've never seen a coating completely solve cam wear. On the other hand, I've seen coatings do impressive things with buckets, surface treatment change journal wear, but never more than a marginal improvement with cam wear. In one applications where a DLC coating wore, we saw accelerated wear elsewhere in the engine; the theory being the SUPER hard coating debris in the oil acted as an abrasive media in the oil. We did not repeat this test, so it's speculative theory.

On the other hand, improving oil flow to the heads has ALWAYS yielded positive results. Modern engines tend to attempt to strike a balance between minimizing parasitic losses AND providing enough oil flow to accommodate newer technologies that are powered by oil flow/pressure. Cams are almost last in line for oil flow. On some stock untouched OEM engines we have seen 0-2psi at the cam journal passage at idle. Making a simple change like bumping idle RPM +150-200 RPMs generally bumps that to 5-10psi, a significant improvement. Depending on the pump type and pressure regulating strategy, pressure scales up with RPM, sometimes smoothly, sometimes not. To make matters worse, some marginal OEM oiling setups can have an extreme high RPM pressure drop as high RPM oil flow can become turbulent enough to cause high flow aeration. The newer Porsche oiling setup uses a load based pressure/flow strategy, which while more complex, actually makes a lot more sense from a lubrication needs strategy.

All that said, I have minimal M156 experience as I'm fairly new to the platform, but will be following this thread intently as I share the same concerns and desire for a solution. Just for fun I'm going to get my hands on an oil pump to dissect, and look for optimization opportunities from that angle as well.

Cwagon

The M159 engines according to nearly every thing I've seen about them don't seem to suffer these problems like the M156.
Besides a few different part numbers the biggest change seems to be the larger oil volume and dry sump oiling system.

roadtalontsi

You're forgetting most of the M159 cars are sub 10,000 miles. Your car cant break down if it never gets driven right?
It's so bad they had to come out with an instrument cluster software update because the maintenance light wouldn't reset unless the mileage changed over 100km or 62 miles. Yes i've done yearly annuals on many cars like this. These are the same owners that request you don't even drive there car more than in and out of the bay. lol. They just want the maintenance records. Somehow a car with over 10,000 units produced is considered collectible and holding value lol.

go team

The SLS has different cam profiles. The adjusters however are the same IIRC.

The Machinist

This is why I don’t like IVD coatings like DLC. They don’t have a bond much sttronger than that of paint, and are very brittle.

Armaloy is an ultra pure coating of hard chromium, which is deposited electrically while submerged in a bath of chromic acid.

I’ll follow with some stark examples of chrome in industry.

The Machinist

I machined all of these parts, and Installed them in the customer machines at my previous employer.

These are some extreme uses of chrome as an anti wear coating in industry. Without the chrome coating, these parts would wear out in a matter of months.

These machines produce 15,000 pounds per hour of products that are compounded together like PVC and EVA. One of these in particular is used to mix the black rubber sound insulation behind the dashboard of the big American 3 automakers and some American built BMWs.



The wavy looking part is coated with chrome.

A similar part being finish machined

Finish turning before coating and final grind

Finish grinding

Same parts after two years 24/7-365 in service mixing 70% limestone with 25% EVA and 5% carbon black 1000 hp electric motor

The coating is only compromised where it suffered mechanical damage from sucking in FOD.

Freshly rebuilt rotors for an older style machine for a different customer.

Different mixer, similar parts and product.

The Machinist

A continuation of this thought—-

You mentioned poor oil supply to the cylinder heads.

I once had a VW that had poor oil supply to the cylinder head due to a blocked oil passage in the block.

I circumvented the problem by using an external oil line directly feeding the cylinder head oil gallery from the port on the oil filter housing.

does anyone know if the M156 has external access to the oil galleries on the cylinder heads?

It would be easy to attach oil lines in this same manner if so.