Repair-It

It was struggling to warm up this morning and wanted to sit at like 170 when cruising. It would sort of bounce around and if I was able to drive a bit slower would eventually hit 195. Definitely needs a thermostat. This is just a wear item and at 105k it is well within the expected lifespan of this part. This is something I 100% expected to deal with, I just thought I had another 10k or so. Meh.

However, I may not want to just do the thermostat. I think I may be able to pull off just the thermostat, but I don't think it's a good idea. The water pump pulley is part way walked forward as they do when they wear, so eventually that will leak. You really should do them together. Adding the WP to the list makes this task more invasive and expensive. When you touch the WP, you have to touch the turbo coolant lines. And the forums say you can't touch them without breaking them. So I should come up with a plan to either replace them or perhaps cobble together a rubber hose type repair which may be cheaper, easier and longer lasting. Needs more research though.

For now, here is some parts information.

And here are the associated instructions for doing the thermostat, water pump and turbo coolant lines.

I may also want to do a belt and pulleys while I'm in there. It is not as quick and easy to get to this stuff so the while in there idea really seems to apply here, even though it jacks up the cost of this job beyond what it purely "needs" at the moment.

Taking stock of major parts that would be required here:

Thermostat, $273: https://www.mercedesbenzpartsshop.com/o ... 2782000615
Water pump, OEM reman, $275: https://www.mercedesbenzpartsshop.com/o ... wtdjgtZ2Fz
WP gasket, $7: https://www.mercedesbenzpartsshop.com/o ... AxLTAzLTgw

The turbo coolant lines are a little more confusing. Perhaps there are 5?
A right and left feed and return. Plus a fifth "water pump to coolant line." Here they are:
Left feed, 2782000900: not available? https://www.mercedesbenzpartsshop.com/o ... 2782000900
Left return, 2782001300, $71: https://www.mercedesbenzpartsshop.com/o ... AwLTAyLTAw
Right feed, 2782000800, $56: https://www.mercedesbenzpartsshop.com/o ... 2782000800
Right return, maybe?? 2782001851, $72: https://www.mercedesbenzpartsshop.com/o ... 2782001851
The water pump to coolant line, 1572000000, $43: https://www.mercedesbenzpartsshop.com/o ... 1572000000

Ok so needs more research and I also need to see which lines actually tend to break because I don't know that it's all of them. And one side might have significant metal sections.

Left feed looks like metal at turbo and plastic at water pump. Found some on eBay.
Left return also looks like metal at turbo and plastic at water pump.

Right feed looks like metal on both ends, with a crimped rubber middle section.
Right return looks like it is 100% metal

The fifth line is all plastic.

So maybe the driver's side ones are the issue?

Helpful reference:
https://mbworld.org/forums/w212-amg/878 ... ost8879515

It looks like I can simply run a rubber house between the left return line and the center (fifth) line which would bypass the plastic shit on both of those. But I may want to buy the fifth line since it contains plastic anyway. I could still do the rubber hose thing. If I don't, I would also have to buy the left return line.

Looks like the best plan is to leave the turbo side of the lines alone (driver's side). It's not clear where the passenger side turbo lines go or if I'll have to touch them to do the WP. They are robust so I was focusing on the plastic stuff which goes to the driver's side.

Looks like I would run rubber hose in these areas: I would buy the middle line and feed line. I would adapt rubber hose from the middle line to the metal part of the return. Then with the feed line I would attempt to cut off the plastic and use just the plastic connection to the WP and run rubber to the other end that turns into metal.

I would buy these things in advance and I could mostly use the parts to engineer the rubber hose size. If I can't cut off the plastic from the new line I would have to do that line at the turbo which looks very tight.

Alright I am making the actual list now.

Thermostat: https://www.mercedesbenzpartsshop.com/o ... 2782000615

Water pump: https://www.mercedesbenzpartsshop.com/o ... wtdjgtZ2Fz

WP gasket: https://www.mercedesbenzpartsshop.com/o ... AxLTAzLTgw

Central turbo coolant line which I will be cutting the plastic line off: https://www.mercedesbenzpartsshop.com/o ... 1572000000

Left feed which I will probably have to buy on eBay. I think I will buy the whole line only to use the one plastic fitting. Then I'll run rubber hose to the old metal line. https://www.mercedesbenzpartsshop.com/o ... 2782000900

I don't need the left return line because I can just run a hose from the central line straight to the left return metal.

I may have to run to various stores for things such as:
- hose clamps (the kind that wrap around and use a bolt to secure). I will need this to route the long return hose around the WP pulley.
- Various U-joint style sockets (though a U-joint style E socket may not be available locally)
- Perhaps a long 1/4 inch ratchet, also perhaps with a swivel head.

Oh, I also need to think about if I want to replace any accessory pulleys or the tensioner. And the belt. This would be the right time I think because much of those things actually have to come off. This would also be a good time to do the oil cooler (or at least the gaskets) but I don't think it's leaking AND if I am successful with the rubber hose upgrade, it would be more removable.

The oil cooler lines may need to come off so maybe I should get O-rings for those.

Belt: https://www.mercedesbenzpartsshop.com/o ... t-39934796
Oil cooler line O-rings x 2: https://www.mercedesbenzpartsshop.com/o ... -129975648

Need to determine if these lines use double O-rings or single. So here are the P/Ns of the lines so I can look at a picture.
A2125001372
A2185000172

Looks like 1 Viton seal per so qty 2 is correct. I could probably reuse them since they are green.

Going to skip the tensioner. It's kinda pricey at $183. If it feels bad then I'll deal with it later.

Various pulleys. There are 4 fixed plus the tensioner.
https://www.mercedesbenzpartsshop.com/o ... 2782020519
https://www.mercedesbenzpartsshop.com/o ... 2782020619
https://www.mercedesbenzpartsshop.com/o ... 6112340193
https://www.mercedesbenzpartsshop.com/o ... 2782020219

I don't know why that last one is pricey. The other thing I could do is test all of them and order only the ones I need. It does say they are all in stock in store. I won't link the tensioner to avoid confusing myself but it is in one of these PDFs.

Actually on this whole list everything is in stock except the WP and WP gasket. And the left feed turbo coolant line that is just not available at all.

Need to add the O-rings for the pass side turbo coolant lines (might be 2x each) since I will be just disconnecting them and reconnecting them. Also need to add the gasket for the oil cooler, since I will have great access to it.

O-rings for turbo coolant lines (buy 4): A0239974445
Oil cooler gasket: A2781840080
O-ring for oil filter housing (not sure if I should buy): N007603030100
Gasket for oil filter housing (not sure if I should buy): A2781840280

Another while I'm in there could be to reseal the passenger side cam adjuster access cover. That's one of the only oil weeps on this engine. It's just RTV. So if I get everything stripped and access looks good, I may pull that cover and reseal. I wonder if I can do it with the adjuster magnets in place.

Since the WP has a $40 core charge I'll order things that I wasn't sure about and when I return the WP for core, I can always bring back parts I decided not to install. Or put them on the shelf forever...

Ordered that one hose from eBay. The rest from the dealer. The bill there is about $1000 even including tax, but I'll get the $40 core back...so $960 net from the dealer. It seems like this puts a dent in my plans to do struts. Oh well.

The code, and some info.

Looks like the heating element is maxed out trying to warm up the engine (to 221??).

My order was ready yesterday which is pretty fast. I guess most of it was in stock. What does that tell you?

As far as the critique that this is an overzealous repair, I cite the following:
- Access to the front of the engine isn't like naturally aspirated so popping back in to target specific failures only when they occur is somewhat inefficient
- I don't know if pulley life is a specific problem on the M157 but in previous engine generations, pulley life can be well under 100k, perhaps due to higher belt tension (because Germans). Due to this and other factors, if a pulley makes any noise or has any play, you don't want to fool around and wait for it to seize on the highway. I guess if mine feel like 100% new still then maybe I wouldn't replace, and return the unused parts. I actually don't hear any pulley noise.
- I have NO coolant leaks but doing just the thermostat ignores the fact that my WP bearing is worn and will eventually fail. It is well within the mileage window for this. And you cannot replace the WP without touching (and breaking) the plastic turbo coolant lines. It is what it is. And, even if they aren't leaking today, there are plenty of documented cases of the plastic lines splitting and sometimes exploding. See above in terms of avoiding side of the road calamites. I also submit that this is not the kind of vehicle that you drive around with a spare pulley or two and some tools. The pulleys are more invasive than a normal engine (due to V8 turbo packaging). Furthermore, that still requires me to purchase the pulley - I am already going to be in the area so why not replace now? I could certainly store the "good used items" but in my experience there is a near 100% chance they will never be needed again.
- The oil cooler/filter housing stuff is not leaking. I understand they CAN leak. I could do this thermostat/WP work and have an oil leak within 10-15k and I will feel silly.
- After completing this work, I should be good for another 100k for these items, which as I said generally, are not life-of-vehicle components. It is what it is.
- Normally I actually would target a specific failure and move on. But that's when the labor doesn't overlap. All of these components are in the same general area and have the same general dependencies for R&R. It makes a lot of sense.
- I wish the thermostat and WP were cheaper but they aren't and I'm not rolling the dice with some random Rockauto brand for this application. But, that is only half of the parts bill on this job. The other half is the while-I'm-in-there items which increase instantaneous cost but remove a future labor excursion.

Thermostat. It's pretty annoying to look at because it sure looks like they could have just done a modular neck with a regular thermostat instead of this molded nonsense. That said, it seems like the labor for just a thermostat would have been pretty easy. Unfortunately that is not the right thing to do in this scenario. Because when my WP fails (and it will) this new thermostat may well be stuck and I'd have to do it AGAIN. Not a smart option.
And here is the new (reman) WP. See the two ports at the 3 o'clock position from the pulley? Those are "covered" by one of the plastic turbo coolant lines. But that does not seal them. What seals them is these, which I didn't buy:

Cover: A2782010103
O-ring: A0239974445

The WP casting has these two ports open for perhaps another application. I was hoping the new one would come with them but looks like they are extra. Sigh.

I may have been able to reuse the caps and their associated O-rings but rather than take the chance I just got all new. Now if they have 2 O-rings per I will need to get two more because I only ordered two...or try to reuse one from the old one. Sigh.

Making things more complicated, I chose not to replace the whole line which means I did not buy that plastic thing that normally covers this and holds those caps in place. So I can either 1) JB Weld them in place so they don't pop out (possibly sacrificing this as a future core but maybe that doesn't matter right now, or ever), 2) Fabricate a simple plate and bolt it in or 3) Cut down and bolt the old thing back on even though I'll be bypassing it with a rubber hose. I am leaning toward option 3, though I may need to get longer bolts since one of them will be holding some kind of hose clamp.

Waiting on those covers and O-rings still but I made more progress to cut down on the R&D required when the car is on the lift.

I did receive my eBay part (left feed line). It's too bad there isn't a separate supply source for the plastic elbow (or a better material), because that is still failure prone even after I cut out the plastic lines. At least my plan reduces the plastic content substantially. Test fit of the line into the new WP just to look at clearances. Decided to go for it and just cut the plastic off of this brand new line. I really need to get to the native nipple size for hose sizing.

Seems like 3/8" is probably the way to go, with a nice stretch over the barbs, based on this dimension. Here is the aforementioned plastic elbow which is the ONLY thing I am using from this brand new feed line. Seems like a waste but the alternative if I use it as-is would be way more labor to replace it at the turbo and I didn't cut out any of the plastic nonsense. Could not source silicone 3/8" heater hose locally. Gates makes it but it's really expensive. So I settled for conventional Gates heater hose which I would still consider a premium product. I think the Napa guy said it is good from -40 to 257F which seems to be good enough for the application, even in a hot, German, twin turbo V8 engine bay. I COULD potentially see return coolant from the turbo being quite hot even if the overall coolant temp is reasonable. It really depends on the flow rate through the turbo. I guess if this stuff doesn't hold up I'll have to switch to silicone which is rated from -65F to 350F. That'll do it.

Fits like a glove. Just enough clearance on the WP casting. So I measured using the original (new) plastic line segment and cut the heater hose to length. Looks good.
For a closer look, these are the ports that are closed off in this application. It's really annoying that for the cost of this they could not just include the correct block offs, unless this P/N is universal across applications (it is possible). I will probably use the old plastic junction as a vestigial cover here and not use it for coolant flow. EDIT: apparently it crosses to kind of everything from a 2011 S63 up through 2019 GLS63. EPC says the stock bolts are M6x16. The holes are like 17mm deep so I can probably use the stock bolt with the hose clamp as long as I don't need to space it out from the plastic with washers to get the hose clamp in a better position.
Here is somewhat of a mockup. I will also cut the plastic line off of this and run hose down to the pump (where the above ports will be covered) and along the WP down to the old metal return line. Somehow I need to rig up a clamp to hold the hose against the WP in the right position so it doesn't hit the pulley or serpentine belt.
But yeah this plan is coming along nicely. I will use one of my special fuel injection clamps on each end of the hose. I need to make sure I have a sufficient quantity of this size.
Only had 3 of these left in my kit so ordered 12 more (same brand).