It's time to change the oil cooler seals on my 2015 GL350 Bluetec with 75k miles on the clock. It's a great time to do it now since we are all working from home lol and I don't need to drive it. Bad thing is that if I found I need more parts I would need to order it and wait, rather than going to dealer to pick up (I don't want to risk getting the virus).

OK back to business. I bought the gasket set from FCPEuro and followed the official WIS document precisely. First I have to praise that the FCPEuro gasket set is pretty nice that it covers almost all needed gaskets and o-rings I can see here. I spent 2 evenings cracking down all the way to the oil cooler. The procedure is pretty straight forward and with tools I have I didn't have any difficulty removing most of the parts. I didn't even use any penetrating oil on the exhaust bolts. It indeed needs some tools, but I feel any home mechanic can do it with time and patience. So after initial inspection I feel it's indeed the oil cooler leaking although it already has the updated viton seals. That essentially means the viton seal doesn't even last till 100k miles though. I inspected the old viton seal and it only stands about 2/3 of the height of the new seals. It's just difficult for a 5'8" guy like me to reach the back of the engine bending myself over even standing on ladders. Some of my current comments:

1. The WIS calls for removal of the EGR valve (the valve mounted on the back of the driver side intake manifold), but it's essentially not needed for the oil cooler seal replacement. The gasket set provided in the kit doesn't have the EGR valve gasket though so I had to buy the gasket separately and wait for delivery. It's not waste of time though as I got the valve cleaned out since it's removed. It was a nightmare to get it out of the intake manifold though.
2. There's a piece of plastic coolant hose that goes through the plastic wall behind the engine, and connects two rubber hoses. One side goes to intake manifold and the other goes to the heater core. I was trying to remove the rubber hose from the plastic hose and the plastic just collapsed... I had to order a new one. It seems this is a very easy-to-damage thing I don't know why MB doesn't put a metal hose here. Part number is 1669970659 on my car but it's been updated to 1669971459.


On the other hand upon inspection I found a few problem so want to have thoughts from folks here.

1. As shown in the photo, the EGR has clogged up the intake manifold, flaps and ports. I got a 10 gallon tote and poured 4-5 gallon gasoline as a cleaning bucket and cleaned most of the shlt out of the intake manifold. It's not like new but just with a thin coat of carb on the inside I don't want to soak it overnight in gasoline since I didn't take the flaps out there are plastic parts. Problem is that as shown in the picture, the cylinder head ports are clogged as well. As shown in the picture, the cyls 1 and 2 are fine. 3-6 have pretty heavy buildup especially the cyl4 is over half blocked. I managed to use flat head screwdrivers, chisel and hooks to get majority of the carbon out from where I can see, but I can't reach the intake valves unless I proceed to removal of cylinder head, which I don't really want to do it at this moment since the engine has been running fine just leaking oil to the bottom. I've thought a few methods to deal with the buildup. Option 1 is just scrape as much as possible and blow/vacuum, then just let it go. Option 2 is basically option 1 plus running some LM5168 after putting everything back. Option 3 is a crazy thought, that's to run some gasoline(or any solvent you guys can recommend) down the ports and let them go into the cylinders. I know that the gasoline will eventually run down to the crankcase through the piston ring opening, and then if I change the oil 2-3 times it should wash the remaining out. It's quite risky though and I honestly don't want to make my garage full of gas smell, but it's probably the best cleaning method I can think about. Any thoughts?

2. Should i get the injector seals replaced as well? They don't show any sign of leakage at this moment but since I'm there and all fuel rails are removed then replacing the seal would not be difficult given the injectors come out freely, and should not cost too much time as well. The seal kit is only about 30 bucks from FCPEuro.

3. Apparently the previous owner didn't care too much about the turbo inlet seal so that it dripped some oil onto the flap motor actuator. The motor is still functioning well but I'm wondering if I should get it replaced as a preventative? The motor is not cheap ($170) so I'm a little hesitant to replace it while it's still working fine, but I certainly don't want to remove the turbo again to replace it next month... Or should I do the flap motor delete?


I will keep posting as I make more progress. The past 2 days has been mostly cleaning work. I honestly hate the gasoline smell and my wife has been complaining me about the mild gas smell from my body as well. I have just bolted down the oil cooler but nothing else. I'm taking my time doing it as I'm not in a rush driving this car (I have another 2012 ML350 Bluetec to drive), also I have to wait for the additional parts to deliver. Any thoughts or suggestions are welcomed!

 

I use the method of working on a single port at a time with a small screw driver and a shop-vac on and removing particals as I scrape. Then after all are scraped, I soak a rag using a red can of brake cleaner and clean the ports till they're acceptable changing out rags as I go. It will never be perfectly clean.

I would caution against doing injector seals unless there is a problem. You could end up creating a problem where there was not one. The engine has to be completely hot, not just warm to do it. I'm talking a 20 mile drive kind of hot or you will play roulette with clamp bolts breaking off in the head. Every bit of it is nerve racking.

 

I guess I will not replace the injector seals then. Leave them till they fail.

I understand it would not be perfectly clean and I'm not trying to clean it all the way down to metal. Even the intake manifold is not cleaned all the way. I managed to clean the ports so there's at most a thin layer of carbon leftover. For the intake manifold cavity I just did the best I could. I'm worried about the intake valves because as I see the clogged port I suspect there's equal thickness of carbon deposited on the intake valve as well and not sure if there's a way to clean it out. I didn't experience any engine running issue though, so I think it should be fine to leave it this way. Just want to see if there's indeed a way to clean the valves since I'm here.

 

Your engine has a lot of gunk for 75k miles.
Here is mine at 180k. I have records that PO did oil cooler at 140k , but don't know if intake was replaced at the time.
We had dispute about intake cleaning on Sprinter forum and there is nice professional chiming there.
He says he is using BG injector cleaners before doing any engine disassembly and it really works, cutting the cleaning time by several hr.
But BG require expensive injection system, that is why I am searching for US supplier of Liqui Moly cleaner.

 

To clean the head ports, pull your glow plugs and work with each cylinder at a time. Start at TDC for #1 and verify with air thought the glow plug that it's all going to exhaust. Then clean. The firing order order is 142536 so keep turning the crank and you'll find them at the top in this order. You can dump some seafoam and get it cleaned better when the piston is at the top.
for so much deposits I suspect your oil vapour seperator and the engine cam oil guard seal (A6420100131) are shot so change them.

 

Thank you for the great input! I had this feeling that it's a lot of gunk for 75k as well so not sure why. Suspecting the PO didn't take good care of it although it has all service record accessible from Carfax all from dealership.

I think the LM intake cleaning you are referring to is the LM5168? It can be found in US just a different number. In Europe it's LM5168 but here it's LM20208. Exactly the same label and many vendors have it including Napa and FCPEuro(OOS at this moment though).
https://www.napaonline.com/en/p/AORLM20208
I'm planning to give it a shot once I put everything back together. I'm just worried the intake valves are gunked up like this as well.

 

Thank you for the great input! I'm going to do it!

 

If you find Liqui Moly cleaner available in US - post it ASAP.
Suppose the European and US cans use different gas for pressurizing, but cleaning ingredients are the same.
Funny how several US sellers list the cleaner, but none of them ever sold it.

 

I just placed an order of 3 at napa and pickup in store on Friday. I will post it when I receive them.

 

By the way, I just looked at my oil vapor separator and the part number is A6420102491. I didn't find the part number you mentioned on my engine from EPC though. Not sure if it was updated in the late models as mine is a 2015 model.

 

I have 2007 OM642. Your must have an updated version but heres what it looks like on mine. This is what the oil separator attaches to on the side of the motor

 

OK so today I bolted down both oil cooler and intake manifolds, as well as the base stand for the turbo.. Torqued the oil cooler bolts to 12Nm and intake manifold bolts to 20Nm according to WIS but I personally feel the torque specs are somehow a little low... The bolts for the turbo base are also speced at 20Nm. Not sure if it's my false feeling. Anyway I found some interesting things.

I disassembled the throttle and PCV feed and look at the clogged PCV feed... I used a small flat head screwdriver and scraped off probably 5mL volume of carbon deposited...Soaking it in gasoline overnight and scrubb it tomorrow.

The next 2 photos show my crankcase ventilation valve. It's not the same as the one used on earlier model and it's much more expensive... Damn MB!

The turbocharger on my 2015 is actually water cooled, in contrast to those oil cooled version in the older models. I would be interested to see which version is in my 2012 ML350BT when I do service for it next time. I see another folk posted the oil cooler seal replacement and found the new gasket between the stand and the crankcase with an additional hole that's useless but it's actually for coolant on those newer models. The 6th photo shows the holes on the crankcase. The largest hole is for engine oil and the one on its left is for coolant. The turbo also has another coolant line shown in the 7th photo, but now I need to source the 2 o-rings for it because the kit doesn't have them. The part number for the water line is 6422030602 as stamped on it. The list price for the water line is $64 so I feel it's not worth replacing it simply for the 2 o rings. If anyone know the part number for the o rings please let me know. I also need to find the o ring for the coolant temperature sensor on the intake manifold. Please help!

By the way, what do you guys use to clean those carbon? I'm currently doing a cheap method that I put ~4 gallons of gasoline in a 10 gallon Craftsman tote. This is a ~20 bucks solution but I noticed that the cleaning ability of gasoline on those deposited carbon is not as good as the carb cleaners, but 5 gallons of carb cleaner will cost more than $100 so I doubt if it's worth switching, given that the difference is marginal and I need to worry about disposal. For gasoline I can simply put into my lawn mower lol. Any thoughts?

 

By the way, I accidentally broke a coolant hose clamp. The clamp has "MU28" stamped on it so I believe it's a 28mm clamp. I do have a lot of generic screw type clamps in my hand but am not sure which one is better? I can't seem to be able to find the clamp except for dealership, which I don't really want to go to these days due to the virus. Anyone know where I can order it?

 

Use internet dealer. It will take some time and you suppose to "guarantee" the package when it arrives, but if avoiding virus risk is your priority..
I am trying to order groceries over the net and even couple of places in Las Vegas took my order, they later cancel it with bogus explanation.
Would you think that with unemployment sky-high people would appreciate safe work?
Even Amazon takes up to a month to deliver goods.

 

I am using internet dealer most of time just I can't locate the parts... Calling them see if they can help.

 

I've been using Husker https://www.mbdirectparts.com/ for years.
Not only they usually have the lowest prices on MB parts, but they also go extra way for customers.
Give them a call if you won't find the part in their catalog.

 

This is the stuff I just picked up from my local Napa store today. Looks identical to LM5168 to me except for the catalog number. They have it in stock for sure. Forgive my hand in the photo
Link to order: https://www.napaonline.com/en/p/AORLM20208

 

Actually if you go to the official website of the cleaner, https://products.liqui-moly.com/pro-...-diesel-4.html

By changing the country/region the articlenumber also changes. For D-GB-E-P it's 5168 while for USA it's 20208. So it should be the same content unless LM is packing different things into those...

 

Lucky guy.
The website will not let me to order. I called the number NAPA gave me for local store, what turned to be central office, or something. They send me to place the special order at store, so I went.
The store is closed. I assume due to Coronavirus, but no explanation. I emailed headquarters couple days ago and they seem to be out of business all together.

 

That's weird. I did the order quite straight forward with no issue at all. It might be location dependent? I'm located in Haverford, PA close to Philadelphia. It might be a restricted item around California due to the emission/environment regulations I guess. If you need I can help you buy some as long as you pay the shipping.

 

Put everything back and tested run the engine today. It took me about 5-6 attempts to start due to the empty fuel rails. The engine runs pretty smooth but....damn it leaks coolant from the back portion of the motor!! Cannot find any leaking from the top so I'm taking the turbo off tomorrow to see what's going on. It's weird I torqued every bolt according to spec and made sure i didn't miss anything. Since it's from the rear portion of the engine I think it should be one out of the 3 possibilities: oil cooler not tightened enough, Intake manifold gasket, or something related to the turbo. Anyone had such issue before?

 

You have EGR cooling hose and cabin heater hoses on the back. Several possibilities.
No coolant at turbo from what I recall.

 

I checked the EGR cooling hose and heater hose they all look good and dry. The leakage comes from the center not side. I took the air filter housing out yesterday and checked the side but didn't find anything so I'm pretty sure the leakage is somewhere under the turbo. I'm taking off the turbo to check today but need to drain coolant first.

The turbo is indeed water cooled. I mentioned this in the previous posts. It has a coolant return line on the driver side of it and the pedestal has an additional hole that coolant runs. I know older version turbos were oil cooled. That's why when you guys buy the new gasket and install on older model there's a hole on the gasket that's not useful, that's the hole for the coolant path on the newer models.

The leakage only happens when the cooling system is pressurized so I think it should be somewhere I didn't torque enough. I filled in the coolant a few days ago and let it sit for almost a week and didn't see a drop on the floor.

 

Could be they added coolant to newer models.
I was rebuilding the turbo on 2007 engine and there was no coolant for sure.
Good luck on troubleshooting.
And BTW on the LM cleaner, I went to local NAPA and they guy would find 171 cans available, but even he could not order it to the store. He called warehouse and they did not help him. I went to NAPA main page and did chat room dialogue to no help. Email to central NAPA office is unanswered. Amazing, simply amazing.

 

Well turns out to be an awfully stupid mistake I made that when I reassembled the EGR cooler with the intake manifold after cleaning, I forgot to torque the 4 bolts... They were only handtight that's why it was leaking. I removed the turbo and found this. Fortunately the bolts could be torqued without removing either of them. I reassembled everything and am going to run a vacuum test for the coolant system to see if there's any more leaks.

I guess it's been too long I haven't worked extensively on any vehicle so a little out of practice lol!