OM642 Failed Right Intercooler line - PeachParts Mercedes-Benz Forum

markg612 · #1 02-14-2019, 11:26 AM

Seems to be a reoccurring issue on the later model 455 pound foot rated OM642 engines, the right intercooler hose splits at the upper end near the throttle housing.

Any of you active techs care to comment?. Doesn't seem to be an issue with the older OM642 fleet rated at 369 pound feet.

Kind of strange it's the cooler end of the duct after the intercooler? Is the rubber suffering deterioration from the resonance pulses from the valve operation starting and stoping the charge airflow?

88,000 in service.

jay_bob · #2 02-14-2019, 11:49 AM

I have a 2014 with 58k, I will give my hose a squeeze and see how it looks.
This is on the driver side coming up from the IC into the mixer correct?

I guess you got a code for boost pressure discrepancy or did you hear it whistle?

markg612 · #3 02-14-2019, 11:59 AM

Right side hose, the cooled side just as it attaches to the throttle housing. The left side is the hot side from the turbo into the "noise muffler" before the intercooler.

No code, although many of the threads I've read got to that point, and no whistling either, however, others have also reported that as well.

Stench of oil smell, which I hate with a hot hate, especially in the garage. I notice it about a week ago, and it was getting worse. my 642s are bone dry and clean, so when the oil smell comes, I know something's been breached. (I change the turbo and breather seal once a year, never a drop of oil in the valley)

I had oil on the back side of the corner of the radiator area on the right, and the right air inlet had a fine oil coating on it as well, investigated further to find more oil coating on normally dry parts. Squeezed hose and saw splits.

TimFreeh · #4 02-15-2019, 11:44 AM

Quote:

Originally Posted by markg612

Right side hose, the cooled side just as it attaches to the throttle housing........ Squeezed hose and saw splits.

My hose failed at the identical point in a 2013 GLK250 so I don't think the problem is confined to the high-torque OM642. Mine failed at 70K miles and it did throw a low-boost error code. Squeezing the hose is absolutely necessary to see where the split was, in my case a visual inspection without squeezing looked 100% OK. As soon as you applied pressure you could instantly see the fissure. The other strange this was that the hose was nice and supple, the rubber looked to be in really good shape - from a visual/tactile perspective it seemed like the hose was perfect.

These later generation CDI's run really high boost compared to the older IDI engines, as I recall 40-50 PSI at wide open throttle?

Kind of annoying but the hose is pretty easy to replace at least in the OM651 in the GLK class.

markg612 · #5 02-15-2019, 11:51 AM

I'd dearly love to get an engineers bend on this, much like the 606's inherent flaw with the resonance valve vain breaking off, I believe these hoses are failing for the same reason, the resonance pulses created everytime the valves open and close and the waves that resonate back in the intake are absorbed by they hose flexing.

This is my better guess than the "oil in the intake lines weakening the hose" bit. if that were true, the failures would be everywhere in the hose, but hey all seem to occur in the right hose at the throttle housing.

markg612 · #6 02-15-2019, 11:57 AM

Quote:

Originally Posted by TimFreeh

Squeezing the hose is absolutely necessary to see where the split was, in my case a visual inspection without squeezing looked 100% OK. As soon as you applied pressure you could instantly see the fissure.

Interesting, might be an infinitely better breather on the OM651, there is so much oil in the 642 intake system, any air leaks is like using green dye in the A/C system to find leaks, as long as the engine is clean like mine are, the tell-tale of failure is evident with oil that shouldn't be there!

TimFreeh · #7 02-15-2019, 01:32 PM

Quote:

Originally Posted by markg612

I'd dearly love to get an engineers bend on this, much like the 606's inherent flaw with the resonance valve vain breaking off, I believe these hoses are failing for the same reason, the resonance pulses created everytime the valves open and close and the waves that resonate back in the intake are absorbed by they hose flexing.

I think this is quite likely what is going on, whenever you play around with pulses and resonance these kinds of things can happen. The material on my replacement hose is somewhat different than the original hose that failed. Maybe Mercedes recognized this issue and came up with a new hose material that is better able to handle pressure spikes and pulses? Hope so.

Simpler=Better · #8 02-15-2019, 03:06 PM

Honestly, this is hte perfect application for self healing silicone tape. I would get a roll in black and run 8 wraps around the crack, it would last for another 80k.

jay_bob · #9 02-16-2019, 12:47 PM

I get home from the road (again!) and my wife says, I can smell a whiff of burning oil when I get out of the car.

So I spent the morning investigating and found that my hose is still perfectly intact. However there was oil seeping past the o-ring at the end of the hose that plugs into the mixing chamber, and that is very near the exhaust manifold. I did see a fine deposit of oily dirt on that side of the engine bay. (Helps that the body is white.)

I pulled the air boxes and Y-pipe and again found oil seepage past the orange ring gasket going to the turbo, a few drops on the wire harness cover that runs right below there, so I cleaned that up really good and put all back together.

I also inspected the air filters, these were replaced according to the CPO documents right before I bought the car in March 2017 about 20k miles ago. They were a little bit dirty but I may go ahead and replace them this spring. Factory interval is 4 yr/40k but I know about how high delta p across the filter increases the blowby, as it causes air to be sucked in harder from the breather.

There was some oil in the base of the turbo inlet, about what I have seen in my other 642s.

No evidence of leakage onto the exhaust under the car.

So she’s due for service B in a few k miles, I may go ahead as part of that renew the o-rings on the boost hose, the orange ring into the turbo, and replace the air filters.

I did notice they made quite a few design changes to the air intake from the older 642s. There are some resonance chambers in the down pipe from the turbo outlet to the right side intercooler. I wonder if they added these to address this resonance problem. The older 642s have a smooth pipe from the turbo down to the muffler to the intercooler.

Also they straightened up the design for the Y pipe and air boxes. Much easier to get the y-pipe off (and back on!) than the older design. Also the air box is much easier to open, only 2 screws instead of 4. And you can actually change the filters without pulling the air box if you want to since the top comes off instead of splitting like a clam shell.

markg612 · #10 02-17-2019, 03:15 PM

Have you checked under the soundproofing over the injectors for seal leakage? The #4 injector seal was leaking on my 07, and the Black Death had that same burnt stench. I had a happy accident with a leaky injector line after I did the oil cooler seals that covered most of the engine and underside of the car with fuel, AND washed away virtually all my oil residue in the valley and down the back of the engine, made it like sparkly new!

PS, I also use chlorinated brake cleaner and compressed air on a warm to hot engine to routinely clean everywhere when I have stuff out or removed that gives better access.

As I mentioned, I replace the red/orange turbo seal annually to keep everything dry. It makes a big difference.

jay_bob · #11 02-17-2019, 06:05 PM

My 2014’s 642 does not have any padding around the injectors. It’s all bare nekkid once you lift the decorative cover.

I went underneath and everything was completely dry. We also went out all yesterday afternoon running around and it’s completely smell free now.

On my E320 I am going to pull the covering to make sure there is no mischief going on under the padding. I may delete the padding just to make sure no trouble hiding below. I think they did that for noise suppression purposes only.