This problem began with a CEL P0102 MAF sensor with low Voltage. I called my son who has the same vehicle and is much more of a mechanical than I am to see if he had any ideas. The first thing he said it's the Turbo intercooler hose/charge air hose. I wasn't a believer yet so I removed and cleaned the MAF sensor, check its voltage, then cleared the CEL. I did order the hose. Things looked good for a couple of days until the light reappeared. This time my code reader said DTC 2, one fault and one pending, but showed N/A in place of the actual code number. So I went to O'Riley's and used their code reader, I got the same reading. So I called the local Mercedes dealer and ask if they would read my code, and they said sure. So I went to the dealer. The mechanic brought the large Mercedes code read out and went through several checks. The reader said I had an intermittent DEF sensor. We checked my DEF it was at least 3/4 full. The code was cleared and I went home. The next day I had to go on the interstate over a couple of passes, neither was super high or steep. Crusie set at 70 mph and I noticed the mph decreasing. I pushed the accelerator to the floor nothing. wouldn't downshift. At the top of the pass, I pulled off shut down the engine, and restarted, merged back onto the interstate all seemed normal until the next pass and the mph started decreasing again plus the CEL reappeared. I was able to make it home with no problems other than I was in the slow lane on the uphill. As I pull into the drive FedEx dropped my new hose, great timing. This morning I checked the current CEL it was P0299 this sounded more like the new hose. I installed the hose which was pretty easy So far it's running great, hopefully, fixed. I did ask the Mercedes mechanic how common the Intercooler hose failed, answer pretty often. Both my son's GLK and our's were around 60,000 miles when they failed. I know this is kind of long-winded, sorry. My point, both of our problems started with the P0102 code, which seemed unrelated to the actual problem. We both had holes we couldn't see in the hose while it was on the car and both holes were in about the same location, on the top side of the hose close to the engine end. You'll need an 8mm socket and a screwdriver, Good Luck

 

Typical failure for the 2.1L Bluetec, but luckily it's an easy fix.

It wouldn't hurt to have a spare hose on hand, just in case.

 

Does anyone know what's causing them to fail? That's not just an old, tired hose issue.

 

It's an engineering failure due to less than ideal design. Basically the hose should've been designed to withstand greater air pressure than the turbos produce, because they expand as the warm up and get coated on the inside with oily vapors. Eventually these weaken the rubber structure and a tear opens up under high boost conditions.

As long as you don't get on it too much, you may not notice, it's when you stomp on the Go pedal asking for max boost that the tear opens up, lets all the pressure out and you end up with underboost condition code(s)

From what I've read, the replacement hoses are not necessarily updated (ie, made stronger). This is why I said you might wanna have a spare on hand, if they go pop around 60-70k miles.

 

It's not the hose that is the problem. They all wear at the exact same point. What you need to do is look at the place where they are wearing and then look at the car. There will be two little ears there on a mount. Grind those down.

 

I have had two blown hoses. The original and the one the dealer installed under warranty. First thing i noticed before the limp home mode was a hissing sound like a tire deflating. Then CEL and limp home mode. I inspected and found the problem and had it fixed under warranty. Less than 2k miles same thing. I inspected and the dealer had installed the hose in reverse. I must admit that the arrows on the hose are confusing as they are not flow direction arrows. The mechanic assumed that it was flow direction. It is not. If I recall correctly the arrow also has "EX" with it. The mechanic thought this was exhaust and the other side was inlet. It really means exchanger. It was installed reverse and the hose contacted a sharp edge and it cut through. I used duct tape and drove it until the stealership could get the car in to change the hose.

 

There are companies such as HPS Performance ( https://hpsperformanceproducts.com/c...arge-air-boots) that make all silicone radiator and intercooler hoses. Silicone is more durable than rubber and can handle temps up to 500F. If someone wants to DIY, 2 1/4" diameter silicone hose and couplers with some aluminum joiners should make something that will last a long time and will probably be cheaper than a OEM replacement hose.

 

The hose i have has over 140000 miles. It is not a common issue as long as it is not installed in backwards. Duct tape will get you out of a jam. If belt and suspenders are needed then use a length of heat shrink tubing. I don't know the size of the hose, but i have seen 3" and 4" heat shrink tubing that will shrink to 50% when heated. This would add a level of security to this issue.

 

Many thanks for the post and links, especially for understanding how the retaining clips work. Was able to swap mine out with minimal effort and aggravation.

 

I think it finally happened to me. 150KM on my GLK 250. Driving home I noticed some weird noise when under load. I thought back to this forum and thank god for this website. Pulled over and inspected and felt a tear in the hose. Was a few blocks from Benz so I picked up a new hose and installed it. Hope that was my only issue and I caught it before it got worse and threw codes.

I noticed a bit of oil in the hose. How worried should I be?

 

Post #4 in this thread:
"because they expand as the warm up and get coated on the inside with oily vapors."

It's possible the oily vapors can accumulate into a "bit of oil".

So ... just what is the quantity of oil you see? Any photo to offer?

 

No worries about a little oil in there. It is normal.

 

Completely normal for some oily vapors to condensate, accumulating up to a teaspoon amount. Pretty much common in almost all turbo engines, nothing to worry about.

Hopefully the new hose lasts a good long time, and good job on replacing it yourself! A stealership would've misdiagnosed it, replaced several much more expensive parts and still not have fixed the issue (or maybe it was just the Milwaukee stealership I went to...)

 

No photo to offer but about a teaspoon to tablespoon of oil in hose on the engine side. I guess the pipe does go up to the engine and some oil my migrate there after 150000KM. Didn't expect it and it worried me.

 

Is there some after market options? I’m in the middle of summer towing my Jetski to lakes here in Washington state and I have to go up steep up hills. since I have those tablet scanners, I was curious how much boost the glk250 made under load and going on a very steep up hill for 25 mins while towing a Jetski fully loaded with gas and the car full of passengers. So during those conditions the GLK makes about 43psi of boost during peak load. I just replaced the hose back in May and yesterday I just blew another hose, so I can’t be constantly blowing hoses since it becomes frustrating. I’m planning on making some sort of hose that can resist more if I can’t find a stronger replacement. This is genuinely an engineering issue. I used to own a supercharged mini cooper s and it made 16psi PEAK and it still had cast iron boost hoses. While the GLK makes 43psi peak and it has thin rubber hoses. Please make it make sense. What was Mercedes thinking when designing these hoses

 

Are you sure the 43 psi isn't the problem? (I don't know what the pressure is supposed to be.) You've had two fail recently. I haven't heard anyone else complain about multiple failures. In fact, I thought the failures were tied to the hose rubbing on something, not pressure.

 

Likely you’re seeing the nominal value, which doesn’t subtract the atmospheric pressure. So subtract 14.7 psi and you’re around 28 psi max.

I assume you immediately get a CEL and under underboost code right after the hose blows? If not, you might not be running OE software and I’ll just leave it at that.

I’ve only replaced the original hose once, no issues since and I’m on stock software, FWIW.

 

So I took a picture of the live data so it peaks at 42 sometimes 43 so if I subtract 14.7, So I make 28 PSI (So you're correct). I do get CEL underboost code just like in May and no acceleration. I'm on the stock tune and stock everything. Also the rubber is very thin and I don't think it can support that much boost. Like how I said my mini cooper made 16psi peak with a pulley and other stuff, yet it still had cast iron or aluminum hoses. The 335i at least has plastic hoses and stock their turbos make 8 PSI they crack due to age. So why Mercedes decided to make these boost hoses out of rubber?

 

Is it possible the hose rubs on anything? Or is it possible that when you reinstalled the new hose you rotated it 180* and the S-bend is not in the same location, thus possibly rubbing somewhere?

Your twin turbo set up is working as designed, spikes up to 28psi is normal but it should settle back down well below that. If you're getting error code(s) and limp mode then you're likely running stock software as well; the reason I mentioned that initially is that some tuning companies effectively defeat a bunch of "normal" values when upping the boost/fuel so that even when you have a problem, the ECU doesn't detect it as a problem. So if you're underboosting because that hose is torn, no CEL to inform you and also no limp mode.

Anyway... when you go to replace the hose again, pay attention to any directional markings on the hose that would indicate direction of airflow. I believe that hose should have an arrow and it should be pointing towards the front of the car.

Once the new hose is on, feel all around it with your hand and see if there is anything nearby that could poke it or tug at it, especially under load when the engine flexes a bit on its mounts. Any pointy or sharp edges should be filed down if possible.

 

It’s not ripped the rubber slipped out of the aluminum clip on the intercooler side end again. And I say again because that’s what exactly happened last time. About bends the hair doesn’t seem to be in a weird shape but I can try flipping around? Since I didn’t see any arrows

 

Many companies make silicone boost or radiator hoses which are stronger and more durable than rubber. Not sure if any are molded for a GLK250, but custom is possible.

 

Does anyone have the part number of the hose handy? My CEL came on within the last couple of days and I'm showing P0299. I wonder if it happened when I dusted that snap-crackle-pop VW the other day? Anyhow, I'm hoping it's the hose...

Could it be 2045280000 ?

Thanks!

 

Seems like this would be a great part for the aftermarket to sell an upgraded silicone hose version.

You can make one but the bigger size could be more challenging than making a custom bent heater hose size

 

These are covered by the AEM warranty, if it's still active on your car. If so, take it to the dealer and let them replace it for free.

 

Unfortunately the 4 years was up in March. The CEL went out and even spirited driving hasn't brought it back, for now.