What you describe is the symptoms of high IAT, but not to the point of full power cut. With my custom intake and boost gauge I could hear the supercharger, and see the boost pressure, but feel little power. Once again, I would have to say the intercooler pump is the place to start... If it's cold out a 1.5k-2k RPM start is normal. I'd say 2k is on the high side though. Mine averages 1.5k cold start for around 5 seconds.

Yeah I have suspected the IC pump since day one as well, but I went away from that thought after my previous mechanic didn't find any problems and I specifically told him I suspected the pump. He said it was running normally. I don't trust him though, so I think I'll take it somewhere else for a second opinion. If it turns out to be the pump I'm really curious to what he was doing with my car

So I finally found a mechanic that could pinpoint the problem. A guy with 7 years as a MB mechanic. First of all, the serpentine belt on the supercharger has to be replaced, (kinda sounds like a diesel engine right now). But the thing causing my loss of power was either my supercharger itself or some kind of leak in the transmission (gave me details, but I cant remember the transmission part). He said he'd do an oilchange on the supercharger, and combined with the new belt, then see if the problem went away, if not, we'd take a look at the transmission.

I'm a bit scared here that I might be looking at replacing the supercharger AND the transmission, that would really kill my economy.
Mechanic didn't say that though, but I'm still fearing the worst. Would be typical of my luck.

Thank god for all you well knowledge people on Mercedes or i would be lost!

I have the same problem with the power loss on the freeway ill be driving and go to pass and there will be no power????

than ill try on a diffrent day and it will work????

ill check all the above soulotions and hopfully it works but any one have a good place to start. i just dont want to but all theses parts if i dont have too ....yet


and thanks for all the help!!!!!

Kevin B

That was exactly what my car did. I would be on the highway, and go from full power to no power several times in one triop. i will get my mechanic invoice and tell you what he did because whatever he did it has never occured again.

reflex92


thanks ill wait to here back from you!!!


kevin b

Chiming in here, this might not be the answer but for me similar symptoms, the fix was to replace the EGR valve, it was intermittent and did not throw any codes, power was lost and I sometimes felt rough idling.

More than likely your supercharger bearing is bad, that should be causing the diesel engine sound. Rarely do our superchargers go out, lots of them were replaced because no one knew that they needed to replace the supercharger bearing. Changing the supercharger oil is a piece of cake, but it won't make a world of difference. I think your performance issues are due to the intercooler pump. The pump can sound like it's functioning normally, but it may not flow as it did when it was new. Plus, the pump does not throw a code when it's bad.

There's a common transmission leak from the electrical connector. This would not cause any severe performance issues, but your tranny may not shift as smooth and feel a bit different.

Yeah that was something like he said about the transmission. Is this expensive and\or worth fixing?
I paid $450 to have the idler tensioner? and belts replaced. They charged me for 3 hours of labor, but the car was ready after 2. Also when I tell them to check the intercooler pump they always tend to change the subject. I think I'm getting robbed here.

Are they replacing the tensioner or just the pulleys. I think if they are replacing the whole tensioner and including labor it may be a good deal, but why does it need to be changed?

An investment in a good ratchet set and you could save your self a lot of money. There are lots of great diy threads on this forum.

Just checked the receipt, it said replaced serpentine tensioner and idler pulley.

It removed the noise from the belts, but it's still a ticking noise coming from the top left of the engine. I took a quick video from my phone.

http://www.youtube.com/watch?v=eCITygyj63A

You can hear the belts are running quietly, but there's still some weird noise in the engine, any idea what it could be? My old car had the same thing, someone told me it was lifter tick. Could it be the same here?
Also could be perfectly normal and I'm just paranoid. It's just that every strange sound I hear from this car makes me scared

I know I am digging up a year old thread, but I am posting this in hopes to help those who have yet to go through this with their supercharged vehicles.

My car is an 03 and I have pretty much gone through all the annoying problems listed in this forum. I have had to replace my intercooler pump, the smog air pump, idler pullies, control arms and bushings, radiator.

Over the years, my car still felt powerful, but has somewhat lost that thrust of acceleration it used to have...but I just thought it was due to car getting old. I top off my window washer tank/intercooler (Evosport Evolution 2 package) every now and then since I also do use my window washer. (For those who are confused with what I just wrote...Evosport kit isolates the intercooler circuit from the engine coolant by utilizing the window washer tank which provides 6.2 liter of window washer water through the intercooler). Never did realize I was loosing to the intercooler...

One day, the dreaded sudden power loss resurfaced, and I just though that the intercooler pump went out again. But then this time it was something different...the car misfires, stalls, and everytime it restarts, it puts out a cloud of smoke (water vapor) from the exhaust. The car is in constant "limp" mode. I had a shop pull the code and was just told that the spark plugs and wires need to be replaced. Got those done but the problem persisted. The car would run fine for few minutes first thing in the morning, then would be very sluggish afterwards. Stumped, I decided to top off my intercooler water reservoir (window washer tank) and realized it was running almost dry. I topped it off and run the car, it started running very rough and water vapor coming out of the exhaust...thats when I realized that the intercooler was leaking water and "water injecting" the hell out of the engine. Took out the old intercooler and there was all kinds of buildup within the core. Apparently it started out with a slow leak which did not affect the car much at first, but the water leak steadily collected microns of dust particle over the last couple of years and turned it into a clay like substance whick also blocked the flow of air through the core. This caused premature hot spots within the core which eventually widened the crack and failed.

The intercooler had been replaced, and the brutal "thrust" is back...all 432hp 427 ft-lbs of torque. Very happy except one thing...flooring it from a stand still causes the torque limiter to kick in and shuts off the gas pedal...have to shut the car and restart in order to get the gas pedal back. It only happens when I floor the car from a stand still.

I think either case, it would be advisable to peek into your intercooler cores every now and then (yes I know its a pain), especially those of you who use aftermarket high flow filters...if you car is sluggish, it just might be gunk accumulation in the intercooler halting the air flow...

Yes, the intercooler can be a main failure point on our supercharged v6 engines. The easiest area to check is pulling one of the intake manifolds. Much easier than trying to view the intercooler itself. If your coolant level drops unexpectedly your looking about 80% intercooler leak is cause. However, the valeo radiator in 02' can be a culprit as well. Internal fault allowing coolant to mix with transmission... Went through that one.

I agree about checking the intake manifolds... except in my case, the intake manifolds were clean and had no signs of buildup...either because I caught it in time, or I only used distilled water. But despite the manifold being clean, my intercooler core had build up and gunk (I collected them from the fins and was able to knead it into a ball of clay-yes it's kinda gross). I've been trying to figure that one out. At least in my case the I was not able to tell from looking into the manifolds.

Regardless of whether you are losing power or not, I still recommend all of you to peek into your intercooler core especially if you are using oiled high flow filters such as K&N or Green. Compared to the oem paper filters, these filter do let more particle into the engine (compared to paper) and for me 9 years worth of accumulation occurred in the intercooler. I will try to post a photo of what the core looks like. The inlet is filthy, but the outlet was relatively clean. I believe just cleaning the intercooler once every blue moon will prevent headaches and keep the air flowing through the core at optimum.

Hi. In the interest of my sanity I want to revive this thread. Also have the exact same problem. Also have a 03 c32 with hesitation problem. Any input from the posters on this thread on how they finally resolved this issue will be really appreciated. Thanks

Did did you ever find out the problem I have the same problem