Ok, I am about 1/2 noob and 1/2 know just enough to get myself in trouble.

I have a 2003 C32 with 145k on it. I have replaced the intercooler pump, and added a needswings PSK. I was intending to put a pulley on it, but my idler went out before I got the pulley bought, and I had to do something. Otherwise, I am stock.

I am having a hard time describing my problem to my mechanic, and it is intermittant so demonstrating has been likewise problematic.

What happens is, while I am moving, usually at highway speeds, I feel a surge or lurch and then, it's like I am driving a 1.2L Geo prizim. I can floor it, and almost nothing happens. The RPMs sloooowly rise, but my 50-70 times could be measured in minutes and the car cannot even maintain speed above 70mph. This lasts for at least a minute, often longer, and then with absolutely no transition at all, the glorious power returns and when I push on the pedal, the magic returns.

At first it had only happened a few times, and the mechanic said it was a gas pedal resistor [or something electronic attached to the pedal] but he tested it and said there was no problem. I get the feeling he doesen't want to screw with chasing an intermittant problem, because he was very clear on how much the troubleshooting parts and labor would cost, and that I should probably wait until it was doing it often enough that I could demonstrate it.

As a side note, said mechanic has also made offers to buy my car, at a discount, so I am 50/50 whether he knows what is wrong and trying to get me to give him a deal, or that he just figures whatever it is he can eventually figure it out. Unfortunately, he is the only game in town besides the full-on Dealer, and I have had MORE bad experiences with them.

If I had to guess, I would say it feels like the supercharger clutch is disengaging, but Mr. Mechanic insists that would throw a code and so far there have been no codes at all. So, since ya'll seem to know everything, help me diagnose this. I am happy to perform any test or check that would help someone figure out what the problem is, just tell me what information you need.

If we can figure this out, I can go to Mr Mechanic and tell him to change part "X" and all will be right in the world

 

Even though you have replaced it already more than likely (95%) this problem is due to the intercooler pump... How long ago did you replace?

 

Sounds diagnostic of a failed intercooler (IC) pump to me. Even though you say you changed it, it's possible it failed again.

When did you change your IC pump and why?
Did you 'burb' the coolant system?

Of course, there are other reasons (SC clutch, etc.); however, I'd assess the status of your IC pump first.

 

I had the IC pump replaced about a year ago, because it ruptured at the bottom where one of the hose attaches and started spewing anti-freeze everywhere. It was replaced with a Factory MB part. Is there a way to prove this without spending another $500 for a new one?


So, if the intercooler pump stops pumping, it would cause a lurch or surge, then, I completely lose power...then a minute or a few later, everything is back to normal?

Edit, Ok, now that I did some reading, I see my symptoms are the same as everyone else...LOL, apparently my NOOB is showing.

So, I see that there are people that use a Johnson CM30 and reverences to a Bosch Lightning pump. Any suggestions on where [and which] to get? I remember from before that the CM30 was not available locally.

 

Sounds like the IC pump to me as well. The reason it probably returns to "normal" is because the temp has dropped enough. When the temp hits a certain range (I don't remember off hand exactly what range) the car shuts of the SC and you loose all power.

Have you checked the fuse? (It's in the trunk) The only way to really test it that I'm aware of, would be to remove the pump from the car and hook it up to a power source. If it spins, you know it's good. If it doesn't, order the pump offline. I replaced mine for $125 bucks. It's a pretty straight forward replacement.

 

Your mechanic should be able to put a Stethoscope kinda thing thru the bumper and to the IC pump. It should be always running if the engine is on. If it's not running, then you know what to do!

 

Ok, here's a dumb question, the part they swapped out last time [that was leaking] was clipped on the front of the overflow bottle, and vertically oriented, right out in front of god and everyone. The descriptions I am seeing and hearing are of a part that is buried under the fender somewhere and comparitively hard to get to. So does that mean mine was modded before I got it? Actually, that might stand to reason if they go out every 40k or so, because that would mean I am due for another one, and that it had been changed at least once before I got it...
I can post a pic if my description isn't clear enough.

 

That is a pump very similar to the intercooler charge pump. However it is for the heater system, LOL...

 

Post a photo if you can.

 

They do tend to go out that often, I'm about to put in my 3rd one...

 

Here's the item that was replaced, smack in the middle of the pictures.
If that's not it, how many stinking pumps are on this damn thing?

 

yeah thats not it. that pump is for the REST feature so it will keep the coolant going through the heater core so you stay warm until the coolant cools off.
got to love the Germans

 

Ok, so I looked into my engine compartment just now and I don't SEE the correct pump, and worse, the shop charged me for the intercooler pump when they installed this...

 

You absolutely positively need to replace your IC pump. If you remove the access panel from the front of your passenger side fender well and peer in you will see it. Here's where I got mine. http://www.autoperformanceengineerin...ml/jabsco.html

 

The IC pump isn't accessible from the engine compartment. You need to take the right front wheel off, and a plastic panel there to access it.

Here's a picture from when I replaced it. The pump is already taken out in this one, but you can see where to find it, if you open that panel you can't miss it.

https://i.imgur.com/YgEzy.jpg

Oh, and by the way, I went to 3 different mechanics, and told them I needed the pump to be replaced, but they all told me they couldn't find anything wrong, so I ended up replacing it myself, and it fixed it)
And if you decide to remove it yourself, remember to open the cap on the coolant reservoir to relieve the pressure, I didn't and it ended up with coolant all over the place :P (Luckily it wasn't hot, could have had a very bad burn there)

 

16mm or 20mm? I probably will replace this myself, but I don't think I want to do it on a 20 degree day...LOL

 

I believe it's the 16mm, but it's been a a couple years and I'm not completely sure. Someone should be able to chime in though. If you don't want to do it yourself, just tell the mechanic you need a new "charge air cooler circulation pump". They code it in the diagrams "M44"

 

Dude, my Mechanic already soaked me for $500 to replace this pump...only it wasn't this pump he replaced, it was the one in the picture... No way I am letting him have another crack at this.

 

Here is when I did mine just for interest. You don't need to take the bumper etc off but you can see where the pump sits. https://mbworld.org/forums/c32-amg-c...n-install.html

 

If you can't find the CM30 you can try the new updated Bosch pump. Its been working well for me so far. I would also test your pump out with 12v and see if its bad or not before wasting money on a new one.

http://www.benzworld.org/forums/atta...2022010-1-.pdf