I'll start with a little back-story as to why I'm tearing the motor apart...

Back on July 31, I was leaving for work that morning when the idle became extremely rough (but idle speed remained a constant 750 RPM). I shut the car off, started again with same rough idle issue. Eventually the car completely stalled and would not even crank. So, after waiting two days for it to arrive I replaced original battery with the MTP-91. Same issue, rough idle. Cranked every time without hesitation, and would run perfect during the warmup idle (initial 5-10 seconds) and once the idle settled into its normal lope, the car started sputtering again. Got the BAS/ESP code and also a check engine light. Strong smell of unburnt fuel.

So, I called AAA and had it taken to the local indie-shop for Mercedes vehicles. Using the Autologic scanner, they found P0105 code (MAP/pressure sensor fault). They cleared the codes, including BAS/ESP. Started it up and ran perfectly. With my permission, they spent about 30 minutes driving it to see if the condition would repeat itself. It seemed all was well, as the car was idling perfectly. I took the car home on August 14 and it ran flawlessly. Installed DCAI on 8/18, car ran even stronger (obviously). Tuesday, August 22, I go out to make a quick errand and -- guess what -- rough idle is back. STRONG fuel smell, sputtering idle, but idle RPMS are still a constant 750 RPM). So, naturally I'm thinking MAP sensor. I researched the P0105 code on MB-World in the C32 section and saw dozens of posts describing a rough idle similar to mine.

So I'm pulling the manifolds yesterday to replace the MAP sensor. MAP sensor is located just at the rear of the intercooler, right in front of the Y-pipe.

As I remove the L/H mani, I look inside and see oil. Waaaaaay too much oil IMO. It's not green, like it would be with the typical intercooler failure. BUT, the previous owner changed the coolant, so it's no longer the OE blue, but rather an orange coolant.

I cleaned the manis with a degreaser and was able to remove most of it. The residue that is shown in the photos had a texture similar to guacamole dip -- oily, but light.

Noteworthy that I have the Needswings catch can. I drained it last night, and since my last oil change (2 months ago) I got about an ounce of oil out of the can. So, it's nowhere near full.

Also noteworthy, I have an unseparated h/e with the Johnson CM30. So it's a high-pressure system.

Does this look like a typical intercooler failure? I only have 52,000 on the car. If so, would this have caused the MAP sensor failure? After all, the MAP sensor is nothing but a nipple that is inserted into the intercooler, and if this gets clogged, it won't read properly.

Ironically, yesterday when I cranked the car to move it back a foot (to allow me to fully open the hood in the garage) the car cranked right up and idled perfectly. The previous 10 starts all had a rough idle.

Advice appreciated.

 

I don't know enough about these engines to provide a real answer, but those manis look gross. When I pulled mine off to send to Rob @ NW there was nothing in them.

That looks to me, (my not-so-professional opinion) like an oil/coolant mix. I wouldn't imagine coolant alone would coalesce on the walls like that. Maybe some combo of poor seals/gaskets is allowing the two to mix???

 

How much coolant has been lost, none or a lot?

 

I've been texting Rudy and he agrees it's 100% an intercooler failure. He guesses it has been that way for a while, although Steve and I pulled the manis at the 45,000 mile mark to install the NW catch can, and I recall a light oil residue (normal) but not this "guacamole" that's in there now. So, it's been within the last 8,000 miles that the failure has taken place. As for the oil still being present, that's a dilemma because I'm running Rob's catch can and it seems to be retaining some oil. But there's clearly oil in the mix. This CAN'T be helping my performance.

When I bought the car, it had the upgraded I/C pump on the unseparated system. I knew the high-pressure system was a ticking time bomb, but I figured since most I/C failures are at around the 80,000 mile mark, I had some time. Guess not.

Note that mine won't have the normal green tint, since the original owner swapped the fluids.

Any chance I could buy some time and simply separate the system, making it a low-pressure system? I can't eat $900 for a new intercooler just yet. Would this potentially harm other systems downstream?

Racing in three weeks, damn the luck.

 

I'm going to check tonight. Until this morning I didn't consider the I/C failure but I did a search for oily intake manis (which lead to threads about intercooler failures) and found several references to "guacamole". And that descriptor is perfect, because that's exactly what this feels like.

I know that at a glance, the coolant hasn't appeared abnormally low so I'm hoping Rudy's assumption that this is a pin-hole leak is correct. Perhaps isolating the I/C fluid from the engine coolant will lower the pressure enough to at least slow the leak.

Still sucks.

 

John, sorry about your trouble. I'm curious, how many miles do you have on it after installing the Johnson? It was no doubt on its way out and the additional flow/pressure did it in. I know I don't have to tell you to get it separated now. Unless you're going with a supercooler, the little spit tank reservoir(vented) that I copied from Tunaglove works real sweet.
Yes, I agree w/ you on your assessment. The good news is you can get in there and get everything sparkling clean like new, and get the thermal coated CAC for replacement.

Edit: I was writing this while you were posting up again, so you answered my question. Good luck w/ it all.

 

Boiling of the water and leaving what you have spread around plus what was burnt would indicate a fair amount of loss.

I expected something like that but all I found was a thin film of oil on the gasket edges and none visible in the plenums. It was a big relief to me as you can imagine.

 

If you're going to truly separate the systems (not just valve them off), you could run straight distilled water in the IC circuit so you're only ingesting a little H20 instead of antifreeze/coolant. Depending how much it's leaking, it might even cool you down a couple of degrees, lol.

 

That's actually a brilliant thought. May have to consider that

Would your reservoir mentioned earlier be adequate?

 

I'm not certain what you mean by adequate. This little tank (a used BMW power steering reservoir off of E-Bay) or any tank that you decided to use is simply a means to fill and monitor the separated IC system. I run w/ straight distilled water and one bottle of DEI chill charger in the IC circuit. It's very cool to be able to remove the cap and actually see the pump pumping, or dip your fingers into and be amazed that it doesn't burn you after you've just done a few hot laps. It's a great solution for those of us that haven't gone with a supercooler that has a fill cap. The whole setup cost me about $30. and a couple hours of time. There are a few more pic.'s in my gallery if that helps.

 

i know you dont want to hear it john but you have to replace the i/c if its bad. separete the system is a good idea, but band aid ideas and racing just dont mix. if you are going to mod and race either road race or drag things will break. you just fix it and move on.
i can come over sun and rip it apart and get everything ready for a new i/c if you want
as a thought you could install 3 of these for the price of a new 1. call and see which has the lowest mileage
http://www.car-part.com/cgi-bin/search.cgi

 

Only when your pit crew is trying to win you that race.

 

I recommend you buy a used intercooler and have it pressure tested before it's installed. Here you go:

 

bad luck man.
umm want to sell your 1/2 mile spot?
I know, I know... damn vultures.

 

The setup you have is a good one, I'll switch to it no matter what because it's clear the intercooler can't handle the extra pressure.

I can always count on you for tough love, hahaha. I emailed Tim (MrMoPar) yesterday, haven't heard a peep but I can't wait long. Hoping he has something and can hook a brother up with expedite shipment.

Thanks for the link. I noticed they're mostly in Canada, one in NY and I plan to call them in a moment. Is there anywhere locally that does pressure-testing?

Nope, I'll be back up and running by then. If nothing else I'll button it all up, run it down the half mile spewing glycol out the tailpipe till she pops.

Then drop a match in the car, walk away and buy your SLK 55 when you get the Cayman S

 

Sorry to hear about your troubles, especially knowing that you only recently acquired this vehicle (relatively) - that is a PIA. At least you are well connected on this forum and are equipped with the knowledge of what needs to be done to fix the problem. One thing I noted from reading your story was that you mentioned the coolant was orange, which the PO had swapped in for the OEM coolant previously. I know one of the only approved coolants other than OEM readily available in the US is Zerex G-05, which is a yellowish hue. Doesn't sound like the wrong coolant would have caused this problem anyways, but any chance the wrong coolant is in there?

 

I know I got scared when I used "another" coolant and then read about how detrimental it is to use the approved coolant with all the anti-corrosive agents and such. I didn't want to take a chance with the intercooler. It may be coincidental but it does seem a fair bit of the failures have had other coolants involved. I immediatly flushed and restocked with the correct stuff. Same with the tranny fluid; as I was uneducated, i bought what Chrysler sold me. Had to flush and put the latest Merc fluid in to solve my shift problems.

I think I will also adopt the BMW canister so that I may moniter the H/E a bit closer. cheers

 

I run a split system and no pressure, 25.0% Anti AND water pump lube. Sorry to hear about the failure. I would like to get to the front of the line, in-case you replace the I/C, could I get the old one. Id like to do an analysis to under this problem and see if I can work up improvements or fixes like the Super cooler, oil seperater or the puller savers that I worked up?? Id do a write up as I did on the Rear I got from Rudy.

Let me know, Id love to get it UNWASHED and original to see whats the deal, Thanks, Woody

 

I'd make you a deal you couldn't refuse on it, haha. Trying to source a used on in good shape (how would you ever really know?) because new is $960 shipped.

I'll take care not to clean it, I'll put it in a ziplock bag.

I need the opinions of you guys, I thought the coolant was orangish/goldish... but clearly the coolant in my car is ORANGE (not gold/yellow) thus the rusty colored guacamole. Now I'm horrified.

My question is, how low is my coolant? I've never added since I've owned it (never paid attention to it, to be quite candid).

For sure, a coolant flush/swap is in order immediately upon replacing the IC.

 

Thanks, The antifreeze can be many colors , mine is the prestone neon green. The color I see is a combination of water-anti freeze and oil vapor making a slurry. The stuff has coated the passages and caused the poor performance. Woody