R171 Intake Manifold repair.

paulguitar said:

Hi everyone. My 2004 350 SLK requires the intake manifold repair as the little flap has broken, according my indy mechanic. I have the repair kit, and the car will soon be going in for the work. He is worried about shearing off bolts that were put on at the factory with Loctite.

Should this be a fairly easy repair or is he right to be worried? Might I be better off just getting a used manifold and swapping them over? Any advice would be much appreciated!

Click to expand...

A search of this site will show you that many have had to do this repair and shearing bolts has not been a problem. The bigger issue is to make sure that the flaps that the broken lever operate and not binding in any way. If they are binding or just starting to bind, the flaps will eventually break and the broken pieces will be pulled into the combustion chambers of the engine. This is not a good situation and could be big problem for the engine. Cleaning the areas around the flaps of all carbon buildup will help to keep the flaps from binding.

It sounds like your mechanic has not done this repair before and so you may want to find someone that has. If you are concerned about just replacing the broken lever, the only other option is to replace the entire intake manifold with new. Buying a used will likely have the same issues as your current manifold in the near future. New manifolds online are not terribly expensive - at least not like buying from a dealer.

Good luck.

After watching some YouTube videos on the subject I decided to order a new pierburg intake manifold from Partsgeeks. Prior to installing the new manifold I replaced the lousy plastic bellcrank with the aluminum one I purchased from Uro. It took several hours to clear all the obsticals prior to removing the old intake. It took around an hour to reinstall the new intake and all the connections. The fishing line worked great on the intake gaskets!

I started investigating the cause of the failure on my old intake. The tumbler flaps operated very easily and surely didn't cause this failure. My personal conclusion is that the bellcrank is poorly engineered and is to weak and brittle. Mercedes Benz should be ashamed of this situation and doing all they can to repair all these cars. Chrysler just issued a recall on the windshield washer bottles because some may crack and leak. This is definitely my last Mercedes base on how they stand behind there product.

My old intake is perfectly find other that it needs the bellcrank replaced. I will take pics and offer it for sale in the next few days. My car runs great again!

Having read this 'resurrected(!)' matter, which is ,obviously, still troubling our cohort, I realised that access to relevant articles on the topic can be hard to find.
The following extract is from a long-ago section entitled 'Weird Electrics' (because that's how the matter began...).
There are pictures of the 'bell crank' problem available on that section for those who continue to be troubled by Merc's bad idea regarding plastic parts they placed in the furnace under our collective bonnet/hood!
Quote:
One picture shows the Air Intake Manifold as it should look, with levers intact and attached to the black 'triangular', rotating part which (regretfully quite often!) breaks.
The other picture shows (besides my questionable manicure...) the fault which causes grief!!
So if you intend to acquire (or indeed already own) a 171 350 SLK and are in any doubt about the way it accelerates, have a look beneath the engine cover and check the Air Box which sits in the middle, on the top of the engine.
And always remember...it's a lovely car but the course of true love never did run smooth!!!!
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Hope it will help.