I got a lot of crud out of my intake manifold, but I cannot say that I was able to notice any improvement in engine performance. In my opinion, cleaning the intake manifold is more of a "feel good" procedure than it is anything else. I did feel better.

I soaked my manifold and crossover in kerosene for a few days, that took care of all of the tar.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Deliberate is the word I prefer to use.

Read about it here.

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Never a dull moment at Berry Hill Farm.

Haven't you been paying attention? You know that he calls his work space Area 51, right? He has to be careful not to get any cavitations in his force fields and no telling when one of those foil hats could short-out on a battery terminal or something.

If you have a 617 with the turbo, make sure you remove the battery cables before you pull the intake/exhaust (you have to pull both to get the new gasket on)
Otherwise, the turbo and exhaust manifold drops and finds the starter pos contact down below!
Just sparks...hehe

I did mine in about 3 hours or so...the cleaning took the longest since I was working with a solvent tank
My exhaust gasket was leaking so thus the removal
BOY DO THESE CARS WHISTLE under boost when they have a blown gasket!
yeowzah...

Hardest part is getting the exhaust back lined up in the event that your flex pipe decides it wants to only flex in one section out of the whole foot and a half or whatever it is *grr*
Have fun!

You will get messy

A clean intake inhales.

A dirty intake sucks.

Also
Noticeable power increase? Doubtful
Combined with fixing the exhaust gasket leak it would be hard to tell anyway
Car does run better with no whistler though

There is just something wrong with seeing a mercedes benz with a exhaust leak "putt putt putt putt" driving around...I felt like a hick

I did it in the middle of the street so when I pulled the plug for the block for the block heater the coolant didn't run into my yard and kill the grass. Started after lunch took it apart with everything laying on the sidewalk, mussled the plug out put the block heater in and put it together and had it running before dark. But then I also did a timing belt job on a ferrari in 1/2 the time the labor books call for and it was my first time under the hood of one of those. Guess I assume everyone works as quick as I do.

Its nice to NOT have an EGR.................no crud buildup. But then I have no oil seperator on the airbox like newer ones do and no good place for a seperator to sit except where the dipstick goes.

there is a cover on the solenoid that hides the contacts on mine. no way to short anything out.

Oh, the Area 51 thing I never did understand.

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Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Wasn't the original Area 51 in New Mexico and related to the Manhattan Project or some other top secret programs?

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

The 'original' Area 51 is near Groom Lake, Nevada approximately about 90 miles north of Las Vegas. The site was selected in the mid-1950s for testing of the U-2 spyplane, due to its remoteness, proximity to existing facilities and presence of a dry lake bed for landings. "Dreamland" is the traditional testing ground for the military's secret aircraft before they are publicly acknowledged.

Tin hats? Nothing that mundane here, mine is made from unobtainium.

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Never a dull moment at Berry Hill Farm.

Thanks for the clarification, only off by one state. Close, but no cigar.

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1961 190Db retired
1968 220D/8 325,000
1983 300D 164,150

Here is the best way that I could clean my intake plenum, and crossover pipe. Buy a spray bottle of Castrol Super Clean (purple bottle) use rubber gloves and after about three rounds of the Super Clean at the spray wash after I used a fillet knife to get out the thick stuff off it was clean down to brite aluminum. After cleaning you should block the EGR hose to render the EGR inoperative so it will not cook any of the tar into hard little balls and cuase piston to head carbon impact. I think that the oil is from the breather line that is in the turbo are intake, I am coming up with some other breather ideas.from

what is the purpose of cleaning the intake manifold? Is it necessary? What are the pluses and minuses about cleaning the intake manifold? Is it simple? What other things to look for while cleaning the intake manifold? Can it be done on a 126? Lots of questions

Purpose: To clean 20 years worth of accumulated diesel guck out of the intake tract.

Necessary? Probably not. On the 617 engine (used in some w126s) , it is not a job I would take on unless I forced to. A leaking gasket or some other intake/exhaust issue requiring removal of the downpipe and manifolds would be sufficient cause IMHO.

Pluses and minuses: An overwelming desire for that fresh-as-a-daisy feeling? Spring cleaning? OCD? Righteousness? Phobias? You tell me. I did it because I already had the parts off to do the gasket.

Other: I have 'zero' experience with the 603 engine (also used on some w126s) but in studying the one I have sitting outside, it looks as if the divorced intake/exhaust design of that engine would allow removal of just the crossover and runner/manifiold assembly. If so, that would simplify pulling these parts considerably and may make it worthwhile on high mile engines that are suspected of having a build-up.

Other things to look for: Once again, I can't answer for the 603 but, on a 617, this would be a good time check out the ALDA line, oil separator and turbo drains (if leaking, you cannot fix that turbo drain w/o dropping the lower pan), motor mount (right side)... et al.

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Never a dull moment at Berry Hill Farm.

Mine ran better after I cleaned it out, and blocked the egr. Also having the manifold off gives you a great oppertunity to change the glowplugs.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200