I have a 95 E300 (Non turbo OM606) with 302k miles that the oil pressure guage started to go down on shown pressure over the course of two days. Knowing the engine is great shape I strongly doubted the actual pressure was low I ordered a new VDO sending unit. I never have had the lower part of the intake off in my 3 years ownership but had to pull it to gain access to the sender which is at the base of the oil filter housing,just above the starter. When i pulled the intake off the head i noticed the intake gasket was cheesy, very thin strip of metal with no "gasket" material on it. It had some slightly oily residual on the mating surfaces. Anyway, changed out the sending unit and assembled the intake with a new OEM gasket (thick).

Upon starting I was back to a full 3 bar cold idle....and super smooth! I thought to myself, what did I do to make it have a improved idle? It must have been that intake was sucking air somewhere causing the intake vacume to be unbalanced? I took the time to make sure all of the crankcase suction lines were all in place, all linkage was clean and lubed and small diameter vac lines are all in good shape.

Anyway, i thought i would pass that along. Also another lesson on the quality of OEM parts is definately a big deal. I bought my car from the original owner and have a 4" thick stack of receipts and will go back and see how long ago that intake was pulled, but that gasket was for the birds.....

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1995 E300 (W124)
1999 ML430 (w163)
2011 GL350 (x164)
2016 Sprinter 144" 4X4 lowtop (906)
2004 E500 (W211) 4matic Wagon (Gold)
2004 E500 (W211) 4matic Wagon Avantgarde (silver)

Just FYI, a diesel engine will run silky smooth with the intake manifold completely removed. There is no "vacuum" in a diesel intake manifold except for the small bit caused by the air filter or the butterfly valve for the EGR system.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

And yet, there it is. Fixing the gasket fixed his idle.

Don’t you just love it when you go to fix one thing and it happens to fix another. Usually when I try and fix one thing, I bugger something else up and have to fix it too. Glad it’s running great for you.

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1998 E300 Turbo Diesel, 221k Miles
2018 Chevrolet Colorado Z71 4X4, V6, 19k Miles
2007 Honda CRV, 115k Miles
2011 Kawasaki Trans Mule, 212 hrs, (grandkid hauler)

IIRC the NA 606 uses a fiber -0080 intake gasket. The turbo 606 uses a steel -0180 intake gasket. Either a mistake or someone tried to save $2 list price

Not meaning to rain on anyone’s parade, who knows what else was touched by plan or inadvertently during this job that smoothed the idle?

Sixto
98 E320s sedan and wagon
02 C320 wagon

To the OP: I've been doing this stuff for 60ish years (started as a kid). Sometimes you get these little gifts from the Gods of Mechanics. My advise - accept the gift graciously and move on. Sooner or later you'll pay for this break with some little bit of nastiness that will fall upon you!



Glad the car's running well for you.


Dan

Yes, I am aware of the vacume, or lack there of on a diesel. It definately has a balance of intake requirement. Upon my assembly of intake I first started it up, it ran good for 3 seconds and settled into a crazy hard lope. I shut it off and pulled the upper section of the intake (not disturbing the intake to head intake gasket). Found I had left one vac line off the main butterfly which blocked off the intake. Reconnected this and put it back together and it was glass smooooth.

That is interesting on the two intake gaskets. Sounds like I had the steel turbo engine version, the OEM gasket I bought was super thick and was laminated steel on both sides.

Drove the car 160 miles today and man I love this laid back engine in the 124.

Sent from my SM-G950U using Tapatalk

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1995 E300 (W124)
1999 ML430 (w163)
2011 GL350 (x164)
2016 Sprinter 144" 4X4 lowtop (906)
2004 E500 (W211) 4matic Wagon (Gold)
2004 E500 (W211) 4matic Wagon Avantgarde (silver)

Here is a pic of that intake gasket, thick as a piece of notebook paper.

Learn something all the time working on cars!

Sent from my SM-G950U using Tapatalk

__________________
1995 E300 (W124)
1999 ML430 (w163)
2011 GL350 (x164)
2016 Sprinter 144" 4X4 lowtop (906)
2004 E500 (W211) 4matic Wagon (Gold)
2004 E500 (W211) 4matic Wagon Avantgarde (silver)