Rough Idling 560SEL
 

It's been idling rough after warm up for months. I replaced plugs, wires distributor cap, tried fuel injection cleaner - still no fix.

Annapolis Motors diagnosis: Intake Manifold gasket and some kind of "guides" need replacement. I stopped listening after I heard $2,000. This must be 95% labor. I'll bet the parts total $100. How many hours is this job? Needless to say, I told them to button up my engine and I'll get another quote (or 2 or 3).

I know that these are sensitively tuned high performance machines and anybody who owns them must be prepared for $2,000 repair invoices, but how is it possible that my 89 Towncar goes 180K miles with relatively little hassle and a baby butt smooth idling engine?

It's apples and oranges, I know. That was rhetorical. Thanks for allowing me to vent! I love my Benzes, but for what the components cost, they should be more durable. Shouldn't they?

Take a look at the pictures in the string from just-n-time
Search on author and look at vacuum leak. It started last spring I think, but he took pictures of where the dealer is going for $2000.

Pointing to the intake gasket says they troubleshot to a vacuum leak did you ask them to show you the problem and how they got to the intake gaskets.

Guides? there are valve guides but you have to take the heads off to replace them and symtoms not just rough idle. Anyone know of other guides they could be pointing to?

For $2000 they should be more than willing to explain how they know thats it and not something else.

Tell us what your symptoms are and what the shop said in detail.

By the way 108K is nothing on that car and valve guides should go 200K on it. so cheer up might be something simple.

Fuel injector guides and seals and intake manifold gasket. Service Tech said the idle changed when fluid was sprayed in the vicinity of the leaking seal.

2000 for that? jeez...bring it to me and I'll do it for half price :rolleyes:

Intake rebuild
 

If you choose to take on this assignment we will never leave you hanging we shall help you to over come the situation no mater how many years go by.
NO but really it is not such a daunting task,my advice to you is to use that camera to document each step and to aid in reassembly. Leaking or sucking air around the rubber seals is the most prominent problem and they are top side unless you decide to go on into the center section and replace the donuts.Start with the injector rubbers and as you will have them out go on to the o-rings on the injector cups.I am not one for spraying the top of the Eng. down with flammables,seems to be the way most check things but as Dave said use smoke! it will suck into those leeks.MY Dad and I had bees so I used the old bee keepers smoker. Well let us know how you are doing and if you need more pics I still have some I did not post. J-N-T:confused:

Intake gasket is not a project that I would care to attempt. Johnhef, if you're serious, let's talk!

I would do the injector seals and the o-rings around the injector guides and see if that fixes the problem. That should be 2 hours labor and about $25 in parts.

Personally, I don't see how they could get more than 4 hours labor to do the gaskets and the injector seals. It's a lot of wrenching, but nothing complicated. I would say $500 tops.

It's pretty simple to test the intake gasket theory. Just get a can of carb cleaner or PB Blaster. Put the red tube in the nozzle. Pull the air cleaner, and with the engine idling, spray along the head-manifold joint and see if you get a change in idle.

I agree with Chuck on that, start with the simple stuff first. They probabaly quoted the intake gasket just incase the injector seals didnt fix it and its in the vicinity of the leak. If you need help or want me to check it out just let me know.

When you purchase injector seals/o rings I'd replace the cups just as a matter of course. Also plan on replacing the air injection/idle distribution hoses. I have no doubts they will be rock hard.

What plugs are you running? Anything w/ a resistor or platinum in it is verboten.

Jonathan

I suspect that is what they did. This is not the first time the dealer has diagnosed intake gasket and it turned out to be something else. That was my previous 126 and I had the problem corrected elsewhere.

Johnhef, you come well referred. I would like to bring this to you for your opinion and your remedy! Where do you do your side work?

Rough Idle Follow up
 

I took the car away from Annapolis Benz and their $2K estimate and took it to Dwayne Crawford at Family Auto in Owings, Md. He agreed with the intake manifold seal and injector seal and guide diagnosis, but also discovered a leaking fuel distributor that had some rust. He did the work, including replacing the fuel distributor with a reman unit for $2200 total. The dealership was charging me $2K for the intake manifold and injector work alone, but now I have a working, non leaking fuel distributor. The intake seal leak caused the car to idle high (unregulated air in the combustion mix) and the high idle hid what would have been an even rougher idle caused by the faulty fuel distributor. The dealer would have done the intake maniford seal for $2K, the idle would have still been rough, then the dealer would have said "now we're certain that it's the fuel distributor". They would want to charge me list price $2300 for the part. They don't do reman units. I would be ready to sue!

Keep in mind that dealer diagnoses tend to be experimental and tentative until they get into the engine to see what's really going on. The independents do not charge as many hours to the customer for diagnostic time and they tend to give more educated diagnoses as a result.

The car idles baby butt smoothly now. It just goes to show the difference in pricing between dealers and the independents. Sometimes I think the dealers have a preprinted $1,000 invoice waiting for us when we get there.

Hi check the co first then the fuel distributor? thats what usually breaks after a long service life for the 126, its not suppose to break that easy but due to the sensitivity of that part towards the kind of fuel you might have used. If you have check out the elctrical side of the car then most likely its the fuel distributor.