[W126 Coupe] MBCOUPES Digest, Vol 72, Issue 14

[Arioli, Frederick]

Gerry,
   Thanks a million for the guidance!  Will pull the valve covers and take a look at the top end.  
Have acquired the exhaust manifold gaskets, copper nuts and the thin copper gaskets from MBZ.  Considered buying the entire headset for each side, may still do so.
   Want to replace as many of the seals and rubber/plastic parts as possible.  Thanks for the links, it's great to be able to hook up with people that have done it before.  
    This site is great!

Fred  

-----Original Message-----
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Sent: Wednesday, June 23, 2010 9:15 AM
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Subject: MBCOUPES Digest, Vol 72, Issue 14

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Today's Topics:

   1. Re: R&R Exhaust Manifold Gaskets (gerryvz)


----------------------------------------------------------------------

Message: 1
Date: Tue, 22 Jun 2010 11:03:19 -0700 (PDT)
From: gerryvz <gerryvz at me.com>
Subject: Re: [W126 Coupe] R&R Exhaust Manifold Gaskets
To: mbcoupes at mbcoupes.com
Message-ID: <6181dde5-6c31-e0b5-955b-d639cf6333a2 at me.com>
Content-Type: text/plain; charset="utf-8"; Format="flowed"

The tic-tic sound may or may not be the result of bad exhaust manifold gaskets.  I'd remove the valve covers and carefully inspect the cam lobes, rocker arms and lifters for wear. A visual inspection with a flashlight ought to do for the cams and rocker arms.

The driver's side (left) exhaust manifold (on US cars) removes from above -- through the engine bay. You will need to remove all of the EGR tubing from the manifold in order to get to it. Helps to remove the valve itself though this is not a requirement.

The passenger side (right) exhaust manifold removes from below the car. You will need to have the car on a lift or at minimum a set of ramps to do this right. You don't necessarily need to jack up the engine to do it. Rather you will need to drop the exhaust downpipe (remove and replace all of the rubber hangers all the way back to the resonator kidneys if not to the muffler itself) to get enough room to drop the exhaust manifold from below the car.
?
The biggest challenge is the transverse pipe, which runs immediately behind the heads along the firewall, and which connects the two halves of the exhaust manifolds. This is held at each end by a clamping ring that must be carefully removed. Also, each connection at the manifold/transverse pipe end must have a new thin copper gasket, which is about 2 inches in diameter. These are cheap to buy from Benz.

In fact, you should replace ALL of the copper exhaust manifold nuts. You can re-use the studs and the bolts that hold the top side of the manifold onto the heads.

If I were you, I'd just order the entire head gasket sets, which contain the exhaust and intake gaskets as well as the head gaskets. In fact, each kit contains a set of intake manifold gaskets, so you will have an extra set (which you can keep or sell). Take the opportunity to remove the intake system and re-seal it, particularly if this hasn't been done before (at your mileage). Good time to also replace the fuel injector holders, O-rings, rubber injector seals and rubber idle air tubes that connect to the injector holders. All of this rubber and plastic is very inexpensive. Only get factory Benz parts. You can get genuine MB parts for dealer cost + 15% if you order from www.parts.com. Don't cheap out and get aftermarket stuff -- get the real Benz parts.

Lastly, two of the eight exhaust manifold gaskets are oriented 180 degrees opposite the other six. I believe they are the gaskets for cylinders #4 and #5 (closest to firewall on right side, and closest to radiator on left side). Install these CAREFULLY and make sure you have them lined up correctly so that exhaust flow is optimized, and so that you won't have to re-do the job.

The metal side of each exhaust manifold gasket should be FACING the cylinder head.

A couple of references that ought to help you:

Chet Hwilka's site:  http://home.comcast.net/~chwilka/cylinder_head_removal_and_replac.htm

My recent top-end refirb:  http://www.benzworld.org/forums/w126-s-se-sec-sel-sd/1525150-1989-560sec-top-end-rebuild.html

Give yourself a full day to do this or parts of two weekend days, casually working. Don't rush it -- take your time.

Good luck!
Cheers,
Gerry


Couple of good references for you

- - - - - - - - - - - -
Gerry Van Zandt
+1 503 805-9316 (cell)
+1 281 518-2960 (work)
+1 832 764-0183 (home)





On Jun 22, 2010, at 11:15 AM, mbcoupes-request at mbcoupes.com wrote:


>

>

> Am getting that tic-tic sound on warming up. Cranked down on the top exhaust manifold nuts, the lower ones are going to need a crawl under the engine.

> Anyone had the pleasure of replacing exhaust manifold gaskets? Was told that the exhaust pipe would not clear the studs on one side. Am I looking at raising the engine in order to get the exhaust pipes off?

> Should I buy the complete headset gaskets for the left and right side, or just the exhaust (and maybe intake) manifold gaskets? Don't need the head gaskets now. There is a lotta stuff hangin' off the manifolds!

>

> Frederick Arioli

> 1990 560sec, 132k

>

>

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