Manifold/exhaust connection

[70chevelle]

Does anyone have any tips or special tools they use when removing/installing the front pipe to the exhaust manifold?  The six bolts are unusual to me in that they are a bolt and nut.  Usually (on American vehicles) the bolt threads directly into the exhaust manifold.  Anyway, I started to replace the exhaust the other nite only to realize that I can see 2 of the six bolts from above, but can only get a socket on 1.  I'm going to try from underneath tonite, but it still seems that I will need a wrench to put on the nut to keep it from spinning.  Any help would be great.

[Tom]

70Chevelle,

Here are some tips:

1.  Start with fresh Mercedes bolts and aluminum crush washers
2.  Use copper based high temp sealant on the bolts and the aluminum crush washers
3.  Search this and yahoo site for a post from Joe Alexander that covers this in great detail.

Best,

Tom

[70chevelle]

Tom,  I have the parts necessary to complete the job, my question really is,
     -  What was the best tool or technique for the job to remove the bolts that connect the manifold to the front pipe?  

It is such a tight area and to compound the situation, it is a bolt and a nut.  Which, obviously, means that you have to keep the opposite end from turning once you break it free.  

I'm sure I'll figure it out after I dig into it, but was looking for any hints from others who have already completed this task.  Thanks for the info on Mr. Alexander, I will search his posts.

[Tom]

here is the relevant post from Joe:

http://index.php?topic=69

[George Davis]

70 chevelle,

A stubby Gearwrench was a real lifesaver when I did this; 13 mm, I think.  It fits in the tight space, and the ratcheting box end was very helpful.

I cheated on reassembly and replaced the stock bolts with stainless steel Allen head cap screws, installed from below.  The screws can be stuck on an Allen socket on a long extension, slid up in place, and the extension can then be clamped to the exhaust pipe to hold the bolt still while you crawl out and start the nut from above.

The bolts will fall out if they ever work loose, but the nuts are self-locking and so far so good.

George Davis
'69 280 SL Euro manual

[Cees Klumper]

I've done these exhaust nuts/bolts thing more than I care to remember. Only for one of the bolts do you have to work from underneath the car - using a long extention on your socket wrench. To keep that bolt in place until I get the nut on, I put some heavy grease on it. The nut you can hold in place by loosely putting a 13 or 12 mm box wrench on it before you retire to underneath the car. Move the right front wheel out of the way first. All this will make more sense once you get down to doing the job.
On all the other nuts and bolts, using two wrenches does the trick. Make sure you use the proper bolts and (split-top) nuts (nylock nuts do not work - the nylon simply melts) and double-check their tightness after driving a fair distance (100 miles or so) - they tend to work themselves loose. If this happens, you  can try remedying it by using several (rather than only one) gaskets inside the manifold/downpipe connection - make sure there is at least one (metal) gasket there!