1993 245 - Weld vs clamp on exhaust pipes

[FireFox31]

Hello, my 1993 245 non-turbo recently had its mufflers replaced. The shop welded the muffler pipe to the old, OEM catalytic converter pipe. Days later, the catalytic converter started rattling.

From what I've been told and read, the pipe at the back of the cat should be clamped to the exhaust pipe. Is this true? Other shops don't want to replace the cat because of this weld.

I bought the IPD cat and header pipe kit, to be sure the correct cat was used. Now I may have to install it myself, though I'm not very mechanical. The header pipe is just 3 bolts, but the weld is the problem. In your opinion, could I replace these parts, dealing with this weld?

Thanks.

[billofdurham]

One of my friends owns a tyre and exhaust shop. When he saw that a previous owner of one of my cars had had every joint of the exhaust system welded he said, "Whoever did this has little, if any, knowledge of fitting exhaust systems. The weld has been put there because he wasn't sure that the joints would seal using paste. Basically he didn't know what he was doing. Exhaust joints should never be welded." His language was a little more colourful but, as this is a family show, I have censored it.

The reason why others are reluctant to tackle the job is the time involved. At first it was thought that they could remove the complete system and separate it on the bench. A second examination showed that they wouldn't be able to get the system off in one piece because of the part that goes over the back axle. It took two fitters 35 minutes to grind two welds down far enough to remove the remains with a chisel. The difficult part was over the top of the pipe where there is very limited clearance between the pipe and the floorpan. Had the complete exhaust needed replacement they would have cut through the pipe and just dropped it in two pieces.

I have pointed out the trouble two experienced fitters had. The job can be done but it is time consuming and will be very difficult if you don't have a hoist.

Go back to the shop that did the welding and get them to undo the rubbishy job that they did then fit your new parts using clamps, not a welder.

Bill.

[FireFox31]

You mention "paste". To my untrained eye, the pipe connection might be affixed using a paste. Today is dark and rainy, so I can't get a good view.

If it is paste, is that easier to work with?

Thanks for your help!

[billofdurham]

Much easier as it is designed to come apart with minimum resistance. However, a pasted joint should also have a clamp. Basically the paste forms a gasket.

Having re-read your initial post one of the reasons why others may not want to tackle the job is that you have cut down their profit margin by buying the parts at IPD. A lot of shops do not like you to supply the parts as they can add a good percentage when they supply them.

Bill.

[FireFox31]

I did apologize to the shop in advance for supplying the part, since I know it hurts their profit.

When I first asked my dealership, they weren't sure which part was needed, and eventually quoted me $1000 for the cat. Upon researching it, I saw the source of their initial confusion and decided to spend time getting the right part.

If I took it back to the muffler shop, I didn't want more of their "universal fit" aftermarket parts. So, I bought the correct part (even though I needed the header pipe also, since nobody sold a cat with a floating flange to that pipe).

I'll insist that the muffler shop install my cat, undoing their weld and using a clamp. They got me into this mess, they'll have to fix it, and take the part profit hit. My 240 deserves better.

[FireFox31]

The repair was bad, so now I have to deal with it. They cut the old welded pipe, shortening it. To recover that ~1.5", they pulled the muffler pipe toward the front of the car (and welded it again). This put a strain on the rubber hangers, which no longer hang straight down, but are pulled forward. On the drive home, one of the front muffler hangers broke with a loud twang.

I'm going to look for replacement hangers of a stronger material and a slightly larger size. Is this a suitable solution? Are the motor mounts also at risk from the excess tension?

[billofdurham]

The easiest solution, apart from taking it all off and throwing it away, is to have someone cut the metal hooks off the exhaust and weld them back on where the normal size hangers should be.

This is something that the clowns who fitted your exhaust should have done whilst they were busy. It is a common modification on after market exhausts for most makes of car. The last exhaust I had fitted need two hooks moved. It took about 5 minutes and there is no strain on the rubber hangers.

As for engine mounts, it is feasible that the extra tension would affect them but move the hooks and you will have no extra tension.

Bill.

[bright]

This is for Bill. What is this paste you speak of? Does it have a brand name?

Thank,s
Lee

[billofdurham]

The correct terminology is Exhaust Assembly Paste. Several companies make it - Holts; Hylomar; Granville; Carplan and others.

Autozone, Pepboys and most car parts dealers will be able to supply it. It is used when joining two sections of the exhaust. A small amount is smeared onto the male end of the joint and it makes a gasket type seal. The job is completed by using exhaust clamps - no welds.

Bill.

[FireFox31]

Do you think the following solution is feasible, and possible for me, who's non-mechanical and has no lift:

1. Cut off the current welded section of pipe, loosing another ~1.5".

2. Add a ~3" piece of pipe, replacing the two ~1.5" sections lost from cutting off welds, releasing the strain on the hangers.

3. Use paste and two clamps to secure this piece in place.

Seems like this will solve the problem once and for all. Good?