Exhaust Assembly Paste for Joints?

[JHZR2]

My ML320 has a cracked exhaust clamp/coupler/

I’ve seen that a range of companies have exhaust assembly pastes that help take up any minor gaps, and aid in putting everything together.

Is a product like this necessary? I’ll be changing that cracked clamp. I figure I’ll pull apart the piping and ensure the joint is clean and ready to reconnect.

 

[Lubener]

Is it leaking?

 

[FowVay]

Those clamps are $20, pick up a couple and replace them all. The part number is stamped on the part 000-490-14-41

 

[JHZR2]

Is it leaking?

No, but if. You take something like this apart, who knows how it will go back together. Thus I want to be prepared.

Those clamps are $20, pick up a couple and replace them all. The part number is stamped on the part 000-490-14-41

View attachment 284213

I have the clamps. That’s not the question or point. When I unclamp the system, potentially the pipes will be separate or separable. Thus the interest in if I would apply something to the joint before re-clamping the connection, as best practice.

 

[eljefino]

Does it take a round gasket like the Elring 738590? I'd have a new one on hand. They're made of sort of a steel mesh with graphite mixed in, and though your joint doesn't flex/rotate the graphite eventually wears and falls out of the matrix.

There's a chance you can reuse it, but you'd be compressing it twice, and probably cinching that clamp down more than you like to take up the space.

It would be a good candidate for cobbling, as the "bells" of the pipes will hold all the product from blowing out anyway. Muffler cement to fill in the low spots is an obvious choice. But that's not a direction you usually go in.

 

[shortyb]

I've done plenty of exhaust pipe/refitting work, ie; muffler install, resonators, downpipes etc. and ALWAYS use an exhaust specific assembly paste when putting it all back together. Not specifically for any leak prevention as that is the responsibility of the mechanical fit (which include gaskets) and no type of paste/lube should be counted on to provide that. It is more to ease stubborn/corroded pipe joints into place and allow some slip while buttoning everything up.

 

[Trav]

My ML320 has a cracked exhaust clamp/coupler/

View attachment 284210View attachment 284211

I’ve seen that a range of companies have exhaust assembly pastes that help take up any minor gaps, and aid in putting everything together.

Is a product like this necessary? I’ll be changing that cracked clamp. I figure I’ll pull apart the piping and ensure the joint is clean and ready to reconnect.

On that pipe no, there is probably a thin round gasket between them as eljefino referred to. Do check the pipe flange flare for being rotted out or getting real thin from corrosion. If it is just chop the joint out and replace it with a piece of SS pipe with the ID the same as your pipes OD and use good clamps like Torca AccuSeal 430 stainless.

https://stainlessworks.net/straight-tubing-stainless-steel/

https://www.verociousmotorsports.co...fFEXmKkTKCDqfKD0GPpn3kCiSN1FHUnOAsUiA7V788zEU

 

[Astro14]

All of my MB have a gasket on that type of joint. It’s sintered metal. About 3/8”-1/2” in cross section. It will likely be beat up.

Get a new one. Wire brush everything.

Check for rotten metal.

 

[M104]

Does it make a hell of a rattle or nothing?

 

[Dave9]

My ML320 has a cracked exhaust clamp/coupler/

I’ll be changing that cracked clamp. I figure I’ll pull apart the piping and ensure the joint is clean and ready to reconnect.

Is it leaking now or do you just like making things hard on yourself?

If not, I'd just change the clamp, not pull it apart. If it starts leaking or rattling later you can still do that.

 

[JHZR2]

All of my MB have a gasket on that type of joint. It’s sintered metal. About 3/8”-1/2” in cross section. It will likely be beat up.

Get a new one. Wire brush everything.

Check for rotten metal.

Further up in the system, yes. Not at this point (#175).

Does it make a hell of a rattle or nothing?

I heard a bit of a rattle which is what made me crawl under and look. That’s where I saw the clamp was starting to crack. If nothing else, the clamp should be replaced.

Is it leaking now or do you just like making things hard on yourself?

If not, I'd just change the clamp, not pull it apart. If it starts leaking or rattling later you can still do that.

How am I making things hard on myself? I’m asking about a product that I didn’t know even existed until I found it accidentally yesterday, while looking for something completely different.

Not really looking to pull it apart more than I have to. But figure I’d ask because if the two parts come apart, the. I’d rather be ready…

See just above, it is recommended by someone else:

I've done plenty of exhaust pipe/refitting work, ie; muffler install, resonators, downpipes etc. and ALWAYS use an exhaust specific assembly paste when putting it all back together. Not specifically for any leak prevention as that is the responsibility of the mechanical fit (which include gaskets) and no type of paste/lube should be counted on to provide that. It is more to ease stubborn/corroded pipe joints into place and allow some slip while buttoning everything up.

 

[Dave9]

How am I making things hard on myself? I’m asking about a product that I didn’t know even existed until I found it accidentally yesterday, while looking for something completely different.

Not really looking to pull it apart more than I have to. But figure I’d ask because if the two parts come apart, the. I’d rather be ready…

That's not what you wrote:

I figure I’ll pull apart the piping and ensure the joint is clean and ready to reconnect.

... Figure you'll pull apart the piping means you think it's going to jump off the joint just replacing a clamp? I took it to mean that you're deliberately going to pull it apart, instead of just putting a new clamp on. Proper fitting exhaust pipes don't tend to come apart accidentally once clamped together for a few years, unless an exhaust hanger or pipe itself broke and you're driving at the time.

 

[JHZR2]

That's not what you wrote:


... Figure you'll pull apart the piping means you think it's going to jump off the joint just replacing a clamp? I took it to mean that you're deliberately going to pull it apart, instead of just putting a new clamp on. Proper fitting exhaust pipes don't tend to come apart accidentally once clamped together for a few years, unless an exhaust hanger or pipe itself broke and you're driving at the time.

I haven’t pulled apart this exhaust system before. How it goes together is based upon me rolling under the vehicle and seeing a cracked clamp, and a review of the EPC image I pasted before. That’s it.

If I look at that image again:

Perhaps I’m wrong but it looks like the two ends just mate up and are held together tight with the clamp.

I have no idea if they’ll drop apart, or if they’re interference fit, or if there is what quantity of overlap between pipe 180 and pipe 130, held together by clamp 175.

You can read more into my comment than I intended, if that’s your prerogative. I don’t care to argue. If it’s stuck together, excellent, then I’ll just clamp it.

I had never heard of this assembly paste before a few days ago. Its utility for my need, and if its worth having on hand is what I’d like to know…

 

[FowVay]

There is nothing in service data for your vehicle's exhaust system. But... here are two options for you: I work aviation so I use the DAM product and it's pricey ($10/ounce) and watery but airplanes actually have exhaust bearings that like to remain fluid and flexible. Grab a can from Aircraft Spruce if you want or track down the Liqui Moly stuff für Ihr deutsches Auto.

 

[JHZR2]

I had some time so I took it apart. The old clamp hardware was not going to release. The hexolobular bolt was rusted enough to be unrecognizable, and a rocket socket couldn’t bite it enough.

Used an angle grinder to cut it.

The pipe fit is very simple.

So, this may need a repair, but it’s the location where/why assembly paste would be useful. I think the exhaust gas leaking is what is causing the clamp to crack and degrade.

So the outer bell of the “female” section needs to be repaired, welded, a new rim welded, or something…

New clamp is on. The exhaust/end section wants to pull rearward, while the engine side is very solid. I think that adds stress to the whole assembly too.

I did apply Ni antiseize to the bolt. The clamp says 35Nm. I was not comfortable even getting to 25Nm. So I stopped before then. Maybe I’ll go back. The bolt is pretty stout. But given the metal cracks, I didn’t want to stress anything too much.

Rattling is gone so that resolves that part for now…

 

[JHZR2]

OK, so after about 300 mi of use, all highway (27MPG), I had a look. I thought I had heard a semblance of a tat-tat-tat noise from underneath while under moderate load on the highway, but it’s a diesel and it could be many things.

I see this:

It is possible that the clamp is not on straight, and use has caused things to shift.

But look at the spot/leakage.

Given that I know there is some cracking in the female end, I think it needs a repair.

Do I use the assembly paste and straighten the clamp, or replace a section with a new female end? I think this is called a ball clamp pipe joint.

@Trav you mentioned slipping a section of pipe over the other, can you expand on how I’d do it here? Are there different flares for the female end that I’d need to match up?

Or just have a shop weld a new female flange on?

The clamp is 72mm. I assume that is diameter. 72/25.4=2.83in. So I’d assume it’s a 2.75” pipe and the flange is proportional?

 

[JHZR2]

Found a stainless joint… thoughts?

I don’t weld. I have a good shop that does.

Slipping it over also makes sense to me if I can expand the one end, leave the other OE.

 

[eljefino]

Your answer comes down to how much you trust what's left of your exhaust, and how much you want to cobble.

It's neat that such a repair part is actually available, so maybe enough others have had success. IE the bell is a known weak spot.

 

[JHZR2]

Your answer comes down to how much you trust what's left of your exhaust, and how much you want to cobble.

It's neat that such a repair part is actually available, so maybe enough others have had success. IE the bell is a known weak spot.

It is a generic part!

Im tempted to try to expand it with a tool, slip it over, and let it seal with the paste that I asked about in OP.

 

[Dave9]

I think the exhaust gas leaking is what is causing the clamp to crack and degrade.

Shouldn't be, proper materials would withstand the heat the same as the pipe does.

Where is the strain relief in this setup? I don't understand any of this, to not just slip fit some pipe together and weld it (or clamp, a standard generic sleeve clamp, if you must) before all this... Okay I see later in the topic that you're drifting that direction, but it took a while.

OEM exhaust setups are great, until they aren't.