Slight water leak from exhaust clamps

[paulrog1]

Hi All,

I've just reassembled my exhaust system from the secondary cats to the rear box.

The engine started today for 15 minutes and whilst checking for any exhaust leaks I found a slight drip of water from a joint clamps.

I know this water is normal condensation generated on a cold start but should there be any water coming from a clamp?

I felt no gasses escaping and everything sounded normal.

On disassembly i found no sealant or paste so I didn't use any on reassembly.

Thanks for your advice.

Edited by paulrog1 on Saturday 16th January 22:09

[AstonV]

Spray some soapy water on the connection to see if you have a small leak.

[Craig elam1]

Some systems have designed in drains to prevent condensation building up in the low points of the exhaust at the back end , usually its just a small hole in the bottom of a silencer, it takes a while for the back to get hot enough to dry it out , on cars that only do short journeys in cold weather it soon builds up.

[N7GTX]

If the engine was left idling then its very unlikely the exhaust temps would be high enough to drive out the build up of condensation. A drive putting the engine under load is the best way to clear it all out and even better in a low gear up a hill. Definitely an essential journey in an AM.

[paulrog1]

I've ordered some leak detector spray as fairy liquid in water was inconclusive this morning.

I've got 2 clamps that drip slightly when the system is warming up and completely stops once the system is fully hot.

I can't feel any leak with my hand, but will try again once the detector spray arrives.

If there is a leak I'll have to get system apart again and use some sealer paste.

[anonymous-user]

What does it matter if there's a slight exhaust leak?

I can't see a problem here.

[JonnyCJ]

Which joint is it Paul ? Mine doesn’t have any assembly paste anywhere and I’m sure it wasn’t used from the factory.

Might be worth a trip to your local Indy after lockdown fir a spanner check whilst on the ramp.

[paulrog1]

Its a clamp between the middle section and rear section, just wondered if slight dripping water was an issue.

I've ordered a bottle of Snoop to see if any exhaust gases leak.

Yeah, my exhaust had no assembly paste on it on disassembly so I didn't use any on reassembly, although brought all new clamps.

As soon as the exhaust got upto temp then no water at all, maybe its always been like that and have never noticed as I'm driving it.

Its only now as I'm almost at the end of the subframe refurb job and just before I put all the covers and wheel liners back on and as the exhaust sections have been apart I wanted to check for leaks,.

Once the bottle of Snoop comes I'll have a better idea.

[JonnyCJ]

Might be worth checking that the centre section is fully pushed into the silencer. It’s a joint where the middle is male, and silencer female from memory, so everything (gas, water) is being pushed to the back and for anything to escape it would need to effectively come back on itself back up the joint and out.

Given the length of the joint i.e amount of male into female, I’d be surprised if water came back along the joint unless it wasn’t seated correctly. I do remember that that joint was a bit of a bvgger to get right.

Are there any witness marks showing where the old joints acted up ?

[paulrog1]

JonnyCJ said:

Might be worth checking that the centre section is fully pushed into the silencer. It’s a joint where the middle is male, and silencer female from memory, so everything (gas, water) is being pushed to the back and for anything to escape it would need to effectively come back on itself back up the joint and out.

Given the length of the joint i.e amount of male into female, I’d be surprised if water came back along the joint unless it wasn’t seated correctly. I do remember that that joint was a bit of a bvgger to get right.

Are there any witness marks showing where the old joints acted up ?

Yeah there are witness marks on the pipes and everything went back the same as before.

Did you run the car before putting on the covers to check for leaks? Did you have slight drips of water?

Thanks Jonny.

[JonnyCJ]

Don’t appear to have any drips, but will be getting AML Performance to go over the whole exhaust system checking for leaks etc when it goes for the next service.

Not keen on running the car on axle stands and lying underneath !

[8Tech]

Simply condensation. Completely normal and small amounts of blowby can occur when assembling joints if no sealant is used. If water is leaking, then gas is escaping. I would always use a small amount of exhaust sealant downstream of the catalysts, or use a cat-safe sealant if on a precat joint. As there is absolutely nowhere else for it to leak from, it must be the joint is not gastight under the clamp.

As mentioned previously, silencers often have small drain holes to allow water to drain at their lowest point.

[Cold]

As above, remove and refit with a small smear of paste. Exhausts don't always go back together perfectly and using jointing paste is an accepted procedure.

[paulrog1]

Ok exhaust back off then!

What paste do you recommend? All joints are after the cat.

Thanks every one for your advice

Edited by paulrog1 on Monday 18th January 07:51

[Veg]

If it is the clamp immediately behind the cats then it may have one clamp one side and 2 on the other (about 4 to 6 inches apart i recall). The 2 clamp side is to fit a sleeve that can be adjusted so both sides seat perfectly and no need for paste. Technique is undo all 3 clamps slide the " adjuster" back a few mm, seat the single clamp side then slide the adjuster to fit on the other side.

Couldn't get mine to seal by less than half a mm and had gas and condensation coming out- then the above dawned on me. Forgot to add when loosening the clamps, moving the sleeve and moving the exhaust use plenty of lube and a lot of Anglo Saxon phrases

[paulrog1]

Veg said:

If it is the clamp immediately behind the cats then it may have one clamp one side and 2 on the other (about 4 to 6 inches apart i recall). The 2 clamp side is to fit a sleeve that can be adjusted so both sides seat perfectly and no need for paste. Technique is undo all 3 clamps slide the " adjuster" back a few mm, seat the single clamp side then slide the adjuster to fit on the other side.

Couldn't get mine to seal by less than half a mm and had gas and condensation coming out- then the above dawned on me. Forgot to add when loosening the clamps, moving the sleeve and moving the exhaust use plenty of lube and a lot of Anglo Saxon phrases

Yeah i know what you mean, those 3 clamps dont leak so I'll leave them alone, just the ones downstream from that.

Do you think Holts Firegum is ok? Or do you suggest a different one?

Thanks

[N7GTX]

Used it on my DB7 when the spherical olive was leaking slightly. A thin smear did the trick and no leaks since. Its a similar type to the stuff that exhaust fast fit centres often use.

[paulrog1]

Or this paste ? -

https://eshop.wurth.co.uk/Product-categories/Exhau...

I'd like to know what you have used on your cars?

Thanks

Edited by paulrog1 on Monday 18th January 17:28

[Cold]

They're all much of a muchness. You'd be ok with a small tube of Gun Gum/Fire Gum from Halfords.