Small hole in new exhaust.

Wig

I just had a Bosal exhaust fitted, rear and middle boxes.

I'm driving and can hear gas escaping from the exhaust under the car,

I check the exhaust and there is a 3mm perfectly round hole at the bottom of the front end of the rear box, just above the weld seam.

The fitter tells me it is supposed to be there as a "condensation hole" !!!!!!!

Never had one of these holes before, and there was no hole on the original Bosal rear box which is 13 years old and is on the car from new. but is a different shape to the new one.

Won't this hole be a source for corrosion over the years to come?

Alter_ego

Should help against corrosion by allowing water to escape. Normally it builds up till some of it pours out of the tailpipe. Never seen this from a car in front?

Wig

http://www.dj-autoparts.be/documents/documents/drainhole.pdf

Of course seen water coming out of tailpipe. but this is a new feature for Bosal exhaust boxes. Water from tailpipe is a chemical reaction of the gases meeting with the atmosphere, technically it is not coming from inside the box but is being created at the tailpipe opening.

There was no problem with the old Bosal box fitted from when the car was new, it was still a sound, sealed box, it only had to be replaced because the hangers had corroded to nothing, the box itself was fine, so all this talk of corrisive water inside the box.. piff paff,

Alter_ego

Wig wrote: »

http://www.dj-autoparts.be/documents/documents/drainhole.pdf

There's your answer then.

Ectophile

Wig wrote: »

Water from tailpipe is a chemical reaction of the gases meeting with the atmosphere, technically it is not coming from inside the box but is being created at the tailpipe opening.

Huh? The main two combustion products of hydrocarbons are water (in the form of steam) and carbon dioxide. So there's an awful lot of steam in the exhaust gases, which will condense out inside the silencer if it's still cold.

For instance, burning octane:-
2 C8H18 + 25 O2 -> 16 CO2 + 18 H2O

konark

That's why it's a waste of time painting your exhaust pipe, even with heat-resistant paint, cos the water is inside the exhaust.

EdGasket

konark wrote: »

That's why it's a waste of time painting your exhaust pipe, even with heat-resistant paint, cos the water is inside the exhaust.

Must be intelligent water, always goes for the most exposed part of the exhaust; the bend that gets spray from the rear wheel!.

bigjl

Wig wrote: »

http://www.dj-autoparts.be/documents/documents/drainhole.pdf

Of course seen water coming out of tailpipe. but this is a new feature for Bosal exhaust boxes. Water from tailpipe is a chemical reaction of the gases meeting with the atmosphere, technically it is not coming from inside the box but is being created at the tailpipe opening.

I think you better rethink the opinion that water is somehow magically created at the tailpipe.

salubrious

It is absolutely fine to have that hole, and some car manufacturers now do it from the factory as standard.

Back in the seventies early eighties it was a common diy practice to drill a hole in an exhaust box.

EdGasket

I got an MoT advisory for slight exhaust leak from bottom seam of centre section. Surely they aren't going to like an actual hole in it blowing gas?