33 Exhaust "Resonator".

[littlebelter]

What is the purpose of the exhaust "resonator" at the back end?

The resonator is rotten so will the engine run ok if I replace it with a bit of pipe same diameter as the rest of the exhaust?

I've always thought it a bit strange the exhaust going down from 40mm or so to a small tailpipe.

Any ideas anyone?

Thanks,

Pete.

[daf44]

hi.
The resonator on my 44 was mainly missing when i got the car and i was going to put straight pipe through as well.
When i was hunting through my shed i found that the silencer box from a mini/metro taking up space for 4 years fits almost perfectly.(the mini itself went some years back)

The box probably does something but the car worked fine on straight pipe, just had a slightly different note on the exhaust.

use whatever you have.

paul44

[spunkymonkey]

The general idea of a resonator box is (strangely) to prevent resonance. They're effectively an empty silencer that lowers the resonant frequency of the whole system to below what should be produced by the engine. That's why a hole (which will raise the resonant frequency of a pipe) can lead to "boominess" at certain revs.

IF the rest of the system is "as new" then you'd probably get some effect at certain revs without it but, with any of the rest of the system in "used" condition, you're unlikely to notice any difference.

[daf44]

hi.

at least that would explain the slightly different pitch in the exhaust note with and without the box.

you learn something new every day .

paul44

[littlebelter]

Yes you learn something every day.

Well, I reckon I'll stick on a straight-through pipe and see what it sounds like!

Thanks all.

Pete.

[littlebelter]

Well, I ended up with a 3m length of copper pipe and an obtuse bend coupling from the local plumbers merchant (£25) and replaced the lot from the silencer outlet to the rear end.

Should last for ever now!

The small cylindrical rubber mounting was also perished so I got a replacement from the local washing machine shop.

Sounds a bit more sporty but quite acceptable.

Cheers,

Pete.

[ericthered]

hey Pete,
did you know that apparently using copper for an exhaust is against the law!

better hope your MOT man does not know! LOL

it gives off poison gases,

might try it myself when mine gives up.

Best wishes,
Eric.

[littlebelter]

Never heard of that before Eric!

dDo you know any more detail on it??

Cheers,

Pete.

[starider]

Hi, the resonator box is important,it was fitted to ensure that Daf cars conformed to European noise regulations and also, believe it or not helps reduce fuel consumption, allbeit only by a small amount.This said there seems to be little concern over noise levels nowadays, so the elimination of the resonator should pose little problem[Danny in Holland can supply new ones].I would always fit a new one on my own Daf's. starider.

[stefan]

I had no idea you could not use copper pipe as exhaust, then again never thought of trying it eather so i have learnt something new.

[ericthered]

hi all,

i remember being told about copper exhausts being illegal many years ago when i was an apprentice (motor mechanic/restorer), when i asked about it i was told it gave off a gas that was poison (not told what the gas was).

anyway, just a few months ago i was having a chat with a friend who worked in the metal/chemical industry and the conversation turned to copper, he told me that the gas it gives off when heated a lot is cyanide and he knew about it being against the law to use as an exhaust material.

i told him that in the past i have polished up old copper pipe and when i breathed in the dust your taste buds go really strange and most things for an hour or so taste disgusting!
he said yes thats the cyanide that has got into your mouth!
i dont know if anyone else has had this experience with copper but it does affect taste buds and this guy knows what he is talking about so it just confirmed what i was told all those years ago.

i dont know what sort of levels it gives off but there is something in it and its not nice, copper also has other poisons locked in that apparently can be released when heated.

hope this helps, thats about all i know.

Best wishes,
Eric.

[littlebelter]

Hmm . . . this gets more interesting by the minute!

Makes me glad I'm not a plumber! Cyanide in the copper and lead in the solder!

I know they use "lead-free" solder nowadays but copper is not banned for your domestic pipes so I presume it doesn't give off its' cyanide until well above the melting point of solder?

But I suppose the best thing is to be on the safe side and look out for a bit of Stainless steel and do the job again as soon as I get the chance.

Regards,

Pete.

[ericthered]

hi Pete,



talking about plumbing, i have read that in some cases if the water in copper pipes is slightly acidic it can release the nasty stuff (or if the pipes a very old) and its not unknown for people to get poisoned by it!

like you say "makes you think?" how are you supposed to know if your water is contaminated other than keeling over one day!

Eric.

[littlebelter]

O.K. so we all go on to plastic pipes and think we're safe. Then in 10 or 20 years time someone tells us that theres another nasty lurking in the plastic pipe

No good for the exhaust though!

Cheers,

Pete.