Subaru/Prodrive Exhaust... Proper leak tests

Subaru/Prodrive Exhaust... Proper leak tests

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Discussion

Jazzy Jefferson

Original Poster:

728 posts

140 months

Tuesday 4th November 2014
quotequote all
Hi

I have a small issue with emissions.

I am led to believe there may be an air leak in the exhaust. It's the only thing I can think of left to check/change.

Can anyone recommend a garage who can actually test this. So far, the best I have managed is "It's just a loud car innit mate." Not a surprise with the prodrive exhaust. But sadly, not enough for me to think they actually checked properly.

I suspect we are looking for a pinhead sized hole, so looking at it, may not yield any results.

Any advice is appreciated. thanks

348jeff

125 posts

126 months

Wednesday 5th November 2014
quotequote all
Make up a mixture of soapy water using washing up liquid then just smear over the suspect area. If there's a leak no matter how small it will blow a bubble(s).

NB Same technique is used to find slow punctures/badly sealed rims on tyres, failed seals in split rim wheels, boost leaks in in pipework etc :-)

226bhp

10,203 posts

127 months

Wednesday 5th November 2014
quotequote all

Jazzy Jefferson

Original Poster:

728 posts

140 months

Wednesday 5th November 2014
quotequote all
348jeff said:
Make up a mixture of soapy water using washing up liquid then just smear over the suspect area. If there's a leak no matter how small it will blow a bubble(s).

NB Same technique is used to find slow punctures/badly sealed rims on tyres, failed seals in split rim wheels, boost leaks in in pipework etc :-)
So simple. I'll give it a go. cheers mate

Jazzy Jefferson

Original Poster:

728 posts

140 months

Wednesday 5th November 2014
quotequote all
226bhp said:
biggrin I lol'ed

226bhp

10,203 posts

127 months

Wednesday 5th November 2014
quotequote all
Jazzy Jefferson said:
226bhp said:
biggrin I lol'ed
I had a little ROFL wink
I wish you the best of luck spraying water onto a warm/hot exhaust.
If the system is leaking and the car is in the air on a lift it will be quite apparent where it is leaking due to the noise and (witness) soot marks, there is no need to do anything fancy.

Athlon

5,000 posts

205 months

Wednesday 5th November 2014
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If your tailpipe is on the silly large side then part of the problem can be scavanged air pulling back into the pipe and being picked up by the probe assuming the lambda reading is off. a way to test if this is the problem is to choke the tailpipe with a rag or something and see if the reading drops into range,if it doeas you need to find somewhere with a long probe...

348jeff

125 posts

126 months

Wednesday 5th November 2014
quotequote all
Obviously you need to do it from when the car/exhaust is cold and you have a limited time frame to look but it most certainly does work.

I found a pinhole sized leak in the seam of a new back box using this method. Try it before you knock it! LOL :-)

andyiley

9,106 posts

151 months

Wednesday 5th November 2014
quotequote all
348jeff said:
Obviously you need to do it from when the car/exhaust is cold and you have a limited time
OK, that means about 3 seconds!


Jazzy Jefferson

Original Poster:

728 posts

140 months

Thursday 6th November 2014
quotequote all
Athlon said:
If your tailpipe is on the silly large side then part of the problem can be scavanged air pulling back into the pipe and being picked up by the probe assuming the lambda reading is off. a way to test if this is the problem is to choke the tailpipe with a rag or something and see if the reading drops into range,if it doeas you need to find somewhere with a long probe...
It's large but not that large. 2.5'' diameter i think. We did try your suggestion, but sadly to no avail.

Thanks everyone for the help so far. I'll keep you posted...

Edited by Jazzy Jefferson on Thursday 6th November 13:59

BigTom85

1,927 posts

170 months

Friday 7th November 2014
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If the leak isn't obvious then it won't be significant enough to be causing emissions problems.

Usually just holding a rag over the tailpipe will make the leak hiss if its slight. Its also unusual to not have any soot marks where it is leaking.

If you are clutching at straws then Cataclean is a good product, I have first hand experience of this stuff bringing a borderline emissions fail within spec. Eurocarparts have it on offer at £13.99 a bottle at the moment too.

Matt Seabrook

563 posts

250 months

Friday 7th November 2014
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If you as struggling to find the leak and even a tiny one can affect the emissions then you need to find someone with a smoke machine (Smokepro) or similar and get then to smoke the exhaust. This will find it.

andyiley

9,106 posts

151 months

Saturday 8th November 2014
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Easiest way I have found to do this, is to get the car in the air & get someone to "block" the exhaust temporarily while you are underneath & normally The additional pressure makes finding the leak much easier as it will be much louder.