HDI high mileage exhaust performance and refitting

John Plum · Unread post by **John Plum** » 16 Apr 2014, 20:45

I would have thought a high mileage cat converter (170000) (in addition to the rear silencer) would seriously hamper exhaust performance due to flow restriction.

Q. What are your thoughts on exhaust performance and mileage?

Q. Have you refitted an HDI exhaust? if so, What does replacement of the main pipe to manifold entail, concerning access, and any unforeseen problems?

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Unread post by **RichardW** » 16 Apr 2014, 22:07

Mine was still running on it's original cat at 160k, still went OK. Doubt it makes a huge difference - less resistance might help the turbo to spool up a bit quicker.

I wouldn't bother touching it unless you have to - getting it off is a right git! I've had mine off twice, and both times I have had to saw off the OS bolt, as I just couldn't get a spanner on the back nut to counter hold it. After you've done this, you find that there isn't room to remove the left over bit, and you then have to saw the other end off, which is no fun either! I suspect a C spanner might get on the bolt head, and a windy gun would help with unwinding the nut, but even so..... And then there's refitting it, which requires some serious single handed dexterity to get the spring clamp back together.

A whole amount of fun

rory_perrett · Unread post by **rory_perrett** » 16 Apr 2014, 22:24

I haven't a clue how many miles the cat on my HDi has done. It was originally on my 2.1td which had done 225k miles. It could easily have done another 100k on the current car. As it is the 2 part design rather than the 1 part of the later cars it is possible to see the cat. Last time it was off for welding up it didn't look particularly sooted or blocked up. As said best left alone unless you have to the manifold end is always an awkward Faff.

Unread post by **Peter.N.** » 16 Apr 2014, 23:29

Just give it a good thrash uphill for a minute or two, all the rubbish that's clogging it will quickly be ejected - just watch the exhaust.

Peter

Unread post by **RichardW** » 17 Apr 2014, 08:27

My trials with getting the exhaust off: http://www.frenchcarforum.co.uk/forum/v ... 6&start=15" onclick="window.open(this.href);return false;

someone else suggested you might be able to access the OS bolt head from the top, but not sure that is possible on later cars with the 'improved' EGR set up. For sure you would need to remove the two electrovalves at the bulkhead to give access round the corner of the engine....

John Plum · Unread post by **John Plum** » 17 Apr 2014, 08:53

Thanks guys. I remember the spring clamp on my TD - that was awkward in a solo effort.
Think ill leave it for now then.
John

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rory_perrett · Unread post by **rory_perrett** » 17 Apr 2014, 09:31

RichardW wrote:My trials with getting the exhaust off: http://www.frenchcarforum.co.uk/forum/v ... 6&start=15" onclick="window.open(this.href);return false;

someone else suggested you might be able to access the OS bolt head from the top, but not sure that is possible on later cars with the 'improved' EGR set up. For sure you would need to remove the two electrovalves at the bulkhead to give access round the corner of the engine....

You can get in from the top but you need a willing assistant who doesn't mind a sore arm. My method these days is to get daughter No 1's other half to get his arm down the back of the engine and get a 10mm ring spanner on the head and then undo from underneath with a deep socket on a very long extension bar

Unread post by **Eddie Nuff** » 17 Apr 2014, 20:35

Changed the cat at 160k. No idea when the exhaust was changed, it's not in the history, and I haven't changed it in seven years. The fixing to the manifold is a pain and is so much easier with two people.

This is one of those jobs where "if it ain't broke don't fix it" is so true.

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