300 TDi discovery down pipe change.

[Pete Attryde]

In answer to my own question of, is a defender 300TDi downpipe (ESR2297) a direct replacement for a discovery 300TDi cat downpipe (ESR3495)? I can now confirm that it is, as I have today fitted one to my truck.

I thought I would try to do a small write up of this relatively simple task:-

Very few tools are required to change the down pipe just a couple of 17mm spanners, a 13mm spanner and a 15mm socket and ratchet and a couple of long extension bars.

Some WD40 or Plus gas to soak the nuts and bolts to help them undo is also probably a good idea.

Removal

Step 1:- Working under the truck using the 13mm spanner loosen the two nuts on the downpipe to centre section clamp.

step 1-a You may need to jack the car up if you haven't fitted raised suspension

Step 2:- Again from under the truck using the 15mm socket, extensions and ratchet undo the 3 nuts holding the downpipe to the manifold. The photo only shows one of the nuts and is taken from above.

Step 3:- Working under the truck undo the top bolt (using the 17mm spanners) that goes through the chassis and retains the crossmember. This bolt also holds a bracket for an exhaust hanger. I found it was not necessary to completely remove the bolt as the bracket is slotted and when rotated through 90 degrees will slide off the bolt. (Sorry no pics as the heavens opened.)

Step 4:- Finally remove the nuts from the centre section clamp freeing the downpipe. As the downpipe comes away from the manifold carefully retrieve the thin metal gasket that goes between it and the manifold and save it for later. The next bit is a little tricky as it involves pushing the complete down pipe forward carefully until the backend clears the crossmember at which point you need to feed the backend under the cross member as you pull the downpipe towards the back of the truck until it clears the axle.

The old and the new.

Refit

Step 1:- Refitting is pretty much the reverse of the removal procedure. I found that by laying the vertical section of the downpipe over at 90 degrees to its normal position allowed it to slide up over the axle easier and then having pushed over the top of the crossmember it was possible to twist it up in to its normal position. As the down pipe is pushed up onto the manifold studs remember to replace the thin metal gasket between the 2 components. Install the nuts on each stud and then tighten to the correct torque figure.

Step 2:- next line up the centre section to downpipe clamp and tighten the 2 nuts up evenly to the correct torque figure.

That’s the downpipe refitted, all that is left is to tighten up the crossmember bolt. It should be noted that due to the fact that the defender downpipe doesn’t have a flexi section it doesn’t have a hanger bracket on it, meaning the hanger bracket originally fitted to the chassis does not need to be refitted. I guess if you are fitting a downpipe with a flexi section in it you would need to re-install the bracket and hanger rubber on the chassis.

HTH

Pete.

I cannot comment as to whether or not removing the cat has made any difference to the performance as I have yet to drive it as I haven’t fixed a slight brake issue yet.

[Mo Murphy]

Good write up Pete, useful to know that the two downpipes are interchangable.

Mo

[white90]

Now a Tech Archive article

[Turbocharger]

I'd be interested to hear if you see any tangible effect from this mod - good info to have, cheers.

[freeagent]

just a quick question... do you have a front anti-roll bar on your disco? as the Haynes book of lies reckons that you have to remove it, and jack the truck up, supporting the chassis on axle stands to increase the gap between the chassis and the front axle... in order to allow the down pipe to be removed....

got the downpipe in the shed, got to do this job sometime

[Pete Attryde]

freeagent,

No anti-rollbar on mine.

I didn't jack the truck up either was a bit tight but I managed. I guess the slightly lifted suspension may have helped but only have about a 1" lift.

HTH

Pete.

[freeagent]

cheers pete, let us know if it feels any different to drive...

[Pete Attryde]

Having now done a couple of hundred miles since changing the downpipe on the truck, I can report back that, apart from saving 200 odd quid over the correct CAT downpipe, There doesn't seem to be a huge benefit from fitting a defender downpipe. I can't say that I can notice a huge difference in the performance although the turbo does seem to spool up a little quicker. Equally she doesn't seem to be smoking anymore than normal so the MOT shouldn't be a problem. Having an auto may however be masking some of the gains if any were made.

I would still say that it is something I would do again as the financial saving is worth it IMHO.

I will be doing somewhere in the region of 1000 miles over the christmas period including the play day at Broxhead so I will give more feed back on fuel usage etc in the new year.

HTH

Pete.

[Pete Attryde]

Update:

Having done a further 700miles since changing the downpipe I definately think it has made some difference to the overall performance of my truck. Nothing major has changed but it definately feels a little stronger and I definately don't have to work it as hard to maintain speed on motorway's, this has also led to a small reduction in fuel usage maybe only 1 or 2 mpg but it still is going further to the gallon.

So definately worth doing in my opinion.

Pete.

[pinny]

Update:

Having done a further 700miles since changing the downpipe I definately think it has made some difference to the overall performance of my truck. Nothing major has changed but it definately feels a little stronger and I definately don't have to work it as hard to maintain speed on motorway's, this has also led to a small reduction in fuel usage maybe only 1 or 2 mpg but it still is going further to the gallon.

So definately worth doing in my opinion.

Pete.

i agree with you definently a drop in fuel consumption and does seem a little bit more power i think the removal of egr has also helped cheers chris