Some time ago, I had the #1 cylinder ignition coil fail on my LR2 with the 3.2L I-6 engine, and shortly thereafter got the dreaded P0420 catalyst efficiency below threshold CEL. I knew what had to be done, so I ordered up a new front passenger side exhaust manifold with catalytic converter, and set about swapping it out. I looked for a DIY or HOWTO for the job and came up short, so here’s how I did it in the hope it might help someone else. Sorry I din’t take many photos but I only had a few hours to get the job done before I needed to drive the car again. The repair manual provides helpful guidance but not enough practical on-the-car guidance, so here goes.

1. Raise the front end and set it on jack stands placed under the unibody frame rails behind the front wheels.
2. Remove both front wheels to make it easier to roll around underneath, although you can get by with just removing the passenger side one. I used an impact wrench on the lug nuts so I didn’t need to have the wheels on the ground to remove them.
3. Raise the hood and remove the plastic engine cover by pulling it straight up and set it aside. You’re going to be getting at most everything from on top of the engine, so lay a thick moving blanket over the front end so you can lay on it without getting bruises on your ribcage!
4. Remove the engine skid/splash pan underneath. 14mm bolts, I believe.
5. Remove the fender liner on the passenger side to make it easier to get at some of the bolts and see what you’re doing.
6. You don’t need to remove or lower the exhaust system from the car. There is enough clearance to do everything including removing the old manifold by just removing the 4 exhaust manifold to flange bolts. The exhaust has a flexible coupler downstream from the flange that makes it easy to flop it out of the way. I used some PB catalyst the night before to soak the bolts with, and didn’t have any trouble getting them off, but I did find it easier to remove the top 2 flange bolts from above.
7. Remove the oxygen sensor for both exhaust manifolds and you'll find it easier to work. Be sure to use a proper O2 sensor socket and they'll come out easily. Remember to use some copper thread lube when you reinstall them later.
8. Remove the exhaust manifold heat shield. I believe there are 3x 8mm bolts, and they’re easiest to reach from the top of the engine. I used a 3/8” drive breaker bar with a 3” wobble extension on the socket to remove the two bolts on top of the manifold, and a regular ratchet to remove the 2 on the bottom. An 8mm flex head combination wrench might also do the trick if you’re stronger than me, but mine were too tight to remove that way. You don’t need to remove the heat shield completely, you just need to be able to move it around to get it out of your way at different phases of the job.
9. It’s a pain in the ass and requires a lot of feeling with your left hand while holding a 3/8” drive breaker bar with a 3” wobble socket and a 10mm socket to remove the exhaust manifold bolts but I found all but the rightmost two easiest to reach from on top, and those two I could reach from the passenger side wheel well.
10. With the manifold unbolted from the cylinder head and the flange bolts removed, it takes some finagling beneath the car, but you can actually maneuver the old manifold/catalyst out the bottom of the car, and slide the new one in without removing the crossmember or anything but the engine splash/skid pan.
11. The manifold/cat I bought came from Rockauto.com and is an Eastern unit. It came with 4 studs presumably to be used on the flange, but I elected to use them in place of the center 4 bolts that hold the manifold to the head, which makes it easier to hang the exhaust manifold gasket and locate the manifold in the right spot. Tightening torque on both the exhaust flange and the manifold to head bolts is 24nm and the heat shield is 10nm.

Hope this is helpful to someone!

Cheers,
Dave

Click image to enlarge

Nice one Dave, will help somebody i'm sure. Common sense isn't very common.
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2007 Land Rover Freelander2 I6 hse Auto

Hi Geotrash,

thank you for your forum post on the Exhaust manifold. I too have an i6 and need to remove the cylinder head following a burst water hose and overheating.

Your advice on the manifold bolts and the heat shield is perfect!

Emma

My pleasure, Emma. I saw your post too and was about to post a link for you, and saw that another kind person had already done so. Good luck with your work on it, and if you can take a few pics and post a few notes when you're done with the process, it would be fantastic!

Cheers,
Dave

axle wrote:

Nice one Dave, will help somebody i'm sure.

No prob, not many of us i6er's so we need to help to each other. Common sense isn't very common.
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2007 Land Rover Freelander2 I6 hse Auto

Emma Scully wrote:

Hi Geotrash,

thank you for your forum post on the Exhaust manifold. I too have an i6 and need to remove the cylinder head following a burst water hose and overheating.

Your advice on the manifold bolts and the heat shield is perfect!

Emma

Hi Paul,

the hose from the thermostat to the bottom hose. It was a difficult one to replace and I suspect the reason why it hadn't been. It had gone very soft and the rubber had started to separate. When it did burst it was losing water almost as fast as I could put it in.

I have tried to work out though what prompted the burst (other than the hose being in poor shape). Maybe the head gasket was already leaking and pressurising the system and the hose was just the weakest link.


The tools I ordered have now arrived so will be back to France next week to have another go!



Emma

Emma,

The Head Gasket on the 3.2 is a big job.

Let us know how it goes.

If you get a chance take a few pictures, it will be an interesting tear-down.

Good luck

Keep us updated

Take care

Paul

Hi Paul,

will do!

Emma

Hi Geotrash

Thanks for the detailed post. I doubt it’s something I’d
Attempt myself but I got here looking for info on removing the Catalytic
Converter.

Why did you replace it? Why not just remove it? Is there
An electronics issue when taking that out?

I suppose the question could be asked why not have the cat?
Well as far as I know carbon monoxide is an unstable gas and
Converts out to the gasses that a catalytic converter does anyway,
Given enough oxygen to do so.

It would seem to me that not having a honeycomb to force gas through
Would help an internal combustion engines effficincy I.e improve consumption
And power? Especially one having done 160k kms. _____________________________________
Me: 2008 i6 HSE Freelander 2 black. (;D)
Me: 1.6l Renault Megane ??? (Sold)
Wife: 2.0l Tucson Gls

Hi Telfred,

Thanks for your post. Removing the cat would trigger a repeating P0420 code that would reappear about every other trip as the O2 sensors register that the catalyst efficiency is below the pre-programmed threshold. In my area, that would cause me to fail an emissions test.

Cheers,
Dave

Hi Dave

Thanks for responding.

Here in South Africa that wouldn’t be a problem
Least not for second hand vehicles. New vehicles
Get co2 tax.

So then the oxygen sensors need to be tricked
To alleviate that fault. Sounds like a software
Workaround.

Does an old Catalytic converter hamper performance
Would removing / cleaning it improve performance?

Regards
Jono _____________________________________
Me: 2008 i6 HSE Freelander 2 black. (;D)
Me: 1.6l Renault Megane ??? (Sold)
Wife: 2.0l Tucson Gls

Just found this thread searching for something else, and given the post above I thought I would add this:
https://www.magnumtuning.com/en/detail/ez-...-rover/lr2

Don't know if that would be any good in the UK because of MOT emission tests. Common sense isn't very common.
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2007 Land Rover Freelander2 I6 hse Auto