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garyRR



Member Since: 13 Mar 2021
Location: Hampshire
Posts: 1286

United Kingdom 
L322 3.6L TDV8 EGR and Cooler Tear Down, Refurb and Re-Build

Ahead of an upcoming job, I thought I'd make an article that may be useful to others to understand how an EGR works and show how to clean and refurb them.

First thing's first, I absolutely swear by ultrasonic cleaners. I bought mine on eBay years ago and it's still going strong today. I have a 3L one, which is actually large enough to clean the overwhelming majority of stripped down engine components. Otherwise, you'll need a load of brushes, pipe cleaners and degreaser. My next point, I find the Screwfix 5L degreaser brilliant when used in conjunction with an ultrasonic and, it's cheap as chips.

So, how does an EGR work?

An EGR is used to lower the emissions of vehicles. Put simply, it recycles some of the gases coming out of the combustion chamber and puts them back in for re-combustion.

But, because the exhaust gases are the result of an explosion, these are very hot and ideally, need cooling before being put back into the combustion chamber - just like cool air enters the manifold system. So, with most EGR assemblies, you have a stage 1 exhaust cooler and a stage 2 control valve, controlled by a motor and a position sensor so, the ECU can dictate how much gas it wants.

Because the 3.6L is a V shaped engine, it has 2 EGRs - One for each bank of cylinders.

Here's a picture of my cleaned up one:



You can see the cooler. The yellow bit is a thermostat on the coolant entrance to the cooler. The gases run from the right to left through the cooler. They then progress to the valve. The small hole on the right is the outlet, back into the combustion chamber.



Let's start stripping it down

Part 1. The cooler

There's just 2x T27 torx screws to detach the cooler from the valve unit. They are mated by a metal and rubber gasket. You will need to replace this gasket because they perish. The part number is LR003831 and it's about £5.

Click image to enlarge


Click image to enlarge


You can see how the cooler tubes really soot up. This can restrict gas flow and also carry soot into the combustion chamber under hard acceleration. How the cooler works is that if it's a cylindrical unit with a number of steel tubes inside. The steel tubes carry the exhaust gases and the engine coolant circulated around them inside the cylinder, to cool the gases. The little thermostat controls the temperature inside the cooler. By maximising surface area around the gases, they can be effectively cooled.

Here's the cooler post it's ultrasonic clean:

Click image to enlarge


Click image to enlarge


Notice how the tubes are now clean. It wouldn't photo but, the inside of the tubes are now also clean steel again.

Potential EGR cooler problems

If you have experienced problems with coolant leaking into the combustion system, even the smallest leak, the EGR coolers are, I think a good place to look. EGR coolers have been known to "crack" and leak coolant into the combustion, replacing coolant with exhaust gases and causing pressure build up in your coolant system. I think the most likely way this could happen is the stainless steel tubes inside the cooler. They are thin corrugated stainless steel pipe which could generate tiny cracks over time.

However, I think one of two causes of an EGR cooler cracking is previous owners of these vehicles topping up or replacing their coolant with tap water or, not changing the coolant regularly enough. This would cause contaminants to build up in the cooling system and weaken the thinnest parts of metal. I haven't a cracked EGR to pressure test however, my bets would be exactly in this location. It's a cheap thing to try vs some of the other alternatives!

The below picture is similar to the pipes carrying the exhaust gases. They're designed to flex so, they're thin and therefore more prone to damage.



The other potential cause is end of life thermostats. Both EGRs have a thermostat. I work on boat engines and the service life of a thermostat in a Saltwater environment is 2 years. In automotive uses, with the correct grades of coolant, I would suggest life is around 10 years. Over time the springs become brittle and the element becomes less effective (these also have plastic casings which will become brittle and break). If you have a faulty EGR cooler thermostat, this may not let coolant into your EGR cooler. You then have hot post-combustion gases at over 500C on top of the block receiving no cooling, accumulating and building pressure... Again, thin stainless pipe is prone to cracking with repeated high heat.

Part 2. The EGR valve

Now, this is the part which can really soot up. Let me first show you the before and after (because you can hardly see the valve beforehand).

Click image to enlarge


Click image to enlarge



Wow! What a difference. There was a deep accumulation of soot. Given the valve only opens by around 7mm in total, a couple of mm will really affect the flow.

You can see how the ultrasonic clean removes almost all carbon deposits inside the assembly (view from the outlet back to the engine):

Click image to enlarge



But, there are sensitive electrics within the EGR valve so, let's first look at the steps.

1. Remove the plastic cover. This is simple. 6x T20 torx screws and it just lifts off (gently). You'll probably find the orange gasket stick to the valve so, remove this and put it back into its slot in the cover.

Once you've got the cover off, you'll find this (you can see how the orange gasket sticks):

Click image to enlarge


Notice how exhaust gases get up here too so, it will all need a clean.

So, what's happening?

The engine commands how far open it wants the EGR. It does this by sending a current to a little electric motor (interesting fact: I Googled the part numbers and these motors originate from photocopiers!). The little electric motor is the cog at the bottom of the picture (you'll also see its power terminals). This is joined by the yellow plastic cog to the wedge shaped cog. The wedge shaped cog is spring loaded (so when there is no power to the valve, it is naturally closed). This cog is connected to the valve underneath.

The yellow plastic cog simply lifts up to reveal 4x T20 torx screws. Remove these and underneath, you will see this (the motor and the valve mechanism):

Click image to enlarge


The motor simply lifts out (put this aside) but, see how dirty the top of the valve gets!

Straight into the ultrasonic for both the section with cogs and the valve unit:

Click image to enlarge


Check for free operation of the valve. That's the servicing done!

Part 3. The electronics

Going to the EGR are 4 cables. 2 go to the motor, 2 go to the position sensor.

Inside the plastic cover are 2x terminals. These can be clearly seen and attach to the motor when you put the cover back onto the EGR unit.

If you are experiencing EGR problems with the valve not acting as commanded, it could be the spring under the wedge shaped cog or it could be the motor. I doubt you can buy the Motors individually but, you can replace them individually.

Also inside the cover is the position sensor. This tells the engine how open the EGR valve is. Inside the plastic cover is a beige coloured cover. When you put the cover on, this attaches to the top of the rod for the valve. Remove this plastic cover and inside is a spring and a couple of brushes onto a track. This actually forms a potentiometer I.e. a certain resistance tells the ECU how open the EGR is. It's entirely possible for this to go open loop or for the brushes to be damaged. You can potentially get away with just replacing the plastic cover for this type of problem.


Re-assembly

Ensure all gasket surfaces have been cleaned with wire wool so, they seal properly. Ideally do this before cleaning or now, being sure to remove all wool debris.

Firstly, use electrical contact cleaner to clean up the contacts on both the motor and In the plastic housing.

To re-assemble the valve, re-install the motor with the notch in the above cog plate matching its position.

Next, ensure the wedge shaped cog is installed fully restracted so that the valve is forced closed. Then, check it opens and install the 4x T20 screws. Re-install the yellow cog.

Click image to enlarge


Then, simply gently push the plastic cover back on (with orange gasket in place) and install the 6x T20 torx screws. Because you're dealing with a gasket, be sure to tighten screws at opposites.

Next, get the new gasket joining the cooler to the valve and align the cut out notch. Then install it the correct way around with the 2x T27 Torx screws. Correct way around is with the gas outlet adjacent to the coolant exit.

Now, insert the new thermostat into the coolant inlet (wider than the outlet). It has 2 little lugs on it that fit into 2 little holes on the cooler. The part number is LR006115 and it's about £10.

Be sure to also replace the two gaskets at either end of the assembly. The exhaust gasket is LR004250. It's about £6. The gas-out gasket is LR003828. They're about £11.

You should now end up with a nice clean and refurbed EGR and cooler!





Click image to enlarge



I hope this helps anyone looking to do the job. 2015 Range Rover Autobiography 4.4 SDV8

Last edited by garyRR on 12th Feb 2022 11:31am. Edited 5 times in total

Post #599809 6th Jul 2021 3:52pm
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Barmybrummie



Member Since: 03 Apr 2021
Location: Somewhere in the valleys
Posts: 585

United Kingdom 2011 Range Rover Vogue SE 4.4 V8 Santorini Black

Excellent write up there, one for the wiki Stan? How long did that take you from start to finish? I have the 3.6 so just blanked mine off, but you can't do that with the 4.4.

Post #599814 6th Jul 2021 4:26pm
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garyRR



Member Since: 13 Mar 2021
Location: Hampshire
Posts: 1286

United Kingdom 

It's about 15 minutes to carefully strip down and about 15 mins to put back together. This is per EGR.

The biggest thing was the queue for the ultrasonic. I gave each significant component a 2x 15 minute cleans, with a rinse inbetween so, just tended to this as required through the evening. 2015 Range Rover Autobiography 4.4 SDV8

Post #599834 6th Jul 2021 6:09pm
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btiratsoo



Member Since: 12 May 2020
Location: Hampshire
Posts: 174

United Kingdom 2009 Range Rover Vogue TDV8 Buckingham Blue

Superb write up garyRR. Where are you in Hampshire? I’m about to hit the button on an L322 and local to Eastleigh if you know it. Marine engineer too.

Can anyone confirm if this is the same EGR as the 4.4?

Ben Current vehicles:
1944 Fordson Standard
1982 Land Rover Series 3 88" petrol
1984 Ford 4610
2009 3.6 TDV8 Vogue
2017 CLS Shooting Brake

Post #599867 6th Jul 2021 10:35pm
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dhallworth



Member Since: 10 Oct 2011
Location: Glasgow
Posts: 2951

United Kingdom 2012 Range Rover Autobiography TDV8 Baltic Blue

What ultrasonic cleaner do you use? I bought one years ago but never had much luck with it.

Agree on the Screwfix degreaser, it’s great stuff. Do you just pour that neat into your ultrasonic cleaner and switch it on?

Thanks,
David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Post #599869 6th Jul 2021 10:48pm
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garyRR



Member Since: 13 Mar 2021
Location: Hampshire
Posts: 1286

United Kingdom 

I live in Southampton.

The EGR is different on the 4.4. The EGR is a "pump" on the 4.4.

Same rules apply though. Valves on the inside. It has a coolant supply and a coolant return hose, one of which is very thin metal (same applies re coolant loss). The internals of the 4.4 EGR would also benefit from ultrasonic cleaning or at least a good degrease. 2015 Range Rover Autobiography 4.4 SDV8

Post #599870 6th Jul 2021 10:49pm
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btiratsoo



Member Since: 12 May 2020
Location: Hampshire
Posts: 174

United Kingdom 2009 Range Rover Vogue TDV8 Buckingham Blue

Nice one. Thanks for the info. Will bear that in mind when I’ve got one on the drive. I’ve pm’d you too.

Ben Current vehicles:
1944 Fordson Standard
1982 Land Rover Series 3 88" petrol
1984 Ford 4610
2009 3.6 TDV8 Vogue
2017 CLS Shooting Brake

Post #599871 6th Jul 2021 10:51pm
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garyRR



Member Since: 13 Mar 2021
Location: Hampshire
Posts: 1286

United Kingdom 

dhallworth wrote:
What ultrasonic cleaner do you use? I bought one years ago but never had much luck with it.

Agree on the Screwfix degreaser, it’s great stuff. Do you just pour that neat into your ultrasonic cleaner and switch it on?

Thanks,
David.


My ultrasonic is a lab type one which heats and cleans. It was about £60 at the time when I bought it.

It's fairly similar to this one, just with old fashioned manual dials: https://www.ebay.co.uk/itm/UK-3L-Digital-S...rid=710-12

Diesel soot isn't actually too bad to dislodge. I find a 1 part to 9 parts water is sufficient. On heavily salted boat parts, this has to be about 5:5 or more. 2015 Range Rover Autobiography 4.4 SDV8

Post #599872 6th Jul 2021 10:51pm
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DrRob



Member Since: 16 Apr 2015
Location: Petersfield, Hampshire
Posts: 4204

United Kingdom 2011 Range Rover Vogue SE TDV8 Buckingham Blue

Great write up. Just to add, the EGR on the 3.6 can be physically and electronically blanked to bypass them completely Thumbs Up 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
New Defender D300 90 on order so "Rory" will be going to a new home....!
1974 Series 3 Lightweight = "Millie"
My preferred specialist: www.glenrands.co.uk
--------------------------------------------------

Post #599885 7th Jul 2021 7:11am
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garyRR



Member Since: 13 Mar 2021
Location: Hampshire
Posts: 1286

United Kingdom 

You do have to be careful over EGR blanking though.

Rules for diesel emissions were tightened in February this year. Secondly, an MOT tester is permitted to fail a vehicle if they notice a physical EGR blank. I know of one such garage locally, without even searching to find out. An EGR delete through software would still pass but then you have the probkem of coolant and gases still circulating inside the EGRs. 2015 Range Rover Autobiography 4.4 SDV8

Post #599889 7th Jul 2021 7:53am
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