Recommended Posts

I did this job about 4 months ago and hoped that I wouldn't have to do it again, however over the last few weeks I have noticed that the car has been losing water, only a little bit but over a few weeks i'm putting in about 1/2 litre in order to top up.

Looking over the engine I've spotted where the leak is coming from 


It looks like the joint between the EGR valve and the EGR cooler, however there is no water flow near this area, my first thought was either a hose but inspecting them they all seem good. Getting my hand around the EGR valve I could see the flow was coming from the EGR itself, there are two small bore water hoses and one of them was very wet.

Ive no doubt you can take the EGR valve off without removing the cooler however one of the bolts that connects the cooler to the EGR is impossible to get at with a spanner, so I chose to remove the cooler and EGR.

Tools you will need:

12mm, 11mm & 10mm spanner, open and ring.

12mm, 11mm, 10mm & 6mm 1/4 drive sockets along with extension bar and mini ratchet.

E8 1/4 drive torx socket

Long nosed pliers and mole grips


a sheet of cardboard/old large box

I have no doubt there are more effective ways of doing this, this way works for me. 

The EGR cooler is located at the back of the engine, held on by 2x12mm nuts, access is a little tight especially on the EGR side of the cooler.


The other end isn't too bad 



firstly remove the engine cover

IMG_1270.thumb.jpg.28408b6d830e5a027d6e85f71a24b5ba.jpg  IMG_1271.thumb.jpg.ff7396292b9644d1f7b52df4a9916e9b.jpg


the cable guide that runs across the engine is held on with 5x10mm nuts, undo these and all the electrical connections for 3 coil packs, cam sensors, fuel pump. the wiring loom is held on across the front of the engine in 3 places, disconnect the 3 plastic clips from the metal brackets.

The loom should now be able to be moved to one side a little easier, it won't be possible to get it right out of the way, but it will be loose enough so it doesn't get in the way.

At the same time disconnect the EGR valve electrical connector 




the rest of the work is now at the back of the engine. 

The high voltage cable are held in place by two brackets, the one on the inverter is held on with 2x10mm bolts, there are 2 grey plastic collars that connect the HV cables to the metal brackets, there is a little tab that needs to be bent back a bit to release the collar from the metal bracket. this allows the HV cables more freedom to move about.


There is one more HV bracket, it is held on with 1x12mm nut and 2x12mm bolts, I couldn't get a picture of these as its too busy round the back of the engine, like the inverter bracket there are two grey collars, each one needs to be disconnected 


The engine wiring loom is also clipped to this bracket, you will need to get to the back of the bracket and pinch the wings of the retainer clip in order to free it from the bracket, finally removed........


once the bracket is removed and the cables moved off to one side you have a bit more access in the rear, the EGR cooler is held on with 2x12mm nuts, however the studs that locate the Cooler also needs to be removed as there isn't enough space to slide the cooler off the studs.


this is a top down view, you can see the stud, this is one of two, the other is impossible to photo and removing that one means working blind. the stud can be removed using either a 6mm socket or an E8 torx 

IMG_1283.thumb.jpg.0e98dcbd26d6315f813c7abcddbe37a8.jpg  IMG_1282.thumb.jpg.43aa91df1f2e61ec9902d30d312a4ca7.jpg IMG_1284.thumb.jpg.d95eb6711efaa6e76aafeefd69abceb9.jpg


if you look at the bracket on the EGR cooler you can see where the bottom bolt sits


rather than undoing the 12mm nut it is easier just to remove the stud and nut in one go.

either end of the EGR and cooler there are two metal pipes that are held on to the cooler/EGR with 2x12mm bolts per end, the cooler end is far easier to undo that the EGR end


The cooler end, the easier end to deal with


 The EGR end, access is very restricted, 2x12mm bolts access is from underneath and will require a 6'' extension bar, the bolt closer to the engine can be turned one flat at a time.

once the two pipes have been disconnected remove the gaskets that sit between the EGR/Cooler and the pipes, they are metal gaskets and dealer only parts. they do have clips that will hold the gaskets in place, but ive never trusted them.

With the pipes disconnected all that's left is to disconnect the water pipes, there will be some antifreeze loss, I normally use plastic hose clamps to stem the loss of water, because ive been losing water I knew there wasn't going to be much loss so didn't bother.

There are 4 hoses on the cooler assembly, 2 large and 2 small, the 2 smaller ones connect to the EGR, the 2 large ones connect to the cooler assembly. with them disconnected the whole unit can be jiggled out from the back of the head, I found that you have to move all the looms around a bit and tuck the pipework out of the way in order to get the unit out bit eventually it will  come out.


Once the old unit was off the car I would see where the issue lay, 


the metal pipe is an interference fit into the alloy body, this has come loose and is now leaking, luckily I have a spare EGR valve and Cooler that I had cleaned out and ready to be fitted.


Now to quote the immortal Haynes manuals, refitting is the reverse of removal 

Getting the studs back into the head can be a complete nightmare, I first put the two metal pipes on either end with the bolts done up hand tight, this holds the whole unit in place, from there  I put the studs back in, connect the water hoses and then the bracket that hold the HV cables on. then its a case of going round and doing it all up tightly. connecting the HV cables to the brackets and putting the engine loom back in place.


The whole job took about 4 hours, Why do it? The EGR coolers tend to gum up over time/mileage, when they do the exhaust gases struggle and tend to try and find the next weakest link in order to escape, now on the Prius and other Toyota engines this weak link is the head gasket.

Mine was getting clogged at 140,000 miles, by 160/170,000 I guess it would have been completely clogged and so could have caused HG failure.


And the need that to put on top of the engine, whilst doing this job you are literally lying on the engine, and there are many exposed studs and nuts, the last time I did this I ended up with a bruised chest


That’s the engine side of the one I used tonight

  • Like 2
  • Thanks 1

Share this post

Link to post
Share on other sites

Well done for a very detailed post! I hope I don't have to do this job as it looks a real pain in the arse.... I'm sure this will help other owners with the same problem.

Sent from my G8142 using Tapatalk

  • Like 1

Share this post

Link to post
Share on other sites

Wow, well done Jason 👏

Is the press fit pipe leaking a common issue?

Share this post

Link to post
Share on other sites

Wow, well done Jason 
Is the press fit pipe leaking a common issue?

I don’t think so, I think mine was just sheer bad luck, or I disturbed it last time I changed the cooler

Sent from my Iphone using Tapatalk

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.