LR3 thermostat housing assembly replacement

[Iamkraig]

Had a small leak in the plastic thermostat housing on the LR3 and at the advice of a Rover tech, I opted to change out the entire assembly and the plastic bleeder T.

In the process, I tweaked an O ring and wound up doing it a second time, so I took pictures and figured I would post a step by step.

I posted this on defender source and tried to copy the entire thread over, but I will have to reload all the pictures.

Edit... loaded the pictures but had to break it into 3 postings to get past the 25 picture limit.

Here is a link to the defender source post with pictures.

http://www.defendersource.com/forum/showthread.php?t=58504&referrerid=9704


Here is goes, hope this helps

Remove the 4 bolts from the engine cover. 6mm and they are like 1/2 turn.

Remove the front under body metal plate to access the oil filter. I think it's 2 -13mm for the larger bolts under the engine and 2- 10mm for the smaller ones into the bumper.

This will expose the oil filter and the 2 coolant lines that fit to the filter assembly. Slide the hose clamp back on the lower line and remove the line from the housing to drain the coolant from the system. I like to use a small 90deg pick to loosen thne hose from the fitting.

Be sure to put something under the truck to catch the coolant. I used a clean plastic tub so I could filter and re use the coolant.
Keep the catch basin under during the process as you will let air in and coolant out as you go.

Next remove the air intake from the throttle body. I found it easiest to pull the flex hose and the small box as one unit so I had more to flex out and could use the rubber fitting on the air box fit some wiggle room. I think this is a 7mm.

With the band clamps loose, there is a single plastic line that comes in to the hose that needs to be removed before the hose can come out. To remove, just squeeze on the ribbed sides of the fitting and pull it off.

With the band clamps loose and the squeeze clamp line off, you can wiggle the air inlet hose off. I found it easiest to get the end off the air box first, then twist and tug to get the end of the throttle body.

Next, I started to pull all the coolant hoses off the thermostat assembly, the egr, and the bleeder T. I like to use channel locks and slide the clamps past the fitting and leave then on the hoses.

 

[Iamkraig]

I found it easiest to also remove the upper radiator hose so I could bend the whole hose out of the way.

With most of the hoses pulled, you will need to remove the throttle body. It has 4- 8mm bolts that are all the same size. I found it easiest to pull the electrical connector before I removed the bolts, just squeeze the flat spot and pull.

Keep an eye for the thin metal gasket that you want to make sure comes with the valve body.

I left the small coolant line attached to the throttle body and folded it all out if the way.

Next, I pulled the clip that holds the temp sensor and removed the temp sensor just to get it out of the way. The new assembly comes with a new temp sensor, but it have me a little more space and makes it easier to see one of the housing front bolts, so I pulled it out.

Next, you will need to separate the small exhaust line from the egr valve. There are 2- 10mm bolts the come thru the exhaust line flange into the valve. I used a 10mm gear type box wrench and it worked great. Keep track of the bolts or you will be fishing with a magnet. Also keep track of the metal gasket that is between the flange and valve.

Next you will need to remove the 4- 8mm bolts that hold the rest of the intake duct to the main black plenum on the top of the motor. This is the hardest set of bolts to get to. You can cheat by pulling the front half of the thermostat assembly, but I learned the hard way that you can't re assemble it the same way without tweaking the O ring, so I suggest you pull the bolts with the assembly in place so you can see how you will need to get the bolts back in.
I used a combination of different length 3/8" socket extensions and the 6" wobble style was the bollucks. It takes a bit of creativity, but you can get in and get to all 4. The passenger side are much easier than the driver side.

The bottom right (facing the motor) bolt is the hardest to get to. It is tucked behind the small exhaust feed to the egr and hard to even see. To get some extra working room, I loosened the bolt that holds the metal coolant line that runs across the front of the engine. You only need a few turns to let the pipe move and get the line out of the way to fit the socket and extension thru the space to get to the bolt.

After you get the 4 bolts out, celebrate with a cold beverage as this was a pain in the ***.
If you drop and parts in the process, you may want to get one of these magnets with a cool led flashlight tip from Lowe's. I was thankful for an aluminum block.

 

[Iamkraig]

There are 2 squeeze type connectors on the top on the duct. Just squeeze the flat spots and pull.

I pulled this section out and used carb cleaner and a scotch brite pad to clean of all the crud from the egr.

With the air ducting out of the way you can get to all 8 bolts that hold the thermostat assembly in place. They are all T30 torx type, 4 on the top and 4 on the front (2 on either side) All 8 are the same bolt. I used a socket wrench torx on a wobble extension and it worked great. The lower one on either side of the front is a bit of a pain, especially the lower drivers side that you can't see, but you can feel it and it's a straight shot for the socket wrench.

With all 8 bolts out, you can pull the assembly. There is no gasket sealant and just 3 rubber O rings that seal it to the block. I just have it a wiggle and tug and it came out.

Most of these pictures are from the 2nd time I did this, so the parts are the new ones. Here are some pics of the old one and the O ring I tweaked by trying to install the new assembly as 2 parts. It makes it easier to get it out and in, but leaks, so I don't recommend it. The new part had the yellow clip holding the 2 parts together that the old one didn't. Just leave it on and install as one unit.

Now that they old one is out, you can put the new one back in. I cleaned off the mating surfaces a little then set the new part back in. The new O ring gaskets that seal to the block are spaced out in the plastic mold. They compress as you fit the part properly. I started the front 4 bolts and finger snugged them. Then started the top 4 bolts and ran then in till they just touched the housing. Then snugged the front 4 followed by the top 4.

Now just follow the same process in reverse. Don't forget the metal gaskets on the egr and the throttle body.

The bolts that are a pain to get out are a pain to get back in. I put little paper towel chunks over the heads of the bolts and pushed the socket on. This worked well to hold the bolt in the socket to get them on the hole.

When it's all together, go under the truck and put the coolant line back on the oil filter housing and re install the metal plate. Then pull the little top vent hose on the top passenger side of the radiator. Use a filter and funnel and put the coolant back in the tank till it comes out of the top of the radiator top vent you pulled the line from. If you need more coolant, it's just dexcool. Refit the little hose and fill the tank to an inch or so above the fill line. Run the truck with the heat on hot. You can bleed the tank on with the black screw and the rest of the system at the bleeder on the top of the engine (hopefully you installed a new brass one when you re assembled it).

I purchased the assembly from merriam

https://www.landrovermerriamparts.co...&siteid=215719

and the brass T from falconworks
http://www.jewellamberoil.com/sales/...roducts_id=278






Hope this helps if you need to do this. It's really not bad.

 

[proper4wd]

Hey Kraig, awesome write up! Glad to see people working on these at home. They are actually much easier to work on that a lot of the older vehicles.

For tricky o-rings, I used to give them a light coating of clear silicon paste before reinstall. Helps everything go back together easily without damage and the silicon doesnt affect anything adversely.

 

[Fivespddisco]

NICE JOB!

 

[morrisdl]

Great writeup! I just did this same job a couple weeks ago at 105k miles. Same problem - small leak in the housing.

 

[spikemd]

Thanks! I changed mine last week at 106k miles. Saw some coolant buildup around a few screws in the housing.

This week, also noticed a leak in my coolant reservoir which will be replaced as soon as I receive the part.

I have the brass coolant bleeder valve also, but then went back to the OEM due to the brass not sealing well with the hose. I have it is the truck as backup.

 

[Ksasr107]

Hello , thank you very much for this thread , I have LR3 V8 4.4 and I have leak in the PCV and in the VVT . I tried to takeout the PCV I removed the 2 screw but I coudlnt remove the hose that you said it squeeze hose , it's very dry and crusty , actually I broke tiny peace of that squeeze pipe . Can you help me please ! Also I want to now if I removed the hose do I must put a new PCV or gust clean it and put it back ! The last question if the squeeze hose that attached to the PCV I want to change it replace it with new one , is it easy to do it ? Thanks

 

[unseenone]

I've got a used one, the whole assembly with T I took off, with clips. if it helps. If you're in trouble.

 

[jymmiejamz]

Hello , thank you very much for this thread , I have LR3 V8 4.4 and I have leak in the PCV and in the VVT . I tried to takeout the PCV I removed the 2 screw but I coudlnt remove the hose that you said it squeeze hose , it's very dry and crusty , actually I broke tiny peace of that squeeze pipe . Can you help me please ! Also I want to now if I removed the hose do I must put a new PCV or gust clean it and put it back ! The last question if the squeeze hose that attached to the PCV I want to change it replace it with new one , is it easy to do it ? Thanks

I would recommend replacing the PCV valve since it is a common failure item. When they fail, oil is sucked into the intake. To remove the hose, you can gently pry up on the clips, just don't break them. Sometimes as the plastic ages, the clips don't release even though you are squeezing it fully.

 

[Rally1]

Useful writeup, a couple notes for my switch out at 128k.

1. Halfway through I wondered why I was doing this myself when I could have paid someone to contort their hand in the game of Operation that was this repair.
2. The paper towel on the bolts trick saved the day, I used to wrap tape around the socket and bolt, but this method was way better.
3. Get yourself a retractable magnet, I never had to retrieve any dropped bolts (luckily) but I did use it to grab them on their way out.
4. I had a heck of of a time bleeding out the air, but leaving the top off the reservoir was ultimately the best method.
5. Get a number of various extension lengths, I probably used 3 different lengths depending on the angle.
6. I also made full use of long needle nosed pliers for pulling and placing bolts.
7. My mechanic quoted two hours, that's impressive and I should have had him do it, it took me a lot longer than that, but like all these repairs if I did it again it would be faster, 3 hours at least though.

 

[DETOUR-GP]

I'm curious as to how you went about bleeding the coolant system? any tips? I have an air bubble in my system and have been struggling to bleed it properly. I get a sudden temp spike when under load uphil and then once I am over the apex of the hill the temp drops instantly to normal.

My initial thoughts were Thermostat so I bought a brand new housing and decided to replace it myself. It sits at the bottom of the radiator and removing the bottom guard its immediately available. I replaced all the clamps screw clamps and fitted it... The car ran perfectly without temp spikes under load but on a trail one clamp came loose and lost all the coolant. A quick fix and I was on the road again but the temp spikes were back so it seems a quick fix bleed didnt work.

So my plan is to drain the system again, fill it and rebleed properly hence the question on bleeding tips.

 

[Abran]

try this:

https://www.amazon.com/UView-550000...&keywords=uview+550000+airlift+cooling+system

 

[Victory_Overland]

Bleeding on mine took quite a while. Once I fill it, I get it up to temperature and then crack the bleeder and reservoir screw and let it run while watching the temps. I then close it, drive it around for a few miles and come home and do it all over again. Generally, most of the air will work itself to the top under normal use but I have yet to be able to bleed it on one attempt alone. I also tend to leave the reservoir screw open partially on those first few drives. Under normal conditions with airflow, there is not much chance of overheating, just keep an eye on it, top it off and then close the bleeder again. Sometimes I feel like an idiot trying to bleed this thing because nothing "standard" on other vehicles works on my Disco 3.

All done with the HVAC on full hot, front and back!

That bleed kit might be a sweet investment for the tool box since the truck is such a bear to bleed manually.

 

[Hell Pie]

I replaced my radiator earlier this year and wrestled with the bleed process. What I found that worked best was to:

1. Make sure coolant is topped off
2. Start vehicle and allow it to reach operating temperature. The heater does not need to be on. I believe the coolant circulates through the heater core regardless of what temperature you've set the climate control system to.
3. Open the coolant reservoir cap.
4. Have an assistant rev the engine at 3000 RPM for 30 seconds or until the temp gauge starts to rise past normal operating temp
5. Once your assistant lets off the gas pedal, the coolant level will suddenly go down. Top it off immediately.
6. Repeat the process as needed.