LR3 thermostat check

PhyrraM

Adventurer
Recently the thermostat housing on my '06 V8 LR3 decided to crack and leak at the large o-ring that seals the front and rear pieces. I replaced the complete housing with one from Atlantic British along with the water pump and both drive belts.

After a slight derailment from a damaged o-ring leaking, it is back together and running. However my confidence is low. It doesn't feel like it is heating up properly...but it could be in my head too.

The upper radiator hose (right/passenger side), heater hoses (again right/passenger side), and the bleed hose running across the radiator to the overflow/fill tank are all very hot. The return hose to the thermostat housing (left/drivers side) is much cooler- warm, but noticeably cooler than the other side. I do realize this hose is after the radiator, but it still seems too cool.

The temp gauge reads fine so far, but this behavior is strange to me. I never paid much attention until the problems. Between using a parts store water pump, having a hard time bleeding the system, the misstep on first assembly, and the truck getting close to red on the temp gauge a few times I'm having a hard time deciding if I'm being paranoid of if this is basically normal for the LR3.
 

DiscoDavis

Explorer
Easiest way to bleed it:

>Don't touch the bleeder T or that tiny cap
>Don't touch the bleed screw on expansion tank
>Remove main cap from expansion tank
>Start motor, (turn heater controls to max heat, ECON) rev @ 3000rpm until 197F, thermostat will open at that point
>The moment it opens (usually helps to have someone with a hand on the large hose to housing), turn motor off
>fluid will bubble and settle in expansion tank
>top off fluid to fill lines in coolant expansion tank
>secure cap on tank, repeat process as necessary
 

ColoDisco

Explorer
The temp gauge is getting close to red since the repairs? You could have a air pocket in the system causing your hose temperature variance. I have been successful manually bleeding thru the bleeder screw on the reservoir. The bleeder T on top of the engine is a time bomb and should be avoided.
Disco Davis' is also a good method as well. Turning the heat on in the cabin is a good way to see if your getting flow through the heater core, which can also be a indicator of a air pocket.

Of course the best way to fill the cooling system is with a vacuum filler if you have access to one.
 
Connor (DiscoDavis) method works great. Make sure front and rear panels are on full heat in the entire vehicle. I also use the bleed screw on the reservoir and burp the large radiator hose while I top it off and while it's running.

First question? Do you have heat in the front and back of the vehicle? If not, you either have air pockets or bad thermostat given the nature of the repairs, I am assuming the only problem leading to the replacement was the crack and leak correct?

Second question? Also, I know you said you replaced the housing and I think my AB unit came with a new thermostat. Did you verify the thermostat is free to move before you installed it? Don't ask me how I know, but I had an aftermarket one that was brand new and it didn't move at all. Not trying to insult your intelligence, just trying to narrow things down and help.

I had an air bubble in mine since I had the entire coolant system off the truck and replaced with all new hoses, pump, reservoir, housing, radiator, and every other component. It took quite a while to get it bled but it all came together. I did not have a vacuum pump, but willing to make a mess, I filled my hoses manually to the maximum extend and then quickly hooked them up. I also primed the motor to get the water pump moving before I started the truck completely. It is not 100% effective but it ensures I have coolant running through the engine and helps stir the air up. I did this a few times and could see the level drop. Also, leave the heater on, open the bleeders ( I use both, just be really careful on the T-Fitting if you have the plastic one), start the truck and you should hear air and coolant spitting. Close them when you see constant fluid flow, let the truck run a bit and shut it down and let it sit bit the bleeders closed. Keep in mind, with the bleeders open, the system will not be at full pressure so use them like you would bleeding brakes. You can also crack the T-Fitting bleeder at this time as well just be careful for safety sake and cracking the plastic T. Then do it again a few more times. I personally believe one needs to use the T-Fitting as air moves its way to the top of the system as the truck cools, hence why the level falls as the air moves upward.

Key is keep the heat on for the thermostat engaged in the process completely. It may take you a few times but you.

DiscoDavis and ColoDisco are spot on so this procedure should work if all components are functioning properly. I only add using the T-Fitting as it is designed even though it is a fragile piece of ********.

Hope this helps, Happy Turkey Day!
 

PhyrraM

Adventurer
I believe I got it. Being fairly hard to bleed and then combined with very large differences in before and after the radiator temps (non-load, driveway revving) was sapping my confidence that everything was OK. It seemed like the thermostat wasn't opening properly, but I'm pretty sure it's normal for this vehicle now.

I used a combination of vacuum filling (hose deteriorated and leaked during process), squeezing various hoses, opening tank bleeder and cap, revving, filling, playing with the heat (F/R) and simple persistence I got it to where I couldn't get any more air out of it. It still has the large temp variance before/after the radiator but I've done about 20 miles with no temp needle movement.

It got close to red a few times when it first happened on the road and I tried to simply top it off, and make it home. when it became apparent that this truck either didn't like that, or was leaking too fast for that tactic to work, I shut it down and had it towed home. I did the repair work and it got close to red again during the initial bleeding attempt. That turned out to be the large O-ring between the two housing parts was pinched. Not sure if I did it or if it came that way as the two parts are clipped together in the box and I didn't separate them first. Once that was identified and fixed, I noticed that the pre and post radiator temps were really very far apart and my confidence was low to start with...so time to post up and ask....
 

ColoDisco

Explorer
Great to hear! Always smart to err on the side of caution on coolant and overheat issues. Land rovers are the worst at taking out engines when overheating. At least that's my experience.
 

jymmiejamz

Adventurer
I used a combination of vacuum filling (hose deteriorated and leaked during process), squeezing various hoses, opening tank bleeder and cap, revving, filling, playing with the heat (F/R) and simple persistence I got it to where I couldn't get any more air out of it.

The hose didn't deteriorate during vacuum filling, it was probably already leaking. Also, having the heat on makes no difference other than to see if coolant is flowing through the heater cores. There is no heater valve on an LR3.

It got close to red a few times when it first happened on the road and I tried to simply top it off, and make it home. when it became apparent that this truck either didn't like that, or was leaking too fast for that tactic to work, I shut it down and had it towed home. I did the repair work and it got close to red again during the initial bleeding attempt. That turned out to be the large O-ring between the two housing parts was pinched. Not sure if I did it or if it came that way as the two parts are clipped together in the box and I didn't separate them first. Once that was identified and fixed, I noticed that the pre and post radiator temps were really very far apart and my confidence was low to start with...so time to post up and ask....

Fortunately the Jag 4.4 is a tough motor and holds up to overheating very well. We've had tons of customers overheat their trucks until they cut off and most of the time we just fix the leak and it is good to go. FWIW, I work at probably the biggest Land Rover dealer in the world and I've never replaced a motor on an LR3.

I usually lubricate that o-ring with silicone, they can roll easily.
 

ColoDisco

Explorer
I will disagree with the overheat statement. One of my LR3 group had his heads warped from a overheat the PO failed to mention.
 

jymmiejamz

Adventurer
I will disagree with the overheat statement. One of my LR3 group had his heads warped from a overheat the PO failed to mention.

Yeah it happens, but not like a Disco or even a 5.0L. Obviously overheating an aluminum engine isn't good, but those motors are pretty tough. On any given day we probably have at least one 3.0/5.0 getting head gaskets or a motor. It wasn't like that with the 4.4.
 

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