Water temp too cool - Read this before changing thermostat

After many summer months of using my TD4 with the heater control set to minimum, a few days ago I needed a boost of cabin heat and was most disappointed the result. With the Water temp gauge just below half way, I assumed correct running temperature but after connecting OBD, the water temp was reading between 65 and 70 degrees, much too low. I assumed a sticking thermostat (partially open)

Reading around the subject on the forums, the following points were noted.

1. Access to thermostat is a long job which requires removal of water pump (although there are reports to the contrary).

2. Don't be fooled by the electric radiator fans running whilst undertemperature. The engine fans come on whenever the A/C comes on and the A/C comes on whenever the heater control knob is in the demist (windscreen) or windscreen/footwell position and the cabin booster fan knob is on (1,2,3,or 4) - This fact is irrespective of the main A/C button - The A/C is comes on to aid demisting and cannot be overidden.

So after altering the heater to prevent A/C & fans coming on, I tried again, this time reaching only about 72 degrees, it was still running cool.

I really did not want the hassle of changing the thermostat but also wanted a toasty cabin for the cold months ahead.

Then I had an idea, what if I could force the water temperature above the opening temperature of the thermostat (about 85 degrees), maybe there was a piece of crud stuck in the thermostat when it last closed (or perhaps it closed incorrectly mechanically) therby holding it partially open. Once the wax sets in the thermostat it is locked in position untill it is allowed to open once again. The fact that it's partially open means that the water temp can never now get hot enough to open the thermostat once more.

So simply by resricting the top radiator hose with the engine running & fans disconnected, it's possible at fast idle to allow the water temp to get to above 90 degrees (mine reached 95). The internal temp gauge at this point was about half way.

The thermostat now has fully opened and perhaps whatever caused the closing problem last time has cleared itself.

I removed the restriction in the top hose and drove the vehicle around for a test drive.

Positive results - Water temp is now about 85 Degrees and heater is as I would expect.

Time will tell whether this is a long term fix or the thermostat will jam again but for the 15 minutes or so to crush the top hose and rev the engine, it's probably a worthwhile test for you to try if you've got a similar problem.

I like your thinking on this one. Good write up too.

Good thinking

Let us know if its a permanent fix

Sounds like a Land Rover Fix

But you could of included some gaffa tape somewhere in the story

Which hose did you restrict exactly? Also, what did you use?

I have the same issue as you, with my temp gauge usually reading below half way and heater function is feeble - i'd like to give this a go...

Thanks for a great suggestion and write up!

Update

Jumped in the vehicle this morning with Laptop & OBD rigged up only to find that it's still not reaching temperature - looks like a new thermostat after all !

However I still think that it's a worthwhile task and may cure the problem on some vehicles. To answer questions raised in the previous posts.

In order to raise the water temperature, You need to restrict the water flow into (out of) the radiator, the easiest way to do this is via the radiator top hose, I used a G cramp (clamp ?) but could use one of those grip bar clamp thingys from DIY stores.

On a similar subject, can thermostat on TD4 be replaced without removing the pump i.e by removing hydra mount & moving engine around to get access to housing cover screws.

I have read and seen other posts on here talking about it being possible to do the thermostat on its own, but apparently it's still not easy. Here is the latest thread RE this: http://www.landyzone.co.uk/lz/f9/thermostat-td4-165307.html


I am going out now to try your restriction method first, then if that fails i'll be looking to get my thermostat done too - it get to around -15 over here from latter november onwards so i want to be warm

Will have to do the thermostat myself if it needs doing - money shortage - so will be looking for any tips i can find to make it easier.

Ok, did this without an ODB reader, just used a g-clamp and two small blocks of wood to restrict / close off the top radiator hose as close to the radiator as possible.

It seemed to get up to temp ok, in about 10/15min and the temperature guage sat at half way - fans were disconnected. After leaving it like this for another 5 min (max), i turned off, took off the g-clamp, reconnected the fans and started up again.

Observasions:
1) my fans did not come on when reconnected although the temp gauge was at half way (rather more than it usually is for me) - at what point do they usually come on?
2) the temp gauge seems to never move past half way - is that normal? although the top hose was clamped off and the temp should have been rising, it didn't budge.

Going for a test drive in a short while to see what, if any, difference it made. Fingers crossed

Report after test drive:

I've broken it more Water temp will stay steady at about a quarter (viz photo) - even less than before....tried clamping again...temp climbs, remove clamp, temp drops. When driving up a very long hill it climbs a little past quarter way. Looks like it's going to be a very very cold winter (was -5 this morning). Don't have cash to let someone else do the thermostat - which i presume is fecked

So, my latest update.

After an unsuccesful result to my initial test, I decided to change the thermostat. There are a number of posts regarding this but this was my method.

1. Remove belly plate, drain coolant through bottom hose
2. Remove acoustic plastic engine cover to give general access topside
3. Remove offside wheel and plastic splash shield
4. Remove both ancilliary & a/c drive belts
5. Remove crankshaft pulley - This did need the use of an engine locking tool which I did have - details of DIY tool in Haynes manual. but offers much more accessibility to removal of water pump. I tried to do it without removing pulley but one of the water pump bolts is very (very) awkward to get to. 22mm bolt very tight so you'll need a lever extension.
6. Undo 10mm bolt on rigid water pipe to thermostat housing
7. Remove hose on the outlet of thermostat housing. I also removed attachments (3 * 8mm bolts) to sump area to remove bottom hose assembly out of the way. Access to spring clip through track rod opening.
8. Remove 4* T30 Torx water pump bolts with 1/4" ratchet & short Torx attachment. Access 3 from below 1 from above
9 Remove water pump through track rod opening.
10. Change thermostat & housing (4 * female torx E8).

Replacment opposite of above, I used blue gasket sealant after cleaning gasket face on water pump.

Things to watch out for

1. Ensure you have properly located engine locking tool. It's basically a dowel pin which slides through a hole in the crankcase & into a hole in the flywheel. if properly aligned & fixed, the locking tool will push about 20mm into the flywheel. There are a number of false locks where the tool only pushes about 5mm into the flywheel, trying to undo the crankshaft pulley bolt if not properly locked my damage the tool and make it difficult to remove.

2. The crankshaft pulley bolt is tight. Unless you're Arnold Schwarzeneger, you'll need at least 600-750mm lever length to undo. (I used the jacking bar off my trolley jack with a 1/2" drive 22m socket & T Bar.

3. Although the coolant is drained prior, when the pump is removed, there is about 1 or 2 litres of coolant which comes out of the block.

3. Surprisingly with the correct tools, the job, although a bit fiddly was much easier that I'd bargained for, It took me about 5 hours in total but I wasted alot of time trying to remove the pump with the crankshaft pulley still on (because i could not undo the pulley bolt). Once I undid the bolt & removed the pulley access was much better. I reckon if I was to do the job again it would take me 2.5 to 3 hrs.

4. I found access to the spring clip on the hose on the thermostat housing awkward so on re-assembly I expanded the clip and wired it open (wrapping wire around the pips to keep it expanded ) On re-assembly the hose was fitted, the clip simply moved into position and then cut the wire to allow the clip to close.

Apart from std 1/4" and 1/2" socket sets together with basic metric spanner set you will need.

• Torx T30 short attachment & socket for 1/4" ratchet for water pump bolts
• E8 Female torx socket or spanner to remove thermostat housing
• 24mm combination spanner to release ancilliary belt tensioner
• 1/2" 22mm socket, T Bar plus strong extension lever for crankshaft pulley bolt (could use air based impact driver also)
• TD4 Engine locking tool -

Thermostat (& housing ) cost £38 + VAT which is expensive for a thermostat but, I could not find anything cheaper. Now water temp (via OBD is 88-90 C and heater is great.) Water temp gauge is exactly 1/2 way.

Excellent writeup - thanks! I will have to do this soon i think.

Quick question - was there any way you could do this operation without removing the water pump as far as you could see? i.e just getting access to and removing the thermostat.

I don't think the housing can be removed in situ. Although it's fairly straightforward to remove the housing bolts, there would be 2 problems.

The thermostat is fitted into the pump assembly with a locating shaft, as such the housing would need to be removed perpendicular to it's face.

1. The rigid pipe in the housing would prevent removal.

2. Some people have forcibly bent the rigid pipe to gain access, even with this bent, I don't think there is enough room to the chassis to allow the removal of the thermostat shaft from it's hole in the pump housing.

I think it would be neccessary to loosen / remove engine mountings to then give greater clearance between housing & chassis.

The reason for removing the whole pump is that when the 4 pump bolts are removed, the whole assembly drops down and thus the rigid pipe is released. The pump assembly is then reterived through the access hole (near the track rod).

I haven't read any reports from people who have tried to remove the housing only. These are only my thoughts on the method.

if you try you can do without removing any pully and will save time but you will have acking fingers after

rsolty said:

2. Some people have forcibly bent the rigid pipe to gain access, even with this bent, I don't think there is enough room to the chassis to allow the removal of the thermostat shaft from it's hole in the pump housing.

I think it would be neccessary to loosen / remove engine mountings to then give greater clearance between housing & chassis.

Click to expand...

Thanks for that - the above is the method posted on the MG forums for the MG75 CDT..which is the same engine as the Freelander.

Will decide what method to use once i get closer to the day of doing it. Reason i don't want to take off the crankshaft pulley is i just had a new one put on and tightened - don't fancy doing it again myself.