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Old 19th November 2009, 15:14   #1
Matt1960
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Default Diesel thermostat change, no water pump removal or engine jacking.

The background to this change, is partly poor fuel economy (last 2 brim to brims are 34mpg and 32mpg of mixed driving), and partly not enough heat from the heater on maximum setting.
I had stated to read on the forum about the thermostat and my temp guage rarely gets above 1/4 to 3/8.
This seems a common problem of the thermostat getting a bit lazy and not closing fully.

I found a thread where people had changed their own, without taking off the water pump, so I pm'd patrolman pete who gave me some extra advice (many thanks) as he had perfomed this task.

I kept having a look at the tiny space to work in and decided to buy a torx e8 ring spanner as it looked the only tool to get to 2 of the 4 thermostat bolts.

Yesterday afternoon I started by removing the undershield, drivers wheel, engine and airbox cover and turbo duct. I took off the 2 power steering pipe clamp bolts and one air con clamp bolt.
Access still looked awkward so I undid the 2 engine mount bracket (black) top bolts and undid the bolt through the bush (it wouldnt come off due to the bodywork). I was the able to swing the bracket upwhilst putting pressure on the air con pipe to get it out of the way.

I then unclipped the thermostat bottom hose with mole grips and slid it down the pipe.
I then went through the wheel arch and undid the bottom clip to enable the coolant pipe to be removed. The coolant was caught in a container. Make note the only reason for taking the drivers wheel off in the whole operation is for this bottom clip.

Working from above I started to contort my hands into the tiny spaces and undo the 4 thermostat housing bolts. This is very time consuming as I could only move each bolt about 1/4 to 1/8 turn at a time. I also kept dropping the spanner as it was often only moved by the tips of my fingers. I decided to hook an elastic band through the other ring and around my wrist to avoid keep picking it up.
Sometimes I could get to a bolt from where the engine mounting bracket was and sometimes I had to use my left hand and go down the left side where the turbo duct would have been and come up from below the thermostat.
These bolts took approx 1 hour to remove.
The coolant rail pipe bolt was easy by comparison, but it would only move away from the thermostat with a lot of force by bending and levering it. Eventually it had moved enough to get the thermostat out.
The new thermostat (PEL100570L) went in past the rigid pipe with a lot of manoevering, and now the difficult bit of rebending the pipe back. I bolted the thermostat onto it and then with pieces of timber started wedging them between the bodywork and using levers, to eventually get the thermostat back to where I could get a bolt attachment. This levering took me approx 1 hour.
Again the thermostat bolts were painfully slow to get back. Another hour.
When replacing the difficult bottom hose clip to thermostat, I sprung it open as far as it would be away from the car with mole grips, then tied it a big cable tie and then it slid on easy and the tie was cut when in position.
Much easier than trying to open it when on the car.
The bottom clip is easy with mole grips through the wheel arch.
Everything went back together as it had been taken off, and the coolant was topped up and bled.

Total time 4 hours.

Looking back at a fiddly and time consuming job, I have a couple of additional comments.
Firstly, I could have saved myself at least 1 hour if I had bought the ratchet torx e8 spanner (about £20) instead of a normal one.
Secondly, I wasted an hour with the bending back of the rigid coolant rail.
I assume it is a metal pipe because it goes near to the exhaust manifold, but next time I will consider buying a 4" piece of silicone coolant pipe and cutting a 2" section of the rigid pipe out, on a straight section, then clipping the silicone pipe onto the two cut pieces. This would give the flexibility needed to perform the job.
I understand silicone pipe can withstand about 170 degrees and it is a small distance from the manifold so I doubt if it gets to that temp, but could be shielded if it did.

With these two points, I would have thought less than 2 hours to be about right for the whole job.

By the way I think it was uneccessary to remove the undertray.

I also have no cuts or scrapes to my hands, which are small (which helps)

My new thermostat is working as it should with the guage at 1/2 and plenty of heating to my feet (at last).
I will see if it effects my fuel economy. Fingers crossed.

Hope this helps someone else and sorry for no photos

Matt

Last edited by Matt1960; 19th November 2009 at 16:19..
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Old 19th November 2009, 17:22   #2
HarleymanFXD
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well done Matt, I envy your patience! 1 hr to take 4 bolts out. My thermostat is a bit on the lazy side though it does come up to temp in town driving, out on the open road the temp on the dial drops but the heater stays warm. Good MPG so I will live with it for now.
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Old 19th November 2009, 18:04   #3
Matt1960
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Yes, I was very patient, but I am sure this is because I had the wrong tool for the job. The trouble is that a couple of bolts only have about 1" between them and the bodywork. This means that you cannot get a socket set on them.
A normal e8 torx spanner only has 6 points to it so each point is 60 degrees apart. Had I had a ratchet spanner then it might only need 5 degrees of motion before any movement occurs. I would have thought 20mins to 30mins max with the right tool.
Matt
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Old 20th November 2009, 13:16   #4
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I had my thermostat replaced but the old one was clogged with gunk and when cleaned seems okay, the new one was fitted anyway. I had the car serviced at main MGR dealer every 15000 miles which I believe should have meant the coolant should have been flushed and changed but obviously wasn't. (100K miles plus).My point is that it may be worth flushing the cooling system before attempting this awkward task. I shiuld say that at 165,000 she is still going like a dream and getting 50+ mpg on journey to work each day. Mostly dual carriageway and motorway but it was nice to have a warm car again.

John
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Old 20th November 2009, 13:47   #5
Matt1960
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Good point about the flushing, although my old stat and housing looked like the new one with no gunk in the cooling system at all.
I suppose with regular servicing/replacement of the coolant at the right intervals, and also using the advanced coolants, perhaps the cooling componants are getting blocked up far less than in the past. I have read others that replaced their stat and it also looked like new.
But from my research, the stat does tend to become lazy with age.

Perhaps not to the extent of putting on weight round its middle.

Matt
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Old 20th November 2009, 19:04   #6
jt002e2762
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Thumbs up Thermostat Replacement.

Hi Matt, good effort replacing the thermostat, and good advice for owners replacing theirs'.
Pig of a job on the Diesel. Jules did mine, and well glad he did!!!
Improved performance and mpg. I had fitted a Hans Temp gauge so am now able to watch the coolant temp rise to where it should.
The needle temp gauge seems just for show, (in real terms).
Have you used the ipk diags to give you the temp now? It's quite interesting to see what temp the coolant reaches on varying driving conditions.
They seem to differ between every diesel 75.
Again, well done, you now know a bit more about your smashing 75.
Cheers, JRT.
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Old 20th November 2009, 20:15   #7
Matt1960
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JRT, thank you for your comments.
Yes for me this time it was a pig of a job. I had looked in the Haynes manual and they wanted to take lots of bits off including the water pump.
The only reason that I can see for taking the pump off is to enable the whole unit to be drawn away from that horrible rigid coolant rail that leads behind the engine.
What do you or any of the experts think about my idea to mod the pipe with a short length of silicone coolant tubing. Do you think it would work, because if it could then the job becomes a reletive breeze. In fact with the right tools, it wouldnt surprise me if it would even take 1 1/2 hours, start to finish with very little taken off to do it, just the engine covers, the turbo duct which just pulls off and the black engine bracket which swings up out of the way with 3 15mm bolts to undo.
Anyway, I will try to access the temp data when I have time to find out how (I did come across some threads on it), but there is no doubt the heater is working very well now, and the guage is showing bang on the half mark which it never did before.
Matt
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Old 2nd February 2010, 10:07   #8
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hi im having the same problem and have to tacle this job myself could anyone tell me where i can get a thermostat for my baby i keep getting told my car has the thermo fixed in the housing but the book say not thanks
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Old 2nd February 2010, 11:15   #9
Matt1960
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I got my thermostat with the housing which is plastic. Part no PEL100570 or PEL100570L(Landrover version which is the same). About £40.
It may be possible to get the stat seperately, but I couldnt find it. In my opinion, and as the housing is plastic, you wouldnt want the housing to fail in a few months as its not the sort of job you will want to do again. So I advise replacing it as a whole.
Matt
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Old 3rd February 2010, 11:32   #10
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hi matt i have now bought my thermostat from the same place you did cheapest ive found thanks just need the kick up the backside to get out there and start the job (a lot easier with your system )thanks will let you know how i got on :lol:
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