 | Home > Tdi > Changed Thermostat, Opend Can Of Worms |
 
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| Shep Member Since: 02 Sep 2013 Location: Pwhelli Posts: 88  
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If it were me i'd just have to check that i'd put the thermostat in the right way round before i did anything else, sorry i don't know the engine but if things changed significantly and for the worse, after the work was done, i'd suspect the work.
Shep A man with no boat is a prisoner |
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12th Sep 2013 6:27pm |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347  
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Unfortunately the thermostat can only go in one way round so it’s not that.
I will admit I didn’t test it before fitting, but as it was brand new from Land Rover I would doubt it was faulty. Also checked to make sure it is defiantly an 88°C which it had marked on it clearly. |
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12th Sep 2013 6:33pm |
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| Shep Member Since: 02 Sep 2013 Location: Pwhelli Posts: 88
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Can you feel the pipes around the thermostat to feel if its opening or not? When it's all very hot is the bottom hose getting heated at all?
Sorry if i'm telling you how to suck eggs 
I might be tempted to test the thermostat (or remove it just as a test) and see if it all changes again, its not often thermostats stick but 'rare things still have to happen to somebody' Shep A man with no boat is a prisoner |
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12th Sep 2013 6:41pm |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
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Top hose after stopping was cool, but then warmed up quickly to very hot once I stopped and tried it, the bottom hose was warmish, but much cooler than the top hose. The expansion tank was also very cool in comparison.
Don’t worry, knowledge shared, is knowledge passed on! I doubt it is the thermostat, (and I have seen posts about the thermostat being removed being advantageous) however, I don’t want to suspect it yet as I can feel it is working, but fear the water pump is what has gone. |
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12th Sep 2013 6:52pm |
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| Retroanaconda Member Since: 04 Jan 2012 Location: Scotland Posts: 2656 
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Test the stat in a pan to be sure. Even Genuine ones are s**t. They're just less s**t than the aftermarket ones.
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12th Sep 2013 6:55pm |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
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As I say, I think the thermostat is working, as the top hose is warming up, however I don’t think there is any push to move the fluids around.
Does anyone have a good test for this? Thank you for replies so far! |
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12th Sep 2013 7:09pm |
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| bpman Member Since: 21 May 2008 Location: Oslo Posts: 8069 
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getting the air locks out is a black-art
when it's warm, if you rev the engine, can you see the water move in the header tank ? does the header tank get warm ? if not, most likely an air lock |
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12th Sep 2013 8:05pm |
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| Retroanaconda Member Since: 04 Jan 2012 Location: Scotland Posts: 2656
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As Steve says above, if you rev the engine you should see it surge inside the header tank.
An airlock is possible, though 200Tdis do not suffer the same nightmare of bleeding that 300Tdis do. I've probably drained/refilled the coolant a dozen times in my ownership of mine and never done anything other than fill it up, run it up to temp and then topped up once settled. They've always self bled. But still worth checking! |
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12th Sep 2013 8:18pm |
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| Skye_Rover Member Since: 29 Aug 2013 Location: Skye Posts: 85 
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Another check to make is that the air bleed hole in the thermostat is upwards, otherwise you'll get the sluggish response form the valve that it appears you have.
The thermostat needs to see a hot stream of water from the bypass circuit for it to open, so it might be worth checking for air-locks and other restrictions on the heater circuit and/or the bypass pipes before condemning the thermostat. Roads? Where we're going, we don't need roads. |
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13th Sep 2013 9:30pm |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
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Had another go at it today.
It’s not getting as hot as it was, however only had a few short runs today. Dropped in on Land Rover and had a quick word with my service manager and we both agreed that it is most likely an air lock, that the best thing to do was to just cycle the engine up to temp then cool down, giving all the hoses a good squeeze. Have done that and it seems to be improving but still running a little hot. Will carry on tomorrow (if the storm allows it!) and if no improvement will take off the viscous fan, aux belts, and take the water pump off and inspect it. As I say the pipework is pressurising, but not in any way up to 15psi and there is no noticeable flow. The story continues…. |
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14th Sep 2013 6:21pm |
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| Shep Member Since: 02 Sep 2013 Location: Pwhelli Posts: 88
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The pump only circulates water it dosn't create any significant pressure, heat and the coolant expanding creates the pressure and the cap is set to vent if the pressure gets too high. The only time you might see any flow would be if the thermostat was open wide (engine hot) and the system actually allowed you to see the flow. Most modern engines have little or no visible flow in the area of the rad cap/expansion vessel.
Good luck A man with no boat is a prisoner |
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14th Sep 2013 6:58pm |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
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Right!
Drove to work and back today and she was yet again very much hotter. Tonight decided to bite the bullet and re-drain the fluid and check the thermostat. Checked it, it was fine, however noticed that the ball in the cage was very tight, and the minute it touched hot water would seal up tight and then not release until well cool. I took this to mean that it was sealing up and not allowing air to pass past the thermostat from the heater matrix (where all the air was) into the radiator and then up into the header tank. So, removed the ball but left the restriction which will have the effect of a small constant flow of heat, which isn’t a bad thing, but also will mean that any air in the system will be free to flow up and out of the system. On thinking about it, the old thermostat had a much better “dingleberry” which would drop a long way free and couldn’t stick shut. So, off came rad cap and filled the radiator with coolant, and then some water which filled it up into the expansion tank to the required level, plug back in, top up expansion tank and then give the hoses a good squeeze. Lots of bubbles and gurgling noises and it all seems to be well. Tomorrow will be the proof of the pudding to see how it runs…. |
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17th Sep 2013 9:53pm |
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| Skye_Rover Member Since: 29 Aug 2013 Location: Skye Posts: 85
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I think that you have nailed it. The jiggle valve should only be a bit of brass, a bit like a rivet, through the bleed valve hole. It isn't meant to block it completely, and a ball valve design will do just that. Those sort of stats are no good on a Tdi, they need to pass a little water through for the thermostat to control, and for the air to purge (and stay purged) from the bypass circuit. The only reason for having anything through the hole is to limit the thermostat bypass when it is closed, so aiding the warm-up speed, by not putting too much water through the radiator before the engine is up to temperature. Roads? Where we're going, we don't need roads.
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17th Sep 2013 10:11pm |
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| shaggydog Member Since: 12 Aug 2012 Location: Kent Posts: 3347
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Success!
All back to normal. Turns out but the ball bearing was definitely the problem. Did think that the design lent itself more to a non-return valve than a bleed valve. Oh well, mischief managed  |
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18th Sep 2013 10:47pm |
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