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| 2.5 Diesel running too cool? | |
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| Tweet Topic Started: Sun Sep 3, 2017 5:38 pm (272 Views) | |
| MJK 24 | Sun Sep 3, 2017 5:38 pm Post #1 |
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Hello, I have just bought a 2.5 D. The engine doesn't seem to get warm. It is only running at 60 degrees. I've owned W201 and W124 Mercedes before with M102 petrols and they always ran at 82 degrees. I don't think it's the thermostat as the heater is pushing out hot air within 60-90 seconds from a cold start. I have noticed that the cooling fan is running continuously though. Is this normal for the diesel? Thanks for any help! |
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| Greek Taxi | Sun Sep 3, 2017 8:18 pm Post #2 |
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Hello 60 is too cool. It will be a knackered thermostat. Flush and replace the coolant while you're at it. You say the fan is running - is it running slowly and you can stop it with your hand? If so, that's normal. It's not really running - they are designed to lightly spin. You will know if it really is engaged and won't dare put your hand anywhere near. When running properly the diesels get up to temperature (90ish) and stay there, regardless of speed, temperature, traffic jams... the cooling system is one of the best things about the OM602. Edited by Greek Taxi, Sun Sep 3, 2017 8:22 pm.
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| MJK 24 | Sun Sep 3, 2017 8:39 pm Post #3 |
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Thermostat will be a cheap and easy fix. Only thing that makes me think it might be something else is that the heater warms up very quickly. You can feel heat within 90 seconds. That makes me think the thermostat is ok? Thanks for your help so far! |
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| Bradders | Sun Sep 3, 2017 8:48 pm Post #4 |
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I took the fan off my 2.5D a couple of yearsago. It sat ticking over for an hour and a half the other day and didn't overheat at all. They don't seem to need the fan. Cant remember what temp. it usually runs at. Will try and remember to check tomorrow. |
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| stwat | Sun Sep 3, 2017 9:38 pm Post #5 |
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Is the fan loud all the time? If so, the viscous coupling could be shot and need replacing. |
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| Greek Taxi | Sun Sep 3, 2017 10:14 pm Post #6 |
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MJK - I can't explain the hot heater. That is strange, I have no idea how it can get hot so quick. But change the thermostat. They don't last for ever, and they're cheap and easy to change. Bradders - yes - my 2.0D never went over 90C in all the years I had it, even in traffic jams in 38C heat in Italy one summer. |
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| MJK 24 | Sun Sep 3, 2017 10:31 pm Post #7 |
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The fan is silent. It's spinning away at what looks like a lower speed. You can just about make out the blades. |
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| MJK 24 | Sun Sep 3, 2017 10:33 pm Post #8 |
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I'll try and change the thermostat this weekend. It could also be the temperature gauge sensor giving a faulty reading? Do you know where this is located? I'm guessing that would also be a cheap and easy swap. |
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| next2normal | Mon Sep 4, 2017 1:37 am Post #9 |
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mine runs just under 80 most times, sometimes 60 my fan never switched on,sometime it will run at 90 up hill, took it for a long 8 hr hard run other week, cleared my dodgy one injector cold running noise, 4 hour drives weren't enough |
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| MJK 24 | Sat Sep 9, 2017 7:40 pm Post #10 |
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Had a quick look this evening. Stopped after a drive. Radiator top hose is hot, bottom hose only warm. Top of radiator is hot but gets cooler as you get near the bottom. Considering the heater warms up instantly when cold which for me points away from thermostat issues, do you think it might have poor circulation from the water pump? As if the impeller was slipping? |
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| mxfrank | Sat Sep 23, 2017 1:50 am Post #11 |
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Replace the water temp sensor. |
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| danny 1984 | Mon Sep 25, 2017 6:38 pm Post #12 |
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Mine sits at about 85, your thermostat might be faulty I'd say. Have you sorted this out yet? |
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| MJK 24 | Fri Sep 29, 2017 11:17 pm Post #13 |
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Hello, Conclusion - it was the thermostat! Changed it for a new, genuine Merc item. Flushed out the red coolant in the system and refilled with the correct Comma G48 and it now runs at precisely 80 degrees up hill and down dale. Heater warms up nice and quickly. Big thank you to everyone who offered their thoughts on the matter. |
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