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| Viscous cooling fan; When does it start to spin | |
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| Tweet Topic Started: Tue Jul 3, 2012 8:32 am (1,733 Views) | |
| Old Slippers | Tue Jul 3, 2012 8:32 am Post #1 |
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Newbie
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Just not sure when the cooling fan should lock up and start to spin fast. The temp guage shows 100c but the fan can be stopped with your hand and spun backwards so not sure if it is OK or not. Any comments please. |
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| barretts02 | Tue Jul 3, 2012 11:33 am Post #2 |
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Part of things
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mine comes on before then, can't remember when but it doesn't go above 100 anymore. I had a problem with mine to start with though. the internal wiring of the clutch had broken so it wasn't engaging. But for most people it seems to be the temperature switch. On my car it was the switch with 2 pins (the one with 1 pin is for the temperature gauge and the one with 2 female pins is for the ECU) but that was for a 2.3-16v, could be different for an 8v. If you remove the plug and join the two connectors in the socket together with some wire you should here the fan engage and it'll be hard to turn. |
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| Gerry Lloyd | Tue Jul 3, 2012 11:59 am Post #3 |
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Monsieur
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That's right OS the fan tends to kick in at quite a high temperature. There was a post recently about fitting a switch that simply shorts the system when you want it to so you can cool the engine at will. |
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| stwat | Tue Jul 3, 2012 4:12 pm Post #4 |
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First off, is your car a 2.6 ? Only the 6 cyl 2.6 engined cars have a viscous fan. If that is not working the only solution is to replace the coupling. If its a 4cyl model then it has an electromagnetic fan clutch controled by a fan switch. As stated above the switch always tends to be the culprit and replacing it sorts the problem out. There is a procedure to test if it is the switch or not by bridging the switch connector with a piece of wire then turning the ignition on, if you hear a clunk and the fan is locked then a new switch is what you need. If the fan doesn't lock then it could be faulty wiring like barretts mentions. |
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| G3MAW | Wed Jul 4, 2012 9:05 am Post #5 |
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Part of things
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If the test doesn't work then the wiring loom to the switch is faulty - usually fails at the firewall where the loom does a 90 degree bend and is run over a 'carrier'. Heat and continuous flexing take their toll over the years......... |
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| Schwarzblau | Wed Jul 4, 2012 10:37 am Post #6 |
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More than part of things
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Mine doesn't cut in till after 100, but you certainly know about it when it does- it sounds like a jet plane! I used to worry but not any more, I've been sat in plenty of jams on the M25 and just let the fan do it's thing. When it does cut in, if you give the engine some revs it's suprising how quick the temperature comes back down. Bear in mind that antifreeze also raises the boiling point of the coolant, so it won't actually be boiling at 100 degrees. |
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| c-wolf | Wed Jul 4, 2012 10:50 am Post #7 |
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Part of things
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As does the pressure in the cooling system. |
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| threepointbadge | Wed Jul 11, 2012 11:07 pm Post #8 |
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More than part of things
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I have a 1.8 with this problem. It is a recent development and I have witnessed the temperature pass the red line stuck in a jam from hell (Silverstone), it shoots up and then the fan kicks in way too late, I bridged the switch to see if the fan was kicking in and it certainly does. I was worried I had damaged the HG but luckily all seems fine. I will be ordering a temp switch tomorrow. Hopefully that will sort it. Edited by threepointbadge, Wed Jul 11, 2012 11:10 pm.
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| stwat | Wed Jul 11, 2012 11:37 pm Post #9 |
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If it happens again in the future, turn both heater dials up to max and run the heater fan at full speed. You would be surprised how much heat this dissipates from the cooling system. |
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| barretts02 | Wed Jul 11, 2012 11:42 pm Post #10 |
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Part of things
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took a picture of dash today (i've got a 2.3 16 valve) this was immediately when the fan kicked in![]() It went up a tiny bit more then started coming down very quickly. I've got an electric fan and the belt driven fan. think the electric one was put on by one of the many previous owners - foam to jam the fan against some brackets and a single self tapper isn't the mercedes oem standard! |
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| stwat | Wed Jul 11, 2012 11:49 pm Post #11 |
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That's exactly where my viscous fan clutch starts to stiffen up, just over the line it is fully locked and like yours comes down to around 85 again very quickly. On my 2.3-16 someone had added a Kenlow adjustable temp dial under the bonnet wired up the the electromagnetic clutch. Pretty pointless really but the car had been used for track days and been to the hock a number of times so I suppose it came in useful then. |
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| threepointbadge | Thu Jul 12, 2012 9:54 pm Post #12 |
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More than part of things
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Hello again, What is the correct term to describe the temperature switch that engages the fan on my car, a 1.8? I was on to the MB parts department today and asked to order one via phone. The gent I was dealing with was not sure what I was after, I have since sent a photo. Reading different threads here shows there are different types according to engine size. Edited by threepointbadge, Thu Jul 12, 2012 9:55 pm.
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| barretts02 | Thu Jul 12, 2012 10:28 pm Post #13 |
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Part of things
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![]() If yours is the same as mine its the 1st one on the left "Temperature switch for magnetic fan coupling red 100c" |
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| threepointbadge | Thu Jul 12, 2012 10:43 pm Post #14 |
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More than part of things
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Thank you kindly sir |
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| threepointbadge | Sat Jul 21, 2012 6:20 pm Post #15 |
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More than part of things
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Hi again. So, I changed the switch today and it has made no difference. The fan kicks in but still way too late. I now think my guage is reading too high. I even think the guage is just faulty or too sensitve. It is "bouncing" at times and if you tap the dash over the clocks it seems to have an effect. Has anyone anything to add? When the car is showing high temperature it doesn't seem excessively hot? It's not boiling the water when the temp is showing 120 C One other thing I am unsure about is the sender to the gauge, I had a look through some posts here. I found a great one posted by Stwat explaining the different types of switch and how there is a different switch for cars with aircon, what it didn't detail in the PDF was the location of the sender to the gauge. I would like to locate this to see if it is connected properly I see a diagram for this part above. Is it also in the same area as the fan switch? Edited by threepointbadge, Sun Jul 22, 2012 11:34 pm.
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8:35 PM Jul 11