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| Radiator mounted fan switch cutin/cutout point too high https://www.ausmini.com/forums/viewtopic.php?f=5&t=79626 |
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| Author: | MattE [ Sat Dec 22, 2012 4:46 pm ] |
| Post subject: | Radiator mounted fan switch cutin/cutout point too high |
Hello, My car has a thermo fan fitted, and is operated by a radidiator mounted fan switch (I believe as was fitted to the UK minis from 1992 until they moved to a front mount rad). Problem is, the switching temp seems quite high. It works - I tested it on the wife's stovetop, but cutin seems to be around 90c, and cutout around 81c. In practice, hot bubbles appear at the rad cap before the fan comes on (I wonder if the mounting point exposes it to lower temps than present elsewhere in the radiator). Has anyone got experience with these switches, or know if this type of switch is available in a lower operating temp? Thanks for any help! |
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| Author: | KLAS [ Sat Dec 22, 2012 6:27 pm ] |
| Post subject: | |
the temperatures seems to be correct for the factory switch. a bit on the low side. remember that the factory uses a higher pressure radiator cap, 16psi are minimum, i uses 18-22PSI, and its designed to work with a 50:50 coolant mix, as this pushes the boiling temp, too. its a quite common problem over here that it doesn't work with the wrong coolant mix (too much water) and/or the wrong radiator cap (pressure to low, as the correct one is much more expensive) |
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| Author: | MattE [ Sat Dec 22, 2012 6:49 pm ] |
| Post subject: | |
Thanks Klas. I must admit to doing this work today without coolant and a cap which may not be correct, so your comments may prove helpful! Do you really mean "on the low side"? If so, I suspect you may be in German winter mode - it was about 34 here today, so very different conditions! Cheers. |
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| Author: | Harley [ Sat Dec 22, 2012 8:39 pm ] |
| Post subject: | |
My fan doesn't kick in till about 100 and back off at 95. No overheating problems. Is your car overheating? The fans aren't meant to run all the time - the engine one is going that. |
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| Author: | MattE [ Sat Dec 22, 2012 8:44 pm ] |
| Post subject: | |
Thanks Harley. The car hasn't been on the road, and only run a few times. It doesn't have an engine fan at the moment, but was cooling down quite nicely with the thermo, once it kicked in. I have just discovered that the cap I had was about 13/16" reach, and the radiator also had a 13/16" neck - so basically no spring pressure at all - so was happily boiling quite early in the piece. So job one is to sort out a proper cap, then go back for another try. I have an unpressurised overflow bottle - I wonder if I still want a recovery cap? |
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| Author: | MattE [ Thu Jun 20, 2013 2:59 pm ] |
| Post subject: | |
Well I'm now going to fit a mechanical fan to supplement the thermo fan - the car is still running hot, even here in winter. One of Canberra's local experts says he never runs without a mechanical fan, so I'm going to follow his lead. I have a late model Rover type here, but can't use it as it fouls the breather can on the timing cover. Will any or all of the others types also foul? I don't seem to have enough room between water pump boss and radiator to fit a spacer...... Thanks. Matt |
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| Author: | Harley [ Thu Jun 20, 2013 6:37 pm ] |
| Post subject: | |
You need a fan spacer or two, the screw heads holding the fan on will only just have clearance. |
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| Author: | MattE [ Thu Jun 20, 2013 6:58 pm ] |
| Post subject: | |
Thanks Harley. Will see what lurks under my dad's house -I think we have a spacer or two. Assuming then it's fan on, then lower shroud, then rad, then top shroud? I won't bother complaining about how fiddly that is all going to be..... |
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| Author: | BALLISTIC [ Fri Jun 21, 2013 7:45 am ] |
| Post subject: | |
You could always give the breather a bit of a "tap"  so the fan will clear it if needs be. From memory I believe there are different thinkness spacers available, i could be mistaken. Personally I prefer to use the metal multi fin fans as they are less prone to failing (which i have seen & experienced) & cool quite effectively without flexing.
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| Author: | MattE [ Sat Jun 22, 2013 12:24 pm ] |
| Post subject: | |
Thanks for help so far. I found 4mm and 17mm spacers, but it seems like I need something in between (for a steel fan). Does anyone know if any other sizes exist? The 4mm is steel, 17mm aluminium. Thanks... Matt |
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| Author: | Harley [ Sat Jun 22, 2013 4:36 pm ] |
| Post subject: | |
Just use two 4mm ones. |
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| Author: | mini_mad_matt [ Sat Jun 22, 2013 4:41 pm ] |
| Post subject: | |
or get the larger one machined down |
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| Author: | MattE [ Sun Jun 23, 2013 7:05 pm ] |
| Post subject: | |
Thanks for both suggestions. I have two 4mm ones, so will go that way, at least for now. Matt |
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