New BDR RT4 Electrical Issues
I took ownership of a new BDR RT4 (#2581) recently and have run into an electrical problem from the very start. For some reason, the cooling fan circuit consistently blows the 30A fuse. I have checked (and replaced) the thermistor (fan switch), the dash-mounted override switch, and the fan circuit relay...no joy. The circuit grounds appear to be good as does the wiring (that I can get to). The car comes up to operating temp very quickly and the fan will initially come on to start cooling. I get the indicator light that the fan is activated. After about 10 - 15 minutes of driving, the temp starts to climb rapidly above 100°C (212°F) to peg the temp gauge. At that point I stop the car and let it cool down. I carry extra 30A fuses and swap it out for the one that has blown.
I am at a complete loss as to why this continues. I'm at the point where BD is sending me a new fan to swap out, but I'm not convinced that will "cure" the problem. Any help or advice would be greatly appreciated. Thanks! Tim |
Are you using a relay?
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I would use my Fluke to check Amp draw on the circuit. I bet you are near or over 30 Amps.
A bad fan motor could cause high Amp draw. John |
I would disconnect the existing power lead from the fan, and run a temporary power wire and fuse holder and simple on/off manual switch directly to the fan and drive it. If it still blows the fuse it's the fan itself, if it doesn't blow it, your problem is in the original power feed circuit.
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thermostat
Hi,
The temp should not rise to boiling! You should be able to drive with no fan on at 185 to 195*, put fan on when you slow down. I would replace the thermostat with a 180* one and burp all the air out of system. As for the fan, turn on fan and put a kleenex in front of rad and see if the fan is pulling air through rad or if they wired it reverse. try a 40 amp fuse as the amperage will spike when turned on. Perry PS; if the fan is blowing air forward instead of through rad the fan motor will labor in the wind and cause higher amperage draw and blow the fuse. |
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With regards to putting a 40A fuse in vice 30A...never a good idea. The fuse is blowing for a reason not related to the amount of amperage running through the system. BDR tells me it is a 30A circuit and I measured it as such. The problem of the fuse blowing appears to happen when it gets to operating temp. Makes me think it is heat related...somehow? |
alt
Well the only difference is the alternator, the rectifier may not be giving a good DC voltage- AC still present?
Good Luck. |
Rugby,
Don't know anything about BDR or its wiring. Having said that, logic tells me there's a possibility that the thermal switch is wired incorrectly. Here's why: you replaced the thermal switch so that should eliminate the switch itself. Then, the fuse blows when operating temp is reached, which is when the thermal switch should activate. If that does happen, it seems possible that the thermal switch is connected to a ground and not to the fan so when operating temp is reached, the thermal switch may short the 12V feed to ground instead of to the fan? My SWAG for the day, Tom PS: On my cars the thermal switch is connected not to the fan, but to a relay. So the thermal switches I have do in fact ground the 12V signal through the relay, not the fan itself. No idea if yours is supposed to be done that way or not. |
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Well...first of all...thank you immensely to everyone who offered advice and comments! It turns out that the original fan installed by BDR was faulty. It definitely "appeared" to work as it came up to speed when on, but as @patrickt surmised, the heat from the engine proved too much for it. I replaced it with a SPAL high performance fan and have not had any issues since. Installed it on Saturday and literally ran it a couple hundred miles with zero blown fuses.
Again...thanks guys!! |
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What SPAL did you go with ? Did you have to drop the radiator ?? Roy |
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It helps if you have a beautiful assistant...which I do! If you need pics, let me know. Tim |
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http://www.clubcobra.com/photopost/d...ount_ellie.jpg |
Just a thought
On a side note I know you said the grounds LOOK good, but lessons learned tell me to remove the grounds-- use a bonding brush too clean the metal then reinstall ,they could have painted before installing them(high resistance ),very common issue on Agusta Westland products also :rolleyes: Keep us posted on what you find.. here is an older wiring diagram https://drive.google.com/file/d/1E5K...usp=drive_link
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