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Re: buffered coolant temp guage

You find the ability to maintain the temp within a narrow range a sign of

> deception? I'm confident that if the guage is in the middle, then the temp > is within 10 or 15 degrees of where it is supposed to be. > > You can f*ck up your car with aftermarket crapola if you want, but I have > no reason to think that my guages are not accurate when they tell me that > all systgems are nominal.

There are occasions where the BMW cooling system fails rather suddenly (V-8 E39's seem more prone than most), typically a crack in the plastic hose connection on the radiator. The buffered system is fine and you're correct that it indicates "nominal" temperature across an acceptable operating range of temps by indicating a 12 o'clock needle position.

An old style temp gauge will rise and fall slightly between the thermostat setting and its max load temp (think steep hill, high rpm, hot day). It will also show a steady rise if coolant is rapidly leaving the system through a leak, an early indicator that you might want to prepare for a rapid exit and shutdown.

The buffered gauge will do neither. After a sufficient amount of coolant has left you'll be confronted by a rapidly rising gauge and precious little time to perform neccessary action.

While there appears to be no way to modify the gauge, aftermarket systems work well and can also report oil temp (a luxury afforded M-drivers vice the worthless MPG gauge), oil pressure, volts, or whatever. These are minor mods, the kits are typically well-engineered and will not harm the vehicle.

R / John

Reply to
John Carrier
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Now, this may not be relevant to modern gauges and cars, but a trick I learned years ago on race cars that you can drive to the track (ahem) is to use the same electrical temperature gauge for both coolant and engine oil temperatures. Obviously, you need to have both sensors present. The trick is just a simple toggle switch to change between them. The temperature ranges are similar.

Reply to
Dean Dark

You also have a low coolant level warning light...

And I'm not convinced the BMW gauge reacts differently than a 'normal' one if a hose split etc.

Reply to
Dave Plowman (News)

A worthy point. That's true. My coolant low warning came on with very little loss (measured in the overflow tank BTW). I'm not sure whether the measurement of coolant level at that location has any associated lag with the coolant leaving at a different location.

Most of my knowledge comes from the roadfly board on which a number of 540i owners described rather catastrophic losses of coolant. (My 530 has not missed a beat, despite 100F+ days.) Perhaps the gauge design wouldn't matter. OTOH, I'd prefer one that reported the proper temperature. I'd also enjoy an oil temp and pressure gauge. Throw in a voltmeter as well. Take the MPG gauge .... PLEASE!

R / John

Reply to
John Carrier

Indeed. I had mine come on after a clip cut into a hose slightly, although I had smelt it on parking up before that, but not found it. Short term - top up, run with pressure cap loosened to get home. Medium term - cut hose, fit jubilee clip, Long term - replace hose.

Normally you would get low coolant long before there was any risk of overheating, and on a slow leak it would tend to show on cold startting when the coolant had contracted.

Reply to
R. Mark Clayton

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