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I apologize for the glare but thought someone might be interested in the photo of the temperature indicator in my 245. We had been on the road for several hours when the indicator started its normal fluctuation from below normal to red hot. The mechanical temperature gauge maintained 160 throughout (probably 20F cooler because I put it in the top of the aluminum head). It is certainly nice not to have to pull over and check the radiator hose for pressure every thirty miles or so. Piece of mind for under $50.00 total cost.
The instrument cluster is from another vehicle so the mileage is off about 70k miles. Notice the rock steady factory oil pressure on the lower gauge!
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Will Dallas, www.willdallas.us, www.willdallas.org, www.willdallas.com 86 245 DL 222K miles, 93 940 260K miles, 88 765 GLE 152K miles, 86 244 DL 200K Miles
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re: "...on the road for several hours when the indicator started its normal fluctuation from below normal to red hot...."
You undoubtedly only need to replace or bypass the Temperature Compensation Board. It should never have been put on these cars, anyway, as they almost all fail and cause those erroneous temperature swings.
Popular legend (I don't know if it's really true) is that they were installed (on '86-on cars) because typical american owners, who were used to idiot lights from their previous, usually american manufacturers, were bringing their cars in for repairs when they noticed (what are actually normal) slight temperature fluctuations. Volvo installed these boards to take the heat off service managers.
The Compensation Board is essentially a "logic" circuit that modifies the signal to the gauge, and so in effect dampens the tempature gauge's movement. Normally, the C.B. only allows the needle to stay on three places on the scale, promptly going from "cold" to "warmed up" (amazingly, to exactly 9:00 regardless of which thermostat you're using), and to "overheating" if indeed, the car is really overheating, in effect rendering the gauge into a "three-position" idiot light itself.
Happily, Volvo really didn't do anything to the gauge itself other than adding this C.B., so you can remove it and bypass its connections -- this leaves the gauge working properly (as on pre-'86 cars), and accurately.
So after you remove that C.B., you can remove and throw away that extra gauge you put in (it's redundant and no better) and use the space for a much better use (e.g., a voltmeter).
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I would have to disagree with the "(it's redundant and no better)" view of the capillary tube gauge. While they may not be as accurate (+ or - 5 degrees on a cheap one as compared to .001 degree on something like a Rosemount or Endress Hauser RTD) they are certainly more reliable than the run of the mill automotive spec gauge. None of my equipment runs electronic sending units when I have to depend on trending the visual data. That applies to the oil pressure gauges also.
Of course personal preference always wins out, I'm just old school on automotive instruments even though I run my molecular distillation equipment with the latest available in electronics.
Regards,
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Will Dallas, www.willdallas.us, www.willdallas.org, www.willdallas.com 86 245 DL 222K miles, 93 940 260K miles, 88 765 GLE 152K miles, 86 244 DL 200K Miles
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Hi. Just an observation or two -- I'm a scientist (neurophysiologist/biophysicist) with my own laboratory full of expensive equipment, like you have (maybe more, but let's not quibble :-).
With all due respect, and empathy (see below), I submit for your consideration that I don't see anywhere near the need for critical accuracy in an ordinary road car as we would need in any of our "professional" experiments. And we aren't driving multi-million dollar factory prototypes, and even if they were I doubt their development engineers would need coolant temperature accuracy "... to .001 degree...". Certainly, a deviation of a few degrees in a road car is meaningless (apt to mean nothing more than a slight grade in the road your on). And, I don't think that the 2-inch gauges that you showed us installed in your car were "...a Rosemount or Endress Hauser RTD..." (whatever that is -- I admit ignorance of these).
Moreover, there are reasons that make remote-sender electrical gauges better than mechanical despite any deficiency in accuracy. I've found one glaring drawback. I'm a member of the MBCA and read this club's magazine's tech articles, and from them I have learned that all too often in older M-B's (ca 1970s and earlier), people occasionally report that they're finding pools of oil on the carpeting under the dash(and sometimes oil drips on their trousers). Invariably, the tech column author suggests that they check their oil pressure gauge, which in those earlier models were mechanical -- with an oil line direct from the engine to the gauge head. If that "plumbing" springs a leak (or the gauge head itself), oil comes out.
This is a problem you wouldn't have in an electrical sender.
In summary, I think that the Volvo's electrical temperature gauge is sufficient and reasonable -- although you're free to disagree :-). And please, don't think this is a criticism of you -- it isn't. I just want to express my different opinion that I don't think mechanical gauges are necessarily better in a car.
However, I must concede that I can fully understand your desire to "fool around" with your car, install more gauges, etc.! In that respect, we're probably two of the same kind! I'm just as guilty as you are -- I can't own a car without wanting to take it apart and customize it -- it's my hobby. I've filled up the two accessory gauge positions on my cars with a voltmeter and outside temperature gauge (a big tach is where my original clocks belong, and I don't care for a clock in the small pods). For another, better example of my compulsions, right now for one of my 240's, I've taken the rear center brake light and both taillight housings out and I'm fabricating altogether new lights to install inside them (brighter, and not subject to the corrosion and "bad contact" syndrome that normally plagues 240 taillights). I don't think I haven't put in a lot of IPD stuff -- their catalog is like a toy store to me.
I just can't leave a car (or a boat) untouched -- maybe it's a disease with me. And do you think I'd let a boatyard tech install my boat's electronics -- heck no! Installing my GPS, Chartplotter, VHF, Radar, and Sonar is more fun for me than using them! Some of my boating buddies are afraid of doing any work on their boats -- for me, it isn't really "mine" until I've cut some holes in it! My wife even accuses me of enjoying working on the boat more than operating the boat!
Some folks play golf -- I install or replace-with-better everything I can -- do you think there's a "ten step" program to help people like me? :-)
So just go ahead and put any gauges you want in your car! Enjoy! I understand, completely! :-)
Best regards,
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Points well said and well taken. But I would suggest another point of view: What do you need to know?
I my case, the temp gauge was either lying or truthing, and removing the TCB made it always truthing. (Sorry about that invented word.) In adding another gauge I am limited to a single space, and I chose a Volvo voltmeter for both my 244 daily drivers. Never a regret. Voltmeter gives me a much better picture of the charging system.
The pic is pretty nifty IMHO, thanks.
Regards,
Bob
:>)
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