This will not be a definitive answer, but may trigger some possible areas to explore regarding temp sensors and the coolant system in general. I believe I may have read somewhere, maybe a Tech Bulletin, that it is imperative that the coolant be 50/50 water/coolant(and phosphate free) so as not to unbalance the ionic ratio? in the system, something to do with conductivity? Also, it is important that the system be completely free of air, otherwise there could be false indications of overheating. Air can be introduced by incomplete purging during a coolant change or top off, or because of a slight leak in the system. I read that some leaks in the system are one way only,i.e., coolant doesn't leak out, however air can be sucked in(pressure leak vs. vacuum leak in the system). Any comments? Pat S.
______________________________ Reply Separator _________________________________ Subject: Re:Coolant Temp Indications Author: Steve Hoge <steveh@emu.com> at INTERNET Date: 11/15/95 10:36 PM
> The coolant temperature warning light sometimes flashes when the gauge > needle is showing max temp, and sometimes when the needle shows normal > temp. I had the same problem this last weekend, just a few days after I had the dealer flush and fill my coolant (yeah, yeah, I know...) Temperature gauge showed normal, right amount of coolant in refill resevoir (couldn't see into the overflow tank), no visible leaking, tight V-belt, etc. I couldn't make heads or tails of the wiring diagram in Bentley - it looked like only a ground leading to the warning light part of the indicator, and the temperature sensor signal *only* (ie, no coolant level sensor) leading to the "gauge" part. The interesting part is that the flashing indicator went away each time I turned off the engine and restarted it. Is it possible that an intermittent sender signal gets "latched"? Also, this problem seems to have disappeared now that I'm back down at sea level from 3000' to 7000' where it was happening. Steve Hoge '77 Loaf (Da Rust Bucket) '89 Syncro GL (Da Dust Bucket)
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