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In response to a post by Bill The Cat in OPINIONS forum...
Suddenly, I had a light bulb come on.
I wonder IF perhaps it's a partial result of cool operating temps, independent of climate. Like, if the engine was operating below the normal range MOST of the time.
That could be the case in M. Fuqua's engine maybe. The gauge certainly gets to mid range pretty quickly, but then again, it doesn't stay there for very long. Judging by the way that M.F. drives (reportedly shorter trips and then 8hr rest period--or more) there just isn't enough heat in the engine to start working on that stuff. Add it over months and years and there you have it.
In the case of 740 & the Rodeo, I think maybe it was because I had let the Rodeo idle for about 8 hours, and the Volvo for six. The Volvo was knocking kind of loudly by the end of the day, but everything checked out OK so I wrote it off to low temp piston slap. What do you know, it's gone away mostly, now that I've fixed it, so apparently I was wrong. It must've been the valves starting to put up a fuss. The Rodeo shut itself off, so it was really victimized pretty badly. But then again, with more cylinders and valves than the Volvo, it's more likely that something fouled and just broke the timing belt.
I'm sure that the reformulated zone gasoline is NOT as good as the other varieties, but it doesn't seem to me that it would be that BAD either. I've never had a single problem outside of this, but I can remember that when they changed the blends around, people were having all sorts of issues with their cars not running properly, blown head gaskets on lawn mowers and smaller 2 stroke engines, and so on.
In my humble opinion, there's no need for mass hysteria about it, but it pays to be cautious. Even short trip cars might have better luck if they spend some time sitting at stoplights in gear, and doing a lot of stop and go driving. It doesn't really heat up the engine, but it's better than doing a lot of idling, or highway driving for five or six minutes while the temp gauge is barely registering. Lately I've been doing some of that myself, which is why I probably notice such a massive difference after an 85mph cruise on the interstate, with a little full throttle acceleration and lane changing thrown in here and there.
The machine shop that did the Volvo's head said that it just must've been sugar in the tank. As embarassing as this sounds, we even TASTED the fuel and there wasn't a trace of sweetness. And as I'd said before... nothing else was fouled. Just the intake/exhaust valves, and the crown of the combustion chamber.
Now I'm thinking, if you had a marginal thermostat (the 740 definitely did--car never warmed up that much, and the heater was blasting all day long while it idled, sapping heat from the engine) that would be the most likely cause. Running cool and fouling the valve stems. In Mulla's case, he's using red Dexcool-type coolant, which I've noticed (very non-scientific) takes longer to heat up, and produces less heat in the passenger cabin.
Was it Pablos who had noticed the same thing? I know someone else mentioned it. And these are generally well-maintained cars with newer thermostats and cooling systems, and coolant.
More to come on this, no doubt.
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Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240
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