Date: Fri, 02 Sep 2005 21:21:00 +0100 From: Pooh Bear <rabbitsfriendsandrelationsnospamail.com> Subject: Re: SAAB Quality Since GM?
Malt_Hound, > wrote: > Johannes wrote: > > > > Pooh Bear wrote: > > > >>mattleibovitchnospaml.com wrote: > >> > >> > >>>I agree. The DIC shouldn't even be a replacement item. GM's various > >>>distributorless ignition setups (since 1984) have proven to be pretty > >>>much trouble free and will last "forever" much like any other > >>>solid-state electronics. Why is Saab's version so very different? > >> > >>Because the're too much clever electronics is in that DI cassette ? > >> > >>As an electronics designer, I'd like to know what the typical failure > >>mode(s) is (are). I'll bet there's something(s) straighforward that's > >>fixable by design. > >> > >>Graham > > > > > > The failure is related to the heat and lack of cooling possibilities when > > mounted on top of the engine. I took mine apart, the insulation in one of > > the coils had burned through, I guess it short circuited. > > > > It also help if you diagnose any overheating problem immediately, i.e. > > don't drive round with the temperature gauge at 3/4 mark. It must always > > be at a healthy 1/2 mark. > > With the way the cooling systems were designed in the late 80's early > 90's, I would guess that you are probably right on the money about the > overheating being related to DIC failues. I mean, it doesn't make any > sense to me that you would use an 89 degree C thermostat, and use a > thermosensor switch in the radiator that first turns the fan on at 87 > and doesn't put the fan at high speed until 92!! > > How did the designers suppose that we were going to cool the engine down > (and regulate it) to 89 degrees with > 92 degree coolant at the outlet > of the radiator? > > And this most certainly was not a GM design issue... The opening temp of the 'thermostat' is merely that. It prevents a cool engine from getting cooling it doesn't need. The coolant will actually be a lot hotter than the thermostat temp once the engine's doing some serious work. You're taking the meaning of 'thermostat' too literally. Graham