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Re: DI swap time Posted by CrNiFe [Email] ![]() ![]() ![]() In Reply to: Maximum DI lifespan, Eugene, Mon, 30 May 2005 01:28:10 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Well, I have been carrying a new DI in the cargo area of my SW for the past year and a half. We just did the 96000 km (60000 mile) tune-up in late January, and thinking ahead about the vacation through New York and Maine on the way to Prince Edward Island, I decided to swap it now.
My personal opinion, having read just about all the DI posts on the board, is that the service conditions matter a lot more than the mileage on the vehicle. As a materials engineer, I learned that breakdown reactions in plastic, resin and other materials used in the manufacture of the DI double with each 20 degrees F (for non-geeks, this is because of the Arrhenius type nature of thermal and chemical cross-linking processes between polymer molecules). Higher temperatures = faster breakdowns. We don`t know the exact service temperature the coil wraps are exposed to in the cassette, but if I was running in desert heat a lot, I would take that into account in my preventive maintenance program for a vehicle.
The other main factor I believe is the time in service, since these same reactions are based on time as well. Longer time = more degradation. My SW went into service in July 2000, so it would be coming up on six years. Since I know the spare works well, I have placed it in the cargo area for clear conscience purposes.
Of course, I didn`t take into account a manufacturing defect in the DI, in the windings, in this analysis. I will just cross my fingers and hope, but you know, the car seems to have more ZIPPPP since I put it in.
I have no regrets about purchasing the spare. It is just like the old days, when you carried a couple of spare belts, some oil, a distributor cap and some oil and radiator mix in the trunk of your Buick or Ford.
Cheers from sunny Toronto
CrNiFe
MY99 9-5SW, 94500km, 2.3lpt first DI retired
posted by 65.92.144...
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