I screwed (could rivet, too) a strip of sheet metal across the front of D's hood four years ago just for this reason.I've also sewn safety wire with some success on other rigs. The trick is to keep any edges out of the fan blast.

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James Marriott
2003 Buick Regal
1983 300D (228k, frau Auto)
1996 Suburban K2500 (192k, 6.5 turbo diesel/4WD towmaster 10,000)
www.engineeringworks.biz
1987 300SDL junker 170k
1982 300SD junker, 265k