Or he could spend that time ohming his glow plugs. From the description he probably has two or three bad ones, with #1 very likely being one of them. They aren't hard to check, they aren't expensive, and they aren't hard to change.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.