Recently my '88 (230K) developed a rattling sound coming from the engine compartment. I took off the head shields when I got it, so it's not that. I notice the sound more at idle, but I don't know if the sound stops upon acceleration of it maybe the sound is just masked by the louder engine at higher RPMs. It's been very difficult to locate by poking my head under the hood. It's hard to tell but it might be coming from the engine itself. It's disconcerting because it sounds somewhat like the bad timing chain I had on my rice burner truck several years ago. I know of course that the B230F doesn't have a timing chain, but is there something that could be wrong with the engine that might give it a rattling sound?