engine starts vibrating upon start up. hard vibe around 1500rpm, smoothies out a bit after that. thought it was the new alt. removed belt started engine… not it…the only other belt runs the water and power steering pumps–no clutch fan, replaced to electric
Sounds like an mis fire to me.
I was wondering the same thing: misfire causing the engine to shake versus a rotational vibration.
As for the latter I wonder if the harmonic balancer is coming apart?
Cheers
DD
What year is your XJ-S and what engine does it have?
Paul
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good possibility. due to work did not drive car for several years, around town a bit when home…spark plugs sounds like a good bet. Michael. 85 xjs
plugs are old. will change
85 xjs. not the original motor
V12?
Something else?
Michael just FYI you can reply to all the posters in the one post as we can all see your responses, and if you want to call attention to a particular one then you can uses there ‘handle’ as I have here; @michael_bucklew2
Jerry,
Chevy 350?
Paul
Paul N.,
Could be.
I was wondering if he meant a replacement V12 due to the original engine swallowing valve seats or other not-so-good things happening … or was it something else, like a Chevy 350 (I think those may be the most common lump engine used in XJSs?).