Does anyone know the size of the 4.2 L series 2 crank case pulley bolt. I don’t have one and want to acquire a substitute to try and rotate the engine. …becasue…The previous knucklehead who owned my car, a 70 Roadster, started to disassemble the engine and removed the damper, crank pulley and assembly now nowhere to be found. . The engine is presumed seized but I want to try and see if it will turn. Ive been soaking the cylinders for a month or so with Marvel Mystery oil. Also without a crank bolt does anyone know an alternative method try and rotate the engine?

 

Is the engine in the car? Can the car roll on its wheels? If so, you might consider putting it in 4th gear and try pushing gently. Spark plugs out of course. There's a bit of slop in the drivetrain, so very gently push the car to get to the end of the slop, then push further to see if the engine turns. Use this "two-stage" push to avoid shocking the engine. There's a danger of cracking a ring or something else very bad / expensive - so don't be too energetic. If it all goes well, an endoscope inspection camera might be useful to look through the spark plug hole before trying a compression test with the starter motor.

This is loosely based on something I've actually done successfully with a boat engine that was difficult to access, but others might have better ideas.

HTH. Dave

 

Gradual bumps in gear as Dave suggests is a good idea. Push forward and backwards. Mark the crank and block to see if you make progress. You only need minor progress and you’ll be on the way.

 

This works on XJ6: see attached
Rgds
David

 

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That is a clever tool, but I believe the OP's problem is no crank nut is installed.

 

I see you are looking for replacement parts for these items in Marketplace. You might post a wanted ad on the JCNA website (not sure if membership is required to post an ad).
Also try some of the vintage Jag restorers. Here in Rhode Island that would be Bassett's Inc and Kane Motorcars. A quick look through Bassett's website didn't show these parts ( lots of other stuff you might need though) but he may have a used parts stash, alternate model parts that are equivalent, or have other vendors/enthusiasts to suggest, maybe in the UK.

 

Thanks much. There will be lots of parts I am looking for before this project is over!!

 

Great tip thanks!