Wrench size for turning over a 3.5L

I’m going to take a look at a ‘49 MK V with a 3.5L engine. I want to try and lubricate the cylinders and then see if I can hand turn it. I don’t know what size socket I need for the crank shaft. I’m hoping someone here has that info.


IIRC the correct size is 3/4 BSF/BSW aka Whitworth but UNF 1” 5/16 is close enough.


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A 1 5/16 works on both my 150 and MKII.

Thanks fellas!

Correct, and this bolt is IMO an example of Jaguar weirdness: its head is Whitworth while its threads are UNF. Were the threads ever Whitworth on early examples of the bolt?

As well as a socket for turning the engine over, the hand starter crank can work if available. I use the hand starter for turning over when setting the rocker arm clearances. Sometimes I use a breaker bar with a socket which has had the outer diameter turned down slightly to give easy clearance through the starter crank path through the radiator.

1-5/16" is correct for the 3.5L pushrod engine. 34 mm would be a little loose but would probably work.

It’s also correct for the XK engine,

in case you get there and find the car was converted in the 1950s. It happened to a lot of Mark Vs.

That’s the same size as my 2.5L. I just didn’t know if they changed things when building the larger engine.

The Starter Jaw part number is C2861 for the 2.5L and C2809 for the 3.5L; the main difference is length; the 2.5 does not have a damper, where the 3.5 does.

Damper? What is that??

Vibration damper on the crank shaft, made by Metalastik.

Used on all 3 1/2 Litre engines on both MKIV and MKV. Supposed to reduce harmonic vibration.

And different variants used on all XK engines as well.


Mark V crankshaft 005

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So I went and took a look. The body coverings are in very good shape. Very little rust, almost no dents, and decent original paint protecting the metal. The interior…or what’s left of it is nothing but rust. No interior what so ever. No seats or frames, no wood at all, very little instrumentation, a steering wheel with nothing in it, a transmission cover but pretty rusted. No sun roof top and no windscreen which helped with the abundant rust in the floor boards. Tho the boot lid is nice and indented, the boot floor pan is gone and the fuel tank has rust holes all over the top of it. The spare tire door is fine but one quarter of the compartment is gone. I’m thinking this car was picked over as a parts car in its past.
The engine is complete but stuck. All the hardware is on the car but bumpers have more chrome curled up and falling off then any still attached to the steel.
I attempted to use a socket to turn the crank shaft but the tie rod was in the way blocking the hex nut. I’m thinking the engine mounts have rotted allowing the engine to slump down. I put a very long open end wrench on the crank with a flattened pipe over it but it wouldn’t turn. I didn’t want to break anything so I didn’t stand on the pipe. Just kidding!
Here’s a photo of the cowl plate.

If any one is in need of any “removable metal” such as the doors, fenders, hood, boot cover, fuel cap lid or bumpers, these are all good, solid parts.

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There are techniques for unsticking a stuck engine. It all depends on how stuck it is, how much rust is inside, and how far you want to go with it.
Some of them can be saved. You may have to destroy some parts in order to save other parts.
I once took apart an XK140MC engine that my brother found sitting in a field. The crank would not turn, which made it quite a challenge to get the split cotter pins out of the rod bolts so I could get the crankshaft out. Then I was faced with getting the pistons and rods out. Ultimately I had to destroy the pistons to save the block.
Interesting to see the Mark IV style ID plate with separate gearbox number plate. This car is earlier than mine.
Any more pictures?

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I didn’t take as many photos as I should’ve but wasn’t thinking about posting them. I just took a few to remind myself of the overall impression.

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Thank you for posting these pictures.
There is plenty useful “stuff” there.