Oil Tube Banjo Bolt Torque Spec

A question came up this week on the XK Forum about the torque on the banjo bolts for the oil feed pipe between the block and the head.
It is 3/8-16 UNC thread, and both center drilled and cross drilled, so the stress area is reduced. Naturally the maximum torque would be less than a normal bolt.
Nothing is given in the XK120 Service Manual.
I wonder, is there an official torque for this bolt specified in the latest XJ6 Service Manuals?

Not that I’ve ever heard about. They’re the most terrifying parts on the car IMO, because a hollow bolt can easily shear and a course bolt into aluminum can easily strip, and either thing could result in a week or more of work to remove the head.

I think the best strategy is to prepare for it beforehand with a well formed pipe that doesn’t rely at all on bolt torque to pull it into correct shape, and that has smooth clean fittings, and goes on with the proper thin, soft copper washers. I like the ones with a raised rib. Some people like the plain ones.

Then apply very modest crush and start it. It will probably leak a bit at first so as it warms up, gradually take up another tiny incremental turn on all of them. If it doesn’t stop after a couple cycles of that, then it’s probably not going to seal with more force.

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No idea of an official number: personally, I would NEVER exceed 12 ft-lbs.

With proper new crush washers, clean, flat and parallel surfaces, that’s more than enough to keep them from leaking.

Sorry I wasn’t clear. I was merely asking if there was an official torque value specified by Jaguar in the XJ6 Manual.
I have an XJ12 S1 manual E172 and it has torque values for all kinds of things in the front.
I would think the factory XJ6 manual would have something similar.

I know its only the Haynes Manual for the XJ6 and there is nothing in there for the banjo bolts. It does have a list of spanner openings though🤣

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I guess the banjos can only be tightened by, as the Rolls-Royce manual states, “an experiened fitter.”


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In the S3 Workshop manual the banjo bolts going into the head are „refit“ and not mentioned in the table with torque values. There’s no banjo bolt on the rearmost main bearing and the oil comes from the filter directly.

Thank you David, that answers that. I did not know that about the S3.

I see in the XJ6 S1 SPC there is still a hole in the block at the lower left rear, but it is apparently just plugged with another C.5846 banjo bolt and C.4146 copper washer.

I’ve never broken one, and I once removed some parts from a derelict Wraith, so I guess I count as an “experienced fitter”. :laughing:

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The S3 blocks I have, plus the Jeep’s, have no plug nor machined hole in that area.

The S1 blocks still use the rear main bearing location. You can see that the feed pipes in the drawings are the same as in the E Type.

This (below) is the best I can do on a S3 block and you can just tell that it’s roughly machined - but there’s no hole drilled, just a flat surface.

I haven’t really had trouble with those so torque was probably thought to be entirely uncritical. Or forgotten.

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If anyone knows what the hole in the last picture is about, I‘m all eyes! Just aft of the dipstick.

The big ones in the bottom face? My XK120 has them too. Probably used for locating/centering the block during the machining process.

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Those are registration holes, to align the raw cast block in the ensuing machine operations.

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I see. Thank you both!

There were early and late banjo oil feeds in the XK120–in some the banjo itself had the annular groove for oil–the bolt did not have a groove…in others the bolt had the groove, the banjo did not. Caution --not to put a no groove bolt into a no groove banjo: there is little room for oil to flow to the cams !!.
I suppose if BOTH were with annular grooves there would be more oil flow ?? No idea of the effect of that on the oil system?? In later engines…over the years–with who knows what replaced parts…good to check for the annular grooves in both banjo and the oil banjo feed bolt. Source: Jaguar factory service manual, B-31 bottom of page…starts with “Important Note”–

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That is a critically important thing to know! Not that I ever really need it, but it’s always cool to find out that little stuff.

If you really wanted to know a yield torque couldn’t you torque ever increasing values until the banjo bolt just snapped and work backwards a reasonable amount from there?
OK, Im braced, let me have it!!!

The problem with that, at least in the XK head, is the female threads are in aluminum and you will strip out those threads long before the bolt failed.

You’re probably right about that.
I just thought the wall thickness of the bolt was quite thin and would easily yield to over torquing.
As far as a value, I don’t think I would exceed 12lbs. At that value the proper washers should be more than sufficiently crushed.

when torque in ft lbs gets low–below 20 or so, I prefer to use an inch lb torque wrench. Small discrepancies in the larger ft lb wrench can mean a lot. Cam bearing caps would be an example. and–Source for the banjo annual groove info is Service Manual B31, bottom of page.