1988 xjs v 12 anybody know the correct positioning of the banjo bolt on top of the radiator?

 

Looking down from the top facing forward:

You should have a long thin tube with two outlets at one end, and a round banjo at the other end with a short outlet from the banjo.

RHS top of rad = banjo bolt. The short take off goes backwards and connects to the centre filler neck at the front of the engine, via a rubber tube. The long part of the tube goes sideways along the rad top to the LHS where it branches into two. The RH of these two connects to a take off from the LHS thermostat housing, the LHS of these two goes to the header tank on the LHS inner wing.

The banjo bolt stack assembly into the rad order is:
copper (or fibre) washer
Steel spacer
copper:fibre washer
banjo part of the thin tube
copper/fibre washer
then in goes the hollow bolt itself through the stack.

It is important to make sure the hole in the bolt aligns with the banjo groove, the washer thicKnesses can affect this. If not, extend the hole downwards to ensure it does. Sealing is always a problem here, so some flange sealer Loctite type stuff is not a bad idea, as long as it is sparingly used and does not block the banjo.

If you need a photo, post again.

 

so as long as it seals it should be good? thought maybe the holes in the top of the bolt may have to point in a certain direction. i drew a line on top of the bolt so i would know where the holes were.

 

No it does not matter which direction the holes are facing. The tube that goes along the top of the radiator has a hollow 'donut' such that the banjo may freely outflow regardless of the orientation.

The thin copper crush washers are one time use in theory... if you reuse them they will most likely leak. If you use thicker generic copper washers (which are what are readily available at auto parts stores) on reassembly, you will have two problems:

1. You could (will?) cause the holes on the banjo to no longer line up with the outflow portion on the tube. Totally stock it is already close. You can fix this by 'slotting' the holes in the banjo downward towards the base with a handheld rotary tool. Don't go crazy, just enough to make up for the thickness of the top washer.

2. Because there are three sealing washers total, replacing all with thicker ones will cause you to lose a significant portion of the available thread that goes into the radiator (mine stripped out with very little torque). A good hardware store will stock 3/8" inner diameter steel spacers in various sizes (my local Ace Hardware has a large selection), and you can replace the stock steel spacer with a shorter one for less than $4 to account for the difference in crush washer thickness. While you are there, see if they have 3/8" ID fiber washers, which unlike copper crush washers you can reuse.

Alternatively FasterJags sells a replacement banjo that has larger holes in the top and is longer, so you can use thicker washers without adjustments. Costs over $30 with shipping.

Cheers,

- Will