Water Manifold take off broken


(David) #1

In replacing the rubber water pipes, etc on my MK IV 1 1/2 litre the take off outlet on the side of the engine water manifold (for the pipe that goes through the bulkhead to the Air Conditioning unit under the dashboard) literally sheared off in my hand as I unscrewed the jubilee clip to get the old hose off. Does anyone have any experience of how this outlet is fitted to the manifold cover (I don’t want to damage anything before I know exactly what the set up actually was), and I cant see if this was a threaded outlet without doing some “digging out”.


The outlet connector before it broke off


It literally fell off in my hand !!

Any information or photo of a possible repair/solution would be much appreciated. Thanks


(Robin O'Connor) #2

It looks to me to be a badly corroded steel fitting in the alli. Try a bit of heat and an easy out, (waiting for the flameing to start) :slight_smile:


(Ed Nantes) #3

The bolt is a standard BSP fitting, so that part is easily replaced
I would suggest maybe better done off the engine.Because if the bolt is like that, the inside of the manifold would need to be checked.If off the engine, the manifold could be soaked in Penetrine firstly , then try an Easiout, And if that fails drill/ mill out the remains of the thread. The ID of the thread is.600" so drill to less than that then you may find a 3/8" BSPF tap will cut out the remains of the thread.
Replac e the bolt with one that is plated and some sealant on the thread.
Consider that if the bolt is corroded, is it likely that other parts of the cooling system are in a similar state.


(Paul Wigton) #4

Ive forgotton the chemical, but @Andrew_Waugh has mentioned a bath in such that eats rust completely… phosphate, alum?

Might be a gentler way to do it.


(- 1950 MkV, 1959 XK150,) #5

I’ve read about a molasses bath being used, but have never tried it myself… ???

Update - DONT use this, I just googled it and it eats aluminium… :frowning:


(Rob Reilly) #6

Yes, it is what is called a banjo bolt. Many early Jags used the same size which I believe is 3/8" BSPP so it should be easy enough to find a new one.
If you are in the US my favorite source is Metric Multistandard.
To Ed’s advice I would also add a few heating and cooling cycles with a propane torch. Drill it out to 9/16" or 19/32" and then what’s left will collapse inwards with a small flat end punch and hammer.


(Andrew Waugh) #7

Alum. Same stuff as you get for making pickles.

You boil the part in an Alum solution. The Alum dissolves the steel part, but doesn’t affect brass or Aluminum.

It will probably put a layer of black smut on the Al, so you’ll end up having to wire brush/beadblast it, so arrange the bath so that only that corner of the manifold is immersed in the solution.

It is a slow process - a 1/2" long #10 screw in a blind hole (with an Easyout broken off inside) will completely dissolve in about 18-24h, so you’re better to drill/grind out as much as possible before you start.

It’s something I picked up from watch and clock making, where the screws are a lot smaller.


(Ed Nantes) #8

SU Carby banjo bolts.
But these only have 2 holes. If you want a hi performance competition banjo bolt for the heater, they sell them for hydraulics [ bulldozers and the like] with 4 holes.
I think LHD MK IV oil lines use these.too.


(David) #9

Great advice - thanks everyone. I start my course of work on it. Anyone got any photos of new or clean parts of the manifold outlet thread, banjo, etc?


(Rob Reilly) #10

Here is a single and a double hollow bolt.

Here is Metric Multistandard’s page with metric threads. I couldn’t find the one with BSPP threads.
8-842-1.pdf (125.9 KB)


(David) #11

Does anyone know the hollow bolt length/thread length for the outlet of my 1 1/2 litre engine, as I want to order the parts and don’t want to over-screw it into the water manifold (when I’ve managed to get the old broken one out).


(Rob Reilly) #12

I believe there are only the two lengths, made for a single banjo as used on the XK120 and Mark VII thermostat bypass hose to water pump, or double banjos, as used on some XK120 water pumps with a heater hose fitted there.
You want to use new copper washers on both sides of the banjo.