Hey there,

well, I'm moving on with my XJ-S and have discovered leaking water rails... Yes, those "darn" pipes... It is leaking from the area where the pipe is pushed into the rubber bush. I assume the pipe has corroded and the rubber is brittle.

Oddly, it didn't leak there before (at least not that I could tell) I filled the system with new coolant. Looking at the "slurry" I got out before flushing it, I think it was run without antifreeze...

Anyhow, I've read that these pipes are "wear and tear" parts which seem to require regular maintance. Has anyone got a recommendation for some good replacement pipes? Stainless steel or copper? Maybe even brass? Being only a short pipe should require rocket engineering

As far as I have seen, I need to remove the entire water rails - from front to rear. 4 little gaskets per side (bodies to engine) and 4 rubber bushs.

Is there anything else I should consider changing at the same time? Thermostats: done. Hoses: done. The extra air valve is a brand new part (original Lucas) so that doesn't need to be replaced...

I was thinking about doing all the sensors at the same time... Other suggestions?

Cheers

Damien

 

Stainless water rails a good idea. The existing rails may be Ok but equally may be rusted a bit. All the gaskets and top hat water rail/manifold seals still available from Jaguar. There is a theory that the water at the back of the engine gets less well circulated and that the water 'short circuits' round the front of the engine. This can be ameliorated by reducing the size of the holes in the front manifolds as shown here:



The hole nearest the front is about 4mm and the next one about 12mm. This is standard practice apparently by the racers. Careful how you undo the water manifold bolts as they can snap, though mine were no problem.

Greg

 

Gregg, how's that been done welded or plugged?

 

@ Greg

I'd be very careful opening the screws... Last thing I want is those to snap in the engine block... Can't be bothered to remove the engine (yet)

Regarding the closing/reduction of opening: I don't think I'll do that. Seems a little too much

Cheers otherwise!

 

Plugged, interference fit and then machined flat.

Greg

 

making a Jag V12 run cool in all climate temps, can be labor intensive and expensive.

but well worth the it! depends how far you want to go.

 

I purchased a 3ft section of stainless tubing from McMaster-Carr for ~$30. I then cut it to length. The pipe is technically considered tubing due to its thin sidewall. I then cut it to size and installed new rubber rings. I also used rtv sealant just to be extra safe. I will post later this evening when I get home with part numbers.

 

Jag Lovers suggest making another little ring around the end for a better seal... Would you say it needs it?

 

I like the look of copper for the coolant rails. I think the look pays homage to grand motorcars of the 20s & 30s.

I've polished and clear-coated at least a dozen pair of copper pipes without adding an additional ring at each end, and have installed them on two of my own engines. I never had any complaints of leaks from customers I sold the pipes to, nor, have I ever had leaks on my engines after installing. The rubber top hat seals heat up and bond to the pipes and housings very well without additional sealant.

 

Scott, do you happen to have a picture of a copper pipe fitted? I am so tempted to use copper, as it just has that classic look you mentioned

And cheers about the housing bond bush things... Sounds perfect!

 

Here you go.
They are kinda buried under all the intake paraphernalia, so someone really has to be checking out your motor pretty closely to notice them, but, they really are like jewels when they're in an organized engine bay.

 

JagZilla, that is really sharp looking!
While doing the rails on mine recently, I also went with copper. I bought 2, two foot lengths of Type "K" hard copper tubing from a company called Zoro. Did not use any additional "shoulders" and it seems to be working just fine.
Here is one side while work was still in progress.

 

Looks good Bill. I see that you also replaced the cam cover bolts with Allen head screws.

Good point. You won't find this size copper at Home Depot or Lowes. I had to buy it in a 20' length from a heating & A/C supply company.

Another important point if someone is planning to clear-coat their coolant pipes, be they copper, stainless, or whatever, is to tape off the ends of the pipe before they clear-coat them. You want bare metal bonding to the top hat seals, not clear-coat.

 

Copper it is! I really love the look of it...

I also thought of simply replacing all the sensors along the rails... Seems mine are all reaaaally old So they'll be redone at the same time.

Do I need to remove the extra air valve separatly?

 

The sensors are brass, so, they look pretty good polished & clear-coated too. I wouldn't remove the AAV from the coolant rail housing unless the gasket is leaking or something.

 

The gasket is luckily not leaking. The AAV is as it looks really new (or recently replaced) so the gasket would have been done at the same time. I asked as the screws/bolts seem awkward to access behind!? I intend on having the rail "bodies" blasted (probably glass blast as it should look tidier).

 

As said, I want to replace the sensors and have stumbled upon this one (the brass one!):



What does it do? If it is important: how can you check if it works right? This may sound "cheap skate like" but I am repalcing all the sensors - just this one seems like the only one to cost an "arm and leg". Basically the price of all other sensors together. I have one spare (from my scrapped XJ-S) and don't fancy fitting a new one for the sake of it...

Is there a way to check if it is working right? Anyone have some suggestions?

 

If the bit you mean is the thing with the two wires to it, and it is on the A bank rear water manifold, then it is the 15 minute timer water temp switch. It keeps the mixture rich for 15 mins after start up, for no real purpose, and disconnecting the wires disables this part of the warmup procedure. The Great Palm's book explains this in detail.

Greg

 

Yeah, that was the one I meant. Hmm, rich running "just for the sake of it"? Not sure if I like that!

 

As I stated earlier I purchased a 3 ft section of SS pipe from McMaster Carr and Cut it to length. Part # 89785K857, cost was $33 plus $8 shipping. I also put a small chamfer on the ends to assist install.