Water rail gasket replacement without removing Inlet Manifold

Replacing Jaguar XJ40 water rail gaskets do-it-yourself – without removing inlet manifold.
The vehicle specifically involved was a 1989 XJ6, 3.6L left hand drive.
Tools needed:
10 mm socket
13 mm socket
less than 8 inch long ratchet
less than 6 inch long ratchet
socket extensions
screwdriver and/or hose clamp sockets/driver
2 medium-size allen key
hammer with wooden handle or rubber grip
nylon/scotch abrasive pad
acetone and rubbing alcohol
lighting and a step
wire brush
rust remover
plastic bag large enough to fit water rail
2 EAC 9745 gaskets
small bungee cord

To begin, I discovered that these gaskets frequently fail when the water rail hose is replaced. The gaskets are more a means of applying sealant to the mating areas then they are a classic gasket. If the water rail securing bolts work their way loose the gaskets will fail if you try to install a new hose. Do yourself a favor and check and tighten these bolts before attempting to replacing the hose.

  1. Displace and secure the battery ground lead.
  2. Remove the air box. Two securing nuts are visible. The third is in the front, down low and difficult to see. I removed the top half of the box first for ease of access.
  3. Unplug and remove the air meter. Be sure to disconnect the ground wire located on the front corner closest to the fan.
  4. Remove the bolt securing the oil filler pipe to the inlet manifold and displace the attached vacuum hose. Displace and secure the filler pipe to the inlet manifold using a small bungee cord.
  5. Jack up vehicle. To maximize drainage and to avoid getting wet, raise only the left front.
  6. Drain radiator.
  7. Displace the expansion tank hose at the water pump and move out of the way.
  8. Remove vacuum hoses from thermostat as needed for access to the water rail through the front of the inlet manifold. Label vacuum hoses as needed.
  9. Remove bypass hose from the thermostat to the water pump.
  10. Displace heater hose from water pump and from the resistor located at the top center of the inlet manifold. Move hose out of the way to open access to the water rail.
  11. Remove hose from thermostat to resistor, noted above.
  12. Displace the vacuum hose from the cam cover pulling it down through the inlet manifold and out of the way.
  13. Unplug the wire from the device attached to the block below the water rail. It pulls off simply.
  14. From under the car displace the starter ground cable at the solenoid using the 13 mm socket and the small ratchet.

The teardown to access the water rail is now complete.

  1. Remove the water rail hose.
  2. Remove the four bolts securing the water rail. The front two are accessed through the front of the inlet manifold. Use the step and a light to look down through the manifold in order to better see what you are doing.

I used the less than 8 inch ratchet, a 3/8 inch to a 1/4 inch adapter and the 10 mm socket to remove the front to bolts. It gave me just enough room to clear the water rail. I used the butt of the hammer, pushed down through the gap in the inlet manifold onto the ratchet handle to release the tension on the bolts to avoid a potential knuckle busting experience.

The rear bottom bolt can be removed from under the inlet manifold using extensions inserted between the manifold and the heater hose. The top rear bolt needs to be released from underneath. There isn’t enough access to use wobble or jointed extensions.

  1. Remove the water rail through the front of the inlet manifold.
  2. Thoroughly clean the mating surfaces on the engine and rail using a nylon pad and acetone, finish clean with a towel and rubbing alcohol.
  3. If the bolts are fouled, clean them using rust remover and a wire brush, or replace with new bolts.
  4. To avoid having to locate the gaskets while simultaneously trying to bolt down the water rail, adhere the gaskets to the water rail using high-temperature coolant resistant gasket sealant, flat side down and allow to dry.
  5. Place the water rail in the plastic bag to avoid fouling the gaskets while feeding the rail back into position. Remember the gaskets are more a method of applying sealant than a classic gasket, they must remain clean.
  6. Remove bag while locating the rail to the block. This can be accomplished more easily by temporarily inserting allen keys through the rail into the bolt holes, one in front, one in back.
  7. Insert and hand tighten bolts into the open bolt holes, then remove the allen keys and insert the final two bolts.

The rear bottom bolt can be tightened by using in extension inserted between the underside of the inlet manifold and the heater hose. The rear top bolt can be final tightened using the butt of a hammer press down on the ratchet handle through the gap in the inlet manifold. The front 2 bolts can be tightened through the front end of the inlet manifold using the less than 8 inch ratchet. The bolt ends are extra long, I had no problems tightening them down one-handed.

I tightened until my ratchet handle started to flex, the Jag spec is 25Nm, I believe.

  1. Reattach and reinstall the hoses, wires, plugs and air intake in reverse order. Refilling the cooling system will take a little more than 8 liters of coolant.

All well and good if the bolts are not frozen, stripped or snapped as they are often on cars with only sealant OEM fitted at the rail, not gaskets. (like mine)

(Mine now has gaskets BTW)

Even with the entire left side of the motor components removed this was a f**ker of a job.

Thank you for the writeup GoCougs I tacked mine yesterday

Just wanted to add I removed the oil filler tube completely and also part of the Throttle Body but if I were to do it again I would remove the whole throttle Body.
I hoped to reuse my water rail hose but ruined it trying to put it back on. I should have left the hose in position on the water pump housing and removed the water rail so I could have put it back on.

I agree those 4 bolts are very “tender” …

A few years ago when I rebuilt the head on my '89 XJ40 I decided to remove and reseal the water rail even though it had never leaked (preventive maintenance :roll_eyes:).

Although I had unobstructive access and was VERY careful … 2 of the 4 bolts still sheared off. A pig of a job removing those 2 broken bolts.

My own water rail story was a nightmare also involving broken bolts, corroded and stripped threads in the block and a helicoil kit. It didn’t help the car was 50 miles away from home base when it all went to hell.
We did the job in a friend’s backyard and used gaskets that we made to seal the rail as none were fitted at the factory for my model year. Gaskets were re-introduced for X300’s.

Is there any worse a feeling when undoing crucial bolts like that and they just seem to turn to toffee and shear off ? That sickening feeling in the pit of your guts when a ‘straightforward’ job turns into a long drawn out nightmare. It’s happened to me more times on XJ40’s than any other car I’ve ever worked on.
The first time I experienced it was changing the oil on my Sovereign and the sump plug stripped.
The latest is the Positive jump lead terminal on the bulkhead/ firewall, I wouldn’t mind so much but it sheared with the slightest of force.

Casso, indeed. :sweat_smile:
You may remember the 12 mm rear subframe mounting bracket bolt that snapped when I was replacing the subframe bushes in 2021. I would estimate it took 15-20 hours to remove the old bolt including acquiring special drill bits and making a helicoil thread.

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The devil in removing and replacing the bolts on the water rail is aluminum oxide that cements the bolt to the block. There is only ONE THING that breaks the hold of the aluminum oxide and that is HEAT. Purchase four new bolts I believe they are 8mmX1.25 thread and anti-sieze compound. Use a small propane torch (small butane may work) and carefully HEAT THE HEAD OF EACH BOLT. Carefully break loose each bolt. If any don’t break free, re-heat and try again. After removing the bolts throw them out and using new bolts, smear them with anti-seize and reassemble. Heat and anti-seize, they are the only solution. It is not difficult removing the intake manifold makes the job possible. Good Luck!

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