Edward F. Sowell
1976 Jaguar XJ-S
The coolant crossover pipe is a black, steel pipe running across the front of the engine, right below the air-conditioning pulley. It connects to the engine at ports beside the thermostat housing on each bank, and connects to the water pump a little to the left of center. Its function, according to the Repair Operations Manual (ROM), is to carry coolant from each bank back to the water pump inlet when the thermostats are closed during warm-up.
All three connections points for the pipe are close coupled with short hoses. This, together with the cramped space at the front of the engine, makes replacement of the hoses difficult. I tried to do the job myself several years ago and wound up having the car flat-bedded to the Jag shop to have it reinstalled. More recently, having the front of the engine exposed to replace the front crankshaft seal, I decided to try it again. I thought it would be easy with all the fans, radiator hoses etc. out of the way. Well, it was a little easier, but still difficult. Getting it off is not bad if you first cut the hoses with a utility knife. Getting it back in place with the new hoses is the challenge. But this time I succeeded, so I thought Iíd jot down the secrets.
It will help greatly if you realize up-front that you are going to have to remove some things for access. Here is my list:
Removal of Crossover Pipe
Since you are going to replace the hoses anyway, take the easy route here and cut all the hoses through the middle of the joints. Then remove the clamps and use a small screwdriver to remove the hose pieces.
Cleanup and Paint
The pipe is steel, and you will probably find it is rusted up at the hose connection points. Brush it vigorously to get to bright steel, then sand the whole thing. Prime it with a Rustolium primer, then flat black paint. This may slow down the rusting as well as making it look a little better.
By the way, the crossover pipe is no longer available for early cars like mine. However, an aftermarket replacement made of stainless steel is available from Cathouse Spares, Sydney. Tel: (02) 9747-2144. If I had been aware of this when I did this work I probably would have bought one. Later, I got one of their stainless remote header tanks and am quite happy with it.
The problem with reinstallation is trying to get all three of the hose joints together simultaneously. If the air-conditioning compressor were not there, it would not be too bad. But since it probably is, you will find that when you get the two end connections made you canít get the middle hose over the water pump inlet because the pipe is hitting the compressor clutch. It's impossible to get a good picture of the situation, but Figure 1 will give you some idea. Shown there is the water pump connection and the connection to the right thermostate housing.
Here are the reinstallation steps worked for me:
Hoses: I got mine from Jaguar, C41373 (2), C41374. However, these are straight hoses in standard sizes so you can probably get them cut to length at any auto parts store. If you go that route have the store cut them to the exact length of the original because if they are too long your job will me much more difficult.
Crossover pipe: C44186 (no longer available from Jaguar). Buy stainless steel replacement from Cathouse Spares, Sydney. Tel: (02) 9747-2144.