4.2 supercharged coolant system schematic diagram.

[J44EAG]

This is the cooling system diagram in schematic layout. It is a little confusing as the engine driven water pump is shown sitting in the middle of the V of the engine. In reality, its at the front of the engine with the thermostat "pipe" in front of it! Some mental "pipe bending" is needed to equate what you see on the engine when compared to the diagram.

The reason for sourcing the diagram is because I have a partially blocked drivers side heater matrix and reduced heat in the cabin. To test for a blockage if your heating deteriorates, switch to the touch screen climate control screen and select the face vents as the heat distribution hot air exit. Set heating level to full hot. If one vent is blowing colder air than the other, you have either a partial or full heater matrix blockage on the cold affected side of the car. No heat at all from both vents indicates a possible electric auxiliary heater pump issue. The pump is located directly under the header tank at the front of the car. It isn`t easy to get to or replace. If you have double length arms that will help! The pump operates full time when the ignition key is turned to position 1. The main engine driven pump operates solely for engine cooling with the aux pipe providing the flow for cabin heating.

Before replacing the partially blocked dual core heater matrix, my intention is to flush the coolant system with fresh water and add two bottles of rad flush. I`ll then drive the car for an hour, flush out the system with a hose and refill with anti-freeze mix if I`ve cleared the blockage. If not, the matrix will have to be replaced. That`s a nasty job accessible which requires parts of the heater unit to be removed via the passenger foot-well area.

Flushing the XJR engine is rather more complex than naturally aspirated models. There is obviously the engine radiator and also the inter-cooler circuit and its separate rather smaller radiator. In addition the cabin heating flow and return circuit need to have coolant evacuation. So its three sections of plumbing to be dealt with. I believe the main coolant radiator has a drain plug on the bottom near side. An engine block drain figures on each side of the engine. To gain access, the large under engine tray must also be removed. Corroded fastenings can make removal frustrating. Not all rad and ancillary hoses to joint to component parts or are they in convenient locations. This makes vacuum or pressure coolant evacuation a bit of a tease. I envisage odd bits of hose, connectors and Jubilee clips being needed to concoct a flushing rig. Flushing procedure will need to be applied at least twice. Once to flush anti-freeze mixture out with another flush needed to remove the rad flush. I`ll need probably a day to get this work done.

More on this when I get the enthusiasm to crawl under a blocked up car and get soaked in the process.

Mike

[Manbearpig]

Eurgh, not a job that can be put off until spring then? I hate dealing with cooling systems this time of year, upside down water running down your armpits. I try to be preventative but its always going to be this time of year when something rears its head.

[poprivet]

I've seen that diagram before somewhere. Might have been in the London Underground