Coolant hoses
 

Hi all!

My heater motor decided to die on my so I have no heat unless driving at around 2500 rpm. I know what it is, I know the fix with the brushes, but I've decided to just replace the whole motor. I figured while I'm "way down in there" with everything torn apart, I might as well go ahead and replace all the coolant hoses, including the valley hoses

What coolant hoses will I need (I know there's a bunch of them), and what is a good reliable source?

I don't need to bother with the actual radiator hoses as I replaced those when I changed the crossover pipe.

1999 XK8 4.0

Thanks!

In the Same Boat
 

I am also in the same position getting ready for the ordeal. I intend to replace the valley hoses, thermostat tower with a metal one and the "spider" octopus heater hose. My car is a 2000 and has zero corrosion as it is a warm weather Florida car. Once I get in there or course I wll do the visual inspection and replace what looks shot.
So far I have purchased the thermostat tower (Welsh) and the valley hoses and the plastic connector (AutohausAZ). I wil purchase the "spider" hose from Newparts. I have all the gaskets which I believe came from Rock Auto.
One thing I am going to make sure to get is a set of hose clamp pliers , expecially the one that has a two foot reach. Also a set of metal fuel line disconnects.
As our cars are both AJ27's I look forward to seeing how you make out. Good luck

Have you confirmed the pump is dead? There are several "no-heat" scenarios for our cars. Easiest is to identify the relay and check resistance. An open circuit would confirm the worn brush diagnostic. If there is some resistance, you can do a shunt wire and force the pump to run from the same relay location. It is very quiet, so it is nice to confirm the pump runs with the engine off. Also double check the fuse of course.

Best of luck, keep us posted.

Don't forget the plastic 3-way connection under the throttle body!!!!! Go to SNG Barratt's site (link below) - they have diagrams with parts list - so you can see exactly what you need. Heater pipe feed and hoses and the water valve pump & hoses diagrams.

https://www.sngbarratt.com/us/#!/Eng...6/13903/1/10/1

You don't need to remove the intake manifold if you're going to replace the auxiliary [heater] pump, but it makes the job much easier as you clear the top of the engine and provide greater access to the pump. MJA6710AA - Auxiliary heater pump (all years). I discovered two separate e leaks, one at the Norma connector on the DS valley hose; and another on the radiator outlet pipe, the black plastic hard pipe black front of block. AJ85885

Removing intake means new gasket s for 8 intake ports, plus throttle body gaskets

8 each AJ83356 Inlet Manifold Seal intake ports

TB gaskets are two styles
NCA3021BA - Throttle body gasket for older '97-?? (the gasket is almost square)
NNE3021AC Throttle Body Gasket for newer cars (the gasket is pointed on one side)

While you have intake off, you should replace valley both heater hoses under the intake manifold, and the plastic part load breather line

2 ea "Valley Hoses / under intake aka Heater Hoses
NCA3945CD Pass side aka Heater Feed Hose
NNE3946CA Drivers side aka Heater Return Hose
NNE3944BA Norma connector T for hose to TB bottom

AJ84880 Part-Load Breather hose (under intake)

plus all the heater hoses, including the octopus hose. These run between the pump, the valve and the octopus hose
MJA-6728-AC - Octopus hose

MJA6721AG Heater hose
MJB6720AC Heater hose
MJA6710AA heater hose

I'm probably missing some stuff, but this is the basic list.

Three men in the same boat
 

Well, it seems this is contagious, and I’m in the same boat. The cooling system in my 99 XK8 works hard in the desert climate of Bahrain. I like to get my hands on my beautiful car, and noticed my hoses are becoming either rock hard or soft and bulgy. Can see some minor weeping at some places esp. at the clamps.


https://cimg0.ibsrv.net/gimg/www.jag...85a7427a0.jpeg

Richard, at British Parts in the UK, is sorting me out with the shopping list above. He’s super helpful, knowledgeable and already stocks pre packed kits for certain jobs ie the Valley hoses debacle. Whoever thought it’s a good idea to route coolant hoses on top of the engine block, obviously didn’t think of how to maintain them

Yep, it's the motor. I've swapped out the relay with no luck, resistance is fine. Prior to utter collapse of heat distribution, I had to decrease the heat to zero, and then increase the heat to high to get anything to come out. Finally, just high worked, then....drive at 2500 rpm for heat...

If the brushes are worn out, the resistance to the ground will be "infinity". Anything like a few ohms means the brushes are likely fine.

You can disconnect the plug to the heater valve as it defaults open. See if you have plenty of heat then.

Also, check the external temp reading on the AC panel. Anything way off like 130 deg means the sensor is bad and the heater valve will remain closed.

I would start with a flush of the core, way easier, way cheaper.

if the heater valve defaults open, by disconnecting the plug, would that not close the valve and prohibit heat? If I'm thinking backwards on this, then I will definitely unplug the valve before anything else.

With the plug disconnected, a properly functioning valve is wide open.

Last (easy) thing to check is that stupid return hose off the heater core, the one with the one-way valve in it. The top part flattens as it bends, supposedly by design, but can collapse and block flow. See if the can use some pressure (vice-grips) sideways to force this hose to open up some more and bring you some heat. This hose is not super expensive and fairly easy to relace with the tank out of the way.

Well now, if the Gods be smiling, then this Saturday I will disconnect the plug and then have some heat. If the valve is faulty, what are the concerns if I do not choose to replace the valve right away?