1997 Vanden Plas with 113,000 miles on it has started to have a coolant leak which seems to be getting gradually worse. I can see where the coolant is collecting, but not where the leak is coming from -- can't find a spot that seems to be the origin. It's collecting under the front three tubes of the intake manifold in front of the throttle body.




The coolant is collecting on a shelf of the block underneath, then dripping on the suspension. It does NOT seem to be coming from the fuel pump. I've followed the hoses and nothing seems wet or deteriorated.

Any ideas?

 

It's almost impossible to see, but the hose from the water pump ends right where your leak is, and it's a fairly common source. Replacing it is difficult, and cleaning the nipple is even worse.

 

Not sure what you're calling the fuel pump..... but it is mounted in the tank, back between the rear seatback and the boot... and as far as I know, not served by the engine cooling system- so yeah, I reckon we can rule that one out as a possible source.


I think RJ's probably referring to what is otherwise affectionately known as the "b*st*rd hose."


Here's a closer look:https://www.jaguarforums.com/forum/x...enewal-101914/
It's not the lower rad hose, but I covered its renewal in that thread..

 

Yup, more than likely it's the hose going from the water pump into the water rail. Just had to do it on my XJR about 2 weeks ago. Not a hard job, but just A LOT of things are in the way to get to it.
I didn't bother totally removing the whole intake since I didn't wanna go through the trouble of disconnecting all harnesses underneath. Just moved the entire front section of the intake manifold out of the way and just enough to get to the house. The hose, you can find on Amazon for about $15 or so. But I was able to get a similar hose with the slight angle bend for $8 at my local autozone. Just had to cut it a little shorter.
Doing it on a regular XJ6 is a whole lot easier compared to the XJR but it's the same concept...

 

Yah, sorry, I meant "WATER pump."

 

I didn't mess with the manifold. I was replacing the octopus hose and the upper and lower radiator hoses as well as the bypass hose, which is the likely source of the leak where it connects to the water rail. Also the water pump.

I did remove the secondary air pump, and when putting everything together I connected the bypass hose to the water rail before replacing the pump.

If you have not replaced the other cooling system hoses, I would suggest you do so at this time.

 

Got it fixed, it was indeed the hose from the water pump to the water rail.

Aholbro1, you are absolutely right in calling it the "b*st*rd hose." What a pain in the butt! Easy if the intake manifold is off, but almost inaccessible otherwise. To get the hose on the nipples required soaking in hot water - and then tightening the rear hose clamp in situ is nearly impossible.

Fortunately this old pastor knows a lot of British cusswords that don't mean anything to our neighbors

 

Hey, I have a similar problem. I have a 1996 Vanden Plas 4.0, and I noticed my coolant is needing to be refilled too often. Half a year ago I had a coolant hose bust and had it replaced. But just about two months ago, my low coolant light came on and I refilled it. I checked the oil then and it was fine. The coolant light came on again a month later, and I topped it off; it was only slightly low. But the light came on again a few days later. It's not low, so I left it alone this time. But just yesterday when checking everything, I noticed the oil was a little low and there was a little contaminate liquid on the stick. There were a few tiny collections of almost bugar like curds on the stick. I am concerned that my head gasket my be going out, but I also read that a water leak from the ******* hose combined with a bad intake manifold gasket could be the cause of my problem.

Any Advice? I also don't have much money for this repair. I need to try and keep it under $300. I can do the work myself, but I don't want to shoot in the dark.

Thanks.

 

I just recently noticed some water contamination on my dipstick also, but it was just condensation. This occurs in winter conditions when the car is driven on fairly short runs. Stop at a Lowes or HD and buy a 1/8 " dia dowel 3 ' long. Stick it down the dipstick tube to the bottom of the pan and if it comes out just showing oil and no yellowish molasses everything is okay.

As to your coolant loss, there are a few places that a leak will not be evident. The primary one is the water rail coupling.

With a pressure tester that you may be able to borrow from an auto supply store and a mirror and flashlight you may find it, but it's not often easy. The connections at the back of the water pump and the pump itself are also good candidates.