Fine Friends of the Jag Forum

I write today to let all know that I have finally, without doubt, root caused and sourced the headwaters of my coolant leak.

My leak was significant, located a puddle in front of the engine, approximately center of the vehicle, favoring slightly the drivers side. At times would be relatively slight, approximately a 6" diameter puddle. Other times the spot would be massive, literally a puddle fish could swim in. From the top of the motor under hood, there was little witness of any leak - no splash or blow off type streaks of coolant across anything.

Also, please note, as this is relatively important, with the undertray on shielding the underside of the car, the coolant could collect in the tray, and either be absorbed/dissipated over time, or run out the back and establish a puddle toward the rear of the motor - perhaps masquerading as another well known source of hose failure, or limiting the initial understanding of the leak.

Also please note that you will likely "smell" burned coolant when exiting the car, perhaps even before you witness the leak on the ground. A person could easily smell the burned coolant when under hood, but not see any visible cause when doing a quick check after noticing the smell.

So, to sum up:
1) Burned coolant smell when exiting the vehicle, heaviest when standing next to the front tire, drivers side.
2) With the under tray on, perhaps no puddle witnessed - but have the smell - or puddle toward rear of engine.
3) With under tray off, puddle toward front of engine, approximately center, favoring driver side.
4) Puddle could be slight, 6" diameter, or very large (OMG large), requiring as much as 1/2 gallon to be added to reservoir tank.
5) When changing oil, noticing coolant leakage on filter body, or on front of oil pan.
6) Under hood no splashes or other blow off witness on plastic bits. With engine warm, scent of coolant very heavy.
7) When attempting to source the leak, notice coolant on pulleys, belts, water pump area, and other bits and pieces that seem a bit odd.
8) When sourcing the leak/changing oil, you notice a bit of coolant collecting on the transmission coolant lines, or the coolant lines mount. The fall path of this leak is primarily onto belts, but trans coolant lines are easy to get to as well, which allows coolant to collect and run down the transmission lines.

IF ANY OF THESE CONDITIONS SEEM ALL TO FAMILIAR:
You may have a "cut" in the backside of the upper section of the "bottom radiator hose", caused by the accessory drive belt coming in contact with the rubber radiator hose.

My hose has a significant "notch" grooved in it from the belt contact. This contact may not be readily apparent, as there is approximately a 1/4" of clearance from the hose to the belt when the car is not in operation. My guess is that over time, and as the engine operates, the hose (which is largely unrestrained) can vibrate/oscillate to the point where contact with the belt is made, eventually grinding a hole in the hose.

In my case, I noticed the smell long before I noticed a leak of any type. Eventually I started getting a leak toward the rear of the motor, and at times of oil change I would be puzzled by coolant on the filter.

I will post images of the failed hose later, for now I will post the pic and PN from the JEPC.

Hope this post is able to help others diagnose an issue where the root cause is a bit mystifying...

Kind Regards

 

Interesting.

How many miles does your S type have?
Is your Jag a 3.0, 4.0, 4.2, or 4.2 super?

I think the hose is the same for all of the engines but am not positve.

I am doing some general maintenance on my 05 STR with 70k and will take a look at my lower RAD hose to check it condition.

 

Interesting find. I would check the belt tensioner and make sure that it is keeping adequate tightness on the belt as well.

 

Car is an 03 STR with 115K. Tensionor is doing his job well, belts are new....

Also note here, that the hose can be "rotated" on the thermostat housing.
So, until monday when I can order a replacement, I picked up some silicone high temp tape ($6) at home depot (anyone with a motorbike ought pick this stuff up as well, put the remainder in my tool kit under the bike seat) - wrapped the offending area well with that stuff, then wrapped that business with some high temp aluminized tape.

Once I completed wrapping, I put vice grips on the band clamp at the thermostat housing, worked the hose loose on that end (did not disconnect), and rotated the entire hose assembly about the end of the tstat housing, providing much more generous clearance between the belts and the hose. Replaced the clamp, and my temporary band-aid seems to be holding.

Kind Regards

 

Ok

So, parts came in, one lower radiator hose from Nalleys (~$70), not too bad.

Installation wasn't bad, once I nixed the lower factory "squeeze type" clamp on the hose. There is just no tool clearance to get "squeeze" on the clamp and get it into position. Save yourself aggravation if doing this hose, and replace the lower squeeze clamp with a standard "hose clamp" with the worm drive.

Other than that, I've attached picks of the failed hose. The residue on the hose is from my literal "band aid" applied as described previously in this post.

Kind Regards

 

I prefer th all stainless screw clamps as well. Rolled edges even better. I also use a little silicone grease on the hose and fittings.

But ... did you try one of these. I've had good luck with it on my Suburban which uses a lot of those clamps.

OTC Tools Flexible Hose Clamp Pliers Steel Locking 24" Flexible Cable Ea 4525 on eBay!