Coolant Hoses

[doug424]

Hello everybody,
My car is now 14 years old and I'm thinking it might be a good idea to change the cooling hoses before a problem arises.
Does the collective have any opinions on material types to avoid or recommend, the characteristics of alternative materials and recommended suppliers.

Doug Barrass,
Ashford, Kent.

[aaj]

Doug

I'm not aware of any after market hoses. However, there is an after market alloy tower (contains thermostat) that seems to get good reviews (some people replace the top cap with the plastic version with an 'O' ring to seal it). I replaced my 'tower' before this version was available & have had the thermostat cove radiator hose spigot break up (2 yrs after replacement) causing me to abandon the XK at 1:00am!

My 2002 XK8 (110K) has had most of the hoses and plastic coolant parts replaced either because they have failed or they have gone soft/brittle. A number of the heater hoses are being replaced for the 1st time next week along with the smaller engine breather pipe from the lhs bank.

There is a thread regarding the Coolant Expansion tank on the BB system which is worth research.

I've had a Jaguar Thermostat (supplied by a main dealer) fail after a few months & they refused to replace/refund because I did not take the XK to them to diagnose the fault! There are replacements available at 1/3 of the cost from after market specialists. The choice is with the purchaser.

Assuming you have an XK8, make sure you have one of the latest water pumps as some of the original fitment one's fail. Again, there is a thread or two regarding this on the BB

One last bit of advice, our XK's are getting old. Always check the hose clips & if in any doubt replace them. If using 'jubilee type replacement clips don't over tighten them.

Hope this is of use

Allan Jones

[doug424]

Hello everybody,

I have now changed the major cooling hoses on my car, a 1998 XK8.

Why did I do it; well primarily because the car is now 15 years old and things will not last forever. I also remember Dave Marks saying at a seminar I went to something along the lines of “…you’ve got to remember that on the continent that Jags are regarded as exotica, and on that basis take spare parts with you or change a suspect part before you go”. Well my car is a LHD one and most of its miles are done on the continent.

Virtually all the procedure I used was based upon that written by Bob Bates and published in the August 2008 issue of the club magazine.

Whilst doing the job I also changed all the spring hose clips for stainless steel jubilee type ones; again I vaguely remember Dave Marks saying that the spring clips can weaken with age.

Doing the job it took much longer to disassemble than to rebuild. The Norma unions on the octopus were especially reluctant to come apart. If fact I had to break both of the push fit connections to get them off. Once apart I found a lot of solidified material inside both of them which to me means that both had leaked on the car. To reduce any such leaks with the new fittings I smeared silicon sealant within the unions when re-assembling.

The metal pipe used to carry one of the heater hoses to the more complicated Norma fitting, was heavily covered in solidified material at both ends. This was cleaned with a miniature wire brush attachment and a Dremel hobby tool.

Actually re-fitting the more complicated Norma fitting was a breeze as once the rigid pipe is pushed in, the outer collar easily moves up in to place to lock the fitting.

I also noticed that sludge formed in the bottom of the bottles I used to gather and store the removed antifreeze. I don’t know what it was but I decanted the antifreeze to remove the sludge before re-filling the cooling system. I also flushed the radiator through as well.

One thing I did find that I was not expecting is that the heater pump and valve are actually mounted on a plate and is fitted as an assembly. This is not what the illustrated parts list would have you believe. That said the assembly was not hard to remove or fit, once you realise that the lower fixing nut can only be accessed from below the car.

The removed hoses were generally in good condition, far better than I expected. The biggest hoses showed evidence of swelling and ageing, and on some the hoses there was evidence of friction or wear against other items (there’s not a lot of space in some places). None of the hoses had cracking or imminent signs of failure.

Overall not a bad job to carry out, but not one I’d recommend for a novice as there was lots of scope for making mistakes or causing damage.

Best wishes,
Doug Barrass.

[mike020150]

Hi Doug,

I think you have been very sensible in changing all the hoses. Even though modern hoses do seem to last longer these days, whatever the car I usually try to change all of mine every 7/8 years. Beyond that the risk of failure and breakdowns and possible resultant engine damage seems to increase. Equally, as cars age and cease production, hose availability becomes more difficult and a small breakdown can become a nightmare to sort out. A stitch in time and all that... Mike.

[ibnct]

Doug,
I don't want to be accused of scaremongering, but the sludge you mention sounds a bit ominous. Could it be that at some time an incorrect antifreeze has been used to top up your coolant. I've heard that mixing certain antifreezes can result in your coolant turning into a sort of smoothie, clogging the cooling system up. A healthy cooling system should result in virtually no contamination of coolant between changes.
Had you noticed any problems with overheating prior to doing the hose change & did your heater appear to work effectively in cold weather?

[doug424]

Hello ibnct et al.

I have owned the car since it was 4 years old and in that time it has only been topped up or refilled with the correct Jaguar coolant.

The cooling and air-con work ok; there does seem to be a little tendancy to be "slow", if that's the right word, to respond to minor changes about the set temperature. When starting up from cold the climate is quick and powerful to respond whether it be hot or freezing outside.

I've had no major problems with the cooling system; the car is on it's third pump (latest version fitted), second thermostat and second tower.

I've used the word sludge but the stuff I decanted out was more of a liquid that a solid; if I agitated the bottle both liquids would flow and then settle out. It looked more like two liquids in a bottle that would not mix well.

Doug Barrass,
Ashford, Kent

[ibnct]

Doug, Mr Doomsayer here again!

Two liquids that don't mix still sounds ominous to me. I'm now wondering if one of these is oil. Perhaps a small leak between the oil & waterways at the cylinder head?

If this mystery contaminant has historic origins,there probably is nothing to worry about. But if it continues to form I think you may have a problem.

Maybe one of our technical experts would care to either put me back in my box or discuss this further?

[doug424]

Hello ibnct et al.

Have a look at this picture I took at the time of the coolant with sludge. The bottle was a 2 litre Coke bottle, doesn't look like oil to me.

Doug Barrass,
Ashford, Kent.

[ibnct]

Hi Doug. I agree that doesn't look like oil to me either. I would expect it to be floating on the coolant if it was.

My best guess now is that it is aluminium corrosion deposits, but I'm colour blind so it is only a guess. A small amount of corrosion/erosion is normal but this looks more than I would have expected. Are you sure you have/had the correct antifreeze /water proportions?

The only other thing that springs to mind is that this could be the remains of your earlier pump blades, but as I'm not familiar with the materials used or what condition they were like when replaced, this is only a guess.

I apologise for any worry I may have caused, it was done with the best of intentions. I now don't think you have a problem.

[doug424]

Update.

Hello everybody,
It's now 8 months since I changed the major hoses on the car. Yesterday I ran it on the drive for 20 minutes while I played with my laptop (more on this elsewhere), turning the car off when finished. As I walked away one of the radiator hoses popped off and coolant ran out. It turned out that all 4 of the big jubilee clips had become loose, the smaller ones were ok. Why this happened I do not know.

I put the hose back on, tightened up all the clips and re-filled the system. Took it for a run today and all is well.

Doug Barrass,
Ashford, Kent.