Plastic quality of coolant hoses - a timely warning

[jonjeffryes]

Just an observation but possibly sound advice for anyone new to s-types. I have spent today replacing the top hose and flushing the cooling system. I had to change the hose because the attachment point for the expansion tank tubing had sheared off.....however on closer inspection, it had not been snapped off with force, the plastic seemed to have rotted and crumbled.

I was really surprised by this as my previous car was a thirty year old Porsche and the plastic fittings were all in excellent condition.

Because of the condition of the top hose plastic, I decided to check all of the connectors - any subjected to heat/hot water were in the same poor condition....particularly the 'T' connector between the expansion tank/Top hose/ Inlet manifold that literally fell apart in my hands. Quite worrying really as my car has been thrown in to a weekly commute of 500 miles around the M25

As a result I spent the afternoon checking all connections under the bonnet, replacing every connector I could find. In addition to the water pipes, the vacuum piping was just as poor. This time, I have temporarily replaced the pipes with silicone hose whilst I order the correct parts from Jaguar. The immediate improvement in engine running was worth the effort (vacuum leaks were clearly evident).

So if you are running an early car and have not yet checked the condition of the water hose connectors, I would recommend that you check now....the loss of coolant at speed on the on the M25 would most certainly been disastrous

Regards

Jon

[J44EAG]

This is a quite normal occurrence, Jon.

On the V8, the plastic thermostat tower can disintegrate in real style. Ali replacement tower units are now commonly available.

Both early and later models of S-type suffer from header tank failure. The early type cars have the tank mounted above the O/S exhaust down pipe which dries out the polypropylene and cracks and splits develop. To remove and inspect requires the panel below the wiper to be removed and the across car brace bar also. Six 8mm bolts secure the bar to the car. These bolts need cleaning and greasing before removal as the exposed threads corrode and those bolts will sheer off if preparation has not been done before removal. Drilling and re-tapping has to be done if a bolt snaps off and is left in the car. This can spoil your day!

Pre-facelift models have their header tank moved to the front of the car where it is cooler. The tank is a nice looking job but the small sized overflow pipe is so small and skimpy that that can embrittle and drop off as time, age and mileage accumulate. So the second generation tank arrangement is not much better than the original. The advantage though is that it is easily accessible whereas the early type is not!!!!!!

Plastic in contact with heat or hot liquids does not fair well. Embritlement of many plastic components is common especially as a car ages. It comes as little suprise to hear what you found. I have been chasing similar issues on S-types for the last nine years!! Experience has taught me to carry a new header tank in the spare wheel well of my car.

Mike

[jonjeffryes]

Plastic in contact with heat or hot liquids does not fair well. Embritlement of many plastic components is common especially as a car ages. It comes as little suprise to hear what you found. I have been chasing similar issues on S-types for the last nine years!! Experience has taught me to carry a new header tank in the spare wheel well of my car.

Mike, good advice. I get the feeling that I am dealing with a car that has seen little if any maintenance of substance for sometime. I will take your lead and purchase a spare header tank just in case!

Oh, and I have one sheared brace bolt ready for my attention already....noted on my dodgy things to fix list already

I was just surprised a the poor quality of plastic used...maybe it's a Ford thing, but similar connectors on my Porsche were vastly superior in quality...or just possibly it's much hotter under a Jaguar bonnet!

anyway, next job lined up are front and rear ARB bushes and drop links..that will be Wednesday when my wife has gifted me a day pass to my garage...wish me luck

Jon

[classicmorrisman]

I was wondering whether anyone else had had this problem.

The point at which the header tank (this one's at the front of the engine compartment) hose joins the plastic coolant housing sheared last week. Fortunately, we were driving through a village, so not at speed and were able to pull over promptly.

The RAC chap did an ingenious job in providing a temporary repair and we were able to continue our holiday until a proper repair was done at the end of the week and a new plastic coolant housing unit installed.

Having had this part replaced, are there any other points I should check, or can I breathe easily again for the time being?

[J44EAG]

V6 petrol models have a couple of rubber breather pipe 90 degree turn units near the throttle body. These are only accessible when it comes to spark plug change time. The inlet manifold has to come off to get to three of the plugs so it makes sense to change those rubber unions each and every time you change plugs on that variant.

On the V8 4 litre model, in addition to the rear mounted header tank, the thermostat tower and also the link manifold coolant pipe are also plastic. Whilst ali replacement towers are available, no one has yet devised a replacement ali link manifold. So if you have an elderly V8 4 litre car, you might consider replacing the unit with a new unit if embritlement is found.

The later 4.2 V8 engines are rather better constructed with ali tensioners, metal link manifold and thermostat unit made as one unit. In my own experience, the S-type has always been a "bit plasticy" in construction with the later X350 being noted as being generally rather more robust in many areas. Both the cabin and engine bay quality appears to have been lifted in quality from around the 2002.5> with models being somewhat improved.

Plastics are certainly not a strong point on many models. German rivals of that period would appear to be constructed at a higher level. i would advise regularly inspecting any car regardless of which Jaguar model you own. All cars need regular inspection and maintenance. Just adhering to standard servicing schedules is frankly an insufficient level to run a car on. As you might well see from many of my magazine articles in the X350 column, much of my own maintenance work is to items which do not appear on standard servicing sheets. Although off thread here on this topic, regular gearbox oil changing is missing from standard schedules. Those of us who have run a Jaguar for a few years, soon learn to change gearbox oil at 60k mile intervals or find our gearboxes reduced to toffee at a later date.

One hopes that the latest Jaguar offerings have addressed these issues. Only time will tell if that is the case.

As any car ages it will need an increasingly higher level of maintenance applied. In addition to the above, steel body shells require regular elevated inspection which in my experience becomes essential from around thirteen years on the road and sometimes before that age. Wax oiled cars will survive longer than a car which has not received such preventative treatment during early years. As an example, my former old S-type at fifteen years of age is now due to have two rear sill sections replaced within the next year due to corrosion issues.

Mike K

[classicmorrisman]

That's very helpful - thanks, Mike. Will certainly see that the breather pipe unions are attended to at the next service (had the gearbox serviced/new oil the other week - alot quieter now).

John