4 litre V8 Thermostat tower mod & fitment. S, XK & X

[J44EAG]

The above cars are fitted with a plastic tower unit from new. At advanced ages, the tower is prone to crack failure due to enbrittlement of the plastic used in construction. This problem is also caused by coolant heat and temperature. Failure causes coolant leaks.

An original plastic Jaguar supplied unit may be refitted or an after market aluminium unit, available from British Parts, Norman Motors or from Dave Welsh Enterprizes in the States. In most respects it is almost identical to the plastic unit exept for a minor detail change to the filling cap. It fits straight to the car without problems. Aluminium would appear to be a more suitable material for the perpose.

Removal of the induction trunking, top,bottom and ancilliary hoses, front coolant manifold and tower is required, together with the draining of approximately 2 litre of coolant from the system.

The unit is bolted via the base flange to the engine. The rear 2 bolts are difficult to remove owing to the inlet manifold overhanging the bolt heads. A socket is impossible to use and the use of a hot bent 85 degree 8mm ring spanner is required to avoid lifting the manifold. Space is severely restricted but the job undertaken in this fashion is not immpossible.

Cylinder head to coolant manifiold o-rings, provided carefully treated can often be reused but replacement with new items is recommended.

The job is relatively straight forward if the bent spanner is to hand. Time taken for the work should be about 2 hours.

Refill the coolant systemvia the tower, evacuate air via the header tank and top up as required.

Full details with pictures of fitment are due to appear in the Ocober 2009 edition of the JEC magazine under the S-type Forum pages.

Mike kennedy. S-type Forum Co-ordinator.

[Richard_E]

Does anybody out there in Webland have any first-hand experience of these?

Are they any good?
Are they good quality castings?
Are they easy to install?
Are there any problems with them?
Any other thoughts, opinions, experiences, or ideas?



Richard.

[J44EAG]

I have one fitted to my 4 litre V8. The unit is all good.

I covered fitment in my article with pics in one of our magazines in October 2009.


You will need a cranked 8mm spanner to remove the obstructed bolts at the rear of the thermostat tower.

The job is straight forward and the part fits straight to the car. No problems since fitting.

Highly recommended mod with high quality part kit available.

Mike

[J44EAG]

Since fitting the new tower apart from changing the o-ring under the top cap the cooling system has worked effectively until a couple of months ago. Monthly topping up however has been required. Try as I might I couldn`t find a leak.

Two weeks ago an unexplained problem occurred. A sudden overheat but little water subsequently added. A released pressure cap got me home. I had a new thermostat in stock and fitted it. Net result was an unexpected instant boil up. Removing the stat for investigation alongside the old unit revealed a problem. I`ll add that when the boil up occurred the radiator was stone cold.

A jug of boiling water revealed that the old stat opened but the new stat DID NOT. Problem. I cut a gasket to fit between the top hose nozzle and the thermostat tower as a temporary measure whilst I obtained another new stat. The supplier of the new stat sent me another yesterday after I phoned him and explained the situation. Obviously he declined to comment when I explained that the new stat was defective and had caused another mega boil up to occur. If head gaskets have been damaged then this will become my problem at a later date.

A phone call to Neville at North East Jag spares sourced a new water pump and a serpentine pulley drive belt which I elected to fit as precautionary measures and to take out of the equation any possibility of a defective second generation water pump. My thanks to Neville for his excellent service. In the meantime, whilst the parts were awaited, I chose to run the car without a stat as no further overheats were evident.

Running with no thermostat caused a slow warm up after which a normal running temperature was noted. Apart from an occasional misfire probably due to engine temperature not being precisely controlled, all seemed well enough for me to undertake a 50 mile return trip to Chichester on the M27. I arrived where I needed to be and later went on to a friend to collect some kit. Having loaded the car in the dark with engine left running and headlights on, I shut all doors. Then the trouble started!

The engine left running whilst I loaded the car suddenly began another over heat session. The fan started up which alerted me of an impending issue. I went to open the drivers door. Locked. Same all round. The fan on the radiator began to run faster or to my mind it appeared to do so.

Locked out of the car, I had no choice but to break the drivers window with a midget sized sledge hammer found in my friends garage. Boy, did I have to hit the glass to break it. Glass went everywhere, the hammer disappeared into the car ending up on the passenger seat. In the process I sustained a number of glass cuts to my hands.

The devastation within the car was appalling. Broken glass everywhere. A little bit goes a long way. Having swept out what glass was possible I returned home and fitted a small boot sized tarpaulin around the drivers door to keep the forecast rain out of the car.

Looks like another call to Neville for a window glass first thing this morning. I know he is breaking a car so hopefully this will provide a new drivers glass.

So just as I thought things couldn`t get worse...they did. How was your day? Mine has been crap!

More on all of this once the parts arrive from dear old Neville.

This post written at 06.27am as I couldn`t sleep. Frustrated First Sea Lord of Fareham Creek suffering from irritating insomnia!

Mike

[J44EAG]

A bit happier now. Some light at the end of the tunnel.

Front water pump bearing shot at 75k miles. Hence the leak. Pulley radial wobble was quite noticeable once the belt was removed. The same goes for the serpentine belt. Images below.

So the pump and belt from Neville at North East Jag Spares and door glass from Eurojag.

Should be up and running again by the middle of the week..

Mike

[J44EAG]

Just arrived from Neville- the generation 3 pump as fitted to the 4.2 V8.

A substantial revision with a very robust metal impeller, anti-frost core plug set at around the 7o`clock position and distinguishable from the early pumps with two bolts holding this two part unit together at the 4 and 10 o`clock positions.

Now awaiting the serpentine belt and can get going again.

The replacement window glass has now arrived from Eurojag thankfully intact. The door is full of glass as is most of the car. These things sent to try us.

Mike

Late edit after fitment.

Further examination now reveals that the core plug is primarily there to blank off a machining hole under a lower hole in the pump spindle extension. This was open to allow coolant to leak out on older model pumps but with possibly disastrous consequences. On this new pump any seal leakage will no longer just pour down the front of the engine. The design of new pump allows coolant in the event of seal failure to drain back into the cooling system and prevent fluid loss. Certainly a big improvement as leakage from the earlier pumps is difficult to see easily. Only a puddle of fluid in the nether regions at the bottom of the engine bay gives any visual indication that something is amiss.

New pump now on the car. Just awaiting a new serpentine belt to be delivered. Promised today but Royal mail taking their time.

[J44EAG]

Here`s where I am now.

New pump on, new serpentine belt arrived and also fitted. This must be fitted around the belt tensioner pulley before any others. Then it is a matter of routing first around the air con pulley, then the power steering followed by the alternator before relieving the tension on the automatic tensioner unit before finally locating the belt on the water pump pulley. Tension is then let off the automatic tensioner unit and the belt is then checked for correct location in the grooves of all pulleys. The belt has to be fed via idler pulleys also. It is a bit of a cuss and a fiddle and took me about ten minutes work. Glad that is over.

Once the belt is fitted, the bottom hose can be refitted to the thermostat nozzle and the system filled with coolant. With the header tank full, I removed the thermostat tower cap, squeezed hoses to evacuate air and fill with coolant. The thermostat tower is then filled to the brim and the cap replaced. Further topping of the header tank may be required after an engine run and road test and establish the correct coolant level.

So that part is finished and an engine run done. My other problem has been the drivers door strip down to replace the broken window. To replace the glass, the door card has to be removed and multi plugs dismantled. To date what with waiting for parts, the car has been unused for a week. When I attempted an engine start, the battery was dead. Down to 7.5 volts and that does mean dead. I found that with multi plugs disconnected from the door lock module meant that interior lights stayed on permanently. Hence the flat battery. A point worth remembering.

A frantic battery removal and recharge has the car going again. This means I can move it from the boatyard secure storage area to the workshop tomorrow and hoover out broken glass in the door and inside the car generally before refitting the radio speaker, door lock module, cables and plugs etc.

My slight concern until a full road test has been carried out is that the car ran with a cold radiator in the yard and the fan cut in quietly. My hope is that I don`t have head gaskets gone. More on this saga tomorrow once I have the clear up done and the door back together.

A few pictures here of the belt tensioner and the wear gauge markings which I highlighted in Tipex to make easier to see and to photograph. With the new belt fitted, the static pointer on the vertical tensioner arm points to the extreme left hand marker. As belt stretch occurs the pointer will move to the right and typically point at the centre scribe line. With no belt present the pointer will relax towards the right and point off the scale. The belt I removed had covered 75k miles and the pointer was just to the left of the centre scribe line. (JPG 802) So there was some life left in the old belt but it showed cracks across the lengthways ribbing so was replaced as preventative maintenance.

More again tomorrow.

Mike

Later edit. Car run for an hour at idle in the yard now without fan coming on or any sign of an overheat. Hopefully I`ve won. Tomorrow will tell!

[J44EAG]

OK. It`s all back together again.

Believe it or not, it took an hour to hoover all the broken glass out of the door. Just as I thought all the glass had been removed, I found some more! A one inch paint brush helped dislodge the glass particles from nooks and crannies. However the various areas of semi setting panel sealer applied at the factory meant the glass would stubbornly hang on in there. Anyway it`s all out now.

A further hour was needed to hoover out the car. Boy, does that broken glass get everywhere. Then the door card back on and testing of the window and locking mechanisms. All fine and now back to normal in that department.

An initial road test suddenly gave an increasing cylinder head temperature. Switching off to let cool for a couple of minutes and then releasing the pressure cap cause some coolant to be thrown out. Topping up with a litre of water and a continued test in heavy traffic and a short sharp blast of hard revving revealed a stable temperature. The heater works well and I can see no sign of leakage within the engine bay. The smell of leaking coolant has also ceased which is most encouraging. Obviously an airlock now cleared. So it looks as if this coolant issue may now be solved. Some harder driving now needed to bring my confidence in the car back up again.

Interestingly, it is now possible to see a copious flow of coolant ejecting from the thermostat tower bypass hose into the header tank. I`d never notice that before with the old water pump fitted. Any reduction of that flow from now on, will cause me immediately to investigate.

Mike

[Montana5]

A most interesting and highly valued Technical Article Mike, thanks for sharing.

Doug.

[J44EAG]

Thanks, Doug.

I`ll get this all written up for Nigel and the story will no doubt appear in the magazine at some later date.

The low speed misfire still persisted after this water pump saga. Misfires are usually plug or coil related so I pulled a full set of triple electrode spark plugs out of stock. These were the ones I won on eBay recently for £1.04 plus £4 postage. Bargain. Buy one and get the other seven free! That`s 13p each or 53p each if you count the postage!!

I`ve managed to change the offside plugs without difficulty. The nearside bank need doing shortly. The problem is access to the rear lower plug cover 7mm bolt. This is right at the back of the engine, right against the bulkhead and obstructed by the fuel purge unit bolted to the suspension turret and completely covered by a thick tripe of cabling and multiplugs. I was unable to get at this late today due to not having a decent 1/4" drive ratchet, lack of light and needing to do some dismantling of the kit around the back of the engine bay. I remember the guy who last changed the plugs having a good cuss. Now it is my turn.

Certainly having changed four of the plugs, the misfire has gone and the engine sounds a tad happier. Again, I`ll write this up for Nigel in due course.

Late edit.

Now after last weeks mayhem, I can report that this cooling system repair has been to date a complete success. The header tank has stayed at the correct level, there are no coolant leakage smells and no signs of anything untoward. It looks like the head gaskets survived at least in the short term.

Fitment of the AC Delco triple electrode spark plus has now been completed and the car feels better on the throttle pedal. The engine is noticeably smoother on pick up and is sweeter on a trailing throttle. It is also quicker off the mark from a standing start. Hopefully this will reflect in an improved fuel consumption.

(Late edit - this story appears on the S-type Forum, page 80 of the June 2012 of our JEC magazine)


Mike

[doug424]

Hello everybody,
I happen to have the inlet manifold off my XK8 at the moment as I'm changing the major cooling hoses. I've already changed the thermostat tower for a plastic Jaguar one, but left the inlet manifold on at the time.

Since I've now clear access I thought this would be a good time to check the torque of the tower to block bolts, but I cannot now find the torque setting. Does anybody have this? I've grazed my JTIS disc and read through all my notes but cannot find the figure anywhere.

Thanks,
Doug Barrass,
Ashford, Kent.