Cooling system refresh advice

[San Jose Scott]

Hi Gang,

Time for the next project. Refurbishing or replacing the radiator, water pump, thermostat, radiator cap, and hoses. Any tips or advice before I jump into it?

[cass3958]

Its cheaper to get the original radiator re cored than to buy a new one.
A re core might cost you £500 and new original Jaguar radiator from SNG is over £1000. A cheap alloy radiator on EBay from China will only cost £150 but they look horrible and although I have never used one I would not recommend one over the original Jaguar radiator.
With the radiator out the water pump is easy to get to. Before removing the water pump attach a water hose to the system and flush it out with running water until it runs clean. You will be amazed at how much rust coloured water comes out of the system. Also flush out the heater matrix radiator as this too holds a lot of rusty coloured water. Once flushed it is easy to remove the water pump from the front of the engine with the radiator out.
Before fitting the new radiator check the balance of the fan blades by spinning it on the pulley and getting all the fan blades lined up and distanced correctly from the back of the radiator.
With the radiator out it is easy to get to the engine mounts and following my latest experience which I will write about soon I would change both of these.
When refitting the new radiator use a piece of cardboard down the back of the radiator so the fan blades do not damage the radiator fins. The fan cowling has to be hung over the fan blades whilst you lower the radiator in to place as it does not fit between the back of the radiator and the fan blades.

[Orlando St.R]

Hi Scott. That's all good advice from Rob and well worth heeding. Are there any particular problems you are looking to fix, given you have listed many of the items in the cooling system?

[San Jose Scott]

Thank you Rob,

Had not considered a few points you raised. Easy advice and am going to take it.. Will order those motor mounts tonight to add to the list of jobs for this go round.

Orlando, No problems. Looking at these as consumables. Any of them going out on a road trip can damage the engine so wanted to change them. After this will go through the ignition system and then the fuel system.

[Orlando St.R]

That sounds sensible. If you elect to replace the thermostat, do make sure you get the correct sleeved one as, without it, not all the coolant flows through the radiator. There's useful discussion on thermostats in this thread: http://jagstyperegister.com/forum_new/v ... stat#p3074. I went down the Watjag/Land Rover thermostat route, but others are quite happy with the SNGB item.

On water pumps, received wisdom says you are better off with a refurbished original part than a cheap Chinese-made new one.

You will find the many helping hands you have on site extremely useful for the radiator removal/replacement. You'd think it's a one man job, but only if that man has four hands!

[San Jose Scott]

Have the sleeved thermostat. Pulled off the housing and it was quite corroded. So a little delay as I wait for the housing. Also ordered a new belt and the studs that the housing was held on with. Those were looking a bit iffy.

When I tried to open the drain tap on the engine block it was frozen shut. Any suggestions on how to un-freeze the tap? If I want to replace it is there an easy way to remove it or do I need to pull the exhaust manifold?

Thanks

[Orlando St.R]

Any suggestions on how to un-freeze the tap? If I want to replace it is there an easy way to remove it or do I need to pull the exhaust manifold?

Well, you could try WD40 or penetrating oil, but it's probably easiest to just replace it, although that's easy for me to say - I've never done it! I don't think you would have to remove the exhaust manifold, but, I agree, it is awkward to get at. The position doubtless works for earlier Jaguars which don't have the swept back exhaust manifolds.

My parts catalogue says the part number is C31616, but SNGB offers a drain plug for that part, which I guess would work - and better for flushing:

c31616.jpg (47.03 KiB) Viewed 3802 times

They do offer a tap as well under part number C2354, which their website says fits the S-type:

c2354.jpg (57.09 KiB) Viewed 3802 times

[Glyn Ruck]

This is the construction of that coolant drain tap ~ C2354. (available from XK's Unlimited.)

engine coolant tap.jpg (100.01 KiB) Viewed 3799 times

Agree with Orlando ~ smother it with penetrating oil & let it soak for a few days. Then try & knock the pivot shaft up against the spring & you will hopefully break the seizure.

Apply heat as a last resort.

Otherwise replace.

[JCS]

As you may want to drain the system frequently in the future, it may be worth considering fitting an armoured drain pipe and repositioning the drain tap/ blank under the dynamo area. The additional pipe can be clipped to the sump set screws. This arrangement encourages more frequent flushing being far easier to drain the cylinder block than fighting to reach the block tap that is often blocked.

If you are having either a re-cored or new radiator you may also find it worthwhile having extra threaded ports in the header tank. These make pressure testing under running conditions very easy and also permit an additional point to return the coolant from the rear of the engine if required.

Norman.

[Glyn Ruck]

Also recommend you use modern OAT or HOAT long life coolant & you will suffer zero depositing, sludging, scaling or gel formation. Even radiator solder will remain bright & coolant clear & bright over extended periods.

We unfortunately don't have totally captive systems, but in a totally captive system, companies like Benz now go 15 years without coolant change.

With our open systems 5 years would probably be a sensible change period but with constant top up could go longer. e.g. 8 years

Your only possible negative might be that the water jacket might be a little fouled up due to negligence in the past requiring multiple flushes for good effect. If one is starting with a rebuilt clean engine/radiator these coolants will maintain performance for a very long time.

The only caveats ~ don't mix different coolants, always top up with premix at the desired ratio (most people don't walk around with refractometers to check concentration for anti freeze properties). Change if the coolant is not clear & bright.