changed the coolant today

[Brakebuster]

so , after three years of topping up with water ( i know i know ) i decided to fully change the coolant

i bought some OAT red coolant from euro car parts for £9 for 5 litres , and got three as i had a spare one in the garage from doing the rad on the X last week

with the old coolant drained from radiator bottom hose and disposed of responsibly , i flushed it through with a hose pipe blocking off and opening several pipes to force the water round , including the heater matrix, the expansion tank was also flushed out, then using compressed air i drove out as much water as possible, and put the bottom hose back on

i took off the nearside front wheel wheel arch liner and removed the atmospheric recovery bottle, this was about a quarter full of quite sludgy coolant, flushed and cleaned i reinstalled it with about two thirds of fresh coolant , and put the liner and wheel back on , i also ensured all pipes were clear and functioning and there was no rot in the area, glad to say there wasn't

then i proceeded to fill the cooling system very slowly , i had both rad caps off and filled from the expansion tank , first 5 ltrs went in , then the next , a fair but of gurgling on the way ,
then i went round the car squeezing some pipes and moving the valve for the matrix, and a bit more coolant moved around, then i got some more coolant in always just dribbling it in very slowly until it came out the front engine cap ,
i then started the engine and let her tick over, and let the pump push around the coolant with the heater on full etc , this lowered the level quite a bit so i added coolant while running until it came out the front cap again , i put the cap on both ends and let her warm up , my drive slopes nose down , so i turned the car round so the rad was high , and turned off the car

let her cool down a bit and carefully removed the caps, there was a whoosh and the level dropped , adding yet more fluid the same way i put the caps back on and turned over the car again until the fan cut in

in total she took twenty litres including two in the atmospheric recovery tank ,

will keep an eye on her for a while just to let al the air burp out and will watch the temps and fans etc

but all seems well so far

job done,

BB

[poprivet]

Good job done. Its a lot simpler on a 3.6

Re the catch tank, I removed mine many years ago as it didn't seem to do much except collect mud and salt. The vent pipe now just points at the ground, never lost any water or needed topping up.

[davidr]

Hi BB. - will be interested to hear how you get on with OAT.
I had an issue with my car some years ago where the pressure built up so much that it split a top hose. The pressure relief is via the atmospheric expansion tank but there is a metal reducer in the hose run that had rusted and clogged up so, although the pressure cap was opening as it should, there was nowhere for that pressure to go.
I hate to teach granny etc but my experience says make sure that pipe is free! Blowing down it and listening for the bubbles in the expansion rank is the way to test it.
Regards
David

[steve_m]

BB, did you open the bleed vent on top of the rad or doesn't yours have one?

[Brakebuster]

thanks for the heads up guys,

yup , top bleed one way valve is working correctly to the front pressure cap from the radiator top , and the rad bleed valve is top left

the atmospheric recovery bottle pipe was blew through and clear of any blockages

OAT should be ok, as its just organic coolant, and has to be better than just water , time will tell i suppose

i will ensure i get all the air out before going on any long runs, a few run cycles to temp should burp out air

on a side note, the coolant that came out wasn't in bad condition, it had just been over diluted with me topping her up after different work in the past, so i bit the bullet and put in 100% ready mixed coolant made with deionised water , better than diluting concentrate with tap water in my opinion


i wasn't ready to go full waterless at this point...still deciding on its ' benefits ' v cost


i did notice that during warmup that the right hand thermostat opened way later than the left hand stat going to the rad ( several minutes ), i can't remember if they are supposed to be the same or different ? this could have been an air lock or stuck giggle pin i suppose, but it did open in the end , will double check it next time.

BB

[davidr]

My understanding was that both banks should warm up at the same rate and therefore the thermostats should open more or less together.
After that, the left bank (B) will always run a bit hotter than the right bank (A) because the top hose for the left bank is baffled inside the rad to feed in about 1/3rd of the way down whereas the right bank goes all the way through the rad from the top.
Have you got a bit of a blockage somewhere or maybe even the thermostats are different temperature ratings?

[BigCatXJS]

I run Red long life OAT coolant in my XJS. However, most folks I speak to suggest that that is not ideal for the V12 and that Blucol is a better choice. Consequently, my next coolant change will probably revert back to Bluecol. I would be interested in folks opinions on this as to-date I have not experienced any leaks but I am concerned about seals and gaskets being compromised in the longer term.

Ta, Rich

Below, an extract lifted originally from the FBHVC website;

ANTIFREEZE

Technology moves forward and new products are constantly being launched with claims to improved formulations and performance. With the recent bitterly cold weather in January antifreeze has been in the headlines, with some alarming stories which at first seem to be about the well-known tendency of antifreeze to find the tiniest hole and cause leakages – but in these cases it has led to catastrophic engine problems.

Traditional blue ethylene glycol is a toxic but highly effective antifreeze and contains silicates as an inhibitor to help prevent corrosion in an engine with mixed metals in its make-up. Bluecol and Blue Star are well known brand names and both of these are declared suitable for ‘classic cars’ on their company websites. Be aware that there are also low- or no-silicate ethylene glycol formulations (usually red) available which may not be suitable for all engines.

Propylene glycol is another well-known and less toxic antifreeze formula and usually contains silicates but Comma, the main manufacturer, have now discontinued it in favour of an ethylene glycol product containing ‘bittering agents’ to make it less palatable and minimise the risk of accidental poisoning.

Both of the above products use inorganic additive technology (IAT). Recently problems have been reported concerning the use of antifreeze mixtures using organic acid technology (OAT). OAT was introduced in the mid-1990s and the products are biodegradable, recyclable and do not contain either silicates or phosphates and are designed to be longer lasting. However these products do seem to cause problems in older engines; over and above the ability of antifreeze to find the smallest crevice and leak, OAT antifreezes have been accused of destroying seals and gaskets and causing a great deal of damage in ‘old’ engines. For this reason the manufacturers do not recommend their use in historic vehicles. These products are usually coloured red, pink or orange.

The final category is HOAT. These products use hybrid organic acid technology in an ethylene glycol base with some silicates in the formulation alongside the organic corrosion inhibitors. The product is usually coloured green and are not recommended for use in historic vehicles.

The Federation are still researching this problem but our advice at the moment is:
· only use blue coloured IAT antifreeze in historic vehicles;
· only use OAT products (‘advanced’ or ‘long life’ antifreeze) if the vehicle used it when new and if specifically directed by the vehicle’s manufacturer;
· never mix different types of antifreeze without thoroughly flushing out the system;
· always replace the coolant within the time scale specified by the antifreeze manufacturer as the corrosion inhibitors break down over time.

[XJR-S]

I've run mine on concentrated OAT with deionised water for the last year (It's cheap to buy in 25L drums, or if you have a condenser clothes dryer you can bottle it yourself!).

It was added at the same time as a pair of new thermostats, removed and flushed radiator, new water pump and a full set of hoses. It was mostly precautionary, there were only a couple of bulging hoses. There wasn't a drip in the overflow tank behind the wing - Should there be?

Bleeding it was a pain, but parking on a slope helped.

[ptjs1]

Well done BB, sounds a thorough job!

I'm also intrigued by the OAT vs Bluecol debate and any other views. I'm just about to drain my system to repair a heater valve plus another long-awaited project! I have to decide in the next 2 weeks which option to choose. Decisions, decisions!!

BB, as a matter of interest, how did you achieve your full flush? Which way did you flush the heater matrix and block etc? I know yours is a V12, but there will be still be some relevance to my AJ16.

Tks

Paul

[Brakebuster]

one says ' full flush ' but I suppose you can never achieve 100% replacement ,

in the V12 the heater valve is always open , and closes for cooling requirement via vacuum, so a car started from cold has an open matrix valve to start with,

I removed a few top pipes and blocked or squeezed tight others forcing hose pipe pressure water around the system , this did result in different coloured water exiting the lower hose , obviously engine thermostats would be closed

I then blew compressed air at fairly low pressure to push out any lying water in the block etc, about a ltr blew out I suppose

BB

[PaulGover]

FWIW, I calculate that a normal drain/refill changes only 70% of the water in the V12, so you need to repeat that 4 times to remove 99% of any previous content (e.g. OAT or Bluecol).

[Brakebuster]

i managed to put 20ltrs of new ready mixed coolant back into the car, this is of the Jaguar ROM's advised 21ltr capacity

so not bad in my opinion

it works out at 95% replacement , and after the flushing exercise the remaining 1 ltr that wasn't replaced was ' mostly ' water
anyway


on a 70 mile run this weekend which was sunny and warm i can say the car seemed to stay cooler, the ram air as ever kept the car cool at 60mph or over, but in slow and standing traffic the temperature didn't go up as quickly or as high as it did before changing the coolant,

so a worth while exercise


BB