Questions questions and more questions…perhaps I should join the local Jaguar Club, but I’m just not a club person. So here goes another…
…original steel overflow tank is rusted internally with a pinhole.
Considering playing with electrolysis to remove internal rust, but may just take to a radiator shop.
However, I do have a gas tank sealer set for my motorcycle that i may not use by KREEM. Supposedly the best.
Anyway, reading their page it states not to use where liquids reach more than 238F.
" Kreem Tank Liner is not designed for use in aircraft oil tanks or tanks using a plastic component also not for tanks containing liquids above 238 degrees F. "
Wonder why not simply use it then?
Never seen a sealant for higher temp cooling system applications as of course all are plastic these days.
although I have never known of one otherwise either.
Anyone used a sealant within their overflow tank? I’d like to keep it original, but steel is just destined to rust again internally, and I intend to run a very tight ship and want to keep cooling system in top shape.
Hi Demian, just had the same problem arise on my S11, I had the pin hole(s) and soldered a patch over the external skin, this would have been 2 years ago or more now. The tank finally gave up the ghost last week, I decided to remove the weld around the lip, that went well but not having any success in repairing the holes I have resorted to a good secondhand unit,
If you intend to keep your original item could I suggest that you part fill it with water and a handful of small stones or better still volcanic rocks that have a rough surface rather than smooth. Replace the cap and give it a vigorous shaking. This will help to remove any rust scaling. You may need to repeat a couple of times until the water exits clean (or close to Clean)
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Resealing the metal petrol tanks is usually successful using POR an proper procedure, Demian - unless tanks are far gone.
However, they were originally coated inside anyway - and used with petrol. No reason why it should not work for sealing water, but while the expansion tank does not participate in coolant circulation; the coolant in it, and engine room temps may reach the quoted temp, however unlikely
Be aware that the expansion tank is subjected to coolant system pressures - which may or may not have any bearing. And, of course; filters protect the fuel system against dislodged lining bits and rust - there is no such protection for the cooling system. Though, in principle; expansion tank debris will not enter the rest of the cooling system…
238°F is pretty much the boiling point of water (100°C). This temperature may be border line for the expansion tank. The main circuit is supposed to be filled to the bottom of the filler neck, IIRC, and the expansion tank sees any coolant only if heat expansion occurs. Under said circumstances water temps will be well above 95°C. Some cool down may take place on the way to the expansion tank, but, occasionally, water temps may reach +120°C and then the tank liner might give way.
In my car the metal expansion tank was leaking as well some years ago, even though looking good from the outside, as the hole was located in the seam. At that time a new replacement part cost less than a professional repair by a radiator shop probably would have cost me, so I didn’t even think about having it repared - and frankly, a tank sealant didn’t come to my mind.
Thank you all for thoughts.
I understand and appreciate them all.
Yes, pressure did come to mind too as concern.
But 238F comes to about 115C … An expansion tank never reaches the same temp as header or block, etc…and the car should not exceed 85C ever anyway. If so there is something wrong. 90C to me would be serious danger zone.
But yes, perhaps too close for comfort.
Will have to take up to a local little radiator shop, see what they say/offer.
Otherwise play with myself (uhh hmm…) and/or ask David at everyday XJs.
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Indeed, Demian, as the expansion tank does not take part in coolant circulation - it seldom reaches coolant temps, though there is a bit of ambient heating in the engine compartment…
You must be a lucky one, ‘90C to me would be in serious danger zone’ - it’s not infrequently seen by Jaguar drivers…
High coolant temperatures does not in itself a danger to the engine - but it may reveal a cooling issue. Alarm is justified when the temps rise…and continue to rise. At some stage, coolant will boil, the red sector on the gauge indicates the boiling point of a properly pressurised system - without pressure, the boiling point is like water. And local engine temps is higher than the coolant - as shown by coolant temps rising after shut-down.
Radiator shops are expers on metal - the tank is steel, but they may still know something…
I successfully welded a patch on my expansion tank in 2010 which bought me another 6 years… Yes, another pinhole leak in 2016 and I decided to bite the bullet and replace (for around £100 iirc)
Shame there isn’t a stainless option… I did look at generic overflow tanks but under the V12 bonnet there isn’t much scope for size/shape/location change!
Many still might. Some radiators include steel flanges of one shape or another as a means to attach them.
When I did my "Hot project’, I had a local shop modify a radiator whie fitting a four row core to it. It included side straps. The project included shortening, The traps were neatly cut and rewelded And in turn the steel side straps were soldered to the brass tanks. Very elegantly…
It’s the wise choice really…also to replace that transmission cooler behind base of radiator.
That thing freaks me out.
Those old things with their dubious welded joints.
One small crack and coolant mixes with trans fluid and good night transmission…as you know.
That cooler is something which must be modified or replaced eventually.
Best.
PS: This looks a bit better, less hot-rod bling, and apparently per search reflects use in an XJ6?
However there appears to be no pressure release cap or hose to atmosphere connection?
Weird.
I suppose one replaces the ever leaking sealing cap at header tank with the 15psi cap therefore?
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The relevant tank on the xk is not an ‘overflow’ tank as such, Demian - it is an ‘expansion’ tank., meant to take the increased volume of the expanding hot coolant, retaining system pressure. If excessive coolant is filled, usual at first system fill or excessive replenishment, the expansion tank fills up and excessive coolant is then vented out of the expansion tank via a hose at the filler neck.
On early systems this excess was simply lost. On later models an ‘atmospheric recovery tank’, an ‘overflow tank’ was added to catch this. And coolant could be ‘sucked back’ into the expansion tank in some circumstances. On the xk the two must not be confused; the pressure cap on the expansion tank opens system to the drain hose when system pressure is reached. In addition, Vent hose(s) allows air to be vented from the cooling system into the expansion tank - to prevent air locks in the cooling system.
On other coolant systems, the pressure cap may be fitted to the radiator, omitting the expansion tank - and coolant is then vented into an overflow tank, functioning like the xk atmospheric recovery tank…
It’s important that a replacement expansion tank fulfils the criteria for correct cooling system operation - a pressure cap is required for proper system pressure. In your case; the perforated expansion tank prevents pressure build-up - which does not interfere with general cooling, and the xk may be run without the spec 15 psi system pressure. But failure to vent air from the engine/radiator may cause problems…
Incidentally, to check coolant levels, always with the engine cold, the expansion cap is removed for a peek…
Another option is to fit the later Series 3 radiator along with it’s plastic expansion/header tank. You can eliminate the small Series 1 header tank and its cap altogether. The swap requires a few other S3 bits as well. The S3 radiator is wider and of a micro-fin design. I think it has higher cooling capacity but am not sure. It’s thinner than the S1, which makes room for an oil cooler if desired.
