Rebuilt Jag XK engine - coolant advice

[Squirrelofwoe]

We are in the process of building an SS100 replica, the 4.2 engine for which came from a deceased family member's 1970 series 1 XJ6. This engine was completely rebuilt in around 2014 by an old gentleman who specialised in XK engines- who I believe is now sadly deceased. Regardless, as part of the rebuild process the engine was chemically cleaned- with the intention being to run the car with Evans waterless coolant.

In recent years there seems to be a lot of negative comments online around the Evans coolant - poorer heat dissipation, flammability, issues with water pumps not being up to the task etc. I broadly understand the science behind why it would have poorer cooling than a traditional water + coolant mix, but the trade-off being no internal corrosion, much lower pressure, and no boiling off under very high temps. It would be going into an effectively brand new system (rebuilt engine, brand new aluminium rad, pipes, thermostat etc), so we are not looking for it to be a band-aid for a tired cooling system- it's the long term preservation benefits and lower pressure that appeal.

We are rapidly approaching the point where we really need to make a decision soon on whether or not to go with it- so I just wondered if anyone on here had any experience with it specifically in relation to the XK engine, or could offer any thoughts that might better inform our decision?!

[larrylamb11]

Personally I wouldn't bother with waterless - the fundamental purpose of a coolant is to draw heat out of the engine and exhaust it into the atmosphere and nothing does that better than plain old water.... The problem with water is it's propensity to freeze and corrode metals, hence the antifreeze and corrosion inhibitors in coolants.
Back when your Jag engine was made an Ethyl Glycol antifreeze would have been standard - it's good at preventing water freezing and protecting all the sorts of metals found in old cooling systems, but degrades over time, becoming more acidic, hence the corrosion inhibiters and the necessity to change it regularly.

Then came the more modern technologies of IATs and OATs, OATs being by far the most prevalent nowadays. They're better than Ethyl Glycol type antifreezes as they still prevent the water from freezing, have better heat transfer than Ethyl Glycol type antifreezes and are much much longer lasting. The point to note about OATs is that they won't protect certain metals like copper and brass, though they are very good at protecting aluminium and iron.

So, as with everything it comes down to picking the right product for your application. Given that your engine is effectively 'new' so you are starting with a clean, new system, what is the right antifreeze to use? The answer will start with what metals you have in your cooling system - if it's all just aluminium and iron, an OAT antifreeze will be an excellent choice. If you've got a brass heater matrix or copper pipes or there are soldered joints in the system you will want to use a traditional Ethyl Glycol antifeeze, avoid OAT and change it regularly. I suspect this is the point at which you've considered going Evans waterless as you never have to change it. There are several points to bear in mind with waterless - it isn't as good at heat transfer, though it can deal with that by having a far higher boiling point. Its more viscous so doesn't flow around a cooling system in the same way water based does and it may require a different type of water pump. It's expensive and it will find every opportunity to leak! It will creep through microscopic gaps water based coolants won't. Importantly, it won't indicate a problem like a traditional water-based system will. A traditional system will boil off if it gets too hot giving a good visual indicator you have an issue, with waterless coolant it will just get hotter and hotter and potentially risk warping and damage to major components unless you happen to spot on your instruments that you have a problem. Further, if you do have a problem when you are out and about and lose a load of coolant, a traditional system can just be topped off with whatever you can find that has water in it... you can't do that with waterless.
Overall I don't opt for waterless coolant in any of my classics and choose whatever is appropriate for the cooling system, changing it regularly. For me, it's the best compromise between technology, sympathy for old cars and comfort, knowing I can get myself home if I have a problem and the fix afterwards isn't going to be expensive and time consuming. You may have different priorities but hopefully the above might help clarify your options.

I do use Dot5 silicone brake fluid in some brake and clutch applications though, so I'm not a total luddite!

[v8250]

100% as per larrylamb11.

I have rebuilt a good number of XK engines and would not consider a waterless coolant. XK engines are very simple, do run 'hot...' and need no added complexity, just good quality traditional coolant that's changed every few years. The added advantage of being able to detect any potential cooling system issues can not be underestimated and makes for simple fault diagnosis.

I remember Roger Williams of Suffolk Jaguar having a thing for the much maligned 2.8ltr engine despite the much free'er rev'ing engine. There used to be a YouTube video of Roger hustling along one of his tremendous Suffolk Jaguar SS100's with the 2.8 engine. Alas, Suffolk Jaguar are no more.

SS100's are great looking cars and owning one is on my bucket list. Good luck with the build / post pics when completed.

[Squirrelofwoe]

larrylamb11 said:

Personally I wouldn't bother with waterless - the fundamental purpose of a coolant is to draw heat out of the engine and exhaust it into the atmosphere and nothing does that better than plain old water.... The problem with water is it's propensity to freeze and corrode metals, hence the antifreeze and corrosion inhibitors in coolants.
Back when your Jag engine was made an Ethyl Glycol antifreeze would have been standard - it's good at preventing water freezing and protecting all the sorts of metals found in old cooling systems, but degrades over time, becoming more acidic, hence the corrosion inhibiters and the necessity to change it regularly.

Then came the more modern technologies of IATs and OATs, OATs being by far the most prevalent nowadays. They're better than Ethyl Glycol type antifreezes as they still prevent the water from freezing, have better heat transfer than Ethyl Glycol type antifreezes and are much much longer lasting. The point to note about OATs is that they won't protect certain metals like copper and brass, though they are very good at protecting aluminium and iron.

So, as with everything it comes down to picking the right product for your application. Given that your engine is effectively 'new' so you are starting with a clean, new system, what is the right antifreeze to use? The answer will start with what metals you have in your cooling system - if it's all just aluminium and iron, an OAT antifreeze will be an excellent choice. If you've got a brass heater matrix or copper pipes or there are soldered joints in the system you will want to use a traditional Ethyl Glycol antifeeze, avoid OAT and change it regularly. I suspect this is the point at which you've considered going Evans waterless as you never have to change it. There are several points to bear in mind with waterless - it isn't as good at heat transfer, though it can deal with that by having a far higher boiling point. Its more viscous so doesn't flow around a cooling system in the same way water based does and it may require a different type of water pump. It's expensive and it will find every opportunity to leak! It will creep through microscopic gaps water based coolants won't. Importantly, it won't indicate a problem like a traditional water-based system will. A traditional system will boil off if it gets too hot giving a good visual indicator you have an issue, with waterless coolant it will just get hotter and hotter and potentially risk warping and damage to major components unless you happen to spot on your instruments that you have a problem. Further, if you do have a problem when you are out and about and lose a load of coolant, a traditional system can just be topped off with whatever you can find that has water in it... you can't do that with waterless.
Overall I don't opt for waterless coolant in any of my classics and choose whatever is appropriate for the cooling system, changing it regularly. For me, it's the best compromise between technology, sympathy for old cars and comfort, knowing I can get myself home if I have a problem and the fix afterwards isn't going to be expensive and time consuming. You may have different priorities but hopefully the above might help clarify your options.

I do use Dot5 silicone brake fluid in some brake and clutch applications though, so I'm not a total luddite!

Thanks for the extremely detailed, informative post- exactly what I was after!

[Squirrelofwoe]

v8250 said:

100% as per larrylamb11.

I have rebuilt a good number of XK engines and would not consider a waterless coolant. XK engines are very simple, do run 'hot...' and need no added complexity, just good quality traditional coolant that's changed every few years. The added advantage of being able to detect any potential cooling system issues can not be underestimated and makes for simple fault diagnosis.

Thank you - I think this is looking like the route we will go down.

v8250 said:

I remember Roger Williams of Suffolk Jaguar having a thing for the much maligned 2.8ltr engine despite the much free'er rev'ing engine. There used to be a YouTube video of Roger hustling along one of his tremendous Suffolk Jaguar SS100's with the 2.8 engine. Alas, Suffolk Jaguar are no more.

SS100's are great looking cars and owning one is on my bucket list. Good luck with the build / post pics when completed.

I will certainly post some pictures up at some point!

That iteration of Suffolk is indeed no longer, but the new Suffolk Classic Services (nothing to do with Roger) are still heavily involved with the SS100 replicas- we speak with them on an almost weekly basis concerning our build and they have been incredibly helpful, both from a technical resource and supplying parts / fittings that were either missed previously or that have since been superseded by superior items. If you do look to get involved with an SS100 they are well worth giving a call.

[Leveret]

For several decades I have thought that it is illogical to 'change coolant every few years' as suggested above. Corrosion is caused not by water but by the dissolved oxygen in the water. Once that is used up, no further corrosion can occur. Our rusty old Mk1 Focus went to the scrapyard at 21yrs old and >160,000 miles with its original pink coolant. The last time the coolant was added in my TR7 was in 2002 when I had to replace the water pump, and even then I did not completely drain it. It is now 44yrs old with admittedly only 73k miles but there is no coolant loss and no sign of CHG failure. The corrosion genie is delighted when coolant is changed because with fresh oxygen it can resume its erosive destruction!

[9xxNick]

I believe there is also the additional consideration that waterless coolants are either 100% ethylene glycol or propylene glycol, both of which are more flammable than a solution of ethylene glycol in water in the ratios used in normal automotive coolant.

If anyone has any additional information on this I would be grateful if you could share it.

[larrylamb11]

Leveret said:

For several decades I have thought that it is illogical to 'change coolant every few years' as suggested above. Corrosion is caused not by water but by the dissolved oxygen in the water. Once that is used up, no further corrosion can occur. Our rusty old Mk1 Focus went to the scrapyard at 21yrs old and >160,000 miles with its original pink coolant. The last time the coolant was added in my TR7 was in 2002 when I had to replace the water pump, and even then I did not completely drain it. It is now 44yrs old with admittedly only 73k miles but there is no coolant loss and no sign of CHG failure. The corrosion genie is delighted when coolant is changed because with fresh oxygen it can resume its erosive destruction!

You've not mentioned one of the biggest killers of coolant system components which is galvanic or dissimilar metal corrosion - there's also crevice corrosion, acidic, electrolytic, contamination etc. etc. all of which are working at creating corrosion in your cooling system all the time..... they're actually pulling the oxygen out of the H2O to react with, whilst making the remaining solution more acidic.
The silicates, phosphates and borates in antifreeze work as inhibitors against these attacks to keep the solution alkaline by binding to the oxides formed in corrosion of cooling system components, precipitating out of the solution and forming a silica gel that coats the inside of the cooling system to prevent further corrosion (anodic inhibition). The problem is that the inhibitors are sacrificial and of limited supply. You cannot load excess silicates into antifreeze to prolong its efficacy as it simply tend to lead to mass deposition and the blocking of water ways. Consequently, it's a balancing act of loading enough to remain in solution and do the job, whilst not so much that they precipitate out and cause unwanted issues. The reason you have to change the fluid regularly is that these silicates are actually being continually used up in chemical reactions and thus become less effective over time - the corrosion never stops, but the anti freeze stops being as good at managing it.... That's why you have to refresh it with a change.

Whilst the old antifreeze in your TR7 may look ok, the probability is that it's PH level is more acidic than it should be and there is unseen corrosion occurring within your cooling system components, most likely with the aluminium components being eaten away at the rubber hose joints and pitting internally.

It's worth noting that the pink coolant in your scrapped old Focus is an entirely different technology in a modern cooling system designed to use it - these are long life coolants specifically designed for the more limited metal types used in modern cooling systems (primarily just iron and aluminium). These are designed to last 5+ years or the life of the car in some cases and should not be confused or compared with the stuff in your TR7.

9xxNick said:

I believe there is also the additional consideration that waterless coolants are either 100% ethylene glycol or propylene glycol, both of which are more flammable than a solution of ethylene glycol in water in the ratios used in normal automotive coolant.

If anyone has any additional information on this I would be grateful if you could share it.

Evans report that their waterless coolant is no more flammable than traditional coolant mixed with water and requires very high temperatures to auto-ignite. Make of that what you will....
Independent testing suggests Evans has a flashpoint in the 107-111°C, whereas coolant mixed with water has a flashpoint ranging from 110-130°C depending on concentration. Given that Evans tends to run at higher standard operating temperatures owing to it's poorer heat transfer capability and increased viscosity, whilst also having a lower flashpoint, it's reasonable to presume that it is naturally at greater risk of combustion - it's actually within it's flashpoint at normal operating temperatures.
In reality, the risk is probably greater still as you don't get the warning of cooling system malfunction like you do with the boiling off of a water mix coolant, as noted above. Consequently there is an increased risk of a mechanical failure that releases a liquid with a lower flashpoint than coolant mix into an engine bay or onto components that are significantly hotter than one might expect with a water mix coolant, increasing the risk of combustion still further.

[lowdrag]

How good to see many people speak against the Evans product. I have always thought about "what happens if I need to top the system up" after finding a leak, and then discovered that you need to start from scratch with the cleansing product and the correct level of Evans and that isn't cheap. I've had my E-type for forty years now and if I had a pound for every time I have been told "you have a leak sir" just because of the overflow i'd be a rich man. The engine was completely rebuilt six years back, I changed the cap and use a new 7lb one (always have) and still it blows out. I am fitting an overflow bottle now.

I think my only difference between larrylamb and I is that I have stuck to 5.1 brake fluid.

[Leveret]

larrylamb11 said:

Leveret said:

For several decades I have thought that it is illogical to 'change coolant every few years' as suggested above. Corrosion is caused not by water but by the dissolved oxygen in the water. Once that is used up, no further corrosion can occur. Our rusty old Mk1 Focus went to the scrapyard at 21yrs old and >160,000 miles with its original pink coolant. The last time the coolant was added in my TR7 was in 2002 when I had to replace the water pump, and even then I did not completely drain it. It is now 44yrs old with admittedly only 73k miles but there is no coolant loss and no sign of CHG failure. The corrosion genie is delighted when coolant is changed because with fresh oxygen it can resume its erosive destruction!

"You've not mentioned one of the biggest killers of coolant system components which is galvanic or dissimilar metal corrosion - there's also crevice corrosion, acidic, electrolytic, contamination etc. etc. all of which are working at creating corrosion in your cooling system all the time..... they're actually pulling the oxygen out of the H2O to react with, whilst making the remaining solution more acidic."

Galvanic corrosion needs an electrloyte. Pure water is not an electrloyte - 'they' cannot 'pull' O atoms out of it. Nor is glycol.

"The silicates, phosphates and borates in antifreeze work as inhibitors against these attacks to keep the solution alkaline by binding to the oxides formed in corrosion of cooling system components, precipitating out of the solution and forming a silica gel that coats the inside of the cooling system to prevent further corrosion (anodic inhibition)."

To the best of my knowledge none of these salts are in my ancient can of Comma Supercoldmaster Blue Antifreeze pure glycol which might provide a basis for an electrolyte. In theory they are protective, but I have read about expensive problems that silicates can cause.


"Whilst the old antifreeze in your TR7 may look ok, the probability is that it's PH level is more acidic than it should be and there is unseen corrosion occurring within your cooling system components, most likely with the aluminium components being eaten away at the rubber hose joints and pitting internally."

I have just dipped a Medi-Test Combi urine testing stick into a sample of my 20th century coolant and am pleased to report the pH is a neutral 7. The proof of my assertion is supported by the pudding of my TR7's continence over many decades.

Edited by Leveret on Wednesday 3rd July 09:36

[lowdrag]

I've just looked it up to remind myself. Here we go:-

Green and blue traditionally represented Inorganic Additive Technology (IAT) coolants. This is generally considered an out-dated type of coolant that contained phosphates and silicates, and required changing every two years on average.

Orange and Red

Orange and red coolants were usually classed as Extended Life Coolants (ELC), and offered a longer change interval than IAT variants, generally up to five years or 100,000. They used corrosion inhibitors and antimicrobial agents to slow wear and tear and offer greater protection for the engine

I feel better for that!