HA, ha, ha, ha, ha, LAMO, LOL!!!
Doug, truer words cannot be spoken. 100% agree.
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Letâs get down to brass tacks here. A great many Jaguar V12 engines are coffee tables today for the same reason: Dropped valve seats. And dropped valve seats are caused by the coolant turning to steam inside the heads. Steam is a lousy coolant, so the area of the head adjacent to the steam rapidly gets very hot â like, probably a coupla hundred degrees hotter than it should be. Not hot enough to melt aluminum, but hot enough for the aluminum to expand enough that the steel valve seat drops out.
Evans wonât turn to steam. Period. Yeah, maybe itâs a bit less effective than pure water, but itâs a couple of orders of magnitude better coolant than steam. Unless you can get air pockets in the head, dropping valve seats should be a non-issue.
Worth $40/gallon? Letâs let those who have dropped valve seats answer that.
Let me get this correct: on a V12, with a decent, clean, and well-maintained cooling system, these steam pockets still are a problem?
Itâs hard to know until the valve seats drop. The steam pockets are more a function of flow rather than temp; your temp gauge can be looking just fine but if there are flow obstructions â such as the upper 1/3 of the 1-1/2 pass radiator getting plugged up â then the coolant can be moving too slowly through the head and starting to vaporize before it moves on. And if your temp gauge sender is on the other bank, you can be blissfully unaware until your engine starts to sound like an old Chevy with bad lifters.
Yes.
No.
Maybe.
I certainly agree with Kirby that flow is is the key issue. And you canât see a steam pocket it it develops.
If your valve seats donât drop then you donât have a flow/steam pocket problem 
Personally, after two V12s over the years, my anxiety level has dropped way down. New radiators, correct thermostats, and proper bleeding of the systemâŠand no dropped seats.
A shred of worry will always exist, I reckonâŠbut nothing that canât be eradicated by a favorite song coming on the radio or the prospect of finding a really, really good pastrami sandwichâŠwhich is hard to do in my neck oâ the woods.
I predict weâll see fewer and fewer dropped valve seats in the future than we did 20-25 years agoâŠthanks in no small part to the internet and Kirby himself. More about âproper care and feedingâ is known, and more widely known, than in the past.
Cheers
DD
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I guess I didnt word my question, properly: does a stock cooling system, beginning with everything top notch, and with regular, periodic maintenance, using standard 50/50 AF/water, result in steam pockets and dropped seats?
Itâs possible, yes.
IMO, thorough bleeding of the system is where many owners or repair shops failed.
Flow is everything and thereâs no 100% certain way of knowing the flow is 100% there.
Knowing what we know now I think the risk is very slight, IMO
Many still become very concerned over coolant temperatureâŠwhich, in and of itself, isnât the key issue. Flow, flow, flow is the name of the game.
The thing about higher coolant temperature is that it might very well be caused by a flow problem.
If thereâs good flow and no steam pockets the valve seats donât give a hoot if the coolant temp is 170ÂșF or 220ÂșFâŠ
IMO
Cheers
DD
Easy to say from the coaching couch. If you had a V12 sitting in the garage right now, would you do the work to make sure you removed over 97% of the water/coolant from the entire system, and spend up to $300 for the Evans coolant needed? A lot of time and money for something that may really not be needed.
Everything in engineering is a compromise Greg.
There is never a âperfectâ solutionâŠ
There are the known facts that one has to take under consideration and make his decision factoring cost, time, longevity, personal psychosis etc etcâŠ
And one is free to ignore anyâŠ
Now, if you had a dropped valve seat Iâm quite sure you would spend that extra $$$âŠ
I havenât and I didnât, and most probably Kirbert either, but the fact is a fact.
And as Richard Feynman said, you canât fool nature.
Aristides
Part of the question, of course, involves the definition of âwell-maintainedâ. If maintained according to Jaguarâs instructions â including a fresh charge of Barrâs Leaks with every coolant change â well, youâve probably already repaired some dropped valve seats. If maintained as we have learned on this forum â installing coolant filters, removing the radiator every couple of years to clear the âtobaccoâ out of the lower half, perhaps even a Lutz mod â yeah, perhaps one of these engines would run a lifetime without ever dropping a valve seat. The problem, of course, is that we havenât conducted a double-blind test with a large enough sample set to know for sure. Yeah, there are owners out there who can claim theyâve never dropped a valve seat â but all of us could claim that, right up until the day we dropped a valve seat.
There is one thing that can be stated with confidence: A well-maintained cooling system is certainly far less likely to drop a valve seat than a poorly-maintained cooling system. So, if youâre not up for paying the big bucks for Evans, at the very least read up on the advice herein and become active in your cooling systemâs maintenance.
That is astonishing: I get the need for filters, if that crap was mandated. I also understand how a lack of flow would be an issue.
I had no real long-term exposure to V12s, beyond a few E Types, and that was mostly limited to required maintenance.
One customer dropped a seat in a â72 E, but that was because of a loss of coolant. After effecting that repair, I was unwilling to get far into the engine mechanicals, plus I stopped working on cars, for a living, in 1991.
Ergo, I never experienced the cooling system issues brought on by years, poor maintenance, and the use of Barrâs leak.
My larger question was, if one began with a pristine cooling system, maintained it as such, and didnt use Barrâs, would Evans show a clear advantage over standard AF/good water, beyond its alleged lack of ability to form steam?
In the many engines that I did have experience with, meeting the above good maintenance criteria, I never saw any significant blockage or sediment.
(Margaretâs engine/radiator were as-delivered, when I rebuilt it a few years ago, and it was clean ss a whistle, and the radiator and unshrouded fan keep it right at 90C, during 42C days. Tweety, whoâs service record and use profile was well-known, also showed very little sediment, and minimal corrosion of the head passages.)
That said, only a very few of those engines had alloy blocks, which may or may not be part of the reason I never really saw issues.
Roger Bywater once reported that Jaguar submitted a brand new XJ12 for Japanâs qualification test (which is apparently really severe) and the car failed the test, overheating badly on a simulated uphill climb. Would Evans have helped? Dunno. IIRC, Bywater said they made some changes to the car for the Japanese market.
Ok, then: a stock cooling system can be overwhelmed by real world conditions: if Evans doesnât boil, it may well have helped.
When your talking about simple overheating in hot weather, under load etc not steam, then the Evans will perform worse as it simply doesnât have the heat capacity of 50/50. You would have to increase the radiator and flowrate to match the cooling capacity of 50/50. Evans is going to have a Cp of 0.5 BTU/lb/F, where as 50/50 is 0.75. Water is 1.0 and would best were it not for the corrosion issues and lower boiling point
Thatâs a critical point: overall, my feeling is, with a well-operating, clean cooling system, 50/50 is still the best bet.
But what again is the trouble here? As long as it doesnât start pinging the engine shouldnât care that much about a few degrees, given that thereâs oil coolers and the main danger with all coolants as I understand it is that the water can start to form steam which canât remove the heat efficiently.
Heat soak doesnât kill engines either.
The reason cooling systems are pressurized to a degree is so the engines can run hotter without the danger of boiling. Iâm sure that if coolant couldnât boil we would run engines hotter from the start. Any engines can and will do fine in hot weather at 210, 220F as long as they donât boil, and the Evans will run hotter, not steam, not much pressure, the only issue here is that the cooling system will reach its limits earlier, yes. But that would give you lots of time to react, if your needle pegs there is enough time to find out that thereâs too much heat, think about it and pull over without any serious dangers as the system wonât fail all of a sudden. Apart from different expansion rates which donât seem to be the problem with V12s that get to hot nothing should change, and if Kirbert says steam is the issue then it is and non-steaming coolant helps. Whereâs the issue I fail to see?
We are all tinkers or we we wouldnât own Jaguars and we wouldnât have such an interesting forum, but the idea of having to closely watch the temperature guage when running in more extreme climes or up grades in the anticipation of having to pull over and let the beast cool down doesnât appeal to me that much. I had to do that enough in my past poor life when I owned less than reliable vehicles. And the boilover when you turn a overly hot car off because of the lack of circulation in a hot head spilling coolant over the garage floor - Im over it. Just my thoughts. 
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Thatâs the thing though; no boilovers ( because it wonât start to boil the way water does) or guaranteed valve seat loss, all you need to do is to check the temperature every once in a while on hot days when thrashing it⊠which you should be doing anyways, right? More peace of mind.
well i used EVANS for 11yrs in a Mazda rotory, and they were noted for hi combustion temps, at a localized point in chamber , never added any coolant in 11yrs, finally decided to take it apart , absolutlely NO corrosion or changes , coolant turned the color of yellow (like BEER), yes i know some of you guys will tear that apart!!LOL>.
it works great WHEN used properly, i used a 7lb. cap. modded coolant pump by me, hoses were all fine!
NOW did you know that it was developed for the Black Hawk helos, for the hydraulic cooling systems,400*F without boiling any bubbles which could cause other problems.(not the engines they turbines).
ron
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