Okay, I've said it before - I'm a Jag newbie.

But this evening I was reading the "XJS Drivers Handbook" for my '91 XJS. Specifically, I was looking up the cooling system specs & maintenance, as I know very little (well, NONE) of the history of this car, other than the strong suspicion that it sat for a *long* time before the PO bought it a year and a half ago.

Imagine my shock/surprise/horror when I saw that part of the drain, flush & refill procedure *in the handbook* is to add two 135mL bottles of Barr's Leaks.

I have NO intention of doing that. I don't see any indication of that in any of the posts on here regarding the cooling system (though, to be fair, there are a LOT of posts dealing with the cooling system, and I've only just scratched the surface).

I'll listen to the collective Brain Trust, but it would take a fairly convincing argument to change my mind on this.

What say ye?

Thanks in advance,

Brad

 

I say WOW! I don't think I'll go with that one either!

 

Do an online search for Kirby Palm's book. He speaks of the cooling system at length, as well as the foolishness of Barr's Leaks.

The short answer is: Don't use. The longer answer is in the book.

You will find the book indispensable.

 

For decades, General Motors procedure for many models at the factory was to put in one or two AC Delco Seal Tabs in each new car's cooling system. It was thought that it prevented customers from coming back insisting on warranty repairs for small seepages. By the mid-90s, they were using robotic machining, quality was improving so the need diminished but the stuff did still have a secondary unexpected benefit of scrubbing scale off of the water pump seals and prolonging their life. Eventually the practice was discontinued. But its not necessarily evil stuff. Troubles arise when people use too much of it thinking if one tablet is good, ten must be better. Or somebody adds more, unaware that the previous owner (or the factory) had already put some in. I don't know about Barr's leak specifically, but I imagine its similar to the GM product which is a natural fiber (but I forget which plant), much like you need in your diet, so imagine, if you put in too much, you wind up with a turd trying to pass through your cooling system. The leak you are trying to seal is microscopic and only needs maybe a few dozen fibers to block it. If the hole were any bigger, the stuff wouldn't work anyway. So while putting in more product may speed up the process of the fibers finding their way to the hole, the intended method is to put in only a tiny amount and let the leak seal itself up over a period of a week or two. If it doesn't stop leaking after a couple of weeks, then the leak is too big and adding more product won't fix it. Its time for a repair. Or if you're seeing it drip on the ground under the car vs just crusty deposits on the engine, the hole is probably too big in the first place. But I think too, GM wasn't trying to preserve their cars for posterity either. They were just trying to get them past the warranty period of one to three years and they WANTED them to start leaking again eventually so they could sell you a new car. So you shouldn't consider any of these products to be a long-term solution. I'm not advocating for this type of product, but I figure if GM put it in new cars under warranty, then its probably OK so long as its used sparingly.

 

Any reason to doubt Kirby Palm's experience? Page 189 (2009 edition) in case you are not familiar with his book, but you should be.

 

Sort the system, no " Bars Leaks" needed. I rebuilt a cooling system on a 1985 XJS as standard as you would on any car and 4 years later no leaks.
Word doc thanks to Grant Francis.

 

i restored my WHOLE XJS without Kirbys book , didnt know it exsisted ,,back 26yrs ago!

when i say rebuilt ,, everything , all body work , floor pans both, rocker panels 2, front rear valances , subframe mounts,bushings, shocks,etc.all paint and mods, wiring on & on!
engine V12 complete redo&modded, trans conversion, drive train rear gear change+LSD!
i have a 2hr video of most of it! on VHS,DUH!, nothing wrong with Kirbs ideas ,but sometimes he insists his way or noway!
26yrs ago i didnt even have a computer or any books XJS, just jumped in and WINGED it! old fashioned Yankee enginuity! LOL.

 

the Barrs leak thing has helped some people sometimes when on the road and a small leak can get you home, far cheaper than a new V12 engine!
ron

 

Dunno, depressurizing the system and frequent enough stops to check the level will take you home without any additives. Note, boiling coolant will not cause damage to your engine as long as the cooling system is full. But when you go easy it won't boil even when depressurized. And then there is nothing to flush out once you have it fixed.

 

Many companies like WYNNS and BG products sales guys visit dealers and offer promotional incentives to use products as preventive maintenance to the service dept with cash refunds when caps, labels and other 'proof-of-purchase' items are turned in for redemption.

I remember bottles of liquid and tablet BARRS LEAKS as well as other 'additives' were part of the 'service-package' of parts issued by the Jaguar dealer for regular maintenance.

Fuel additive as well as oil and other chemicals additives were part of the package.

Some mechanics used the products and some discarded the 'snake-oil' depending on the point of view and shop 'culture'.

Just some of my experiences from Jaguar dealer employment.

Some products work and some cause problems!!!

 

Hello

Back in my heavy machinery days - we used to utilize Morey's heavy duty oil stabilizer in all our oil tanks.

One day - one of our gifted employees had a hose blow on the hydrostatic drive and ran her dry. We fixed the hose, put oil back in and it did the rest of the season. We pulled her to pieces in the off season - no wear/damage at all. The oil sticks to the metal parts and is difficult to get off if needed to - but in the case of overheating or lack of lubrication, it prevents metal onto metal contact.

Would I use this in a high performance engine - no, would I use it in my 40 year old jag that I want to cruise daily at 110km/hr maximum.- yes

In my opinion - some additives are good, some are not - just need to do the research and make an educated decision

Cheers
Steve

 

.

SEG, have you ever heard about the V12 dropped valve seat problem?

when boiling takes place , in certain hot spots exhaust seat area mostly , the boiling has no coolant contact only superheated air, aluminum expands and the seat starts to move around.
and sometimes the hot valve can Microweld to the seat(after shutdown), next time the engine turns over the seat is pulled loose!

something to be said for Evans coolant, 375/400F boiling point, never any super heat, because most engine wont run at those temperature anyway! (you will have other things to do at that point).
and YES Evans requires some mods to use it PROPERLY!
and i aint no salesman for them!, i have used it on some other engines,with good results!
ron

 

Once I spent a summer in an exotic region of this world. Mountains, not much civilization. I made friends with locals. There was a team of dump truck drivers, they used plain water for cooling. Their radiators were insufficient to cool their trucks going fully loaded uphill. In first few kilometers they went boiling and these dudes kept going, just stopped every now and then to add water. I was curious indeed. They used V8 gasoline engines, aluminium blocks and heads. They said these heads warp practically instantly when low on coolant, even if the temperature is in normal range - this would be because of air pockets. Yet, with filled cooling system and boiling no damage was done.
See, boiling is not the same as air pocket. It is vapor pocket, and vapor is the same coolant, just not in the liquid form. It forms and disappears too quickly to be dangerous.

 

SEG, if you want to run a Jag V12 in an overheated condition,you just go ahead! you say that a hot spot in the cylinder head will not cause DETONATION and blow a gasket?

let us know what happens,, i have been around a lot of Race car Jag V12s, at Daytona Race track , and by far 90% of DNFs was from overheating !
in fact check most Jag shops that will work on a V12 will say most have been overheated!
ron

 

That's exactly the point, boiling is not overheating. Overheating is bad to any engine, I agree. Pressurized system wont boil till at some 105 or 108 °C. Depressurized system will boil at 100 °C. Yet, boiling won't cause any hot spots, it's just some bubbles of vapor. Try to think outside of box. You have idee fixe boiling is overheating. I say it is not. Well, I have nothing else to say, so go in peace.

Edit: You may have a closer look at boiling process. You cannot heat water over 100 °C (without pressurizing). As long as your engine is filled with coolant it may boil but it remains at 100 °C. The process of vaporizing consumes lots of energy. Look at a pot of boiling water on the stove, as soon as you lift it the boiling stops, it needs energy to boil (vaporization). The same process the other way releases energy, that's how refrigerants work.

 

SEG we seem to be on opposite sides of thoughts!

you say its OK to run a JAGUAR V12 in a contiunous overheated condition, for the next 100/200miles or more we may have to drive 400 miles before next road stop?
excerpt article: Fact; 11 Atmos. pressure water does not boil till 400F*.

Combustion pressure can reach as high as 500 Atmos. ALL water droplets and Water Vapors, Irrespective of Anything else , becomes GASEOUS , and CANNOT transfer heat away from that local area, Exhaust valve seats!

i already see that we may go on forever, but quick bio of me, my 1st engine car, 1949 now 2019 is 70yrs playing with engines/cars, and its just possible that may have learned somethings along the way,HANDS ON! LOL?
ron