Anyone here familiar with this device? Is it wise/safe to use on an XJ-S? I have used mine on my 2-liter Alfa with great results, but just want to ask before trying it on the Jag.
If you’re not familiar, you hook it up to an air compressor and it draws a vacuum in the cooling system. You put the attached hose into your coolant and your coolant replaces the vacuum, leaving a full system with no air in it.
https://m.media-amazon.com/images/I/41UeqVC8aoL.AC_SX355.jpg
As with any coolant path system, the thermostat(s) are usually closed, thereby restricting the flow path towards the radiator, from the engine, when the coolant temp is low - there is also the coolant flow path through the cabin heater exchanger, controlled by a solenoid operated valve (electrically or by vacuum) - on the XJS, the thermostats have a little bypass hole, equipped with a jiggle pin in it which would give very little coolant flow during the use of the method of the unit you are suggesting using - I suppose, that in theory, the unit will work ok, just will be slow - very curious to hear your results - Tex.
You will get the most benefit from systems where the heater core is above the cooling system or where the engine is above the radiator(s) such as some mid engine cars. The XJS is very good about self bleeding the air out. You did not mention if it is a 12 or 6 cyl and what year. Very little problems with any of them but if the dual radiator cap HE, make sure you fill the cap over the water pump until the water is filled in the header tank. This will assure no extra air. Even if you don’t, it will bleed itself.
Thanks for the tips. Sounds like the “by the book” method is reliable and simpler, so I’ll try that first.
Mine is an ‘87 V12, BTW.
I’ve emptied/filled my V12 cooling system twice now with no issues. The key (as explained in book) is elevate the left/front end of car up a good foot. I simply put a jack under the left side of subframe so front end is up high with left a bit higher. Remove the bleeder bolt, which should now be highest point of cooling system. Fill above water pump while engine is cold and not running, until you see coolant coming out of bleeder bolt.
I usually only need two runs with overnight cooling to top up the system, usually only adding a tiny bit each time.
I found it helpful getting one of those coolant measuring siphons, with the plastic balls in them, to tell you your coolant/water mix. I thought I was pretty good about putting in 50/50, but found out I was 60/40.
After the overnight cooling, what’s your method for topping up?
You should fill it from the cap at the crossover pipe.
Don’t open the header tank cap, it’s lower and it will just introduce more air in the system.
Installing a flushing T at the heater hose also helps a lot.
I’ve seen the flushing tees. How do I use it?
Just open the cap on filler that’s above water pump, and top up. I also sometimes squeeze both upper hoses a tiny bit to get any air out.
Hello Jay - the following four pictures, from my service manual, show the cooling system, for the XJS HE V12 engine, which should be what you have in your 1987 XJS - hope this will help you with the understanding of the system parts and flow path, and the recommended renew of the coolant -
You have to install one at the highest part of the heater hose.
As you fill up you open the bleed screw and you will be amazed with the amount of air that will go out.
Since, someone might be googling it, like i did.
I did try it out, since i have the tool
Fail
at first attempt it did vacuum the system to the half of the way and then suddenly vacuum dropped to 0, lol, it sucked all the coolant from atmospheric tank to engine block and started to suck air via that atmospheric tank.
i removed the hose to atmosperic tank and capped it, but still i couldnt reach desired 50-60 cmhg no matter what, and it didnt leak! , as when i stop it did hold the pressure, maybe because there was still some coolant inside (one from plastic tank). i stopped at 45 cmhg, and tried to fill the coolant, well, by the time it reached 0 cmhg, i still had empty top hoses (i could see, as i have transparent coolant filters) and empty wing tank.
I decided not to bother any longer and filled the rest using classic method.
Good luck
I guess one could say vacuum sucks but gravity will always prevail.
