How the coolant atmospheric Tank works and simple viewing modification V18 Jaguar XK8 / XKR (X100)

Engine coolant Atmospheric tank operation and viewing modification.
Short video explaining in basic terms how the atmospheric tank works and why its important to check now and then. Also gives details on a simple modification to improve visual assess to the fluid level in the tank.
Credit to Gary VanRemortal for giving me the idea for the simple mod. V18 Video 18
Part of a series of short videos on the experience I’ve have running my own 1996 Jaguar XK8.
This is not an official guide and for general information and interest only.
Current Playlists on the O&DR Jaguar XK8 Channel
Buying your Jaguar XK8 (what you might want to know and need)
• Buying your Jaguar XK8
Servicing your Jaguar XK8 (regular items)
• Servicing your Jaguar XK8
Maintain your Jaguar XK8 (less regular items)
• Maintain and Repair yo...
Repair your Jaguar XK8 (things that break)
• Playlist
Modify exterior your Jaguar XK8
• Modify exterior your J...
Modify interior your Jaguar XK8
• Interior your Jaguar XK8
Modify performance your Jaguar XK8
• Modify performance you...
Interesting stuff Jaguar XK8
• Interesting Jaguar XK8...
Lockdown list (lists of things you can do whilst locked down for 3 months)
• Playlist
Upgrade cam tensioners, guides and chains (Task by task videos of the process I used).
• Upgrade Cam tensioners...
Supercar experience (In car action from Oulton Park)
• Playlist

[@hewyn1]

Well, we’ve come a long way since the radiator cap just sprayed everything over the engine bay! An excellent modification. Thanks Damien!

[@ODRModurol]

Nick, yes it’s a bit different and not helped by the fact it’s hidden away. But at least people can be aware of it now, thank you for the comment regards Damian

[@craigwilliams1928]

Thanks again for going to the trouble of posting these videos Highly informative and a good way of us gaining information and bouncing around advice

[@ODRModurol]

Craig, no problem, hope the videos help. Much appreciate your positive feedback, regards Damian

[@Bainderosa_Technologies]

I enjoy your videos and expertise on the XK-8. I have owned a 2005 XK-8 convertible since 2008, and have had my share of do-it yourself repairs and garage repairs. I recently had a garage replace the 2 rear quarter windows due to the cable assemblies going haywire.$4000 later (had other items repaired also), my XK-8 is happy again. I also had the dreaded hydraulic hose rupture at the top latch a couple years ago, in which case I repaired it myself with the better (not Jaguar OEM) hoses. I now have the bad door agar microswitch, which is my next project. Pertaining to this video, I do think it was rather poor of Jaguar to position the overflow tank in a non-accessible location, especially when Ford managed the company when my XK-8 was built. Ford did fix a number of problem areas with Jaguar production, especially by getting rid of the Lucus Industries issues. What a nightmare I had with my 1993 XJ-6, which I eventually sold.

[@ODRModurol]

Danny, glad you enjoy the videos and I hope you find them useful. Thank fully I don’t have a convertible and all it’s complexity’s. The coupe is a quite a lot simpler and easier to live with, maintenance wise, regards Damian

[@dreamhunter1950]

Learning a lot by your videos 😊

[@ODRModurol]

Roland, thank you for taking the time to comment and say so. Much appreciated regards Damian

[@abee5744]

Hi Damien, I’m getting the low coolant warning every time time the car warms up (it’s fine when cold). I’ve confirmed the the sensor and magnetic float are fine (I guess the fault would be present all the time if not) and am now wondering whether a lack of coolant in the atmospheric tank could be to blame as the issue seems temperature sensitive. I haven’t check the atmospheric tank yet but could this be a possibility in your view, or is to contrary to the logic of how the system functions?

[@ODRModurol]

A Bee, sounds like interesting problem. I would recommend starting with the obvious practical checks first ie checking the atmospheric tank. If that’s empty fill it to halfway and top up the expansion tank. Once that’s that’s done if you still have a problem then can start further investigation into anything less obvious. Keep it simple if possible. Hope that helps regards Damian

[@richardsutton01]

My expansion tank has always been empty since the car was new but it really doesn't make any difference. All that matters from a cooling perspective is the level of coolant in the header tank when the engine is at operating temperature and provided that the header tank is full at operating temperature then the engine is being fully cooled. What will happen is that some coolant will be released by the header tank valve and pass into the expansion tank where it sits until the engine is switched off and cools down again. That fluid will then be sucked back into the header tank, possibly with a little air but that doesn't matter because no fluid has been lost so when the engine heats up again the coolant expands exactly as it did before and fills the header tank before pushing a little over into the expansion tank. This cycle repeats ad infinitum and cooling capacity is never compromised. Richard

[@ODRModurol]

Richard, the problem with the coolant is it contains 50% water. The fluid in the atmospheric tank is exposed to the atmosphere. The fluid is hot and some of the water evaporates over time. You continually loose fluid with this system. Hence if not topped up you will loose enough coolant to allow air to be drawn into the system. As the air can get trapped in the system the header tank can still be full even with some air in. This will continue until you, hopefully, get a low fluid warning from the header tank. Jaguar actually advises vacuum filling for the 4.2l to avoid air traps. It wasn't a big issue to check and fill it. One less risk to take. That's my thoughts, thanks again for the comment regards Damian

[@richardsutton01]

@@ODRModurol But even if that were the case, the fluid loss through evaporation in the expansion tank would only continue until the volume in the system is just sufficient to expand so as to completely fill the remote header tank at running temperature but not enough to push any coolant past the valve. At that point the system has reached equilibrium and any evaporation losses will stop. Either way, it's not a big deal. Richard

[@ODRModurol]

Richard, could right could be wrong. For the sake of a couple of extra litres of coolant in the atmospheric, I would recommend to air on the side of caution. Reducing the risk of getting air in the system is the goal. This is how the system was setup by Jaguar to run. I am assuming the Jaguar engineers had good reason to do it that way and we just trying to figure it out why. If you where correct the header would just vent to the floor and not the bottom of a bottle. However, if you want to test your alternative theory no problem. Let us know how you get on. Thanks for the discuss point regards Damian

[@nathanlozada5469]

Hello Damien - mine is a US XK8 LHD - do you know where the tank is positioned - on the left (drivers side) or right (passengers side)?

[@ODRModurol]

Nathan, I believe LHD and RHD are the same for the location of the tank. LHD is left - drivers side. Hope that helps, regards Damian

[@daven6357]

Out of curiosity Damian have you been into the corresponding cavity on the LH side wheelarch where the carbon filter for emission management is housed? Just wondering if you had any maintenance suggestions for it - I can't find anything!? Just wondering as I get the occasional fuel smell while driving despite any bulkhead grommets/seals apparently being sound and no fuel leaks. Have refilled my expansion tank after watching this video, something overlooked previously. Nice idea for the access 'door', I missed this out as I have a cheap remote access/fibre optic lead camera from Jaycar here (like Radio Spares in UK) used for various jobs but also great for inspection of head(s) through spark plug holes to name but one application.

[@ODRModurol]

Dave, sorry haven't had any issues with the fuel vapour carbon filter, fingers crossed, so haven't done any research on it. You might be best asking a question on the 'Jaguar Forums' as I am sure someone will be able to help with it. www.jaguarforums.com/ If you get any good information please share. Thanks for the comment Damian

[@davidewell7427]

Is there a sensor in the atmospheric tank? Or if it low will system tell you it low on coolant?

[@ODRModurol]

David, no there isn’t a sensor in the atmospheric tank. The coolant level sensor is in the expansion/fill tank. The only way to check the atmospheric tank is by removing the wheel liner and viewing the level. Hope that helps, regards Damian

[@victorporter1496]

Hi Damian, after watching your video I decided to check the level on my atmospheric tank but found it empty, just like Andy’s. Is there a Jaguar document that mentions that the tank must be partially full? If so, what is the correct way of ensuring this?

[@ODRModurol]

Victor, it doesn't mention the fill level anywhere in the Jaguar manuals I have, except 'the bible'. The logic is something like this but I'm no expert. The only way on ensuring you are not introducing air back into the system whilst cooling down is to make sure the Atmospheric (degas) tank has some coolant in it. Then you KNOW you are not doing that. Without that confirmation you can't tell if you running with some air in the system. Although only small amount as otherwise you would get the coolant level alarm (unless you've hot wired it). You may well have excess coolant in the pipe to the expansion tank but you don't KNOW as you can't see it. Hence, it just good practice to see a bit of the excess coolant and know what's happening. Its simple to add coolant in there. You can remove the fill pipe plug at the top of the Atmospheric tank and simply pour coolant in. Then clip the plug back in, job done. Hope that answers you question. Not a big issue just good practice. Thank for the question respect the choice of others to do differently, regards Damian.

[@victorporter1496]

O&DR Jaguar XK8 Hi Damian, appreciate your reply. I’ll put some coolant in the tank and keep my eye on the level. Cheers, Victor

[@ODRModurol]

Victor, Appreciate your time and effort to mention your thoughts. Its good to discuss these things that are a bit blurred, Thanks Damian

[@zerepl]

Hi Damien. Once I verify the tank is low how do you recommend I fill it?

[@ODRModurol]

Angel P, there is a pipe going in through the lid at the top. You should be able to remove the lid and pipe together and then fill from there. Hope that helps regards Damian

[@mikechaffin8100]

Just had a check of mine... The header tank seems to be full. The atmospheric tank has a very small amount in but the fluid in there isn't red. Difficult to tell but it looks like water. Shall I get some coolant and half fill it to see what happens, or try to get rid of whatever is in there first?

[@ODRModurol]

Mike, sounds like water as the coolant is water based. If there is only a small amount it won't dilute the coolant very much anyway or you can adjust the dilution of the coolant you add. Best to half fill and let the system draw it in and out. Hope that helps, thanks for the comment regards Damian

[@richardgarrison284]

Correct me if i am wrong, but the level in the chimney pipe will always be the same as the main atmospheric tank unless a vacuum is maintained to the engine. Any time you remove the fill cap to add coolant the vacuum is broken and the level will equalize.

[@ODRModurol]

Richard, I think you are correct. But a vacuum is maintained whilst there is fluid in the atmospheric tank and this draws fluid back into the system during cooling down. The main issue is that the fluid is 50% water and open to the atmosphere. Over time (many years) this evaporates and this reduces the amount of fluid in the tank to zero. Then without knowing, you are drawing air into the system. Hence the idea of checking the tank on these 20 year old cars. Thanks for the input and comment regards Damian

[@MickMacSpoz]

Hi Damian. Great info as always, however, this one has confused me. I originally watched your other COOLANT video as I’ve been getting intermittent Low Engine Coolant message. It only last for a few minutes then goes away. How do check the level? Do I look in the header tank and fill up there or do I need to check the atmospheric tank in the wheel arch like in this video? Hope you can advise. Thanks.

[@ODRModurol]

Mick Mac, Sorry for any confusion. To check the coolant level manually you check the level at the expansion tank in the engine bay. This is where the level float is so you can see it is actually low. The level is only correctly maintained if the atmospheric tank has fluid in. You could have a sticky float, empty atmospheric tank or a leak somewhere, or combination. I would start with the easy stuff check the atmospheric tank and look for any obvious coolant leak. The naming of these items is a bit wrong. The 'expansion tank' acts as a coolant manifold and houses the level sensor. The 'atmospheric tank' is where the excess expanded coolant goes and returns to maintain the level. Hope that helps, regards Damian. PS here's the video on the expansion tanks. kzbin.info-2y20KZkHy8

[@MickMacSpoz]

@@ODRModurol Thanks. I’ll investigate further.

[@ODRModurol]

Mick, good luck👍 regards Damian

[@olegfrul5873]

Hi Damian, thanks for all your videos - good lesson to study and save time and efforts if troubles up. Question - sometimes the steam comes from right wing as well as smell of antifreeze in saloon when ventilation running - is it normal for second extension tank? Didn't check level there yet but level in upper tank is basically same, topping 200 grams every 1000 Km - is it normal?

[@ODRModurol]

Oleg, thank you for your kinds comments. Sounds like a leak on one of the heater coolant hose connections. Unfortunately, they are plastic and become brittle over time. They are in between the bulk head and engine under the throttle body. Not the easiest thing to access and repair. Might be worth checking the second tank it’s probably empty but it shouldn’t be releasing steam as you describe. Hope that helps regards Damian

[@olegfrul5873]

@@ODRModurol Thanks Damian, all noted

[@ODRModurol]

Good luck with the repairs, regards Damian

[@AndyK.1]

Personally I don’t think the level is that important. It’s nice to have, but I’m not concerned with the level. Mines been empty since new

[@ODRModurol]

Andy, just trying to figure out / explain how it works and what happens if nothing’s in the tank. You’ve got some margin of error for small leaks if the tank as something in. You must agree it’s not easy to check without a simple mod. Value your input and opinion good to have some discussion, thanks Damian