Bleeding cooling system?

[dontknowz]

Hi does anyone know if the cooling system on caddys are self bleeding or weather you have to do a full bleed like on most cars aka blowers on full heat, expansion tank open ran up to temp. New to caddys and its taking ages to get anywhere near warm, recently had a water pump replaced and had to top the antifreeze up due to the light coming on the dash so I’m guessing its got alot of air somewhere in the system. Also don’t know if this is normal but when cold theres no coolant running through the return on the expansion tank I’m guessing this is because the thermostat is closed but not 100% because on all my other cars the antifreeze is cycling straight away and you can see it moving in the expansion tank.

Any helps appreciated just getting a bit frustrated not knowing enough cheers

[BenT]

I can't speak for the current generation of Caddy, but the MK2s, 3s and 4s are all self-bleeding. But it takes a while! My Octavia with the MK4 Caddy engine took at least 100 miles after draining and refilling before the coolant level stabilised and no longer needed topping up. My 1.6 MK3 took far less miles to sort itself out.

How many miles does yours take to warm up? Mine's taking between 4 and 6 miles to reach operating temperature which is quite normal. If it cools down while driving at low speeds then your thermostat might be stuck open. Quick and cheap to fix.

And yes, perfectly normal to have no flow to expansion tank or radiator until the thermostat pops open.

[dontknowz]

Mint mine takes about 3-4 miles to warm up ill just keep a bottle of antifreeze in the van then ive only done about 8 miles so far so will keep checking.

Thanks for your reply i was panicking thinking something was broke


Sent from my iPhone using Tapatalk

[BenT]

That warm up time's good

Hopefully it's just trapped air causing the coolant to drop. If it still does it after 100 miles or so you might want to check that the coolant pump's not leaking, in case the o-ring's got pinched.

[dontknowz]

Im hoping its just air because I’m hearing like a bubbling noise when i turn the van off once its been up to temp. Ive had it get pretty hot almost at 4 notches past 90 on the temp gauge which is very annoying don’t fancy a warped head ,luckily i caught it in time and put the blowers on full and that was enough drop it back to centre of temp gauge im gonna give it a good run Monday and see if anything has improved if not it’s going to a garage.


Sent from my iPhone using Tapatalk

[DW2207]

After renewing my secondary coolant radiator on my mk4 caddy, I carried a 5l bottle of g12 that I would have to top up a bit at a time over a few weeks and a couple hundred miles of driving. It's now at the correct level and so far no problems.
I probably lost around 2.5l of coolant on the removal of this radiator and have refilled pretty much the same amount.

Sent from my SM-G981B using Tapatalk

[dontknowz]

Hi me again so ive drove it around 200 miles and had runs about 20 miles here and there and im not getting any overheating but iam getting a low coolant but as soon as i take the top of the expansion tank it fills back up again? Has anyone experienced this




Sent from my iPhone using Tapatalk

[Doc]

Coolant returning to the reservoir when the cap is removed with the system warm is normal. The cap should only be removed and the level replenished when the system is cool.
If the level is below minimum when cool it needs a good top-up. Bring the level up to just above the marked area when cool, it'll do no harm as any excess when hot will just overflow.
If the level needs to be topped up often, you must be losing coolant somewhere.

[dontknowz]

Hi so ive had this happen twice now when cold ill loosen the cap and all the coolant will return and itll be right on the max line, the picture was taken when the system was warm so didn’t open it. So should the coolant system at any point go below minimum or is this normal on vw?


Sent from my iPhone using Tapatalk

[Doc]

Definitely not normal, when the coolant system is warm the air in the reservoir should be under pressure and the level should rise. The fact there's more air in there than there should be suggests something is pressuring the system with air, that might be the head gasket or charge cooler.

[dontknowz]

Yeah ive been reading the same things im hoping its just trapped air creating a vacuum because of it needing to be bleed


Sent from my iPhone using Tapatalk

[Savaloy]

Sorry to revive an older thread, but im have the exact same issue and i was wondering if you have had any joy in finding out what it was in the end?
When the engine is cool, the level is at the max but after driving and being up to temp (no over heating issues) once pressurised the level drops and brings on the low coolant lamp on the dash. Then when opening the expansion bottle the coolant then returns back to the max mark again... so annoying.

[dontknowz]

So mine has basically stopped doing that now it’s taken probably 1.5-2 litres of antifreeze over a couple of weeks if its lowering the level then theres definitely air somewhere, its a pain to bleed because you cant just let it sit at idle with the cap off like most other bleeds ive done because itll never reach temp so i just kept doing 20 mile motorway runs and kept topping it up


Sent from my iPhone using Tapatalk

[BenT]

I'd check the head gasket... When you can, leave the van overnight after you've driven it and open the coolant tank lid the following the morning. If there's a gurgle or release of gas then something's leaking air or exhaust gases into your cooling system.

[Savaloy]

yeah i must have done around 500miles now but the van still has a moment where it feels like the level is low until i open the expansion bottle lid which it then all rushes back to the max mark.

BenT shouldnt it be slightly pressurised when opening the cap after letting it cool down over night?