Hi All,

 

I have a 10 year old Roomster 1.6tdi. The cam belt and water pump were changed by the dealer before I bought it in June but I have just found out that they put the old coolant back in. 

I would now like to replace the coolant. Any advice on doing this myself without a vacuum unit would be appreciated.

Is it important to drain the system with the heater on?

Is it OK to drain only from the bottom of the radiator?

Is I believe airlocks are difficult to get rid of so extra care is required.

 

Any advice would be much appreciated,

 

 

Welcome, however you have posted in the Octavia Mk2 forum, not the Roomster.

You do not need a vacuum unit to change the coolant.

I expect the heater is air blending  so the matrix is in the circuit all the time. It is fine to drain from the bottom of the radiator only.

Make the coolant mixture slightly stronger to compensate.

Running the engine without the coolant header tank cap to allow air to bled out.

If anyone has specific Roomster comments please feel free to comment

Hi ,

Many thanks for your very helpful advice.

Keep the cap on.

 

If they have filled to MAX and after a run and coolant and engine up to temp the coolant drops between MIN and MAX that is fine because there is no FILL to the Level mark.

 

The Pressurised system will bleed just fine and any coolant lost will be via the overflow if all is well. 

Thanks

Hi all.

 

I'm changing the coolant on my 1.6 tdi 2013 cayb too. There doesn't seem to be any coolant drain plug underneath so I'm just planning to remove the bottom radiator hose. There doesn't seem to be a service manual anywhere online though despite a lot of looking and nothing on youtube for the tdi.

 

Am I right in thinking the two very big hoses underneath by the radiator (about 60mm diameter) are air hoses of some kind?.

 

Once I find the coolant hose, do I need to disconnect more than one hose, or will everything flow out if I open the circuit at a single point?

 

Thanks all - surprisingly little information online for this given it's a super common engine.

48 minutes ago, mattyuk22 said:

There doesn't seem to be a service manual anywhere online

Erwin.

6 hours ago, mattyuk22 said:

Am I right in thinking the two very big hoses underneath by the radiator (about 60mm diameter) are air hoses of some kind?.

 

Yes, I have mistakenly removed the intercooler hose expecting coolant to drain out

 

Once I find the coolant hose, do I need to disconnect more than one hose, or will everything flow out if I open the circuit at a single point?

 

Yes but after the initial splurge it will start glugging, best to remove the expansion tank filler cap to allow air in.

 

Brilliant. Thanks Bergerac. Yes I did the same thing and freaked out when I thought there was nothing in my radiator but thin air. Why on earth there isn't a coolant drain plug is beyond me. Intercooler hose - thank you you have taught me something valuable.

 

I drained the coolant from whichever hose was the first one to spit out red coolant and refilled with radiator flush and water via the expansion tank.

 

My plan now is to drive around a bit til the thermostat opens, then flush with clean water, then refill with coolant. What I don't get and would appreciate a bit of help on, is that UNLESS I remove the thermostat (after a painful experience with a blown head gasket I don't want to go down that road again), then every time I drain the engine from the bottom radiator hose, I'm only ever going to be draining off half the old coolant - ie. the bit that can get past the closed thermostat. Unless I want to be draining 70degree-plus coolant that is.

 

Is that correct? And if so is the normal method just to keep driving til the thermostat opens, coming back home, flushing again, then going for another drive and so on, such that the amount of old dirty coolant in the system is "halved" each time. That doesn't seem right to me - you'd never get all the old coolant (or radiator flush) out doing that.

 

What am I missing? How do the shops do it - they can't be removing the thermostat every time can they?

 

Sorry for the dumb questions - I have watched a lot of videos on this, but can't quite work out if I'm being dim.

Edited 16 August, 20241 yr by mattyuk22

On 26/12/2023 at 13:30, Ootohere said:

Keep the cap on.

 

If they have filled to MAX and after a run and coolant and engine up to temp the coolant drops between MIN and MAX that is fine because there is no FILL to the Level mark.

 

The Pressurised system will bleed just fine and any coolant lost will be via the overflow if all is well. 

The overflow?

blue you can ignore the original question on the thread - i resurrected it to ask a different question

Thermostats have a small hole usually with a jiggle pin to keep them clear, the purpose is to allow the coolant to flow over the wax element to avoid the engine getting way over temperature before the stat opens, a secondary role is to aid in draining the system.

 

The diameter of the hose to the header tank and air hole in the stat need only be very small compared to that of the lower rad hose being drained because air is far less dense than water.

Thanks JR. Are you saying that all the water will drain from the CAYB engine when I remove the lower radiator hose, regardless of which "side" of the thermostat it sits?

I have also read that the coolant on this engine is constantly being pumped into the coolant expansion reservoir and one way to flush the coolant is just to remove the (upper) hose feeding coolant into the reservoir, attach that to a waste bucket, and just keep topping up the reservoir with new coolant until you see the "fresh" coolant flowing through the upper hose.

 

Is that a bad way to do it, and again, would ALL the coolant be replaced or would I have problems if the thermostat wasn't open?

 

See here - https://www.youtube.com/watch?v=wfECBbTP7Tw

 

Thanks in advance for any help.

6 hours ago, mattyuk22 said:

I have also read that the coolant on this engine is constantly being pumped into the coolant expansion reservoir and one way to flush the coolant is just to remove the (upper) hose feeding coolant into the reservoir, attach that to a waste bucket, and just keep topping up the reservoir with new coolant until you see the "fresh" coolant flowing through the upper hose.

 

Is that a bad way to do it, and again, would ALL the coolant be replaced or would I have problems if the thermostat wasn't open?

 

See here - https://www.youtube.com/watch?v=wfECBbTP7Tw

 

Thanks in advance for any help.

That is a VERY bad way to "replace" the coolant, because you won't know how much "antifreeze" is in the system.

I think the theory is that if you have pre-mixed antifreeze and you just keep pumping the new stuff in until it comes out of the "top" pipe of the expansion reservoir (plus a bit more for luck), the system is rully replenished with the new coolant. Would that not be the case? Watching to the end of the video the guy says to do it with a hot engine so the thermostat is is already open when you start replacing.

1 hour ago, Paws4Thot said:

That is a VERY bad way to "replace" the coolant, because you won't know how much "antifreeze" is in the system.

 

1 hour ago, mattyuk22 said:

I think the theory is that if you have pre-mixed antifreeze and you just keep pumping the new stuff in until it comes out of the "top" pipe of the expansion reservoir (plus a bit more for luck), the system is rully replenished with the new coolant. Would that not be the case? Watching to the end of the video the guy says to do it with a hot engine so the thermostat is is already open when you start replacing.

The point is not just to replace the coolant, but to wash debris out of the system at the same time. This usually involves 3 or 4 complete changes of water in the system, then let it dry pretty much completely (say till the hoses stop dripping), and finally refill using measured quantities of liquid.

Ah that's a fair point. So maybe the approach in the video might be appropriate for a "younger" car, but probably not an older one which might have accumulated more crud.

 

As per usual, I'm in the process of flushing mine (driving round with flush in the system for a couple of days), but have managed to trigger some diagnostic codes on the system. Suspect I may have left something loose; hopefully will sort it when I get back under the car. When will I learn...?

ok, ignoring the error codes, I can't work this out.

 

If I open the bottom radiator hose with a cold engine, I only get about 4 litres of liquid out (even if I run the engine for a minute to pump out any dregs). The manual says the CAYB engine takes 8.4 litres of coolant so I'm missing a lot!

 

I can fill it back up again at the expansion tank, and run the car, but I feel like I'm always going to have some coolant flush left in the system, and I don't see how I can fully get it all out and replace it with new coolant if I can only drain half the system at once.

 

Is there any way to completely drain the coolant system without taking the thermostat out? Is there a separate hose for the intercooler that I need to take off? Totally lost. Can't find anything clear online and nothing for this engine.

Just found the workshop manual online. Says to disconnect the left charge air hose and a couple of other hoses. WIll try that and see if I have any luck.

Are you certain that 8.4 litres is not a typo?

 

Its nearly double what I would expect.

Here is the extract from the owners manual.

 

So I followed the instructions as far as I could. Only thing I couldn't do was disconnect the bottom end of the hose to the engine oil cooler so I disconnected the other end which is about 10cm higher. Disconnected the charge hose and hoses both sides of the coolant recirculation pump as per the manual instructions. Even turned it over just to spit out anything left in the system.

 

Refilled and took it through heat up/cool down with heater and ac on and off.

 

Fully topped up it took about 4.5 litres of new coolant.

 

Like I say the manual says 8.4 litres. Does anyone have any idea what the issue might be? I'll contact skoda and ask if it's a typo.

 

Snip from the manual below saying to remove hose from oil cooler. Incidentally, not sure what o-rings they are on about replacing; there aren't any.

 

 

 

Edited 10 September, 20241 yr by mattyuk22