It is possible that with damaged water pump you had a local overheating issue what causes boiling and air pockets.
Yet, that would result in overheating in general what you would see on the dash with the temp gauge climbing.

As per heater core - coolant flows through it all the time and you have no control over it. The only thing that you do is to adjust the mixing flap.

I am puzzled why they did not verify everything the first time around. Why all of sudden you need to replace thermostat which was fine when they were doing system flush? And now water pump?


From my experience with the I5 - it is not easy to burp. Preferred way to change coolant is vacuum (what I hear). I did it regular refill and it took me a while to stabilize the coolant level.

 

Thank you replying -PLP-

Their Master Mechanic, initially admitted to me after I returned for the boiling coolant that they did not have a coolant flush machine (?), they just drained, checked for leaks, …

He tested the AC for heat and made the assessment it was the thermostat when no heat was entering the cabin.

 

He tested the AC for heat and made the assessment it was the thermostat when no heat was entering the cabin.

Which is faulty assessment, because thermostat does not control flow to the cabin heater. The heater core is on the small loop which is before the thermostat. The supply comes out from the head, goes to the heater core, and then returns down, next to the thermostat, which may be closed or open and the flow should be through the heater core no matter what.
Water pump could be a culprit here, but would present itself in other areas as well.

If the system was not properly bled, it still should push coolant through the lines...

Is he sure the in/out are cold? Maybe it is the mixing flap is not opening? Or the cabin filter is clogged?

 

Just wanted to add, car temp has always been stable. No indication of overheating, would a water pump failure be instantaneous or gradual fluctuations of engine temp, I’m wondering

 

OK, we are getting somewhere.
Yes, flush the system. I hope they hose flush in reverse flow. Especially for the heater core and radiator.

Could be two wrong coolants got mixed and chemistry was not nice...

Some do chemical cleaning, say fill with weak acid (5% vinegar) the system and drive for a while. Drain, repeat if necessary.
Then fill/drain 3 times with distilled water (fill and drive).

 

Wholeheartedly agree, we are making informed progress. Although did find it odd that the drained coolant was full of particles, since they said they did do a coolant flush 10 days earlier when replacing the coolant flange.
Could that amount of particles accumulate after one week after the initial flush(?), I’m doubtful , but this a separate issue.

I like your suggestion on flushing, but not sure how they will do it, until I chat w them.

Thank you for allowing me to bounce thoughts and concerns with you. Could I buy you coffee or a beverage of your choice? Send me your Venmo/Zelle/PayPal details.

 

Wholeheartedly agree, we are making informed progress. Although did find it odd that the drained coolant was full of particles, since they said they did do a coolant flush 10 days earlier when replacing the coolant flange.
Could that amount of particles accumulate after one week after the initial flush(?), I’m doubtful , but this a separate issue.

Did they flush it properly, or at all, to begin with?

Thank you for allowing me to bounce thoughts and concerns with you. Could I buy you coffee or a beverage of your choice? Send me your Venmo/Zelle/PayPal details.

Very kind of you, but no need to.
I help you, you help someone else, another one helped me (@GTI's or @Marek K or others) ... that's how it works here.
If you are near here, I do not mind grabbing a beer with you.

 

Did they flush it properly, or at all, to begin with?




Very kind of you, but no need to.
I help you, you help someone else, another one helped me (@GTI's or @Marek K or others) ... that's how it works here.
If you are near here, I do not mind grabbing a beer with you.

Thanks again bud.

 

Think you need to find yourself a new shop that actually deals with VW.

Was the coolant level actually low when the icon came on, was the temp normal?

 

Initially the coolant level was low when the icon came on. I topped up with what I had on hand. Land Rover brand, did a 50/50.

After that things seemed to fine for a week until the icon started coming on intermittently for brief periods , coupla seconds. I correctly or mistakenly assumed it was a coolant low level sensor that was coming on and off. Coolant level seemed within spec

 

Update:

Finally picked up car yesterday.

The final analysis and remediation. The original water pump appeared to be fine. The radiator was flushed. Reinstalled and tested. Coolant finally circulating however they noticed that the original water pump although working the flow was weak. They decided to replace the water pump and the end result was much better.

They decide to bypass the heater core (based on my previous discussions I had mentioned I rarely used the heater), from a cost perspective (they said it would be pretty expensive to replace?).

Coolant circulating, top and bottom hoses now both hot.

Sequence of events recap.

Dec. coolant warning light. Checked coolant level, low. Topped up with coolant on hand, Land Rover brand. 50/50
Week later coolant warning light on again. Coolant level within spec.
Coolant light intermittently on after 10min drives, on then off.
Took to auto shop for coolant flush and insist on replace with G12.

1. Coolant flanger replaced (leak). Early Jan.

Car returned. Fine for a week, then coolant warning light back on, now coolant boiling. I did consider whether there was an air pocket that caused the boiling coolant but the car did run for a week with no symptoms?!

Car back at the auto shop.

1. New thermostat (original not opening completely)
2. New water pump (original not working efficiently)
3. Radiator flushed
4. Bypass heater core.

After a 10 min drive radiator fan did not switch on like before after a short drive, I assume coolant now circulating.

I’m still learning how to be more concise, however decided to long post so someone else can learn from my experience.

Thanks to -PLP- for walking by my side.

 

Would need to know what exactly was used from the LR Velar

 

One could surmise your problem started with a leaking coolant flange. You added a non VW-approved coolant which maybe added another issue, or maybe not. Anecdotal (I have never experienced anything like that) "information" from various sources have us believe that mixing different types of coolant could cause major problems including jelled-up coolant, coolant lines/radiator/heater core/water pump/thermostat corrosion that plugs up the system, etc, etc. In your case, I doubt that the "chemical" reaction was so fast that corroded anything and produced those particles you mentioned.
In any case, running the car w/ a bypassed heater core is just not right. Even if you live in Florida/S. California, there are still days when you might need to operate the heater. I know it is a very involved job (need to take a lot of the under-dashboard or the dashboard off to have access to the housing - I replaced one in a C4 Audi 6 I had) - hence expensive if performed by a shop, but you could also try to flush and back-flush it. You undo the hoses at the firewall and pump soapy water/vinegar/CLR combo type of liquid (or radiator flush) until you get the liquid comes out clear. You could flush the radiator as well and even the engine pasages - provided you figure out where the drain plug is on the engine side (I'm not talking about the radiator drain).
If I were you, I would definitely try to flush the heater core. Buy yourself a small pump and flush that sucker.