Loss of coolant/overheat, looking for ideas

r11

Veteran Member
Joined
Mar 6, 2012
Location
NJ
TDI
2012 Passat TDI SE 6MT (BB'd), 2015 Passat TDI SE 6MT
Few weeks back (and well less than 1000 miles of driving), during regular oil change at a local dealer ('15 Passat TDI at 100K, have NOT yet had PhaseII done), decided to be nice to me car and requested coolant flush. Up to this point, car been completely worry free, outside of plugged heater core that still needs a fix (I hoped that coolant flush might revive it, but it didnt). Oil changes at dealer, as it is less expensive compared to DIY.

Yesterday, driving on local street, noticed white smoke/steam coming from under the hood. Temp gauge started to climb toward 220F.

Stopped, popped. Seemed to be steam, not burning oil, coming profusely from the turbo/exhaust manifold area. Coolant tank completely empty & bone dry. Towed her back home.

Looking for ideas.
#1 being the kid mech messing stuff up during flush (cracked coupling, loose hose), resulting in slow coolant loss and eventual overheat ? I park the car in the driveway and would have noticed coolant leak, there wasnt one. Didnt smell antifreeze the car either.

Nasty scenario, as dealer wont ever admit to doing anything wrong and the dieselgate 11/162K wty doesnt cover this ???
Dunno to what extent the engine got cooked, esp the piston rings might be baked in at this point (be burning oil like crazy going forward). At the minimum would want to replace the oil as it is cooked.

#2, may be turbo went caput. Dunno how it would result in coolant loss. This is a good scenario, as it is 100% covered by the dieselgate wty. Be an uphill battle may be, but the wty verbiage is pretty clear on it.
 
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oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Well it sounds to me like you have a leak. Since you've been driving around with a bad heater core, you probably cooked one of the hoses going to it, coming out of the EGR cooler.

The CVCA engine has a most complex cooling system, worse by far than any 4 cyl TDI before it (probably by a factor of two), with all kinds of little fragile hard to access bits that can fail.

So, you need to pressure test the cooling system and try to find where the leak is, and of course fix the heater core.
 

r11

Veteran Member
Joined
Mar 6, 2012
Location
NJ
TDI
2012 Passat TDI SE 6MT (BB'd), 2015 Passat TDI SE 6MT
Went to the dealer that did the flush.
1st, Parts Dept. They do have the heater core, qty 1, in stock, along with bracket kit/orings. About $100 altogether. Good thing, as after market parts are know to have fit issues. IDParts has these in stock, for may be $10 less.

2nd, Svc Desk. Scheduled an appt, hoping may be they will trace it to something not dunn right at the time of coolant flush during my prev appt there jsut few weeks ago, so at least they would do another flush and replace the coolant for free. Of course chance of them admitting to any wrongdoing is nil. While at it, do the heater core as well, as I would need that heat come fall. $100 part, prolly 3hr labor by the book, they would disregard that the system is already devoid of coolant. Had them reserve the heater core for the job.

Asked the jefe if core is covered under dieselgate wty. As sure as day is bright, in about 20 msec the answer of NO came back. Will ping VW anyway.

I have an exceptional local come-to-you Audi/Porche wrench, see if I can get him to come 1st to diag the issue. Would much rather give my $$$ to an indy mech. Thankfully I have another car I can drive in the interim.

Abt heater core being plugged causing strain - I thought it was benign, outside of not having heat (which is a blessing during summer :). There's a valve that wont send hot coolant to/through the core, unless there's a call for heat ?
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
There always is, and needs to be, coolant flow through the core. That's why when they clog up, they can cause an EGR cooler efficiency DTC. The EGR cooler on that engine is a big stainless steel setup that slides INTO the DPF/catalyst assembly, it is literally INSIDE the exhaust system. If it doesn't get good coolant flow through it, bad things can happen.
 

r11

Veteran Member
Joined
Mar 6, 2012
Location
NJ
TDI
2012 Passat TDI SE 6MT (BB'd), 2015 Passat TDI SE 6MT
Wowser. Good to know, thanks ! I

Popped the hood just now. Visible antifreeze spray around the EM area, it puddled up on the ABS actuator horizontal surface good good. Not oil, watery pinkish fluid ie G12 ?

The heater core hose connector, on the engine side of the firewall, it also wet. I see a smaller hose going to that connector with what looks like a crease in there.

Was able to get the indy to come in tomorrow, hopefully he can diag this one and if stars align, after a run to the dealer for parts and coolant, fix the thing. At least, with no coolant in there, wont be too messy.

What pressure can we get the system up to, to test for the leak ?

Oilhammer - from your experience, what is likely to fail there ? Also, do you have a diag may be, with PN#s, in case we need to ID the failed component ?

Thanks again !
 

r11

Veteran Member
Joined
Mar 6, 2012
Location
NJ
TDI
2012 Passat TDI SE 6MT (BB'd), 2015 Passat TDI SE 6MT
On the heater core. Got the part and the required (oring & such ) kit at the dealer, abt $100. The (indy) mech said it was the easiest job ever to get it to slide in and mate with the piping there. During the test, the hot air from the vent was super hot, nice !

On the leak. It was the "heater hose" assembly, developed a hole in the plastic nipple joint area, where the smaller (EGR?) tube connects to it. Thankfully local dealer had it in stock, another $60.
Noone will ever know if the dealer performing the coolant flush few weeks ago, contributed to the failure or plastic frayed from hot coolant not being able to pass through the plugged heater core.

As a side note, plenty of coolant remained in the system, I thought she blew it all out.

Good thing I didnt risk taking it to the dealer, could have been $2-3K easily, simply no telling.

While VW did extend heater core on 12-14 (CKRA) TDIs to 10Y/120K, there's no such thing for CVCA, which is what I have. One could argue CVCAs are even more susceptible to this, but it is what it is.
Some folx reported some dealers being sympathetic & splitting the cost of repair on CVCA. From a few service advisers I spoke too, none showed any interest in getting it done under wty, so I decided to not even risk it.

And lastly, do NOT ignore lack of cabin heat. Even the in summer and/or warmer climates, when no cabin heat is needed, what you most likely have is the plugged heater core. And it is NOT BENIGN, but a dangerous condition that could to MUCH worse things. Thanks to oilhammer for pointing it out (more on it in this very thread)
 

04SlvrJetta

Veteran Member
Joined
Aug 1, 2007
Location
Wheeling, WV
TDI
15 Passat SE DSG
R11, oilhammer, do either of you have the actual part number or part name for the hose assembly or the plastic piece that you described as failing?

I’m also wondering about my core.

It’s been quite a hot summer, but one cool evening when we were coming home from somewhere my wife put the heater on and then turned it up and said it didn’t feel like she was really getting any warmth. I did not think a ton about it because I think the blend door motors that control the heat may have a problem because I noticed the AC is cold, but doesn’t seem to blow really fast even though the blower is on high speed and sounds that way and also changing airflow dial doesn’t seem to redirect the air. I haven’t had time to investigate that yet. But last weekend we were in a mountainous area in Virginia getting a puppy and on our way home a couple of times pulling really steep grades, temperature started to come up and then as we would level off it would drop right back down and so I told my wife I need to do investigate it and that possibly one of the cooling fans was not working or something. Well, before we got home, when stopping for fuel, the low coolant warning and light flashing came on and after a few minutes of thinking, maybe it heating up head boiled some coolant out or whatever I tried to top it off with some water just to finish the 150 miles remaining home. Then I saw pink coolant running from under the car. Of course everything was fire hot and it was 9 o’clock at night but I found the leak to be that composite housing where the top heater hose goes together with that small line which I presume comes from the EGR cooler.

So I’m going to do some research here but I’m curious how you can determine if the heater core is plugged , well, not necessarily plugged, but having reduced flow or whatever so that I can determine the extent of what it is that I need to do.
 

04SlvrJetta

Veteran Member
Joined
Aug 1, 2007
Location
Wheeling, WV
TDI
15 Passat SE DSG
I did review core replacement thread which has part number for core & seals. Seems those who posted went from gradual heat loss to immediate heat loss but I didn’t see anything about testing flow or anything like that.
 

NSTDI

Veteran Member
Joined
Jan 26, 2002
Location
Nova Scotia
TDI
15 Passat
The doors in the ac/heater system would throw a code even though the cel is not triggered, the doors can cause loss of heat and or loss of ac. Not sure what level of scan tool needed to read the codes, other than dealer/vcds. I’d suggest a scan as you may have more than one issue?
 

04SlvrJetta

Veteran Member
Joined
Aug 1, 2007
Location
Wheeling, WV
TDI
15 Passat SE DSG
Thanks for the reply. It’s something I’ve never done but need to bite the bullet! I’ve asked questions in a different thread & seems vcds is the way to go!
 
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