Heater works until engine reaches temp

BarryMunson

Well-known member
Joined
Aug 13, 2004
Location
Cleveland Ohio, U.S. of A.
TDI
2014 Passat tdi SEL
I have a 2014 Passat TDI. THe heater works on both left and right side until the engine gets to temperature and then it stops heating. I got a code P2457 before this happened.

I measured good delta T across heater core bibs before it shut down.
I also performed the vent control recalibration procedure.

I do not have any manuals to looks and the flow diagrams and am wondering if the EGR cooler is the root of this problem in that maybe the Cooler is bypassed until the engine warms up and then is directing flow through something that is clogged at the EGR or EGR cooler?
 

Rico567

Top Post Dawg
Joined
Jun 13, 2003
Location
Central IL
TDI
2013 Passat TDI SEL Premium (Turned in 7/7/18)
Maybe the heater core is completely plugged, and the heat you're getting from a cold start is the supplementary electric heater, which is going to shut off when the engine temp comes up.
 

BarryMunson

Well-known member
Joined
Aug 13, 2004
Location
Cleveland Ohio, U.S. of A.
TDI
2014 Passat tdi SEL
Maybe the heater core is completely plugged, and the heat you're getting from a cold start is the supplementary electric heater, which is going to shut off when the engine temp comes up.
You mean that there is another electric heater in the cab near the heater fan? I dont understand how I can get a differential emperature across the heater core bibs if it were clogged.
 
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jrm

Veteran Member
Joined
Jul 24, 2013
Location
Oregon
TDI
2013 Passat SE with nav (totaled)
yup 1000w electric grid to give instant heat and yep its clogged. there is a video explaining why it gets colder as you get toward the passenger side but its completely true.
 

251

TDI Owner/Operator
Joined
May 11, 2002
Location
NW IN
TDI
2015 Passat TDI SEL
Yep - your heater core is clogged up and what heat you are getting is off the auxiliary electric one. When my core went down had to drive two hours to home in freezing weather. I found if I tried the heater every 15 minutes I would get heat for about a minute or two then it would blow cold again so the auxiliary heater was what was giving me heat for a minute. This was at 65 mph with a warmed up engine. Under the circumstances the little heat I got was welcomed and yes, after I got home heater was replaced under warranty by VW dealer.

I'm old school and tend to leave the heater off until engine gets up to normal operating temperature. Yeah, I know it's a habit I need to break... :rolleyes:

Just curious, anyone here know at what temperature does the system switch from electric to coolant heat?
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
Also if you have the same temp on both "in" and "out" of the heater core, then that's showing that no heat is being dissipated by the core. If you have a clean core there should be a delta across the ports, showing that heat is going to the cabin.

As the core clogs and creates it's own bypass so that flow won't be completely restricted and cause overheating issue. This is why so many people never really notice any issues, its just the heater output slowly chokes itself out. Lots of CJAA owners have had the same code the OP did after the emissions fix cause the EGR duty cycle relies on the EGR cooler more, thus boils the coolant if flow isn't near maximum.
 
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93celicaconv

Veteran Member
Joined
May 22, 2013
Location
Wisconsin
TDI
Turned in my 2010 Jetta TDI Cup Edition to VW, DSG, Nav, Sunroof / Replaced with a 2015 Passat TDI SEL Premium
Lots of CJAA owners have had the same code the OP did after the emissions fix cause the EGR duty cycle relies on the EGR cooler more, thus boils the coolant if flow isn't near maximum.
Can I assume the 2015 EA288 engine does not have a similar characteristic as the EA189 (CJAA) engines have in previous model years with this emissions fix (and with heater core clogging problems)?
 

BarryMunson

Well-known member
Joined
Aug 13, 2004
Location
Cleveland Ohio, U.S. of A.
TDI
2014 Passat tdi SEL
It looks like I can go under the car and perform a CLR cleaning of the core. Has this worked in the past? I have a circulation pump that I can hook up and backflush with CLR.

Any good procedure for this?
 

740GLE

Top Post Dawg
Joined
Aug 19, 2009
Location
NH
TDI
2015 Passat SEL, 2017 Alltrack SE; BB 2010 Sedan Man; 2012 Passat,
Can I assume the 2015 EA288 engine does not have a similar characteristic as the EA189 (CJAA) engines have in previous model years with this emissions fix (and with heater core clogging problems)?

Not sure, only major difference I'm aware of is its a variable displacement electro-mechanical water pump.

But that won't prevent the coolant from turning to junk due to "over heating" the coolant, we need more and more 2015's with +100K on them before anyone can say the issue is solved.
 

Rico567

Top Post Dawg
Joined
Jun 13, 2003
Location
Central IL
TDI
2013 Passat TDI SEL Premium (Turned in 7/7/18)
It looks like I can go under the car and perform a CLR cleaning of the core. Has this worked in the past? I have a circulation pump that I can hook up and backflush with CLR.

Any good procedure for this?
The heater core in the NMS Passat is not accessed from under the car, but from under the dashboard. There are threads with photos showing this. The design of the heater core is not particularly amenable to being flushed, as it has a number of passages between two manifolds, thus once a few passages are opened, the flushing fluid will just run through them, and the majoriy of the passages will remain plugged.
I have not read of any good procedure for flushing the core once it is plugged; replacement is the cure.
 

BarryMunson

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Joined
Aug 13, 2004
Location
Cleveland Ohio, U.S. of A.
TDI
2014 Passat tdi SEL
RICO 557,

I found the procedure for removal through a door cover in the driver's footwell. I is not too difficult from what I see and the dash does not have to be moved away.
 

93celicaconv

Veteran Member
Joined
May 22, 2013
Location
Wisconsin
TDI
Turned in my 2010 Jetta TDI Cup Edition to VW, DSG, Nav, Sunroof / Replaced with a 2015 Passat TDI SEL Premium
TSB 80-15-04, for the 2013 & 2014 Passats with the CKRA EA189 TDI engine suggests excess flux used in the aluminum cooling system components mixes with the coolant, resulting in highly acidic coolant over time, and corrodes the aluminum materials. The aluminum oxide particles end up clogging the heater core. If during the replacement process,the coolant wasn't properly flushed, refilled, flushed again, and refilled, the replacement heater core will plug again.

It looks like the TSB came out sometime in early to mid July 2015. My MY2015 Passat TDI SEL Premium was built prior to July 2015, so I'm wondering if I would have the same flux contamination issue. A key is measuring the coolant pH to see if it is at all acidic. I think if it is, the problem could be corrected before the corrosion process gets to far an compromises the system. So I think periodic coolant pH testing is prudent as a leading indicator before the corrosion starts and before heater core plugging starts.

I'm sensing overheated coolant is not the problem (breaking down the coolant), but I'm sure elevated coolant temperatures help accelerate the corrosion process if the coolant is already acidic from the flux mixing with it.
 

BarryMunson

Well-known member
Joined
Aug 13, 2004
Location
Cleveland Ohio, U.S. of A.
TDI
2014 Passat tdi SEL
TSB 80-15-04, for the 2013 & 2014 Passats with the CKRA EA189 TDI engine suggests excess flux used in the aluminum cooling system components mixes with the coolant, resulting in highly acidic coolant over time, and corrodes the aluminum materials. The aluminum oxide particles end up clogging the heater core. If during the replacement process,the coolant wasn't properly flushed, refilled, flushed again, and refilled, the replacement heater core will plug again.

It looks like the TSB came out sometime in early to mid July 2015. My MY2015 Passat TDI SEL Premium was built prior to July 2015, so I'm wondering if I would have the same flux contamination issue. A key is measuring the coolant pH to see if it is at all acidic. I think if it is, the problem could be corrected before the corrosion process gets to far an compromises the system. So I think periodic coolant pH testing is prudent as a leading indicator before the corrosion starts and before heater core plugging starts.

I'm sensing overheated coolant is not the problem (breaking down the coolant), but I'm sure elevated coolant temperatures help accelerate the corrosion process if the coolant is already acidic from the flux mixing with it.

What pH test kit is good to use? There is a WIX test kit but I think I read that it is for green coolant.

Any coolant system cleaning agents that work well or does it have to be coolant fill, coolant flush and coolant fill again?

I also See Coolant Pentosin G13 available. Any thoughts in this?
 

93celicaconv

Veteran Member
Joined
May 22, 2013
Location
Wisconsin
TDI
Turned in my 2010 Jetta TDI Cup Edition to VW, DSG, Nav, Sunroof / Replaced with a 2015 Passat TDI SEL Premium
Acustrip ACU 1550 would be a great product for testing pH in red, green, blue coolants, including HOAT types. However, I'm not sure Acustrip is around making theses strips any longer.

Regarding your question, the VW TSB says the coolant needs to be completely flushed at least twice to get most of residual flux and aluminum oxides out of the cooling system, or the chance of another heater core plug is likely.

Pentosin G13 would be the correct coolant for you (I think).
 

BarryMunson

Well-known member
Joined
Aug 13, 2004
Location
Cleveland Ohio, U.S. of A.
TDI
2014 Passat tdi SEL
Thanks everyone for the help.
I have a new core to go in but I cannot get on the 6 mm bolt in the engine compartment. I can only get my ratchet near the 6mm head but only with my finger tips. The ratchet fell down into the netherlands below. That prompted me to remove the lower plastic drip pan under the engine to find the ratchet and maybe reach the the 6 mm bolt from below. Did not find the ratchet yet and I cannot get the new ratchet I bought on to the bolt.

Has anyone found a good way to get at this bolt?

I got the passenger compartment panels removed and tried tugging on the heater core lines with some hose pulling pliers insulated with a sliced section of rubber hose. After tugging the lower line for 5 minutes, I got a sixteenth of and inch gap between the flanges.

Does anyone have a good way to tug these off? I cant imagine that the 6 mm bolt has to be loose to get the core lines to tug off.
Any input here on this and how to get to the 6 mm bolt?

Thanks. Barry
 

16vjohn

Vendor , w/Business number
Joined
Jul 12, 2007
Location
Salt Lake City, UT
TDI
EA288 CVCA 6MT
That 1kw supplemental heater provides dismal heat... like barely enough to defog the windows. If you don't believe me, put a 1500w space heater in your car on a cold morning. I ran it for 15 minutes and it barely made a difference.

Obviously the clogging heater core is a thing with the NMS, but don't assume the auxiliary heater is making up for it as part of your diagnostic process.
 

edandemma

Member
Joined
Jun 27, 2013
Location
Derby, Kansas
TDI
09 Jetta
in 2014 had an issue with our 09 JETTA TDI, zero heat as the temp got warmer. Flushed the heater core by pulling the lines, connecting hoses from a submersable pump that was in a bucket of very hot water. Flushed the core, did it in both directions. A lot of contaminates came out. Did a coolant flush and system ran just like new.
 
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