2015 Jetta TDI Overheating

[Cecil14]

Hey all,

Grabbed an inexpensive 2015 Jetta TDI just after the holidays last year. It’s got right around 56k miles on it.


Background: It was definitely in an accident involving the front end and passenger front corner. I don't see anything mechanically wrong under the hood so far from that. From the records I’ve got before we picked it up, the heater core and thermostat were changed last August, a couple thousand miles ago at most. There is something going on behind the dash that I need to dig into: with the fan on, the blower is hitting something, the driver’s heated seat doesn’t work, at all (lights on the switch do come on, though), TMPS reset button doesn’t work, and there something else I can’t remember right now.


Problem for this post: it’s overheating. A lot. It runs really well, but with any kind of load on the engine the temps climb high quick. I have found that leaving the overflow cap a little loose help. With the cap tight, it’ll overheat just sitting idling, with it loose the car will at least idle. If you’re driving down a completely flat road, you can idle without it boiling itself, but any hill or rise at all and the temps go up. When the temps get on the higher side, the heater stops blowing warm air (guessing due to air in the system at that point?).


Work so far: I have verified that the fans work, and they do come on during normal operation. I do not know if the shutter assembly works, but I removed it and it made no difference. I have not found a good procedure for testing the electric auxiliary pumps yet, if anyone has that it would be appreciated. I have pulled the radiators and flushed both with fresh water, they appear to flow fine with nothing unexpected coming out of them. They did not appear to leak, either.


Any suggestions for next steps would be appreciated. I’d rather not just start throwing parts at it, but I need to get something moving pretty soon. It’s been sitting in the garage for too long now. Any common issues with these that anyone knows of? I have another 2015 TDI that I bought new in 2017 after the scandal stuff was subsiding, that’s been rock solid for ~53k miles so far.

Thanks!

 

[turbobrick240]

The water pumps on the '15's have an actuated shroud that fails frequently leading to overheating. That's probably the problem, but it could also be a faulty thermostat.

 

[Cecil14]

Are you referring to the shutter assembly behind the bumper? Or is there something on the water pump itself?


Water pump and thermostat are my leading theories so far. I've been meaning to pull the thermostat and test it, just haven't had a chance yet. I'd really love something super convincing before I dig into the water pump, but if it's the last thing I've got I'll pull the trigger there.

 

[turbobrick240]

No, the water pump shroud is part of the pump itself. It's not visible until the pump is removed from the engine. The replacement pumps did away with the failure prone shroud. Could be the thermostat too. Neither job is much fun. Good luck!

 

[Cecil14]

Joy! I've got the majority of the front end apart right now, so the thermostat won't be super horrible. Looks like that's my weekend. lol


Thanks a bunch!

 

[06bluebeetletdi]

Is it a volkswagen radiator or aftermarket? If aftermarket, i would replace with vw. Check the fans as well.

 

[Cecil14]

Is it a volkswagen radiator or aftermarket? If aftermarket, i would replace with vw. Check the fans as well.

Honestly not sure, it looks pretty OEM, but I'll have to check for part numbers. I've watched the fans, and I know they are coming on.

 

[Cecil14]

Here's what we finally ended up with:


Upon opening the cooling system, it had clearly been filled with regular green antifreeze after the previous repair. We replaced the thermostat (previous one tested fine), water pump, and timing set. We flushed everything possible with water, both radiators and heater core flowed well and clear.



For what it's worth: our replacement pump DOES still have the shroud. It's an incredibly stupid design, and definitely should never have made it to a production car. The increase in mileage/emissions must be next to immeasurable, and the added cost/problems easily outweigh it. But whatever, I know what to look out for now.



So far everything appears to be good. It has taken quite a few flushes once everything was back together to truly clear out the system. I have not found a good way to completely drain/flush the system, short of pulling the lower hose and back flushing as much as possible. We're now able to drive it extended distances, even on some very steep hills, without overheating.


Thanks again for all the help.

 

[FXDL]

Yes the replacement pump does still have the stupid shroud as of 2020 and a cheap plastic impeller too, which maybe the shaft was turning and not the impeller. It is activated by coolant temperatures of the cold winter etc., it shrouds the impeller allowing the engine to warm up faster and the coolant electric heaters to kick in and warm you, till coolant reaches a specified temp. They were back some 6 weeks ago over 400 bucks up here, but at the last minute before getting my timing belt etc., changed, they drop some 200 bucks thank god.
Always change the water pump when changing timing belt etc..
The water pump on mine was losing coolant through the holes that are in the pump pulley, which I would suspect was the pump seal on the shaft behind the pulley. Dealer up here wants 7 hours labour to do the timing belt so better do everything when its all apart, same amount of hours if they have to back in to just change the pump.
I believe there is a small electric pump too for the coolant circuit, another dumber idea.
Just a normal water pump with cast iron impeller, not plastic and remove the shroud and the solenoid that activates the stupid impeller shroud.
Very stupid idea as they just should of had two thermostats, one for engine coolant and one for the heater/core system as Chrysler has in some of their vehicles. VW gets dumber and dumber by the day with their so called engineering.
Next diesel will be the Chev., Cruise Diesel for me, even if VW comes back with a diesel again, or a Honda Civic Coupe gasser.

 

[Cecil14]

There are two electric pumps on the 2015, one for the heater and another for the intake cooler. Definitely not my favorite setup.


I have contemplated leaving the connector for the water pump disconnected, so the computer cannot trigger the shroud, but decided to leave it be for the moment.


The water pump/timing kit replacement really wasn't that bad compared to many other things I've done. Not something I want to do frequently, but I'm sure I could do it easily on a Saturday next time. The biggest problem for us has been getting all the crap coolant out. There's just no good way to completely flush the system on these. No low point that captures all the various pockets.


Overall, the Jetta is still the easiest vehicle I've ever worked on. You couldn't pay me to touch a Cruise, diesel or no. Build quality isn't even in the same league.

 

[FXDL]

You couldn't pay me to touch a Cruise, diesel or no. Build quality isn't even in the same league
Far as I am concerned VW quality isn't really any better than the Cruise, in fact to some extent VW is worse . VW is just getting worse and going down hill as I see them now. VW,s are just too expensive and too many things break and or fail on them.
Their diesels are money pits and the more I talk with VW gasser owners the more I see they are likewise. I have had a 1990, 2001, 2006 real junk, 2010 and now 2015 TDI's. My option, the way I am now seeing their true colours.
Honda may burn more fuel but for reliability they have VW beat hands down. Cost of more fuel or always having to repair a VW and the cost of repairs out of this world for them.
Each their and what they believe and or like.
Happy Fathers day if that applies to you Cecil14.
I am a father of two and I wonder if they will even remember. LOL.
Be safe and your family too now eh.

 

[Cecil14]

Your money, if you like the Cruise better, grab it. My observations definitely don't match yours, though. My 06 TDI was rock solid for ~210k miles. I put brakes on it and did fluid/filter changes. I got a killer deal on it, too, so I couldn't have asked for a better car. Then I got the 2015 as part of the 2017 "new" deal, way cheaper than new. This latest one we paid well under value for also.



I wouldn't pay for a new one, that's for sure. Everyone (VW included) is way too proud of cars right now. And the used market is just now starting to come back from the cash for clunkers BS over a decade ago. Gotta love it.

 

[FXDL]

I wouldn't for sure buy a Cruise diesel, would have to think hard on it for sure.
To honest would rather have a Honda Civic and spend more on gas rather then repairs or have me a older Chev., gasser pick up with small block V8 such as the 350 CI small block and before all the computer crap was put on them.
You were lucky with your 06 as most of them were boat anchors.
Each their own, I guess eh.

 

[Cecil14]

...You were lucky with your 06 as most of them were boat anchors. ...

That's the first I've ever heard that. I've know a dozen or so others with '05.5-06's and outside of the standard maintenance, none have had major problems. The dual mass flywheels tend to fail around 200k, but that's a ton of miles in and not a terribly difficult or expensive fix.


Granted, a dozen isn't a huge population, but even online I've not heard any major hate for that era TDI.

 

[jokila]

That's the first I've ever heard that. I've know a dozen or so others with '05.5-06's and outside of the standard maintenance, none have had major problems. The dual mass flywheels tend to fail around 200k, but that's a ton of miles in and not a terribly difficult or expensive fix.


Granted, a dozen isn't a huge population, but even online I've not heard any major hate for that era TDI.

FXDL does not know what he speaks. Major complainer really.

 

[oilhammer]

FXDL does not know what he speaks. Major complainer really.

True that.

You can find the late variable displacement water pumps withOUT the shroud, certain ones. They still have the plug, so the ECU is happy, but it isn't actually doing anything.

You want to see stupid, check out the water pumps on the VAG gassers (the EA888 engines).

 

[goingftl]

True that.

You can find the late variable displacement water pumps withOUT the shroud, certain ones. They still have the plug, so the ECU is happy, but it isn't actually doing anything.

You want to see stupid, check out the water pumps on the VAG gassers (the EA888 engines).

Where can you find those pumps?
I am trying to this same job currently.
I can't find a good kit that includes the water pump, timing belt and other associated parts.

 

[Cecil14]

I never did really look for a shroud-less pump. I used the kit from ECS Tuning with good results:

Timing Belt Kit

Includes timing belt, water pump, and related hardware

www.ecstuning.com

Most of the parts are OEM, but they give a breakdown of sources for almost everything.

 

[goingftl]

Thank you!
I'm working on it currently in the evenings. And I have it taken apart pretty well. I have it down to just the timing belt. But I'm a little nervous to just take the belt off. How do you ensure that the timing stays correct?

 

[goingftl]

No I do not. I ordered th ECS kit and am waiting on it to take it apart further.

 

[Cecil14]

Timing Belt Kits

Get all the right parts in one box and save yourself a ton of time! Our VW TDI timing belt kit comes with absolutely everything you need to get it done fast!

www.dieselgeek.com

Get a set of timing belts tools from there.

 

[goingftl]

I see that the site has a set of tools for 2009-2014. Is it the same for the 2015 2.0 TDI engine?

 

[Cecil14]

This set should do:

Timing Tool Set for all 2009-2014 TDI engines

We leveraged our 20+ years of servicing TDIs to produce the finest specialty timing tool set for your CBEA, CJAA, or CKRA engine! These tools function phenomenally and are meant to last a lifetime yet not cost a fortune. Every component is manufactured in the United States. Our six piece set...

www.dieselgeek.com

 

[oilhammer]

Here is a water pump sans variable collar:

Water Pump (CVCA CRUA)

Geba water pump for the CVCA and CRUA engines. This is a non-variable pump and the sensor opening is blocked off. This pump does not include the solenoid valve. It must be swapped over from t...

www.idparts.com

Other places have them, too.

 

[Cecil14]

Awesome. That is definitely something I will be looking at for my next refresh. I've got another one coming up in ~30k miles...

 

[greengeeker]

Somewhat related....

I wonder what effect deleting that rear aux pump would have?

Self study says this guy is there to flow coolant through the egr cooler and heater core, presumably when the main coolant pump is shrouded (no coolant flow). It also has a function for high coolant temperatures to boost coolant flow through the head. I'm curious to know why the EA288 head would need this feature? I mean, it has a similar/same coolant jacket design as the previous generation (CBEA/CJAA) which didn't require this feature. I wonder if this was one of those "if we have it there, we might was well use it."

So, back to the question of deleting.
If you installed a shroud-less main coolant pump I would think this would force coolant through the heater core all the time (like it did on the (CBEA/CJAA). The only question is whether or not the aux pump has an appreciable benefit during high coolant temperature operation.

 

[Cecil14]

I wonder if that pump is active after the car is shut off? I believe the front one is, to pump coolant through the aux radiator and intake manifold. I wouldn't be surprised if they use the rear pump to cycle coolant through the head after shutoff, as well.

For anyone curious, our problem ended up being a warped head. Even after all the other work, it would still overheat on steep grades. I checked the coolant with an exhaust gas kit, and sure enough still getting exhaust gasses in the coolant. Pulled the head, and it looked like a roller coaster. $1200 for a 20k mile engine, and we're back in business. Everything has been working great for the past couple weeks now.

 

[greengeeker]

ha. I find it interesting and not at all ironic that you would ask that question considering the fact that you had a warped head. Perhaps it should run after the engine is shut down...

 

[Cecil14]

ha. I find it interesting and not at all ironic that you would ask that question considering the fact that you had a warped head. Perhaps it should run after the engine is shut down...

Oh, I know why ours was warped, and it had nothing to do with after shutdown cooling. lol

 

[Cougsfan]

what was the final verdict on this issue? I have a 2015 Jetta SEL that was hit in the passenger side. Some folks just do not know how to navigate round a bouts, but I digress! Car now over heats causing the upper heater hose to fail. Part# 5K0122157K. Gone through 3 in a month.