Coolant loss and overheating, what's the solution?

[Tdimrtwo]

I have a 2015 GSW TDI with 130k miles that I bought new. So far, it's been great, but for about the last 6 mos, the low coolant light will come on, and I have to add a cup or two of coolant. Couldn't see any leaks, but it was almost due for timing belt/water pump, so I thought I'd see if the new wp fixed it. Still losing coolant, looks like it's blowing out the overflow bottle, but only 1-2 times per month, so I figured I could live with it.
Now I'm heading to Yellowstone with the family, and we have a real problem. Luggage on top, bikes on the back, 75 mph speed limit, and I'm having to add coolant every half hour. Finally the low coolant warning pops up again, the temp guage goes high, and I knew that the jig was up for the GSW. So, I left the car at my sisters house, rented a minivan and went on to Wyoming and Montana. So now I'm back, I towed the car home, and I'm trying to solve the problem. I've seen the coolant loss thread, and it seems to fit with my symptoms until it got really bad and overheated. The explanation seems to be that dpf regens boil some coolant out of the reservoir, resulting in low levels. So is my dpf on it's last legs and frequent regens are causing the problem, or did I just overheat the engine from too much load? Or am I barking up the wrong tree entirely? If the issue is dpf, then a Rawtek delete kit might be the best solution. Any advice would be greatly appreciated, since I really need to get this fixed. I'm assuming a 2015 with 130k miles is out of emissions warranty, and I'm on my own on this.

 

[IndigoBlueWagon]

Emissions warranty is 11 years or 162K miles from the original in-service date. If I'm correct about that then you're still covered.

The symptoms you describe are classic for blown head gasket. But this car is more complicated than the early TDIs so it could be something else. EGR cooler, the air-to-water intercooler, regens boiling coolant as you mentioned, leaking heater core (although you'd smell that).

If you have fault codes for the DPF then take it to the dealer and see if they'll cover that repair. They may find something else wrong that they will also cover. It's worth a shot.

 

[Tdimrtwo]

Thanks for the response, here's an update: I've been driving the car around town today and everything now appears to be fine. Never turned on the CEL, never threw a code, and no overheating or loss of coolant. I suspect it will boil a little out of the expansion tank during dpf regen, as it did before. I'm now thinking I just overheated the engine by driving 80 mph with luggage sticking up 2 feet above the car on the rack. Is that even a possibility? I would think that VW would put in a large enough cooling system to prevent overheating, but I know that the mk7 is a unique system. Any thoughts??

 

[IndigoBlueWagon]

No, it's not a possibility if the engine is OK. I once drove my MKIV Golf 500 miles to a race track in Canada and it performed perfectly. One lap on the track pointed out the head gasket had failed. Normal driving didn't create the condition where it would show. You car should be able to run at top speed, loaded or not, with no ill effects. If it won't, something's wrong.

 

[740GLE]

Comparing a mk4 golf coolant system capability to a mk7 is quite a brave

Who did the TB? what water pump went in? DId they do a full flush of the coolant or just refill what little was lost?

Did a CEL or DPF warning light come on (other than low coolant/high temp)? If not, and there are no codes, you may be SOL on the warranty front.

If you're willing to nuke out the problem and are committed to the car for another 130K, I'd say a DPF delete and egr cooler delete is mighty tempting to rule out half the problems you may be facing.

 

[whizznbyu]

Would pressure testing the system give you a clue?

 

[IndigoBlueWagon]

Comparing a mk4 golf coolant system capability to a mk7 is quite a brave

I wasn't comparing cooling systems, I was comparing operating conditions. My point is that a vehicle with a cooling system problem can be driven gently without issue, but the problem will emerge when the cooling system is stressed, as it did for the OP. Just because gentle daily driving doesn't show a problem doesn't mean there isn't one.

You could try the traditional diagnostic checks. After the car sits overnight are the coolant hoses hard when you squeeze them? Does pressure escape from the coolant bottle when you loosen the cap (again, after an overnight sit)? If so, that's an indication of a failed head gasket. However, as 740GLE indicates, the problem could be any number of other things including a poor performing water pump, a leak in the EGR cooling system, or something else. Few, if any, of those issues will create codes.

 

[JohnTF]

Pressure test , look for leaks with car up in the air , do not forget to check if water/coolant comes out the exhaust . not running , then running .
When you 1st pump up the pressure , sit and watch the gauge for at least 5-10 min. cold , then try warm engine .
Get some litmus paper to check PH of coolant , do this against new coolant - should be close , a little off is not bad - but not extreme .
Also look with flashlight for stains at ALL hose / coolant connections .
And do not forget the heater core , possible wet passenger floor / or drain - drain is for AC condensation at bottom of car .

 

[benshaw]

tiny flat specs of soot in coolant bottle? that you can see with naked eye.

 

[740GLE]

if there was an issue with the Air to water Intercooler i think there'd be some stumbling/rough idle as coolant was pushed into the intake when not on boost. I'm thinking more of EGR cooler or the main water pump. The electric pumps all seem to have a controller that will scream if it's not working properly, drawing proper current or open connection.

The water pump was touched last, so that'd be my first suspect to rule out.

 

[Tdimrtwo]

thanks for the advice, I’ll try to provide some additional info:
1. The coolant loss problem preceded the timing belt/water pump replacement.
2. I did the timing belt myself, ( I have with all of my cars for the last 25 years) Kit was from ID parts, new WP was conventional with metal impeller to eliminate the OE electronically controlled water pump.
3. I completely drained the cooling system and replaced it with new antifreeze/distilled water provided by ID
4. No CEL or codes and no way to reproduce the problem, so I’m guessing warranty work isn’t likely.

I’m committed to keeping the car running since I really like it, and you can’t get a new one any more.

I’ve been daily driving it ever since, and haven’t had to add anxqy coolant or seen any hint of overheating, but obviously the problem is still there, and will reappear at the worst possible time.

I’ll do a pressure test as soon as possibl, and likely do the rawtek delete/Malone tune to eliminate the dpf as the culprit.

thanks for all the great advice, I’ll post updates when I have new information.

 

[IndigoBlueWagon]

Have you seen this? https://forums.tdiclub.com/index.php?threads/ea288-cooling-system-bleeding.516300/

 

[Tdimrtwo]

I did see this thread. I didn‘t use a vacuum fill method add coolant, so I assumed it doesn’t pertain to me. But I’d sure like to bleed it properly to remove any air pockets. Anyone have a procedure for bleeding the coolant system on a crua engine?

 

[sootchucker]

I did see this thread. I didn‘t use a vacuum fill method add coolant, so I assumed it doesn’t pertain to me. But I’d sure like to bleed it properly to remove any air pockets. Anyone have a procedure for bleeding the coolant system on a crua engine?

Join me in the coolant troubles!
I’m willing to bet you and I have the same problem. These motors are a ***** to bleed. There’s got to be a way and I just haven’t figured it out. I’m 3.5 month in to trying to bleed this. I’ve ruled out my head gasket because the pressure test has great results and my car only overheats when it wants to. Not every time.
We both have air in the system no doubt about it.

 

[JohnTF]

I would have mentioned earlier , but too many chances of this changing between earlier models I have had , newest 03 1.9 .
Checked my 03 factory manual , and many decades of other cars , truck & heavy equipment .
Top off reservoir attach " pressure tester " start engine and run until at least one fan cycle [ I would add , just in case keep close watch for overheating { in case something is wrong with the fan system }] , then let cool down and fill to max fill mark , and start & cycle fans again .
Remember to turn heater temp control all the way on , most other cars / trucks turn on AC also .
Do this until the reservoir stops going down , do not overfill .

 

[sootchucker]

I would have mentioned earlier , but too many chances of this changing between earlier models I have had , newest 03 1.9 .
Checked my 03 factory manual , and many decades of other cars , truck & heavy equipment .
Top off reservoir attach " pressure tester " start engine and run until at least one fan cycle [ I would add , just in case keep close watch for overheating { in case something is wrong with the fan system }] , then let cool down and fill to max fill mark , and start & cycle fans again .
Remember to turn heater temp control all the way on , most other cars / trucks turn on AC also .
Do this until the reservoir stops going down , do not overfill .

i dont think this is going to assist on this platform. we have two or three cooling circuits in one, and somehow they all must be bled simultaneously by running pumps, opening valves, etc etc.

 

[Tdimrtwo]

I've been daily driving it now for almost a month, no coolant loss or hint of overheating. I now believe that the dpf regen along with the 80 mph+ driving and increased drag from the roof rack and bikes combined to cause the overheating issue. I think that I simply operated the car under conditions that VW didn't anticipate or design to handle.
thoughts?

 

[IndigoBlueWagon]

I don't buy it. VW's cooling systems typically have more headroom than that.

 

[1854sailor]

I don't buy it. VW's cooling systems typically have more headroom than that.

Agreed. I find that coolant temps tend to rise more in slow traffic than at speed even with a loaded roof rack. Slowed down by a couple of accidents and road work on the trip down from RI to MD last week, the coolant temp got up to ~215°, once rolling again it came down to what I consider normal, ~195°...

 

[Tdimrtwo]

While my 03 ALH has gone 300k without any cooling problems, the “coolant blown out the overflow bottle” thread suggests that dpf regens can cause coolant to boil off on CRUA engines. The CRUA apparently has a very different and more complicated cooling system. I guess I could put the 3’ tall roof rack back on and try to duplicate the problem, but I don’t really want to chance overheating the engine again. So, I think I’ll pressure test the cooling system, then do the dpf delete and see if that fixes the problem. Anyone have a better idea?

 

[TurboABA]

What about doing some logging of DPF regens and temps at these increased drag\loads to validate all these theories?
The tools to get some data do exist and are fairly inexpensive if you really want to solve the mystery.

 

[740GLE]

timing to capture regens that happen every 250 miles might be tough to peg down. Can an active regen be triggered while driving via VCDS? I know it can while stationary.

 

[TurboABA]

@130k+ miles, if still on original DPF, chances are that his regens are quite frequent, especially if not always cruising on freeways, etc......
Yes, you can trigger an active regen with VCDS.

Regeneration while Driving
Prerequisites (General):

• Ignition ON
• Engine ON (Idle)
• Coolant Temperature above 70 °C (see MVB 002.4)
• Particle Filter Load below Specification (see MVB 108.2/3, VCDS should give the specified values)
  • If the Particle Filter Load is above Specification the Particle Filter needs to be replaced since the car may burn down when regenerating.
  • If the Particle Filter Load value in MVB 108 is blank, use alternate group 241.2/3 instead.
• Power Consumers ON (Light, Seat Heating, Front/Rear Window Heater, Climate Control)
• Engine Hood Closed

Conditions (Driving Cycle):

• Vehicle Speed above 60 km/h (40 MPH)
• Engine Speed between 2000-2500 RPM (4th or 5th Gear, Automatic Transmission in Tiptronic)
• Duration approx. 10-15 Minutes
• Exhaust Gas Temperature before Turbo Charger above 170 °C (MVB 099.2)
• Exhaust Gas Temperature before Diesel Particle Filter above 150 °C (MVB 099.3)
• Exhaust Gas Temperature after Diesel Particle Filter above 150 °C (MVB 099.4)

Drive the car based on the above Conditions until the Particle Filter Load is as low as possible (close to 0 %). In case the Regeneration fails there can either be problems with the Driving Cycle Conditions or with the Engine Hardware.


[Select]
[01 - Engine]

[Security Access - 16]

• Enter the Code shown by VCDS next to Adaptation Enabling (e.g. Regeneration while Driving)

[Do It!]

[Adaptation - 10]

• Select Channel for Regeneration while Driving

[Read]

• Enter/Save 1 as new Value.

[Save]
[Done, Go Back]

[Meas. Blocks - 08]
Select Blocks 099 and 108 at once.
[Go!]

MVB 099.2: Exhaust Gas Temperature before Turbo Charger
MVB 099.3: Exhaust Gas Temperature before Particle Filter
MVB 099.4: Exhaust Gas Temperature after Particle Filter

MVB 108.2 or 241.2: Particle Filter Soot Mass (calculated)
MVB 108.3 or 241.3: Particle Filter Soot Mass (measured)

Now Start the Driving Cycle and keep watching the Measuring Blocks (2nd Person required).

[Done, Go Back]
[Close Controller, Go Back - 06]

 

[Tdimrtwo]

I definitely would like to figure out what’s going on and get it fixed. As it stands now, I’m afraid that it could happen again any time that I load it up for a long road trip. Also, I’m not sure if I said it before, but I never saw the temp gauge move above 200 until after the low coolant warning came on. This makes me think that a dPF regen may have boiled away enough coolant to cause the engine to overheat. Could running the car at a sustained high load (80+ mph, 3 foot tall roof rack) cause extra soot in the DPF and trigger more frequent regens? Of course, it’s all just a theory now until I get some solid data to see what’s really going on. Does VCDS have a way to log data, or do I need to look for something else?

 

[TurboABA]

You may want to read up on the DPF system before formulating these theories without any supporting data. A sustained high speed, high load, high constant rpm condition for an extended period of time would be a desirable scenario for more efficient regen cycles. You'd be under passive regen most of the time with less frequent active regens while having additional\improved cooling capacity.

 

[740GLE]

Also it's the EGR cooler that would be dumping heat into the coolant system, not the DPF.

Also seeing the charged air intercooler has a separate coolant loop (which doesn't factor into the dash coolant display) except for the expansion bottle, you're intake air temps may have been a constant +200-300F plus a regen and added heat of the EGR cooler and that caused coolant to be pushed out.

Granted the ECU should pull power back if IAT are too high to prevent any issues.

 

[TurboABA]

@Tdimrtwo

The simple fact that you're adding two cups of coolant every two weeks for the last 6 months is a CLEAR indication of an issue..... you're just in denial and are ignoring the signs about having an underlying issue.

 

[Tdimrtwo]

TurboABA, your comments are understandable, given that you're working with limited facts. However, IMHO the condescending nature of your comments shouldn't have a place on a forum designed to help people solve their problems.

After I towed the car home, I topped it up with coolant and began driving normally, although I carried a jug of antifreeze in the back at all times.
During the next 6 weeks, I drove over 3,500 mostly highway miles without adding coolant, and had no discernable coolant loss. I checked the level every couple of days, and it remained just below the top line on the expansion tank. This included a 600 mile round trip over Labor Day to the same destination on which the car had previously overheated. I had the bikes on the back but didn't have the roof rack and 2+ foot tall luggage bag on top. The ambient temp was about 5 degrees cooler, but I drove the same speed as before.
If I have a head gasket leak or some other underlying cooling system issue, it is apparently no longer causing problems.

Additionally, the coolant blowing out the reservoir thread has 73k views and 320 replies, with at least 20 people claiming that they are experiencing the same problem. That seems to me a good deal of evidence pointing to an issue with the EA288 cooling systems, specifically that under certain conditions, DPF regen cycles will trigger coolant loss.

I haven't had a chance to do a pressure test or combustion leak coolant test, but that's next on my list.

 

[TurboABA]

I may be perceived as an @s$, but that must also mean that you are aware of the fact that your coolant circuit is not as simple as they used to be......



You basically have 3 separate partial circuits, a switchable WP, and a lot more related components which all need to play along nicely for the thermal management to work properly. Due to all this complexity, simply guessing at the root cause without data logging or monitoring various MVBs, will have you going around guessing at A LOT of stuff.

I'm not suggesting that the additional drag of your roof rack stuff is not making your EA288 work harder, I'm simply suggesting that you have another problem which needs proper diagnosis, and this has reduced the ability of your very complex and capable thermal management system to operate at full capacity\efficiently. As a result, you (and potentially 20 others) might be jumping to a conclusion prematurely.

 

[TurboABA]

Furthermore, I just noticed something very interesting, which I had previously overlooked.

2. I did the timing belt myself, ( I have with all of my cars for the last 25 years) Kit was from ID parts, new WP was conventional with metal impeller to eliminate the OE electronically controlled water pump.

This might have significantly decreased your EGR cooling and the overall ability of the ECM to properly apply thermal management as intended.
Your DPF will also be fulling up at an accelerated rate as a result.
You can easily check your soot\ash loads with VCDS as well as get some clarity on how often active regens are taking place, etc.