Overheating 1000km From Home

So first off, we're back on the road and it seems okay now. Earlier today, when setting out to drive from Calgary to Vancouver, the 2015 TDI decided to start overheating.

The temperature gauge was at the top and a warning appeared on the dash. We pulled over and I saw nothing unusual under the hood. Normal coolant level in the reservoir, upper rad hose was cold. Most hoses I could touch were cold.

At idle, temperature would return to normal. Driving more than 50km/h it would start to climb quickly.

We went to a VW dealer and they ran through all their diagnostic procedures, found nothing, and then the car worked perfectly after that.

I'm thinking this is the electronically controlled shroud that can cover the water pump impeller when the computer wants the engine to warm up quicker. It was probably sticking, but came unstuck while the dealer was working on it.

I have a feeling this is not the last we'll see of this problem. So what I'm here to enquire about is if there are other water pump options to eliminate this over-complicated one?

Yes, IDParts has a non-variable version of the stock pump and there is anecdotal evidence that dealers are now using this version as a replacement.

Thanks. Probably see one of those in our future.

We're in Sparwood, British Columbia now, so well on our way home!

Anyone know how the shroud mechanism works? Does the computer just send a signal to move it, but if it doesn't move, it just assumes it did and stops trying?

Mike_04GolfTDI said:

Anyone know how the shroud mechanism works? Does the computer just send a signal to move it, but if it doesn't move, it just assumes it did and stops trying?

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Don't know for sure, but I assume its a "normally open" sleeve that only receives a signal for cold (closed) operation and relies on spring pressure to return to normal hot position.

I think if I recall correctly from the 2.0 TDI EA288 study guide, the design is not that smart... it fails in the "cold" operation mode.

anything can "fail" in the incorrect place. If the gauge on the dash moved above 190F she def overheated due to some sort of coolant issue, and those WP are known failure points.

I'd bring it into the dealer and document the issue, they'll probably replace the WP as a precaution as I don't believe they install the variable/sleeve pumps anymore.

The pump is supposed to be a fail-safe design, however, there are documented cases where it has failed in the closed position too.

There isn't any easy way to take a look at the waterpump without taking bits of the engine apart, I'd want to tap on it with a steel rod if I suspected it sticking while on a road trip and disconnect the control solenoid until its replaced.

Yeah, my mistake. You are right, I checked the EA288 guide again. As pointed out, anything can fail in the incorrect place...

Is this N489 solenoid for this control testable using VCDS, using Basic Settings or Output Tests?

a solenoid can only be tested if there is some sort of visual or mechanical confirmation it's worked (limit switch being primary one) my guess is no.

The other way would be to monitor coolant temps and see if they dramatically change once activated.

So far the problem hasn't happened again. Hopefully this was a one-time glitch because I do not relish having to dig into the engine to replace the water pump at this point. It only has about 40,000 miles on it. Far too soon to be needing to fix things.

Mike_04GolfTDI said:

So far the problem hasn't happened again. Hopefully this was a one-time glitch because I do not relish having to dig into the engine to replace the water pump at this point. It only has about 40,000 miles on it. Far too soon to be needing to fix things.

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Thats the best time cause its still under warranty isnt it?

Mike_04GolfTDI said:

So far the problem hasn't happened again. Hopefully this was a one-time glitch because I do not relish having to dig into the engine to replace the water pump at this point. It only has about 40,000 miles on it. Far too soon to be needing to fix things.

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And you're going to wait for it to happen again? The universe gave you a friendly tap on the shoulder, the next time it will be an ACME anvil on your head! Chances of a one-time glitch: 5%, chances of VW's bean counters cutting costs by deleting reliability design features from the original pump design: 95%.

You and the dealer have done all the right things so far; now follow through and have them replace the pump with the non-variable version under warranty.

We don't know how tolerant of an overheating event the cylinder head is, but regardless, you don't want to test it with a second event if you can easily avoid it. There is already documented evidence of pump shroud failure (seizure) on the EA228 and you and the dealer have correctly diagnosed it, so...just take the next and final step.

The comprehensive warranty expired in January, and the dealer didn’t diagnose anything.

They couldn't get the problem to happen while they had it. It’s just me assuming it’s probably the water pump shroud because that makes the most sense.

It’s my wife’s car so it’s up to her what to do. She knows what the issues are. I’m willing to put a water pump in if she wants, or maybe she’d rather get a shop to do it so there might be some kind of warranty.

If the engine does start overheating again, I’ve told her to stick the transmission in manual mode and drop it down a gear to get the rpm up, and with minimal throttle get it to a safe place to stop. With higher rpm it runs cooler due to less cylinder pressure, lighter load, and the water pump is spinning faster so it might move a little more coolant. In neutral you could watch the temperature go down rapidly if you rev it, so the idea is just have the engine doing as little work as possible, but spinning fast to get what little coolant flow is possible with that damn shroud closed. Of course, most of all, get it stopped somewhere safe asap.

RIP TDI said:

Yes, IDParts has a non-variable version of the stock pump and there is anecdotal evidence that dealers are now using this version as a replacement.

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Will this pump cause a code

Smontana16 said:

Will this pump cause a code

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No codes. You transfer the solenoid to the new pump, so the computer still can see it.
The whole mechanism is not there, the coolant passage is blocked, and the new pump has a metal impeller.

Someone suggested on another thread to unplug the pump to prevent having it close off the impeller supposedly preventing the problem altogether. I have thought about doing that but not altogether sure it will really prevent the problem. I have also heard that unplugging the pump will not trigger the CEL but may set a soft code.