Coolant pump 2 on CBBB (2.0 CR 125 kW) is defective

Hello,

According to VCDS, my V178 sensor has failed. A new one has been ordered, but I can only replace it next week. I've been driving with the defect since last Friday, and so far there have been no noticeable issues other than the warning light. Even when parked, there's still a humming sound coming from the engine compartment for about 30 seconds, like before, so theoretically, the pump should still be running.

The pump pumps coolant to the EGR cooler. Could there be any consequential damage to the EGR cooler due to the pump potentially being stuck? I mostly drive in stop-and-go traffic and around 100 km/h, but occasionally I can also drive at 120-160 km/h.

Is there anything special to keep in mind when doing the swap? Unfortunately, it is not mentioned in the common guides, and the bracket is quite obstructed by the intercooler pipe.

Yesterday, I was at least able to read the part number for ordering (5N0 965 561, which is the Pierburg version), because unfortunately, two different manufacturers use different brackets. I just ordered a new set of screws; apparently, they tend to break easily.

Quote:

The pump, of course, pumps coolant to the EGR cooler. Could consequential damage occur at the EGR cooler due to the pump, which may be stationary, I mostly drive in stop-and-go traffic and around 100 km/h, but occasionally I can also reach speeds of 120-160 km/h.

Who is going to give you a serious answer to that? I would replace that part as soon as possible.
It's possible that something similar to cavitation damage could occur in the EGR valve.
You would have to disable the AGR (Abgasrückführung system) to be sure...

It will be replaced as soon as possible. I should have the part tomorrow.

Unfortunately, it won't be possible until Monday because of the stage setup. And I still have to drive there. No extremely long distances, but perhaps a total of 250-300 km.

Hi,
As the exhaust gas temperature increases, the exhaust is routed through the cooler. It's clear that the exhaust is hotter than the coolant. And that's where the problem lies when the coolant is stationary: steam bubbles can form.
It should be checked whether the pump in the primary circuit still ensures a certain level of flow. You should avoid driving conditions with a high EGR rate when the engine is warm, and almost all driving conditions fall into this category.
Whether the system automatically deactivates the AGR (Exhaust Gas Recirculation) if the pump fails would be a reasonable way for the system to limit the scope of the error. Is there anything visible with VCDS?
Which pump is running?
hg
Herbert.

Hello,

According to the diagram in SSP403, the EGR branch appears to be a dead end, and the mechanical pump has no chance of working. However, the electric pump seems to be still functioning. When I clear the error code, it sometimes disappears for up to 40 kilometers. And it (pump 2) hums for the usual 30 seconds, as expected.

My concern was also the high percentage of agricultural land use in the EU5 region.

I am currently unable to participate in logging trips. Most likely, I'll only be taking it to the workshop for one more trip tomorrow.

Okay, so the new pump has been installed since yesterday. It was somewhat manageable by loosening the two brackets of the intercooler pipe and using a piece of wood as a spacer. A suitable Torx bit with a ratchet wrench proved helpful for the three pump screws, providing a space-saving drive. A standard 1/4" ratchet wouldn't have fit on the rear mounting bolt of the pump.

The connector can be unlocked by inserting a small screwdriver under the delicate tab on the side of the connector and gently pressing the tab away from the pump.

Sure, here's the translation:

"Tips:"

There are two different pump manufacturers, Pierburg 5N0 965 561 and Bühler 5N0 965 561 A, and fortunately, each comes with its own mounting bracket. They cannot be identified based on the part number. The screw on the bracket is difficult to reach, so if possible, try to obtain the original pump again, using the part number you read.

The three Torx screws that connect the pump to the bracket are self-tapping and are screwed directly into the plastic of the pump. It's quite difficult to use a ratchet wrench to install them. It's helpful to pre-thread the screws a little bit before installing them while they are still in the disassembled state.