Water Pump | 18/20 Teeth Material

hello

In online forums, it's often discussed that the older water pumps used in the AEL/T4 engine sometimes caused engine damage. The reasons for this are unclear, but it's said that there's a "better" water pump with 20 teeth. However, the water pumps I install in my engine always have 18 teeth, and I haven't had any problems with them.
Could someone explain this to me in more detail? And what should I do in my situation?

If you install a 20-tooth camshaft sprocket, doesn't something else need to be changed as well? Do you also have to replace the camshaft, or how is it supposed to work?

I'm just thinking about it because I only recently came across the 18/20 tooth theory, and now when I'm ordering parts for my car, I'm basically only finding pumps that have 18 teeth.

"Thank you."
Hello.

Hmm, interesting, but with the AEL Volvo (D5252t), it's exactly the opposite:
20 teeth were old, 18 teeth are new, and this has been the case for about 10 years.

"Water pump of death": The problem was the water pump bearing, which had the known defects.

Ideally, every water pump (WP) should have been replaced with the new version by now. Otherwise, a readjustment of the valve timing might be sufficient; the tensioner should be able to compensate for any issues.

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Now, the pumps that I install in my engine always have 18 teeth - but I haven't had any problems with that.

According to Volkswagen, 18 teeth is correct. Moreover, it will rotate slightly faster than one with 20 teeth, and possibly circulate a few percent more coolant.

Okay, thanks everyone. I found a hint suggesting that the problems were related to the 18 teeth and were resolved when using the 20 teeth.
it was also illogical – because otherwise all the Volvos would have to break down – and exactly the opposite is true of the engine; it just keeps running and running...


Thank you all!

Hello.

Since I'm dealing with the "ES" (ZR exchange) again now, I did some online research.

It seems that on the T4, it's actually true that it used to have an 18-tooth gear but now gets a 20-tooth gear.
With a few minor issues – the timing cover gaskets are borderline and put considerable stress on the belts, and the gasoline engines have received a new water pump impeller (with a slightly offset keyway).
Krude's argument: "With 20 teeth, you get 10% less speed, which means less stress on the bearings, and since then, everything has been quiet... topic closed."

But why are the older 18Z variants specifically prescribed for Volvos and Audis with TDI engines?
He probably had the 20Z engine from the factory originally.

Will those old "T4 death camp work programs" be disposed of there?

Or is there another solution to the puzzle?

hehe - so, Volvo didn't get any of those upgrades. Some Volvo enthusiasts install them themselves, like retrofitting a freewheeling LIMA (which isn't a disadvantage for the damper), and you can't buy diamond-coated parts from Volvo either - and the newer shock absorber... well, it might be necessary now because nobody produces the old ones anymore.

Although Volvo used the TDI engine until 2001.

However, there are no such issues with the Volvos either.

Hello.

Hmm, not everything fits in the Volvo.
"Other aluminum oil pan (6.5 liters), intake manifold, valve cover, etc., custom fuel injectors, a modified MSA15.8 control unit (with a faulty climate control system and an AGR valve that cannot be disabled), including a mass airflow sensor, different timing belt drive, etc."

But why this "AntiVWT4" wapu downgrade?

Okay, thankfully I have the MSA15.7. With that, AGR (Agricultural Grant Register) isn't a problem. However, it still uses its own protocol and is difficult to read. But I have everything I need.

"Many people modify the oil pan when needed – it's unclear why Volvo used something different. More importantly, the engine simply doesn't fit well in the car, and that's noticeable. I believe the engine isn't particularly user-friendly for modifications in general, especially if you don't already have experience with it. Although, thinking about the T4..."
At least the later D5 engine that was originally made by Volvo, which I once owned, was a dream for mechanics!

However, it's also true that the engine in Volvos, given its development stage, functions quite well – provided you take some care of it and perform certain basic maintenance tasks.


Hello.

Hello.

Here's some new information on the topic: Back then, Volvo took a different approach and had its own pump developed. Very few vehicles were delivered with the "old" 20-tooth pump, and even if they were, you don't see any of those anymore. Instead, most Volvos now use an 18-tooth pump with a rather robust, double-bearing original design.

VW likely reduced the speed by using a gear with 20 teeth to protect the bearings.

Given the current circumstances, I have a question about the material. Based on our current knowledge, I would only buy and use genuine Volvo pumps – and that's what I intend to do.
Now, both of the TDIs have relatively new timing belts with equally new aftermarket HEPU water pumps – something similar happened to a colleague, and there are many reasons why that might happen.
He disassembled them and reported on substandard storage conditions, especially in contrast to the original pump (he disassembled both).
Does anyone know about HEPU pumps and their quality? Should I be concerned and have a service replace the pumps with original parts?

Thank you for the tips.

Best regards,

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He disassembled them and reported on inadequate storage, especially in contrast to the original pump (he disassembled both of them). Does anyone know about HEPU pumps and their quality? Should I be concerned and have a service replace the pumps with original parts?

Who is the right person to reliably answer this question for you?

I've seen and experienced quite a bit regarding water pumps.

This applies to Volkswagen and other makes in general.

Original parts and aftermarket replacements can both fail. However, I've only been using original equipment (OE) parts from VW for a long time. While VW doesn't manufacture these themselves, I haven't experienced any premature failures of these OE fuel pumps in my TDI engines. The price difference is negligible, and it gives me peace of mind.

For the A6 2.5 TDI V6, I have already replaced two defective water pumps (aftermarket parts) before their warranty expired. It's a good thing that I didn't install them myself .

It goes without saying that the remaining parts will also need to be replaced automatically when replacing the V6 engine.

For my Fiat (gasoline engine), I have already installed a Hepu filter. So far, nothing has come back [meaning no issues or problems].

Hepu=schlecht? Hmm.
I installed one in the spring, but after only 10,000 km (engine damage, main bearing failure), it had to be removed and is now just lying around.
However, I was also surprised to see why Volvo installed its own water pump with large "Volvo" lettering in the protected TDI engine.
So, there was no shortage of providers...

I think I still have both of them somewhere. Would you like to borrow them and "play" with them?

Thank you for the answers.

If you have the pumps, I'd like to disassemble them and see how they differ. The insights gained from that might be helpful to some people here.

What would the cost be? Shipping to Austria.

THX
best regards, uwe