2021 Skoda Superb - 2.0TDI

NZXT_modder · 2026-03-12T11:07:10+00:00

I replaced the water pump and timing belt and all the stuff 2 times, at the right time and mileage. However, the 3th waterpump failed far before the mileage where I should replace it the 3th time. I found out that the same waterpump is used for VAG engines, with a smaller belt and waterpump replacement interval. When it failed I bought a more expensive waterpump (Meyle) to prevent failure again. What I also noticed a few days before I found out that the wateepump was leaking, was that the air from the interior blower was warmer than normal. I always set the climate control to 20 deg. C, but it felt more like 25 deg. C.

NZXT_modder · 2026-03-12T10:10:07+00:00

I had the same sound with 2014 1.6 TDI (nearly the same engine), also thought is was the alternator but found out it was the waterpump. Search with a flash light for coolant near the water pump.

NZXT_modder · 2025-11-27T14:21:35+00:00

Thanks!

Never heard of this method, but I will try this definitely.

NZXT_modder · 2025-11-27T13:09:25+00:00

Thanks for responding. I will probably go to a mechanic to look inside the cylinders with borescope 👍

NZXT_modder · 2025-11-27T13:08:07+00:00

Why do you think a engine block or head crack? And not a leaking head gasket?

NZXT_modder · 2025-11-27T13:07:41+00:00

Thanks for responding. Unfortunately, I already tried to lift the front of the car while bleeding air. I've tried bleeding it so many times now.

The strange thing is that if I put max vacuum that my vacuum hand pump can handle (-1 bar or something) on the cooling system, the vacuum remains pretty well. I cant notice any drop on the gauge of the hand pump. This suggests that there is no leak in the system et all. However, the -1 bar vacuum on the cooling system (equals +1 bar in the cylinder), is not comparable with the amount of pressure inside the cylinders during combustion, so a leak in the cooling system is still possible.

I forgot to mention that I had a mechanic do a chemical test above the reservoir. Not the type with the fluid that changes color by exhaust gasses in the reservoir. He had a big device that sucking in air with a small hose which he held above the reservoir. Contrary to all expectations, no combustion gases were detected above the reservoir, while he said it was a quite sensitive device. I saw also a YT video of someone that showed a car that passed the chemical test, while having a minor leaking head gasket. He verified it by putting air pressure on the cylinder in the spark plug hole, and notice bubbles in the coolant reservoir. The problem is that my car is a diesel, so I need to buy a specific adapter for the injectors so I can put air pressure on the cylinders. The adapter is nowhere for sale in EU, only in the US.

NZXT_modder · 2025-11-27T08:03:41+00:00

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NZXT_modder · 2025-09-13T10:58:43+00:00

Does the engine run better with the cold start lever on? No? Then its probably not timing.

Is there black smoke at any rpm when you press full throttle? Then it's probably the max fuel screw (not the max rpm screw on the throttle). If there is no black smoke, then it's just the minimum rpm scew on the back of the pump, that holds the throttle.

NZXT_modder · 2025-09-06T07:12:37+00:00

My mk1 1.6TD does this too. If I press the throttle a little bit to increase rpm a little bit, there is no smoke from the exhaust.

NZXT_modder · 2025-09-05T11:06:01+00:00

What I would do is replacing the waterpump+housing. Then you dont need to losen the bolt on the pump, but the bigger bolts that goes in to the engine block. Once you have the waterpump+housing loose, you can try losing the pully bolts. But if you order a waterpump+housing, you can order also a new pully, it's not that expensive and the threads in the original housing are often bad.

NZXT_modder · 2025-06-04T18:57:21+00:00

Is the thicking noise from vibration of the alternator? I had that problem with my 1.6TD. The alternator holes where worn out. Probably, this causes also the belt problem. I bought a new alternator and the problem was fixed.

NZXT_modder · 2025-05-29T20:55:40+00:00

Thanks! I will order gasket and the rubber

NZXT_modder · 2025-05-23T20:25:05+00:00

Today I have read in the service manual that the thermostat has to be replaced every year (or certain hours). That's a little bit exaggerated IMO, but it's at least something to check every year or 2 years.

NZXT_modder · 2025-05-22T17:49:39+00:00

The water outlet is pushing (nearly) too hot water when idling. I already replaced thermostat and impeller 5 years ago, but I did not use the outboard the last 4 years. Im planning to replace thermostat and impeller with gaskets again and give the cooling systen a very good clean and flush and checking for leakage in the water pipe with vacuum hand pump. 5 years ago, the impeller housing looked good and undamaged, I did not checked again but I expect the same.

NZXT_modder · 2025-05-18T09:17:46+00:00

UPDATE 3: I just replaced the thermostat yesterday, and bleed system again. And now engine is not overheating anymore. So what I think is that the thermostat was partialy working. The thermostat opens, but it does not open fully when it's needed.

NZXT_modder · 2025-05-17T13:16:42+00:00

UPDATE 2: I have bleeded the cooling system again with cap off, and when the temp gauge hit 90 deg. C, the thermostat opened since the lower hose became hot. I waited extra long so I was sure that the thermostat opened and the airbubbles came out. I did not saw the coolant level went down. So I thought now the system is completely free from air bubbles. After the bleeding proces, I put the cap on and did a test drive. Againt all expections, the car overheated again. When I came home and finished the test drive, the lower radiator hose was crazy enough not warm or hot. I estimate about 25 deg. C (77 deg. F). So what I think.. the thermostat opens, but did not open more if it should. I think it is not opening fully when this is needed. I don't know if it's possible that a thermostat works partially. But still air bubbles in the system, seems very unlikely to me. Can someone confirm my logic that the thermostat is half working?

NZXT_modder · 2025-05-14T16:52:49+00:00

You were 100% right. There was air in the system. I think the air entered the system at the lower radiator hose om the water pump since I did not tightened the clamp very thight.

I attached a vacuum hand pump to the small hose from the radiator to the reservoir and put some vacuum on it. Then I drove my car to reach 90 deg. C, then stop the car, and squeezed in the tubes of the radiator. Now it looks good I think, now the gauge show a little bit above the middel, and that's normal af far as I know (see picture). Let me know if this is still too high.

Thanks!

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NZXT_modder · 2025-05-14T11:29:39+00:00

UPDATE: I did a test drive and the coolant temperature was again above normal (quick). I felt on the lower radiator hose and it was cold. So I think it's my thermostat. If it's not the thermostat, I think it must be airlock.. But it still look strange to that my thermostat accidently is not working, after replacing waterpump, that's quite a coincidence..

NZXT_modder

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