Gongal66

Quick update about the pressure test. After around 18 hours of having the pressure test installed, the pressure went down to around 0.5 BAR as you can see in the photo: And no drips under the engine whatsoever. I also checked all the connections and bone dry. Removed the sparkplugs (as you can see they are in really good conditions) , removed the fuel pump fuse and cranked the engine, no coolant was inside the combustion chamber, so at lest in cold conditions, no coolant is going inside. But that doesnt rule out that could be entering to the oil, and thats the only thing that i can think could be causing this problem. A small leak that intensifies when as the engine gets hot and the coolant system gets pressurized. Gonna study a little bit in how to proceed about changing the headgasket, do not like the idea of going head first in the repair without knowing what to do. Any tips for this job will be appreciated. Thank you all for your help by the way. Gonna keep you updated with any news about this little thirsty engine.

After a couple of hours, the pressure was down to almost 1 BAR, and no drips in the cardboard. I also think thats way too much mayo for only condensation, probably a small leak in the headgasket is pushing little by little coolant inside the engine and to the oil. Tomorrow im gonna check for any drips, and before starting the engine im gonna remove the sparkplugs to see if there is any coolant inside the combustion chamber. just in case. Luckily, as Breezy_Pete mentioned, changing the headgasket is not that difficult and is cheap enough. Only the gasket itself and new headbolts to not reuse the old ones, anything more?

Another one from under the pump, no visual residue as far as i can see. Under the radiator bone dry too.

The oil cap is usually like this, i asked a couple of mechanics, searched the web and even asked the AI about it, the same answer in all: this engines suffer from a lot of condensation inside the engine, and since is always driven in the city at slow speeds, it doesnt have time to dissapear. But i think this could be too much for only condensation. The watery residue is crystal clear by the way, and no coolant residue can be seen but i dont know anymore. A couple of photos of some connections. I didnt clean them at all, this is his state after all this time.

Today i lifted the car on jackstands and installed the pressure tester in the expansion tank. It didnt lose pressure inmediatly, so im gonna leave it there until tomorrow, with the undertray removed and a cardboard placed underneath to see if any coolant gets there. I attach a couple of photos i took in the process (sorry for the bad quality, i was on the floor, holding the phone with one hand and a light with another 🤣) As you can see, the coolant is really clean, a little but faded because we are refilling with destilled water, but any sign of oil or debris in there. As you can see, the coolant level is really low, it didnt give the "low collant" warning, but it was close to it. By the way, the engine is completly cold (didnt started it since yesterday) and when opening the cap, a little bit of pressure was released, does that mean headgastek problems? The rig im using, as you can see, i gave it around 1.3 BAR. Gonna leave it there until tomorrow and see what happens.

I had a little bit of trouble getting it back in place indeed. But after some swearing, it was done. As far as i can see nothing leaks from there.

At the end of this week gonna check it out, if there is pressure in the system when stole cold what could mean? Headgasket? It starts smooth, no lumpiness or anything. Obviously i do not have the ear of a experienced mechanic but it seems to start just fine.

As far as i can remember, opening the cap off when the engine is cold releases some pressure yes. I opened the cap yesterday and didnt release any pressure, but we refilled the tank a couple of days before, dont know if that makes any difference. And what do you mean with "slightly uneven"?

I replaced the expansion bottle too, it was a brand new OEM part that i got directly from the dealer. Doesnt seem that is cracked or damaged in any way, and totally clean and without moisture on top. Also, the trick of pouring flour over the the top was a new one to me, never heard of that trick before HAHAHA

Yes there is a small pipe that goes from the expansion bottle to the thermostat housing. How do i need to proceed with the bottle test? There is emulsification in the oil cap, not much, but i read that in this engine is normal, as we use the car for short city trips, so no time to evaporate all the condensation. The oil is pretty clean also, once i even drained all the oil into a clean bucket to check it close, and it was totally clean. Could a bad headgasket make some coolant pass to the oil, but not the other way around? Again, the coolant is perfectly pink since the beginning, and not a single bit of smoke coming from the exhaust. Next week gonna check the core plugs, thank you for the advice. And i also checked the radiator yes, no signs of leaks either, i removed the fan shroud to have a clear sight and nothing.

Nope, it doesnt overheat at all. I drove it hard to test and it holds at 90°C without a problem. By EV cap you mean the expansion tank cap? One of the first things that i did was replacing it with a new one from Febi.

Hello everyone! First time posting here 👋 I have a problem with a 2002 Fabia 1.4 MPI, engine code AZF. We bought it in September 2025 from a family that barely drove it, and before them it belonged to an elderly man who didn’t drive it hard, but also wasn’t very interested in maintaining it properly either. The little fella has 185k km, and at first glance it didn’t seem to have any major problems when we got it. One of the first things I did was drain the entire cooling system (it was really dirty, as the eldery man used some type for sealant, probably to attempt to fix the problem that im gonna describe now), replace the old thermostat housing, expansion tank and cap, belts, oil and filters, flush the brake fluid (it was completely black), and clean the cooling system using a Liqui Moly product. After that, I flushed it a couple of times with distilled water before filling it with the correct G12+ VAG coolant. The car drives great. I also changed the rear shock absorbers, and it does its job well for a little city car. The problem started a couple of months later, when suddenly the low coolant warning light came on. I checked the entire cooling system for leaks and noticed some residue around the water pump, so I thought: well, they are cheap enough to replace. It was still the original one, so fair enough. I removed it by supporting the engine from underneath, used some Loctite 5923 to seal it (if you don’t know that product, do yourself a favor and get a bottle — it can seal even the worst engines), and put everything back together. Since I was already there, I also checked the engine compression. I can’t remember the exact units, but all four cylinders were around 14 bar. By the way, during all this time I haven’t seen any smoke coming from the exhaust — no blue, white or black smoke at all. Basically, it doesn’t smoke. A couple of weeks later, the low coolant light came back on. I opened the hood and, indeed, the coolant level was low again. This is driving me nuts. I can’t find a single drop of coolant anywhere, even after a good hard driving session on back roads. I checked from above, lifted the car and inspected underneath, and all the joints and connections are dry and clean. Today I also checked the heater matrix, since I read that it can leak inside the cabin, but again: bone dry and spotless. I bought a coolant pressure tester and next week I’m going to lift the car, pressurize the whole system and inspect everything again. I’ll also take some photos and post them here so you can see the general condition of the engine. In the meantime, does anyone have any idea what the culprit could be? By the way, we have to refill the coolant when the light show up all the way to the max (all of this when the engine is cold of course) once every 3 to 4 weeks more or less. I work repairing industrial electronics and, as you can see, I like fixing all kinds of things, but this thing is driving me crazy because I just can’t find the issue. This engine isn’t even that complicated, come on! Thank you in advance, and have a great day.