AFN is trending

Hello!
My car always pushes coolant out of the expansion tank on the highway, and as a result, it overheats. I've already replaced: the expansion tank, the cap, and the thermostat, but it's still overheating!
I have to be honest, I'm not very satisfied with the 110 hp engine. I had a 1Z before that only had 90 hp, but it never gave me any problems! I really pushed that one to its limits!
Okay, so I've had a GTI TDI with an AFN engine for about a month now. First, the power suddenly disappeared while I was on the highway. After a lot of troubleshooting, it turned out the turbo hose had burst – a terrible hose for 76 € . Before that, I also replaced the MAF sensor (160 € ). In between, I also had to replace the timing belt, serpentine belt, engine seals, and valve cover gasket. And now, it's running hot. I have to be honest, this is almost too much for just one month!
Okay, the head gasket needs to be replaced, and the coolant is clear. Does anyone have any suggestions?
I don't notice it in the city, but above 150-160 km/h, the water temperature immediately rises to 115-120°C, and the oil temperature reaches 120°C.
My father has a Passat 1Z with over 200,000 km on it. It jerks during acceleration between 2000 and 3000 RPM. It doesn't misfire, but it jerks as if the half-shafts are about to break. We've already replaced the throttle body and the error memory is clear, but we don't know what else to try, and no one can figure it out. We've also checked the basic settings, but everything seems to be in order. It doesn't lose power, in fact, it performs quite well overall, but it has this unpleasant jerking. I APPRECIATE EVERY TIP!

Hi,

That doesn't sound good regarding your AFib.
If you can rule out leaks in the cooling system (without pressure in the system, water will normally boil at 100°C), I suspect a blown head gasket or a crack in the cylinder head.
The best course of action is to remove the cylinder head, inspect it for cracks, replace the head gasket, and also replace the timing belt, tensioner, and possibly other components. Install the water pump and see if the problem still occurs.
If the coolant is clear, it only means that there is no connection between the oil channels and the cooling system. However, combustion gases can still enter the cooling system through a defective head gasket.
Tip: When the engine is warm CAREFULLY remove the coolant reservoir cap, or preferably, let the engine warm up with the cap open. A stream of coolant will come out of the hose that connects to the top of the expansion tank. "There should be no air bubbles, and it may occasionally reach speeds of up to 2500 RPM even when stationary."
Again: if the beam is interrupted by bubbles here, combustion air will enter the cooling system!

Best regards, Rainer.

Also, if you can't replace the head gasket yourself, it's going to be expensive; you should probably budget around 500 euros.
The cost of a timing belt, tensioner, and head gasket replacement should be around 150 euros, based on a rough estimate.
And also, the impeller inside the water pump might have detached from the shaft, although I don't know how common that is in TDIs; a friend of mine had that problem once and spent ages trying to figure out the cause.

Hello,

Is your cooling system clogged, especially the radiator? In other words, does your radiator get properly hot?


Regarding the stuttering issue with the 1Z:
Please check the N75 valve (bypass control). You can find a lot of information about that in the forum...

Sure, thanks!
"The pressure in the system is increasing to the point where it's forcing water out of the valve on the expansion tank, which is, of course, also causing the temperature to rise."
I've heard about potential head gasket issues and possible cracks, but I don't want to deal with that. It only has 86,000 km, and those miles were driven with care!
The issue with the water pump impeller can be ruled out, as I checked it when I replaced the thermostat and it appeared to be in good condition.
What the f*** am I doing?
Do I really have to replace the cylinder head? Does anyone have another tip that doesn't rule out anything simple?
I'm almost thinking about selling the cabin again and buying a new one right away!