Passat 3B: Engine Overheating & Temperature Issues

hello fellow enthusiasts.

'I've been having problems with my Golf 3 for a while now, specifically the well-known gurgling sound in the heat exchanger and the poor heating performance in winter. The coolant consumption has also remained within reasonable limits, which is why I've held off on repairs so far. However, I'm now experiencing major issues with the coolant temperature, and my radiator has already boiled over twice. You can drive normally for hours, and then suddenly it won't accelerate properly, and a little later it starts to stutter – at the same time, the temperature jumps from 90 degrees to 130 degrees within seconds. The cooling system then builds up such high pressure that the coolant literally spurts out. This weekend, I removed the thermostat and am currently driving around without one. Now, the temperature remains permanently in the blue zone, but so far I haven't noticed any further overheating. Is it safe to drive without the thermostat during the summer, or is it harmful to the engine? It seems likely that I will need to replace the head gasket, but I'm not really sure if that will solve the problem. The error memory and all relevant values have been checked multiple times with VAG-COM, and nothing unusual has ever been found. Perhaps someone here knows a solution or has experienced a similar problem before.'
Sparkling greetings!

hb2000

Incidentally, there is no tuning or anything similar installed that could have a negative impact .

This weekend, I removed the thermostat and am currently driving around without it. Now, the temperature remains permanently in the blue range, but so far I haven't noticed any overheating issues.

Perhaps the error messages 'gurgling, bubbling' and 'overheating' are not related. Try installing a new, or 'less sensitive,' thermostat and observe what happens. It will cost a few euros at VW.

Driving with a cold engine significantly increases fuel consumption and wear }, and can also lead to engine damage (I would be particularly cautious about this with the AJM engine).

hello fog machine.

Driving with a cold engine significantly increases fuel consumption and wear, and can also lead to engine damage (I would be particularly cautious about this with the AJM engine).

I've already replaced the thermostat twice, and I made sure that the dealer didn't give me a thermostat for a gasoline engine instead of one for my diesel. It's possible that the thermostat is occasionally getting stuck, but as I said, I can drive for days and then it happens suddenly again. Does anyone know the part number for a cooler thermostat? Or do the parts experts at the dealer have access to these exclusive items? Of course, I don't want to risk engine damage, but temporarily it should work for testing purposes.

Best regards.

hb2000

Part number?! Yes, if one were legally entitled to access as a private individual.

If it occurs sporadically, it could also be due to a leak in the cylinder head gasket. This happens when air bubbles prevent proper circulation of the coolant. However, there would have to be a significant amount of air for this to happen.

The thermostat from a gasoline engine shouldn't be a problem; it will just open earlier (making it cooler).

At my parts supplier (not a dealership), I can choose from thermostats that come with the specified opening temperature.

Take a look here; there are usually several options available (at least for my vehicles), and they have the original part number.
http://www.autoteile-shopping.de

"When he cooks, are the radiator hoses equally warm? Is your viscous fan still working properly? Does the second electric fan also turn on (if yours has one)?"

hello

'Last time, I unfortunately only touched the upper hose – and it was incredibly hot. I hadn't even thought about using a fan, because it didn't start up at all. It hasn't needed to run throughout the winter, but it definitely should have been working last summer. What surprises me is that this happened with an outside temperature of 20 degrees Celsius, and I was only towing a trailer weighing 500-600 kg.'

Best regards.

hb2000

hb2000 wrote:

hello Last time, I unfortunately only touched the top hose – but it was incredibly hot. I hadn't even thought of the idea with the fan yet - it didn't start up at all.

If it happens again, try to access the lower hose.

If you have a viscous fan like I do, it's always spinning. You can test the clutch. The electric fan should be running when the engine is overheating. I might check that too.

I might be able to explain the rapid temperature increase like this. My vehicle always displays 90 degrees Celsius, even when it's only at 75 degrees. If it then shows 90 degrees when it actually reaches 110 degrees, but after that it starts displaying the correct temperature again, then the temperature will naturally rise quickly. If it goes above 110 degrees, it will soon start to overheat. However, with an outside temperature of 20 degrees Celsius, there must be more going on than just a faulty electric fan.

Quote:

I have already replaced the thermostat twice, and I made sure that the friendly mechanic didn't give me a thermostat for a gasoline engine for my diesel. It is also possible that the thermostat gets stuck occasionally, but as I said, I can drive for days, and then it happens suddenly again.

I had the exact same problem a year ago at 140,000 kilometers.
It was the ZKD (cylinder head gasket). At first, I checked if the ZK (spark plug) was loose - I could easily turn it about 90 degrees. After that, the temperature problem disappeared, so I cautiously drove another 6000 km. The pressure buildup remained within reasonable limits, and with careful driving, it no longer pushed any coolant out.

Looking back, I wouldn't ride for as long again, because the zirconia crown had already become quite deeply embedded in the tooth structure, so it was just barely salvageable.

He could easily pull it back 90 degrees.

I would be careful with that - they are stretch bolts after all; if you replace them, it's best to use new ones (or, for extreme tuning, stud bolts made of chrome-molybdenum steel; those can also be reused ).

I wouldn't worry about the screws; I only didn't tighten the head bolts. My understanding (or rather, what I read somewhere, although I can't recall the exact details) was that cylinder head bolts are reusable (it was said they could be used 1-3 times). I mentioned this before, but it wasn't addressed.

"In my GIII gasoline engine, I reused them again, but they only had a few thousand kilometers on them (the head was still warped despite being checked by the repair shop)."

Since the screws are relatively inexpensive, I would replace them when changing the head gasket anyway. If there are problems later, it will be more expensive to fix.

Quote:

I would be careful with that - they are stretch bolts after all; if you replace them, it's best to use new ones (or, for extreme tuning, use stud bolts made of chrome-molybdenum steel; those can also be reused icon_biggrin.gif).

He shouldn't just rip it off right away, but should take a closer look to see if the ZK (presumably a component) might be loose, like it was in my case.

I used ARL screws as replacements (12.9 grade instead of 10.9). The tightening specifications are the same as for the AJM. However, caution is needed when tightening them. With a thread engagement depth of only about 20mm, it can be unsettling, so make sure to lubricate them thoroughly according to the manufacturer's instructions.

I cannot determine whether using these screws and the resulting higher tensile stress will cause damage to the threaded holes in the engine block, or not – perhaps someone can calculate that.

hello

He shouldn't just rip it off immediately, but should take a close look to see if the ZK (ceramic capacitor) might be loose, like it was in my case.

He's probably going to start doing that soon too, because this whole thing with the cooling water is starting to annoy me.

The idea about the missing thermostat wasn't a good one either, especially with outside temperatures around 20 degrees Celsius.
Is the coolant temperature gauge just leaving the blue 'cold' zone during a highway drive?
At 120 km/h, the engine was running at around 2500 rpm. I didn't push the engine to higher speeds.
when the temperature is just coming out of a cold range outdoors - meaning there's far too little temperature.

Best regards.

hb2000

I would have it checked. If it's the cylinder head gasket, I would replace it with a new one. Whether or not to use new stretch bolts is important, and the torque value is crucial; see: [link/reference].

BM wrote:

I had the exact same problem a year ago at 140,000 kilometers. It was the ZKD (cylinder head gasket). At that time, I first checked if the ZK (spark plug) was loose - I could easily turn it about 90 degrees. After that, the temperature problem no longer occurred, so I cautiously drove another 6000 km. Looking back, I wouldn't drive for that long again, because the ZKD had already become deeply embedded in my head, and it was just barely salvageable.

Hello.

I had it checked. If it's the head gasket, I will install a new one. Whether or not to use new stretch bolts is important, see:

I will check the cylinder head bolts this week and, if necessary, tighten them if it really turns out to be the cause...

Regards,

hb2000

Good luck!

Don't come complaining later when things are completely out of control, okay?