Z22SE Wet piston top

BGTS

Member
Hello guys,

My Vectra started to loose a bit of coolant for some time. I had to refill around 250ml every 2 weeks / 800 miles or so. It turned out to be a hole in the radiator. Worth to say that aside this radiator hole and a water pump leak some years ago, the coolant system always performed perfectly. Had not the slightest sign of dirt of gunk or traces of anything besides coolant and water. Coolant never got old in there and the original expansion tank is clean too.

After the radiator change at the shop, the system was filled beyond the COLD mark to compensate a possible level drop if the air purge would not be done completely yet. I ran the car for 800 miles / 3 weeks and the level didn't seem to change, which felt odd to me. If there's too much coolant in the system, it should be expelled through the expansion tank valve, right? I took the excess myself, leaving it at the COLD mark.
Coincidence or not, the system started to loose coolant again. I changed the tank cap for peace of mind (the other one was not too old). Still leak somewhere, not to the ground or around the water pump. No oil in the coolant, no coolant in the oil. Also, I don't think it's normal to hear a slight hiss when taking the tank cap off one day after stopped the engine.
The hoses never get rock hard and the car never overheated at my sight (don't know at the shop). I bought it with 75000 miles. Now, it has 150000 miles and was built almost 20 years ago.
Now, I can't be sure if it started right before or after the radiator change, but when engine is cold, I sometimes have misfires for a minute or so. "It's time to change the plugs" I thought. So I did, but the misfires didn't go away. After around 2000 miles with the new plugs, one morning I decided to check how they were:


Spark-Plugs.png


I have done the plugs 3 or 4 times myself in this car, always dead cold, always with torque wrench, 20nm.
I am not a mechanic but the no.3 seems a bit oily and the no.4 seems to have some traces of coolant, don't you think? Sorry for the lack of focus on no.4, it seemed nice on the phone, but there is a pink stain where it should be white at the centre.
Besides that, the spark plug wells were dry but the top of the piston no.4 was wet. Not a puddle, but some moisture at the surface. I tried to understand if it was oil, fuel or coolant with a long cotton and it was golden dark like oil but if coolant was mixed with the carbon dirt, it would be dark too, right?

What's your thoughts?
Thanks in advance.
 
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