ZKD Failure: Replacing After 45,000 km

Hello.

I'm going crazy. I had the seal replaced for a lot of money 45,000 km ago, and now I'm noticing that I'm leaking coolant again. It's still very slight, but it's starting .
'Last time, I was told that my cylinder head had a slight warping (possibly due to coolant leaks or scoring caused by head movement, whatever the reason), and that it might be worth trying again with a new gasket. They explained that the gasket would compensate for that 1/100 mm.'
Now I'm facing a dilemma!

Question.
- Is it possible to mill a flat head (AFN) with a Z-axis compensation (ZK) without the pistons hitting the valves and causing excessive compression?
- If so, is that common practice?
- If so, how much do you think it would cost?

P.S.: It's a G3 AFN with 214,000 kilometers (or miles, depending on the context).

Isn't it generally easier to just put something back on if you've already taken it off?

Or was that only the case in the past? With the JP and JX models, I've experienced it this way...

m;

Hello Martin,

Well, initially, that was my first thought. Then, I just assumed I could cut it down in a straightforward way, which was a completely naive assumption.
The master's response was that it was not possible.

That's exactly why I'm asking. Surely, 5/100 mm can't make that much of a difference, right?

Hi,

No, in my case, there were no signs of any machining marks, no warping, and no scratches or erosion.
Theoretically, it should be possible to mill the cylinder head, but the compression ratio would remain almost the same since the combustion chamber is already located in the piston. However, milling too much material could still lead to problems because the open valves could then collide with the piston too far down.
If you're going to machine the valve seats, you might as well also rework them, as the valves will naturally seat a bit deeper in the head anyway.

However, before replacing the gasket a second or third time, it might be worth considering replacing the entire head. It doesn't cost that much either.

Best regards, Rainer.

Rainer K. wrote:

If you're going to mill it, maybe you should also rework the valve seats at the same time, as the valves will then sit a little deeper in the head anyway.

Hi Rainer,

Is this not compensated for by using head gaskets of different thicknesses (single-hole, double-hole, and triple-hole)?

Rainer K. wrote:

However, before replacing the seal a second or third time, it might be worth considering replacing the entire head.

It doesn't cost that much either.

I also see it that way. I can recommend http://www.motorkaputt.de/.. I had new glow plug thread inserts installed there once. They were very friendly and, above all, FAST. Don't go to www.motorenkoeln.de or www.motorensuche.de/.com; I had to deal with them through my lawyer because my cylinder head hadn't been returned after 4 weeks!!!! It was sent back unrepaired, a great shop. I think everyone knows how it is when your car stands in front of the door for over a month without a cylinder head.

Hello,

I'm going crazy. I had the seal replaced for a lot of money 45,000 km ago, and now I'm noticing that I'm leaking coolant again. It's still very slight, but it's starting .
'Last time, I was told that my cylinder head had a slight warping (possibly due to coolant leaks or scoring caused by head movement, whatever the cause), and that it might be worth trying again with a new gasket. They explained that the gasket would compensate for that 1/100 mm.'
Now I'm facing a dilemma!

Question.
- Is it possible to mill a flat head (AFN) with a Z-axis compensation (ZK) without the pistons hitting the valves and causing excessive compression?
- If so, is that common practice?
- If so, how much do you think it would cost?

P.S.: It's a G3 AFN with 214,000 kilometers .

Hi,
How long ago was that? Is there no more warranty on repairs? If there are signs of washing residue in the head, it's common practice to have it remachined. If necessary, a thicker gasket can be installed afterward.
It's a different story, of course, when the sealant has already been applied several times and the thickest layer is already in place.

I've personally seen it happen at a friendly dealership's workshop, where a mechanic tightened the cylinder head bolts after replacing a gasket (my car was there for tire service, and I prefer to watch rather than sit in the waiting room).

'So, anyway, he followed the instructions and tightened the bolts with the specified torque, and then, as instructed, he added another quarter turn, crossing them over. Then, suddenly, he said 'Damn!' because one of the screws unexpectedly turned too easily, or because it didn't provide the expected tightening force during that quarter turn...'
Don't ask me what happened to it. As far as I'm concerned, an engine like that is a prime candidate for another premature head gasket failure.

Who knows what they did to your engine.

Greetings.

Eike.

Thank you very much for the tips.

I will definitely consider having a brain implant.
It's infuriating that they not only didn't do it right away, but they also told me it wasn't possible.
It's going to be expensive for everyone.
Does anyone know anything about enforcing warranties and warranty claims? As mentioned, it only has 45,000 km on it.

haehnlein wrote:

Rainer K. wrote: If you're going to mill it, maybe you should also rework the valve seats at the same time, as the valves will then sit a little deeper in the head anyway. Hi Rainer, Is this not compensated for by using head gaskets of different thicknesses (single-hole, double-hole, and triple-hole)?

Hi, and what do you do if you already have the 2 or 3 hole gasket installed?
I once posted about the slight thickness differences between the 2-hole and 3-hole versions in an old thread.

Best regards, Rainer.

Rainer K. wrote:

Hi, and what do you do if you already have the 2 or 3 hole gasket installed?

Hi Rainer,

have a four-hole made.