For the sake of information sharing I will take a stab at your questions and statements and see if others chime in with additions or subtractions.
You plan to do a head gasket sometime in the future eh? And you have to have parts at the ready to swap in and out. The space to work on it is borrowed. So when it comes to a situation like that I look at the current gasket and figure out if I have a one, two or three tab one installed now. You should be able to see notches cut out or the area just to the side of the radiator hose. I buy both, what I have and the next size down. Then just return the unused one or sell it on the forum here or otherwise.
Why do that? Some of this you already know. Once the head is off you measure the distance the piston rises above the block and fit the proper gasket in there upon assembly. What is the risk of putting a thicker one in? Really no risk just that as you mention the tolerances are pretty tight on these engines due to compression of near to 23:1. Piston rings and seals need to be adhered to, otherwise you are fighting poor performance, hard starting, smoking out the back and a host of other things found in the forum that you just wouldn't have to deal with IF you put in the proper thickness of gasket in the first place.
Does it matter that the gaskets really aren't that much different in thickness? VW wouldn't have given us options if it didn't matter. I know from personal experience that getting the right one makes a big difference in how the engine behaves. I rebuilt one head and they just did as you mentioned and threw the fat gasket on there for safety sake. Well the protrusion measured for a 1 notch gasket and when it came to starting, it made all the difference in the world. Barely touch the starter now and it runs, before it was a grind for a couple of cylinders before it lit.
As for deck flatness the tolerance again is something near .004 thousandths IF I remember right. Any idea how thin that is? Paper is thicker. And you read in this forum how folks have a heck of a time getting their "new" gasket to seal up after spending all that time pulling the head and cleaning it up. But they forgot to put a straight edge on it and slide a feeler gauge under it between cylinders and around the outside edges. You really can't goop the crap out of a gasket when your pushing 480 PSI at it every stroke. Which is where you should be if the cylinder is worn well and not all sloppy. Oh, that is another issue. Out of round cylinders are a danger too. An exaggeration is egg shaped but that is what they can look like. If you have that problem you are into a bore and oversized pistons. You can't see that or measure it until you pull the head either.
The reason we care about flatness on the heads is that we move them around from this block to that block sometimes. So you have to watch if someone says they overheated the head. Getting it back to straight is a heat and pressure application not a skimming. That might leave you with a cam that isn't straight in the blocks. So yeah you get it to bolt down and tighten but now there is a torque on the upper part of the head and parts and things will start going bad for you in short order if you start pumping a turbo up on the poor little 1.6.
And yes, you might just have a bad reservoir cap. They come apart and the holes might be dirty or the seals might be shot and it just lets the hot steam out. Does the cap sound like there is air coming out of it when you run it for a little bit and then turn the cap? Are the hoses harder after it warms up compared to prior to start up?
Stick with us and I think you will get into the VW's quirks and such.
Today I swapped some snow tires on my Rabbit as they are better tires and realized, or maybe just noticed, the rear ones on the same snowflake rims are just a little higher profile than the fronts. That is what I get for buying used tires. I think I will try them on the Caddy and see if they look better there than what is on it now.
Topic: 1.6td - first head gasket job questions (Read 3781 times)
