2000 Volkswagen Jetta Coolant inside Engine Block?

You're about to take on a pretty big job that you haven't convinced me is necessary. First of all, there are so many different antifreeze formulations today and your first mechanic is aware of that. The differences have to do with the additives that protect specific metal alloys used in your engine. To address all the confusion, some manufacturers have developed a universal antifreeze that can safely replace a number of original formulations. Prestone has one of those, so it is very likely there was no problem leaving it in there. Those can even be mixed with many original equipment antifreezes. In addition, there is a red antifreeze that most mechanics want to get gone and never use again. That's the Dex-Cool used in most GM cars. When the Prestone was put in your system, you likely got exactly what your engine needed, plus some additives to protect metals that your engine doesn't have.

To drain all the coolant out, there is at least one drain plug on the side of the engine block. We never bother with those because customers are more concerned with time and labor dollars. You can fiddle with that on your own time, but we would get fired for wasting our customers' time with that. Instead, we just run water through the system from a garden hose to flush all the debris out. You were waiting for something to drain that was never going to come out through the radiator petcock or by removing the lower hose. The little dripping you were getting was from the coolant slowly running down from higher up in the engine, and after waiting all day, there was still about two gallons in the engine.

Because we're left with straight water in the block when we're done with the flush, we add straight antifreeze. We never use the 50/50 mix with which you're paying for half water. Your system should take about two gallons of new antifreeze to go with the two gallons of water stuck in the engine. Once the radiator is filled, you may need to burp the air out of the system that pools under the thermostat. Some thermostats have a tiny bleed hole to do that, but for those that don't, failure to bleed the system manually is a common cause of overheating and a warped and leaking cylinder head. That air prevents the thermostat from opening because they have to be hit with hot liquid. Hot air won't do it. If there is no bleeder screw on the thermostat housing, you have to remove a temperature sensor or some other threaded plug in that area. As the air comes out, the level in the radiator will go down. To know if manual bleeding is necessary, pay close attention when the engine warms up. If the coolant starts to flow through the radiator, and the upper hose gets hot, that's all you need. If nothing is flowing, you'll need to burp the system, then add more antifreeze right away when the level goes down in the radiator.

Once the radiator is full, warm the engine up so the coolant will circulate and mix thoroughly, then test the freeze point. The best you can do is around minus 50 degrees Fahrenheit, but minus 35 degrees is better. Your freeze point will tell you if you have to add more antifreeze or more water, and that can be added to the reservoir. That will take a few warm-up / cool-down cycles to mix, so don't recheck the freeze point for a few days.

What makes you think you have a leaking head gasket or cracked head? I suspect you didn't understand what the second mechanic said about coolant inside the block. Where exactly do you want it to be if not in the block? In rare cases coolant can leak through the head gasket into the engine oil, in which case you'd see the oil level rise way too high, but it's more common to leak into a cylinder, then get burned and go out the tail pipe as a thick white smoke. There's a quick chemical test that can be done at the radiator to check for a cylinder head gasket leaking between the cylinder and the cooling system. If that turns up showing no leak, leave the head and gasket alone.

First of all, you only gave me part of that information. I deal with people here every day who lose things in translation, mainly because mechanics do a very poor job of communicating with their customers. That is not intentional, but it is a common reason so many people don't trust us. I'm running into the exact same problem right now with a friend who is unbelievably confused after being presented with three entire options for replacement struts for her car. Part of what we do here is to explain that which is confusing, and when practical, to tell people how to diagnose and repair their own car.

You've just included the second chapter of your story, but somehow you think I should have known all those details earlier. If you think I sounded condescending, I'm sorry that you can't hear the inflection in my voice or see my facial movements, but you are again, assuming something that isn't there.

I'm still skeptical that a head gasket is leaking, based on the information you provided.

The wrong coolant is not going to damage parts in your cooling system very quickly, but it appears you DID get conflicting information from various sources. I don't know how you picked which one to believe, but there's a major problem with your JB Weld story. No one is going to remove a cylinder head to fix a crack that way. If the crack is on the outside, that's a different story, but you would have seen the coolant leaking out. There's just too many details that don't add up, and it would be irresponsible for me to not warn you to slow down until we're certain of what is wrong. Replacing a cylinder head is a real big job loaded with pitfalls. At the very least you'll want a copy of the manufacturer's service manual. Read through the pages of instructions, line drawings, torque specs and procedures, and special tools needed before you start. Too often these projects end up in your yard with a "For Sale As Is" sign in the window.

If you do indeed need to replace the cylinder head and you do it successfully, I will be the first one to congratulate you, but I'm not going to take any satisfaction in finding out that didn't solve the problem.