2000 Beetle question Bubbling water tank, no power

[Bumbalawski]

My daughter just purchased a 2000 Beetle with a 2.0. It had problems. The previous owner had overheated it. It still run and sounded fine, but I did not drive it. This is where we are at. The previous owner had replaced the waterpump and timing belt recently. But when I added water, it run out both ends. The freeze plug in the front of the head was still in but dislodged and the plastic housing in the rear of the head was shot (looked like it had melted). I pulled the waterpump to double check the impeller. It was fine. I installed a new freeze plug and plastic water housing. I filled it with coolant (the correct stuff) and took it for a ride (real short one). The check engine light come on and it had 7 codes in it. The car would die above half throttle on a pull. I cleared the codes and went for another ride. Now it dies just above an idle under a load. No check engine light and the dreaded blinking red temperature light has appeared with a girgling noise in the water tank. There is no water in the oil and no white smoke out the exhaust. Possibly a head gasket problem, I would assume, but why does the car die above an idle? Is there a "limp mode" and I need to reset something? Need help on this one. I have been a drag racer for 40 years but these "new fangled" cars are a pain in the "posterior".

[simonsi]

Originally Posted by Bumbalawski

The check engine light come on and it had 7 codes in it.

What were the seven codes?

You may have an air lock after refilling with coolant, does she hold a level or is it continually dropping?

Did any of the vacuum lines get melted in the overheat? If the plastic housing was melted then it may have cooked the coolant temp sensor, they are cheap and can cause a myriad of running problems so may be best to replace that in any case.

Is the engine still correctly timed, crank and camshaft marks still line up?

[Bumbalawski]

I just worked on it some more. Removed the thermostat, replaced it with a new one (drilled two 1/8" bypass hole as I usually do), refilled it and now it seems to have cooled down. All the lines look good. It reved up fine in neutral (it is a stick), but as soon as it hit 3000 rpm under a load, it began to die. Then the check engine light come on. As I was returning home, it began to run fine. Reved to 6000 with no problem. Then the 3000 rpm die returned. Got 3 codes 132, 135 and 303. I pulled the plugs before running it and they looked fine. The timing belt is correctly aligned (marks lined up). I am beginning to think (which is usually dangerous) that the cat is crapped out (plugged). Comments please.

[The Cheat]

132, 135, and 303 (if those are p-codes) mean that there's an issue with cylinder 3 misfiring (replace the plugs with oem only, same with the wires...ngk or bust) and your o2 sensors are dying. the o2 sensors dying would cause some running issues, especially if the pre-cat one is failing (which it is). replace that with a bosch one.

try that, go from there, report back.

[Bumbalawski]

I cut the cat loose (I can weld it back on) to check it for plugging up. It looked OK. But when I unplugged the O2 sensors, the connectors were full of water. Both of them. I blew them out with air until dry. Cleared the codes (left the cat loose) and took it for a ride. It now revs up and no codes. The water appears to have travel down fron the expansion tank via the O2 harness when I was trying to bleed the system. I will put the cat back on and see what happens.