Please help me with my 2000 Saturn LW2. I purchased the vehicle last year with 119,000 miles on it. I had to replace the electronic ignition switch last August and the water pump in December. Since the timing and serpentine belts had to come off to replace the water pump, I had those replaced as well. Then, the tensioner pulley for the timing belt, which was not replaced, went bad within two weeks of getting the car back, and I had to replace that. About two weeks ago, the car started making a rattling/tapping/almost like a diesel-like sound. My mechanic says it's coming from the top of the engine. It's a 24 valve V6 DOHC engine, if that helps any. He changed the oil, the plugs, checked the timing and serpentine belts, ran an emissions diagnostics to make sure that the catalytic converter wasn't a problem, checked the oil and fuel pressures and all everything's good. He said that the car passed the emissions test. Accompanying this diesel-like tapping sound is a loss of power. My mechanic has no idea, and we are at a total loss. Have you ever heard of this type of thing before or have any ideas? One of his employees is going to listen to it with a stethoscope, but they don't think that this is going to really help. Thanks so much for your time. NOTE: the car had a clean CarFax when purchased, and, per my mechanic, the previous owner obviously maintained the car very well.
Have the valve and ignition timing rechecked to include checking the knock sensor and EGR valve
June, 20, 2011 AT 4:44 PM
My mechanic says that he's checked these, and they're good. Catalytic converter is good, too. He's very concerned with the loss of power, as well. Any other ideas?
June, 20, 2011 AT 5:19 PM
Could be caused by one of the following below
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Crankshaft position sensor
Manifold absolute pressure sensor.
Fuel pressure regulator leaking or defective fuel pump.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.
Note: If it doesn't apply disregard it and keep testing.
June, 21, 2011 AT 4:32 PM
Ok. I gave the list to my mechanic to check out. However, I don't know if this will help you at all or not, but here goes. He says that the noise is at the top of the engine, front intake cam and towards the drivers' side. Hope this helps.
June, 25, 2011 AT 9:44 PM
It sounds like valve tapping to me. And on an engine with over 100k miles, I'd consider that the most likely cause. Valves not opening and closing properly will still deliver clean emissions, not trigger any fault codes, and, yet, because they're impeding proper internal air/fuel flow, will seriously degrade engine performance. With the right Chilton's or Haynes manual, this is something you can replace on your own, because the mechanic is going to charge quite a bit on labor.
June, 25, 2011 AT 10:01 PM
I've been waiting for 5dys for a comeback -but no show-
When I answer a question I can deal with it all the way -It depends what's coming back to me to force me to fire all my heat rounds. Some experts don't like to be stepped upon, unless a back-up is requested. I for one been here 5yrs I know how it goes and who's who and what they got-
Sometimes I'm not even sure if my answer will fix it hard to do over the net-The name of the game is play it by ear
In conclusion answer the open new questions I'll deal with mine-
June, 27, 2011 AT 5:36 PM
Ok. I got the car back from the mechanic and have driven it. The noise goes away (or at least I can't hear it) around 1500 rpms. All the time you're accelerating you can hear it. Inside the car it sounds like a rhythmic "tick, " but outside it makes more of a tapping, or, as I say, diesel engine sound. Mechanic says that it's a stuck hydraulic lifter, but he recommends driving it. What do you think?
June, 27, 2011 AT 10:09 PM
Not exactly a cheap proposition to replace lifters. I would replace it, but then again, it's something I'm quite familiar with replacing and can do it myself. It may or may not get better over time. I'd give it about 1000 miles or so and if it hasn't gotten better, consider replacing the lifters.