Thread: 2004 Grand Prix - HELP ENGINE KNOCKING

Hello - What the hell is wrong with my car?

I hope someone can help me I have a 2004 GP I have had the car since 2006. Just hit 200k now the engine is knocking as if it is not getting oil and it is running hot.

My mechanic check out everything can't figure out why. He recently put new value and intake gaskets on it because they were leaking. He said when he started the car after he installed the gaskets it was idling low so he adjusted the hormonic balancer. The car ran great that evening I picked it up. She felt almost new!!

The next day when I got to work the low oil pressure light came on and there was a little knock so I went about a mile down the road to Advance Auto. We checked the oil and it looked like it was 2 quarts low so we added 2 quarts. Drove for about 15miles and got off the expressway and it was still knocking but louder the temperature gauge started moving towards hot and the low oil pression light kept screaming, drove to the nearest oil place and had them check the oil he said I was 2 quarts over and he heard the loud noise also.

The car was running fine until we replaced the gaskets. Fine as in I had to add anti freeze often and by the time I got my regular oil change I was about a quart low. So the leaks were NOT heavy. I probably could have not got them fixed and kept adding antifreeze and oil.

I don't want to get a new car yet. Actually I was planning on keeping the car when I do get a new car because I love this car!

I'm not sure how you adjust the harmonic balancer. It has a key on the crankshaft that it is tied to. There is no adjustment. Also, replacing the upper/lower intake manifold gaskets and valve cover gaskets does not require removing the balancer at all so not sure what's going on there.

If your "mechanic" spilled coolant into the engine when removing the lower intake and did not flush the valley out with a quart of oil and then do an oil change BEFORE starting the engine, and then change it again after letting it run for a few minutes then you likely spun a bearing due to coolant mixing with the oil if the knock is coming from the lower end.

Depends on what the "low idle" really was. If the old stuff was leaking then it likely had a vacuum leak that would cause it to idle higher than normal. All my 3800's usually idle fully hot around 750-800 in park.

Does the oil on the dipstick look like a chocolate milkshake? If so then you have coolant getting into the oil from somewhere. If this is the case then do NOT drive it anymore until you can figure out where the knock is coming from. Also check the oil pressure sending unit that is attached to the oil filter adapter. They like to go bad and drain the oil rather quickly while running. Mine started leaking and I almost lost an engine to it.

Originally Posted by FordMan77

I'm not sure how you adjust the harmonic balancer. It has a key on the crankshaft that it is tied to. There is no adjustment. Also, replacing the upper/lower intake manifold gaskets and valve cover gaskets does not require removing the balancer at all so not sure what's going on there.

If your "mechanic" spilled coolant into the engine when removing the lower intake and did not flush the valley out with a quart of oil and then do an oil change BEFORE starting the engine, and then change it again after letting it run for a few minutes then you likely spun a bearing due to coolant mixing with the oil if the knock is coming from the lower end.

Depends on what the "low idle" really was. If the old stuff was leaking then it likely had a vacuum leak that would cause it to idle higher than normal. All my 3800's usually idle fully hot around 750-800 in park.

Does the oil on the dipstick look like a chocolate milkshake? If so then you have coolant getting into the oil from somewhere. If this is the case then do NOT drive it anymore until you can figure out where the knock is coming from. Also check the oil pressure sending unit that is attached to the oil filter adapter. They like to go bad and drain the oil rather quickly while running. Mine started leaking and I almost lost an engine to it.

Thank you for your response Sorry I was wrong he did not adjust the Harmonic Balancer.