Just had my oil and filter changed and almost immediately noticed a knocking sound. Two days later my check engine light began to flash and the knocking got louder

SOURCE: will oil pan gasket cause check engine light to come on

it would have to be a very bad leak to cause a vacuum leak but that big you couldn't keep oil in it most parts stores will scan it for free in hopes to sell the parts to fix it

SOURCE: car won't start wants to turn over but nothing.

sounds like you have a blown head gasket this would explain loss of coolant and running poorly excessive smoke.

SOURCE: knocking noise in the engine.

have you check the level of the oil... if it is down you are either dumping it on the ground (major oil leak) or it's burning oil quickly... i suspect if you ran it without oil the damage is done... either buy some stp oil conditioner (thickens the oil) or start using 50 weight oil.... all that will do is keep it quiet mostly.

one thing tho... don't try these solutions if you live in a cold weather climate... the oil will get so thick because of the cold you will have trouble turning it over.

Robert

SOURCE: I have loud knocking sound when the throttle is

Make sure you have enough oil in the engine (though it's likely too late) If you have knocking and oil light on, sorry to say, you likely have lost a rod or crank main bearing (engine needs to come out of car and completely apart (very expensive) Options are a re-manufactured or scrapyard replacement.

SOURCE: I have a 2007 PT

You can take it to auto zone or advanced auto parts house and they will check the codes for you for free.then you can look up the code on internet and see whats going on hope this helps

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