Hi. That is not necessarily a sign of a bad transmission. Usually an engine vacuum leak will make the rpms flucutate. Or if the A/C is on, the rpms will raise and fall slightly when the compressor turns on. The roaring noise is probably a bad whel bearing. Or just could be the tires. Thanks, Eric
So a vacuum leak causes it to make those noises even though I had the engine replaced 5 months ago ?
No. I said the vacuum leak or a/c compressor turning on, can cause the rpms to fluctuate. A roaring noise can be from a pulley on the front of the motor which would probably have been transfered over from the old motor. Thanks.
Hello I am still not satisfied with my answer. Let me state the problem again so maybe you can give a more elaborate answer
My car RPM goes up to 4 while in park; while driving it makes a humming noise and when I am coming to a stop it jerks a little. Is this a sign of a bad transmission or what ?
No. It is not the sign of a bad transmission. A bad transmission will not make rpms go up to 4 in park. A vacuum leak or a bad throttle position sensor will make the rpms go up to 4 in park.
The humming noise can be from the engine, such as a power steering pump. Or a humming noise can be from the tires or wheel bearings.
Sounds like you have more than one problem.
Thank you sorry if I was rude earlier
No problem. If you want to continue we can discuss the issues you are having and try to narrow down what to look for. But remember I can not hear any of this. I need the best descriptions possible to try and come up with a worthwhile solution. Thanks, Eric