Yes both are possibilities. Also axle, driveshaft, .....
Fault with the clutch probably.
High revving when changing gears in a Megan sedan can be attributed to several factors, including the engine's characteristics, the driver's shifting technique, or potential issues with the clutch or transmission. If the engine is revving excessively, it may indicate that the driver is not fully engaging the clutch or is shifting too late. Additionally, if the vehicle has a performance-oriented engine or a manual transmission, higher RPMs during gear changes may be normal. Regular maintenance and proper driving techniques can help manage revs during shifting.
the transmission is slipping
because someone probably turned the engine on
Highly-inflated ego.
Basically all you gotta do is, at a stand still go to first gear, hold.in the clutch. Rev the engine to about 4-5 thousand. Simultaneously let out the clutch and floor the accelerator. Or... Rev up to the red and dump (lift clutch up very quick) the clutch, then hold on tight, be careful when reving to the red, too often could sheer the engine mounts or blow the cam which will cause the head to fail.
Assuming you have an automatic, suspect low trans fluid level. If it is a standard, the clutch is slipping.
I just got an old 1992 manual gear Mazda protege dx 4 door. When I put it in gear after a few seconds the engine is revving but it doesn't seem to be engaging like it should. It's like I'm giving it the gas and can hear it, but it isn't accelarating like it should. Could this be the transmission fluid? How do I check it...I can't see a dipstick in the motor? In Answer to that question, you don't see a dipstick because it's a manual transmission, what your experiencing here is a burnt clutch not a lack of fluid, becaus your engine is Reving, and your getting no output.... sounds like you should just get another transmission with a good clutch in a used scrapyard, lesss expensive then the labor for a brand new clutch!! Just a thought Mat
Sounds like you may be slipping the clutch or over reving the engine when the clutch is partially engaged ? The Forester has a weak clutch plate compared to the 170 HP that some of the engines produce and it is easy to burn the clutch which gives off an acrid burnt smell like brake pads in an emergency. I get this sometimes when reversing a large trailer or caravan, however the clutch still works so only replace this when it really needs to be replaced.
Some of the early signs of transmission trouble will be gear slipping (this is usually felt as a jerk of the car when it changes gears), or loud engine "reving" as it start to take off. Some transmissions fail in the top gears which means that you wont be able to get to your top speed.
Slipping, over reving, sounds like rocks in the trans.
Driving in low gears. Pushing hard on the accelerator ("flooring it"). Going uphill. Driving with excessive weight (like a trailer). Either shift up or lay off the gas to bring your engine speed down. This is a classic symptom of a "worn clutch" in a manual transmission vehicles. The friction disc cannot transfer power under load so it slips under load causing excessive engine reving. Excessive engine RPM at idle can be caused by a vacuum leak or by a stuck Idle Air Control (IAC) valve.