My mazda b2200 transmission is making a grinding noise when I attempt to engage it in any gear when eccelerating it will make this sound before it goes into gear but it runs just find during driving

this manual transmission?
seems. so
the tip of shift levers love to get worn and not allowing the shift rail forks to hit 3rd gear.
a pure simple mechanical failure and is shifter tip end parts bad, some are even made of plastic.
or
3rd gear synchro- ring is super worn out and the main clutch drags. (seen it and fixed them)
if clutch has master cylinder is the fluid always at top line or drops in time every weak.

Sounds like it need gear oil changed or gears are not meshing right do to wear or bearings

make sure that your vehicle has a "on the go" 4wd operation
if not , you will have to all but stopped to get around the gear slashing
if you have "on the go " engagement , then is a problem in the synchro rings of the transfer case
take it to an accredited transmission specialist for a proper diagnosis

Reverse is not "synchronized" forward gears are, so it does make some noise, try shifting to 2nd before engaging reverse to slow gear rotation and limit gear clash or grind.

Does the vehicle crank over? or does it make a grinding sound like the gear isn't contacting. If your hearing a grinding noise chances are the flex plate are missing teeth that the starter engages. Only way to replace that is to remove transmission. If your hearing a clicking noise check to make sure the battery connections are tight and the terminals are clean.

May possibly be a worn out throw-out bearing.

The clutch needs an adjustment. What's happening is the clutch isn't completely engaging while you shift, causing the grinding. Once properly adjusted, the grinding will disappear.

i have a mazda mallenia 2001 and it makes a loud sound when i hit 45 mph or 3 gear,could it be the transmission. or what els how could i fix it. m
need help

Well depending on the noise, it could be a starter, or it could be whats called the flex plate (assuming yours is like most and its an automatic) There is a sheetmetal plate that bolts to the crank of your engine that then allows the torque converter of your transmission to turn. This Flexplate that connects the turning part of your engine and the main turning part of your transmission also has a ring of teeth on it that the gear of your starter engages into to turn the engine round to get your car started. If its a tinging or clanking sound similar to to the metalic sound of aluminum or light stainless frying pans then it might be a flexplate going bad. If it sounds like a deep clunking noise it might be an engine problem. If the initial sound is more of a grinding kind of noise and then goes away after a few seconds of running the starter may be staying engaged after the engine starts. That would be the starter and maybe an additional problem with the flexplate as well. If its a flexplate sound there should be a cover on the bottom of the transmission directly behind the engine that has just a few bolts . Jack up the car, put it on jack stands or drive it up on some ramps. Unbolt the cover and see what the flexplate looks like. See if the teeth are bad and lightly push it with a screwdriver or something and see if it is loose. If could also be a torque converter going bad but the transmission would normally slip if that was the problem.
Hope this helps you narrow it down...

Is it standard shift??? if so, look under the truck and see if the drive shaft is turning. It could be the clutch, U-joint, or the rearend gone out.