Manual Transmission noise C180 W203 model

That sounds like gear noise is maybe the issue.

OK let's do a little check. with the car in a clear area and no kid's or anyone around the car get in and start the engine.Now do you hear the noise with the car sitting at an idle.Let's say yes then put your foot on the brake and put the car in gear do you hear the knock if so hold the brake secure make sure no one is in front of the car and apply the gas lightly if the noise stop's then you have a loose torque converter to flywheel the bolt's are not tight..Now if you hear the knock and it's high pitch metallic then chance's are it's a rod or lifter in the engine.If the noise is a thumping dull noise you have a bad crankshaft.My guess is the torque converter because you said the transmission was worked on and a lot of time's without Loctite and the proper tourque the converter bolt's will work loose.GOOD LUCK HOPE THIS HELP'S

DID YOU RETURN EACH HOSE TO ITS ORIGINAL POSITION. SOUNDS LIKE YOU HAVE THE PRESSURE AND RETURN IN THE WRONG PORTS

Try checking the flywheel, usually if there is alot of noise from the transmission it is not the actual transmission. This can happen due to wear on the flywheel, or just the bolts simply coming loose. If after you check it you can't find the problem let me know and I will do my best to help.

Sounds like a blower motor for heater and A/C

Hey Gary, take your car and get the transmission fluid and filter changed immediately... you will be glad you did...(expensive lessons speaking!!!)

the harmonic balancers were known to come apart as well as the belt tensioners

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...

I would have to hear the sound to be sure. My guess would be possibly the starter gear is not disengaging fully. If it is a standard then I would probably say that it is your clutch bearing is not releasing, maybe clutch needs adjusting. If it is an automatic, The noise could be coming from the torque converter, they make noise just before they go. Listen underneath while truck is running and determine if the sound is by the oil pan, the starter or at the front of the transmission.

I guess you know no matter what the noise is the transmission will have to come out and be overhauled, one question, have you checked the CV joints on the axle shafts?