for the las week sometimes when i was at a rd light and i had the trans engaged in 1 gear , clutch in sometimes the car would simply start going and i couldnt disengage the gear so i had to turn off the car and when i let off the clutch it wouldnt go back up so i said to my self slave or master, anyways i took it to the dealer and they couldnt find nothing related to the clutch itself (they replaced the throw out bearing recently) so i orderd a new slave and a new master, any ideas on how to change them

the car is a 1985 euro 16v

You did check the fluid?
I believe the brake and clutch share a common reservoir, like on my 124.
The prior owner (my aunt) had the same problem, and I wound up being tasked with fixing it. Scratched my head for a while looking for the clutch reservoir, then realized the situation.
Clutch feeds from higher than the brakes, so it fails first, as it should! Level does not need to be super low to cutoff clutch fluid supply.

If not the fluid, it will almost certainly be the slave. Clutch masters rarely fail, in my experience. Internally, slaves are subjected to the moisture and crud than settles to the lowest point in the system. Externally, slaves take more of a beating from splashing and road grime.

Best of luck.

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1986 300E 5-Speed 240k mi.

anyways i already recevied both , im looking to fitting the myself but i dont know if i should , how big of a job is it ?

I have not done one on your model, but I have probably done a dozen or more slave replacements over the years, and a couple of masters.

The slaves tend to be very easy. Usually just 2 or 3 bolts, the hose, and the linkage bits. Flush/bleed the system, and you are done. Access is usually pretty good under the car. The toughest 'gotcha' would probably be if the hose fitting does not want to turn. Hate when that happens. Sometimes it's easier to just get a new hose, and cut the old one off. The old one may be rough anyways.

Masters vary. Not complicated, but access can be troublesome. I believe yours may be located behind the firewall, which can be a pain, and a bit messy in terms of fluid spill potential on the inside.

I would rate it a reasonable DIY project.

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1986 300E 5-Speed 240k mi.